HK1034828A - Signaling protocol for satellite direct radio broadcast system - Google Patents

Description

Signaling protocol for satellite direct radio broadcast system

The present invention relates to satellite broadcast systems, signaling waveforms for formatting (formatting) broadcast data, and processing and remote radio receivers for transmitting satellite payloads.

Currently, over 40 billion people have either generally become dissatisfied or considered unacceptable with respect to the low voice quality of short-wave radio broadcasts, or the coverage limitations of Amplitude Modulation (AM) band and Frequency Modulation (FM) band terrestrial radio broadcast systems. These people are mainly distributed in africa, central south america and asia. There is a need for a satellite-based direct radio broadcast system to transmit signals such as audio, data and images to inexpensive client receivers.

Some satellite communication networks have been developed for commercial and military applications. The primary purpose of these satellite communication systems is not to meet the need to provide flexible and economical access to a certain space segment for multiple independent broadcast service providers, nor to meet the need for customers to receive high quality wireless signals using inexpensive customer wireless receiver units. There is a need to provide service providers with the ability to directly access satellites and the ability to select the number of space segments to purchase and use. In addition, there is a need for an inexpensive wireless receiver unit capable of receiving a time division multiplexed downlink bit stream.

In accordance with one aspect of the present invention, a method is provided for formatting a signal for broadcast transmission to a remote receiver, wherein a broadcast service has at least one service component (e.g., an audio program, video, data, still image, paging signal, test, message, full image symbol (panchromatic symbol), etc.) mixed with a Service Control Header (SCH) in a broadcast channel bitstream frame. The SCH dynamically controls service reception at the remote receiver.

According to another aspect of the invention, the service has a total bit rate of K bits per second or n times the minimum bit rate of L bits per second. The frame period is M seconds. The number of service bits in each frame is n × L × M = n × P bits per frame. The SCH has n × Q bits, and the number of bits in each frame is n × (P + Q). For example, the total bit rate for the service is 16 to 128 kilobits per second or n times the minimum bit rate of 16 kilobits per second, where 1 ≦ n ≦ 8. The frame period is 432 milliseconds. The number of service bits in each frame is n × 16 kbits per second × 432 msec or n × 6912 bits. The SCH has n × 224 bits, and the number of bits in each frame is n × 7136.

According to another aspect of the invention, the service comprises more than one service component. Bits of the respective service components are interleaved in each broadcast channel bit stream frame.

According to another aspect of the invention, the service component is an integer ratio of the minimum bit rate of the service. When the bit rate of one service component is insufficient to fill the interleaved portion of the broadcast channel bit stream frame, additional bits are added to the frame.

In accordance with another aspect of the invention, services are synchronized to an SCH corresponding to a first and second broadcast channel using independent bit rate references. There is no requirement that all broadcast channels have a single bit rate reference. A satellite is positioned to determine and compensate for the time difference between each individual bit rate reference of the broadcast station and the clock on the satellite.

In accordance with another aspect of the present invention, a service component containing an analog signal such as audio is compressed using an encoding scheme such as the motion Picture experts group or MPEG encoding scheme (i.e., MPEG1, MPEG2 or MPEG 2.5) and a selected sampling frequency (e.g., 8 kilohertz, 12 kilohertz, 16 kilohertz, 24 kilohertz, 32 kilohertz and 48 kilohertz). The service components may be compressed using an MPEG2.5, layer 3 coding scheme.

According to another aspect of the invention, the SCH includes fields selected from the group of bits consisting of a frame header indicating the start of said frame, a bit rate index indicating the bit rate of said service, ciphering control data, an auxiliary data field, an auxiliary bit field content indicator relating to the content of said auxiliary data field, data relating to a segment of a plurality of frames transmitted using said auxiliary data field, and data indicating the number of service components constituting said frame.

According to another aspect of the invention, one broadcast channel may be designated as a primary broadcast channel, while other broadcast channels may deliver secondary services related to the primary broadcast channel. Thereby effectively increasing the bandwidth of the broadcast program on the primary broadcast channel. Information is provided in the SCH of each frame of each broadcast channel to support a remote receiver to receive broadcast services from a primary broadcast channel and a secondary broadcast channel. In accordance with a preferred embodiment of the present invention, the auxiliary bit field content indicator is provided with a flag indicating whether the auxiliary data bit field includes a primary or secondary service and an associated service pointer including a unique identification code corresponding to the next associated broadcast channel. The ancillary data bit field may be different from frame to frame and the associated service broadcast channel need not appear in consecutive frames.

In accordance with another aspect of the invention, the SCH may be used to control a particular radio receiver function requiring a long bit string. The long bit string is transmitted over a multi-frame segment. The SCH includes a start flag that indicates whether a secondary data bit field contains the first segment or the middle segment of a multi-frame transmission. The service control header is also provided with a segment offset and length bit field (SOLF) that indicates the total number of multi-frame segments to which the current segment corresponds and is thus used as a counter. In other words, the SOLF of each intermediate multiframe segment is incremented until the total number of segments minus one is reached. The multiframe segments need not be located in consecutive broadcast channel frames. In addition, the auxiliary bit field content indicator includes data bits of the service tag corresponding to the auxiliary data bit field content.

In accordance with another aspect of the present invention, a Service Component Control Field (SCCF) is included in the service control header for each service component provided in a broadcast channel frame, which allows demultiplexing and decoding of the service component at the radio receiver. The SCCF indicates the length of the service component, the type of service component (e.g., data, MPEG encoded audio, video, etc.), whether the service component is encrypted, the encryption method, the type of program to which the service component belongs (e.g., music, voice, etc.), and the language used in the program.

In accordance with another aspect of the invention, the SCH includes a dynamic ancillary data bit field for transmitting a dynamic tag byte stream to a receiver or display screen on the receiver, such as a text receiver. The dynamic label byte stream does not relate to a specific service. In this way, the wireless receiver does not need to be tuned to receive a particular service when receiving the dynamic tag byte stream.

These and other features and advantages of the present invention will be better understood from the following description taken in conjunction with the accompanying drawings, which are an integral part of the original disclosure, in which:

FIG. 1 is a block diagram of the architecture of a satellite direct broadcast system constructed in accordance with one embodiment of the present invention;

FIG. 2 is a flow chart depicting a sequence of operations for end-to-end signal processing in the system of FIG. 1, in accordance with one embodiment of the present invention;

fig. 3 is a block diagram of the structure of a broadcast ground station constructed in accordance with one embodiment of the present invention;

FIG. 4 is a block diagram illustrating broadcast segment multiplexing, according to one embodiment of the present invention;

FIG. 5 is a block diagram of the structure of on-board processing of a payload according to one embodiment of the present invention;

FIG. 6 is a block diagram illustrating an on-satellite demultiplexing and demodulation process in accordance with one embodiment of the present invention;

FIG. 7 is a block diagram illustrating a rate alignment process according to one embodiment of the invention;

FIG. 8 is a block diagram illustrating on-board switching and time division multiplexing operations according to one embodiment of the present invention;

FIG. 9 is a block diagram of the structure of a wireless receiver used in the system of FIG. 1 and constructed in accordance with one embodiment of the invention;

FIG. 10 is a block diagram illustrating receiver synchronization and demultiplexing operations, according to one embodiment of the present invention;

fig. 11 is a block diagram illustrating a synchronization and multiplexing operation for recovering a coded broadcast channel in a receiver according to an embodiment of the present invention;

fig. 12 is a block diagram of a system for managing satellites and broadcasting stations according to an embodiment of the present invention;

FIG. 13 is a block diagram of the structure of the broadcast, spatial and radio segments of a system constructed in accordance with one embodiment of the present invention;

fig. 14 is a diagram illustrating service component interleaving performed within a frame period of a service layer of a system constructed according to one embodiment of the present invention;

FIG. 15 is a block diagram of the structure of the service layer of the broadcast segment of a system constructed according to one embodiment of the present invention;

FIG. 16 is a block diagram of a pseudo random sequence generator for scrambling a broadcast channel according to an embodiment of the present invention;

FIG. 17 is a block diagram of the architecture of the service layer of the radio section of a system constructed in accordance with one embodiment of the invention;

FIG. 18 is a block diagram of the structure of the transport layer of the broadcast segment of a system constructed in accordance with one embodiment of the invention;

FIG. 19 is a diagram of a broadcast channel frame in the outer transport layer illustrated in FIG. 18 and a primary rate channel frame in the inner transport layer illustrated in FIG. 18;

fig. 20 is a diagram illustrating symbol interleaving in a primary rate channel, in accordance with one embodiment of the present invention;

fig. 21 is a block diagram of a broadcast channel Viterbi encoder for use at an inner transport layer of a broadcast segment according to an embodiment of the present invention;

fig. 22 is an illustration depicting a process of demultiplexing a broadcast channel into primary rate channels, in accordance with an embodiment of the present invention;

FIG. 23 is a block diagram of the structure of a spatially segmented transport layer of a system constructed in accordance with one embodiment of the invention;

fig. 24 is a diagram illustrating a time division multiplexed downlink signal generated in accordance with one embodiment of the present invention;

FIG. 25 is an illustration of rate alignment on a satellite, in accordance with an embodiment of the present invention;

fig. 26 is an illustration depicting a process of inserting a slot control word into a time division multiplexed downstream bit stream, in accordance with an embodiment of the present invention;

FIG. 27 is a block diagram of a time division multiplexed frame sequence generator for use in accordance with an embodiment of the present invention;

fig. 28a and 28b are block diagrams of the structure of the transport layer of a radio segment in a system constructed according to one embodiment of the invention.

In accordance with the present invention, as shown in fig. 1, a satellite-based radio broadcast system 10 is provided for broadcasting programs from a number of different broadcast stations 23a and 23b (hereinafter both 23) via a satellite 25. A wireless receiver, generally designated 29, is provided for a subscriber, which is designated one or more Time Division Multiplexed (TDM) L-segment carriers that are transmitted downstream by the receiver from a satellite 25, wherein the carriers are modulated at a rate of 1.86 mega-symbols per second (Msym/s). The designated subscriber radio receiver 29 demultiplexes and demodulates the TDM carrier to recover the data bits constituting the digital information content or program transmitted from the broadcasting station 23 through the broadcast channel. According to one embodiment of the invention, the broadcast station 23 and the satellite 25 are arranged to format the uplink and downlink signals so as to enable an improved reception quality of the broadcast program by a relatively inexpensive radio receiver. The wireless receiver may be a mobile unit 29a mounted on the transportation vehicle, a handheld unit 29b, or a processing terminal 29c having a display.

Although only one satellite 25 is shown in fig. 1 for purposes of illustration, the system 10 preferably has three geostationary satellites 25a, 25b and 25c (fig. 12) using the 1467 to 1492 megahertz (MHz) band that has been allocated for Broadcast Satellite Service (BSS) Direct Audio Broadcasting (DAB). The broadcasting station 23 preferably uses the feeding uplink 21 in the X band, i.e. the frequency band of 7050 to 7075 MHz. The satellite 25 is preferably arranged to operate three downlink spot beams, indicated by 31a, 31b and 31 c. Each beam covers about 1400 kilo-square kilometers in a four decibel (dB) drop in power distribution from the center of the beam and about 2800 kilo-square kilometers in an eight dB drop in power distribution. The beam center margin may be 14dB according to a receiver gain-to-temperature ratio of-13 dB/K.

With continued reference to fig. 1, the uplink signal 21 generated from the broadcast station 23 is modulated in a Frequency Division Multiple Access (FDMA) channel of a ground station 23, which is preferably located within the viewing range of a satellite 25. Each broadcast station 23 is preferably capable of uplink connection to one of the satellites directly from its own facility and is capable of generating one or more 16 kilobits per second (kbps) primary rate increments (prime rate increments) in a single carrier. The use of an uplink FDMA channel allows great flexibility in sharing the spatial segments between multiple independent broadcast stations 23 and can significantly reduce the power and expense of the uplink ground stations 23. A Primary Rate Increment (PRI) of 16 kilobits per second (kbps) is preferably a very basic building block or basic unit used in system 10 for channel size and may be mixed for higher bit rates. For example, for quasi-compact disc quality sound or multimedia broadcast programs containing image data, PRIs may be mixed to produce program channels with bit rates up to 128 kbps.

Conversion between uplink FDMA channels and downlink multiple channels in each carrier/time division multiplexed (MCPC/TDM) channel is accomplished from the baseband level on each satellite 25. The primary rate channel transmitted by one of the broadcast stations 23 is demultiplexed into individual 16kbps baseband signals at the satellite 25 as described below. The individual channels are then routed to one or more downlink beams 31a, 31b and 31c, which are a single TDM stream of a single carrier signal. This baseband processing provides advanced channel control through uplink frequency allocation and channel routing between uplink FDMA and downlink TDM signals.

End-to-end signal processing performed in system 10 is described below with reference to fig. 2. The system components responsible for end-to-end signal processing are described in more detail with reference to fig. 3-11. As shown in fig. 2, the audio signal from an audio source at broadcast station 23 is preferably encoded using MPEG2.5 level 3 encoding (block 26). The digital information assembled by the broadcast service provider at the broadcast station 23 is preferably formatted in 16kbps increments or PRIs, where n is the number of PRIs purchased by the service provider (i.e., n x 16 kbps). The digital information is then formatted into a broadcast channel frame having a Service Control Header (SCH), as described below (block 28). The periodic frames in system 10 preferably have a period of 432 milliseconds (ms). Each frame is preferably assigned n x 224 bits for SCH for bit rates close to n x 16.519 kbps. Each frame is then scrambled by adding a pseudo-random bit stream to the SCH. The scrambling mode information control implemented by one key allows encryption. The bits in the frame are preferably sequentially encoded for Forward Error Correction (FEC) protection using two concatenated coding methods, such as the Reed-Solomon method, and then interleaved and convolutional coding (e.g., trellis convolutional coding as described by Viterbi) (block 30). The coded bits in each frame corresponding to each PRI are sequentially partitioned or demultiplexed into n parallel primary rate channels (RRC) (block 32). To recover each PRC, a PRC sync header is provided. The n PRCs are then differentially encoded and modulated onto an intermediate frequency carrier frequency using a modulation method such as quadrature phase shift keying (block 34). The n PRC IF carrier frequencies constituting the broadcast channel of the broadcasting station 23 are converted into the X band, as indicated by arrow 36, to be transmitted to the satellite 25.

The carrier from the broadcasting station 23 is a single carrier/frequency division multiple access (SCPC/FDMA) carrier single channel. At each satellite 25, the SCPC/FDMA carrier is received, demultiplexed and demodulated to recover the PRC carrier (block 38). The PRC digital baseband channel recovered by the satellite 25 belongs to a rate alignment function that compensates for the difference in clock rate between the on-board clock and the clock of the on-board received PRC carrier (block 40). The demultiplexed and demodulated digital stream from the PRC is provided to a TDM frame assembler using routing and switching components. The PRC digital stream is routed from the demultiplexing and demodulation equipment on the satellite 25 to a TDMA frame assembler based on switching sequence units on the satellite 25 controlled by command links from a ground station (e.g., the satellite control center 236 for each work area in fig. 12). Three TDM carriers are established corresponding to the three satellite beams 31a, 31b, 31c (block 42). The three TDM carriers are up-converted to L-segment frequencies after QPSK modulation as indicated by arrow 44. The wireless receiver 29 is configured to receive any one of the three TDM carriers and demodulate the received carrier (block 46). The designated wireless receiver 29 synchronizes the TDM bit stream using a primary frame header provided during on-board processing (block 48). A Time Slotted Control Channel (TSCC) is used to demultiplex the PRC from the TDM frame. The digital stream is then re-multiplexed into the FEC encoded PRC format described previously for module 30. The FEC processing preferably includes decoding using a Viterbi trellis decoder, deinterleaving, and Reed-Solomon decoding to recover the original broadcast channel comprising the n x 16kbps channel and the SCH. The nx16 kbps segment of the broadcast channel is provided to an MPEG2.5 layer 3 source decoder for conversion to audio. In accordance with the present invention, audio output is available through a very inexpensive broadcast radio receiver 27 (block 52) due to the processing and TDM formatting combined with the broadcast station 23 and satellite 25.

Uplink multiplexing and modulation

Signal processing to convert data streams from one or more broadcast stations 23 into parallel streams for transmission to a satellite 25 will now be described with reference to fig. 3. For purposes of illustration, four sources 60, 64, 68 and 72 of program information are shown. The two information sources 60 and 64, or 68 and 72, are encoded and transmitted together as part of a single program or service. The encoding of the program including the mixed audio sources 60 and 64 will be described later. The signal processing for programs that include digital information from sources 68 and 72 is the same.

As described above, for a particular program, the broadcast station 23 assembles information from one or more sources 60 and 64 into a broadcast channel characterized by 16kbps increments. These increments are referred to as primary rate increments or PRIs. Thus, the bit rate conveyed in the broadcast channel is n x 16kbps, where n is the number of PRIs used by a particular broadcast service provider. In addition, each 16kbps PRI may be divided into two 8 kbps segments that are routed or switched together through the system 10. Segmentation provides a mechanism to deliver two different service items over the same PRI, such as delivering a data stream with a low bit rate voice signal or two low bit rate voice channels for two languages. The number of PRIs is preferably predetermined, i.e. set in advance by the program code. The number n is not a physical limitation of the system 10. The value of n is typically set according to business factors such as the cost of a single broadcast channel and the cost that the service provider wishes to pay. In fig. 3, the value of n for the first broadcast channel 59 of sources 60 and 64 is equal to 4. The value of n for broadcast channel 67 of sources 68 and 62 is equal to 6 in the illustrated embodiment.

As shown in fig. 3, more than one broadcast service provider may have access to a single broadcast station 23. For example, a first service provider may generate broadcast channel 59 and a second service provider may generate broadcast channel 67. The signal processing described herein and based on the present invention allows data streams from several broadcast service providers to be broadcast to the satellite in parallel data streams, thereby reducing the broadcast costs for the service providers and maximizing the use of the space segments. By making maximum use of the space segment, the broadcasting station 23 can be implemented in a less expensive manner using low power consumption components. For example, the antenna on the broadcast station 23 may be a Very Small Aperture Terminal (VSAT) antenna. The payload on the satellite requires less memory, less processing power, and therefore less power, thus reducing payload weight.

As shown in fig. 4, the broadcast channel 59 or 67 is characterized by a frame 100 having a period of 432 ms. The period is selected to enable the use of the following MPEG source encoder; but the frames paired with them in system 10 may be set to different predetermined values. If the period is 432ms, each 16kbps PRI requires 16,000 × 0.432 seconds =6912 bits per frame. As shown in fig. 4, a broadcast channel includes n 16kbps PRIs, which are delivered in groups in frame 100. The bits are scrambled to enhance demodulation at the wireless receiver 29, as described below. The scrambling operation also provides a mechanism to encrypt the service according to the service provider's options. Each frame 100 is allocated n x 224 bits corresponding to one Service Control Header (SCH), thus a total of n x 7136 bits per frame and a bit rate of n x (16, 518+14\27) bits per second. The purpose of the SCH is, among other features, to transmit data to the respective radio receiver 29 tuned to receive the broadcast channel 59 or 67, to control the reception mode of the various multimedia services, to display data and images, to transmit decrypted key information, and to address the particular receiver.

With continued reference to fig. 3, sources 60 and 64 are encoded using MPEG2.5 layer 3 encoders 62 and 66, respectively. As shown by processing block 78 in fig. 3, two sources are added sequentially by a mixer 76 and processed using a processor at the broadcast station 23 to provide a coded signal in 432ms periodic frames, n × 7136 bits per frame containing the SCH. The modules shown in the broadcast station of fig. 3 correspond to those executed by a processor and relate to programmed modules such as digital memories and encoder circuits. For FEC protection, bits in frame 100 are encoded using Digital Signal Processing (DSP) software, Application Specific Integrated Circuit (ASIC) and application specific large scale integrated circuit (LSI) chips, which are suitable for both tandem coding methods. First, a Reed-Solomon encoder 80a is provided to generate 255 bits each time 223 bits enter the encoder. The bits in frame 100 are then reordered according to a known interleaving method, as indicated by reference numeral 80 b. Since this method spreads the impairment bits over several channels, the interleaving coding also provides protection against error bursts encountered during transmission. With continued reference to the processing block 80, a known, constrained length-7 convolutional encoding method is provided using a Viterbi encoder 80 c. The Viterbi encoder 83c provides two output bits for each input bit, producing a net output of 16320 FEC encoded bits per frame for increments of 6912 bits per frame provided in the broadcast channel 59. Thus, each FEC encoded broadcast channel (e.g., channel 59 or 67) includes n × 16320 information bits, where the information bits have been encoded, reordered, and encoded again so that the original broadcast 16kbps PRI can no longer be identified. But reorganizes the FEC encoded bits according to the original 432ms frame structure. The total coding rate for error protection is (255/223) × 2=2+ 64/223.

With continued reference to fig. 3, n × 16320 bits of the FEC encoded broadcast channel frame are sequentially divided or demultiplexed into n parallel Primary Rate Channels (PRCs) using a channel allocator 82, where each PRC delivers 16320 bits over 8160 dibit symbol groups. This process is illustrated in fig. 4. The broadcast channel 59 shown is characterized by a 432ms frame 100 having an SCH 102. The remainder 104 of the frame includes n 16kbps PRIs, where each PRI of the n 16kbps PRIs corresponds to 6912 bits in each frame. The FEC encoded broadcast channel 106 is appended after concatenated Reed-Solomon255/223, interleaving and FEC 1/2 convolutional encoding as described in connection with block 80. As described above, the FEC encoded broadcast channel frame 106 includes n × 16320 bits corresponding to 8160 dibit symbol groups, where each symbol is assigned an index number 108 for purposes of illustration. According to the present invention, symbols are allocated on the PRC 110 in the manner shown in fig. 4. In this way, the symbols are spread in terms of time and frequency, thereby reducing errors generated by transmission interference at the wireless receiver. Assume for purposes of illustration that the service provider of broadcast channel 59 has purchased four PRCs, while the service provider of broadcast channel 67 has purchased six PRCs. Fig. 4 illustrates the allocation of a first broadcast channel and symbols 114 over n =4 PRCs 110a, 110b, 110c, 110d, respectively. To recover each group of dibit symbols 114 at the receiver, a PRC sync or preamble 112a, 112b, 112c, 112d, respectively, is placed in front of each PRC. The PRC sync header (hereinafter collectively referred to as reference numeral 112) contains 48 symbols. The PRC sync header 112 is placed in front of each symbol group of 8160 symbols, thus increasing the number of symbols in each 432ms frame to 8208 symbols. Accordingly, the symbol rate becomes 8208/0.432, equal to 19,000 kilosymbols per second (ksym/s) in each PRC 11O. The 48 symbol PRC preamble 112 is used to synchronize the radio receiver PRC clock to recover the symbols from the downlink satellite transmission 27. At the processor 116 on the satellite, the PRC preamble is used to eliminate the timing difference between the symbol rate of the arriving uplink signal and the rate at the satellite used to exchange signals and assemble the downlink TDM stream. This can be achieved by adding, extracting a "0" or neither adding nor extracting on each 48 symbol PRC during the rate alignment process used on the satellite. Thus, the PRC preamble transmitted on the TDM downlink has 47, 48 or 49 symbols, as determined by the rate alignment procedure. As shown in fig. 4, symbols 114 are assigned to consecutive PRCs in a round robin fashion such that symbol 1 is assigned to PRC 110a, symbol 2 is assigned to PRC 110b, symbol 3 is assigned to PRC 110c, symbol 4 is assigned to PRC 110d, symbol 5 is assigned to PRC 110e, and so on. This PRC demultiplexing process is performed by a processor on the broadcast station 23 and is represented in fig. 3 as a channel assignment (DEMUX) module 82.

The PRC channel preamble is allocated using the preamble module 84 and the adder module 85 to mark the start of the PRC frame 110a, 110b, 110c, 110d of the broadcast channel 59. The n PRCs are differentially encoded sequentially using a set of QPSK modulators 86 as shown in fig. 3 and QPSK modulated onto one IF carrier frequency. Four QPSK modulators 86a, 86b, 86c, 86d are used for the PRCs 110a, 110b, 110c, 110d, respectively, of the broadcast channel 59. Accordingly, four PRC IF carrier frequencies constitute the broadcast channel 59. An up-converter 88 is used to up-convert the four carrier frequencies to their assigned frequency locations in the X-band for transmission to the satellites 25. The up-converted PRCs are sequentially transmitted to antennas (e.g., a VSAT)91a and 91b through an amplifier 90.

According to the invention, the transmission method used at one broadcast station 23 introduces n single-carrier single-channel, frequency division multiple access (SCPC/FDMA) carriers into the uplink signal 21. The SCPC/FDMA carriers are distributed in a grid of center frequencies, preferably 38,000 hertz (Hz) apart from each other and grouped in 48 contiguous center frequencies or carrier channels. This organization of the set of 48 carrier channels provides for demultiplexing and demodulation processing on the satellite 25. The respective 48-carrier channel groups need not be contiguous with each other. The carriers associated with a particular broadcast channel (i.e., channel 59 or 67) need not be contiguous in a 48 carrier channel group and need not be allocated in the same 48 carrier channel group. The transmission methods described in connection with fig. 3 and 4 thus allow flexibility in selecting frequency locations and optimize the ability to fill the available frequency spectrum and avoid interference with other users sharing the same frequency spectrum.

System 10 is advantageous because it provides a common basis for increased capacity for various broadcasters or service providers, where broadcast channels having various bit rates can be relatively easily constructed and transmitted to receiver 29. Common broadcast channel increments or PRIs are preferably 16, 32, 48, 64, 80, 96, 112 and 128 kbps. Due to the processing described in connection with fig. 4, the wireless receiver can interpret broadcast channels having various bit rates relatively easily. The size and cost of the broadcaster can thus be tailored to the capacity requirements and financial resource limitations of the broadcaster. A financial-scarce broadcaster can set up a small VSAT terminal that requires relatively little power to broadcast 16kbps of service to its service area, which is sufficient to deliver voice and music of much higher quality than short-wave radio. On the other hand, a large broadcaster with sufficient financial capacity can broadcast FM stereo quality services with a slightly larger antenna and 64kbps of power, and by further increasing the capacity can broadcast quasi Compact Disc (CD) stereo quality 96 kbps services and full CD stereo quality 128 kbps services.

The frame length, SCH length, preamble length and PRC length described in connection with fig. 4 are used to achieve some advantages; the broadcast station processing described in connection with fig. 3 and 4 is not limited to these values. A frame period of 432ms is convenient when using an MPEG source encoder (e.g., encoder 62 or 66). 224 bits are selected for each SCH 102 for FEC encoding. To simplify the implementation of multiplexing and demultiplexing on satellite 25, the 48-symbol PRC preamble is selected to achieve 8208 symbols per PRC 110, and thus a symbol rate of 19,000 ksym/s per PRC, as described below. The symbol is defined to include two bits to facilitate QPSK modulation (i.e., 2)²= 4). To further illustrate, if the phase shift keying modulation on the broadcast station 23 uses eight phases instead of four, then this is due to a three-bit combination (i.e., 2)³) Corresponding to one of eight phases, a symbol with three bits is more convenient to process.

Software may be provided at the broadcast station 23 or, in the case of more than one broadcast station in the system 10, a Regional Broadcast Control Facility (RBCF)238 (fig. 12) may allocate spatial segment channel routes through a Mission Control Center (MCC)240, a Satellite Control Center (SCC)236 and a Broadcast Control Center (BCC) 244. The software optimizes the use of the uplink spectrum by allocating PRC carrier channels 110 where there is space available in the 48 channel group. For example, a broadcast station may wish to broadcast a64 kbps service over four PRC carriers. Due to the current spectrum usage, it may not be possible to use four carriers at consecutive locations, but only at non-consecutive locations within a 48-carrier group. And the RBCF238 using its MCC and SCC may assign PRCs to discrete locations within different 48-channel groups. The MCC and SCC at the RBCF238 or at an individual broadcast station 23 can reallocate the PRC carrier of a particular broadcast service to other frequencies to avoid intentional (jamming) or unintentional interference with a particular carrier location. The current embodiment of the system has three RBCFs, one for each of the three regional satellites. One of these three facilities may control additional satellites.

As will be described in greater detail below in connection with the on-board processing of fig. 6, an on-board digital polyphase processor is used for on-board signal regeneration and digital baseband recovery of the symbols 114 transmitted by the PRC. The use of 48 carrier groups distributed over center frequencies spaced 38,000 Hz apart allows processing using a multi-phase processor. Available software on the broadcast station 23 or the RBCF238 enables a defragmentation, i.e., defragmentation process, to optimally assign the PRCs 110 to uplink carrier channels, i.e., a 48-carrier channel group. The principle of uplink carrier frequency allocation defragmentation is not different from known software that reorganizes files on a computer hard disk where data is stored in a segment-by-segment manner over time, thereby reducing data storage efficiency. The BCC functionality on the RBCF allows the RBCF to remotely monitor and control the broadcast stations, thereby ensuring that their operation is within a specified tolerance.

Payload processing on satellite

Baseband recovery on the satellite is important for completing switching, routing and assembly of TDM downlink carriers each with 96 PRCs on the satellite. The TDM carrier is amplified using a single carrier single-wave tube operation on the satellite 25. The satellite 25 preferably includes eight on-board baseband processors; only one processor 116 is shown. Preferably, only six of the eight processors are used at a time, with the remainder providing redundancy in the event of a failure and commanding it to stop transmitting as the situation requires. A single processor 116 is described in connection with fig. 6 and 7. It should be understood that the same components are preferably provided for the other seven processors 116. Referring to fig. 5, the encoded PRC uplink carrier 21 is received at the satellite 25 by an X-band receiver 120. The total uplink capacity is preferably between 288 and 384 PRC uplink channels of 16kbps each (6 x 48 carriers when 6 processors 116 are used and 8 x 48 carriers when 8 processors 116 are used). As described below, 96 PRCs are selected and multiplexed for transmission by respective downlink beams 27 onto a carrier having a bandwidth of approximately 2.5 MHz.

The individual uplink PRC channels may or may not be routed to all or some of the downlink beams 27. The order and location of the PRCs in the downlink beam may be programmed and selected by a telemetry, ranging and control (TRC) facility 24 (fig. 1). As described in detail below in connection with fig. 6, each polyphase demultiplexer and demodulator 122 receives a single FDMA uplink signal in 48 consecutive channel groups, generates a single analog signal, and demodulates serial data at high speed, wherein the 48 FDMA signals are time-multiplexed onto the analog signal. Six of the phase demultiplexers and demodulators 122 operate in parallel to process the 288 FDMA signals. A routing switch and modulator 124 selectively couples a single channel of six serial data streams to all or a portion of downlink signal 27, or none of the downlink signal, and modulates and upconverts the three downlink TDM signals 27. Three Traveling Wave Tube Amplifiers (TWTA)126 amplify the three downlink signals, respectively, where the signals are transmitted to the surface through an L-band transmit antenna 128.

The satellite 25 also contains three transparent payloads, each including a demultiplexer and downconverter 130, and an amplifier bank 132, which are configured into a conventional "bent-pipe" signal path that converts the frequency of the incoming signal for retransmission. Thus, each satellite 25 in the system 10 is preferably equipped with two communication payloads. A first type of on-board processing of payloads is described with reference to fig. 5, 6 and 7. The second type of communication payload is a transparent payload that converts the uplink TDM carrier from a frequency location in the uplink X-band spectrum to a frequency location in the L-band downlink spectrum. The TDM stream transmitted by the transparent payload is assembled in the broadcast station 23, transmitted to the satellite 25, received and frequency translated to a downlink frequency position using module 130, amplified by a TWTA in module 132 and transmitted to a beam. The TDM signals are the same for one wireless receiver 29, whether they come from the on-board-processing payload shown at 121 or the transparent payload shown at 133. The carrier frequency positions of each payload 121 and 133 are distributed on a grid spaced 920 kHz apart, the grids being staggered in halves from each other so that the mixed frequency positions of the signals from the two payloads 121 and 133 are spaced 460kHz apart.

The on-board demultiplexer and demodulator 122 is now described in more detail with reference to fig. 6. As shown in fig. 6, the SCPC/FDMA carriers, each represented by an index 136, are allocated to 48 channel groups. One channel group 138 is shown in fig. 6 for illustration. The carrier waves 136 are distributed on a center frequency grid spaced 38 kHz apart. This spacing determines the design parameters of the polyphase demultiplexing. For each satellite 25, it may be preferable to receive 288 uplink prcscc/FDMA carriers from some broadcast stations 23. Thus, preferably using 6 polyphase demultiplexers and demodulators 122, an on-board processor 116 accepts the PRC SCPC/FDMA uplink carriers 136 and converts them into three downlink TDM carriers, each carrying 96 PRCs over 96 time slots.

An uplink full-beam antenna 118 receives the 288 carriers and each 48 channel group is frequency converted to an Intermediate Frequency (IF) which is then filtered to select a frequency band occupied by the particular channel group 138. This processing is performed in the receiver 120. The filtered signal is then provided to an analog-to-digital (a/D) converter 140 before being provided as input to a polyphase demultiplexer 144. The demultiplexer 144 divides the 48 SCPC/FDMA channels 138 into a time division multiplexed analog signal stream that includes QPSK modulated symbols that sequentially provide the contents of the 48 SCPC/FDMA channels on the output of the demultiplexer 144. This TDM analog signal stream is routed to a QPSK demodulator and differential decoder 146 in a digital fashion. The QPSK demodulator and differential decoder 146 sequentially demodulates the QPSK modulation symbols into digital baseband bits. The demodulation process requires symbol timing and carrier recovery. Since the modulation is QPSK, each baseband symbol containing two bits is recovered for each carrier symbol. The demultiplexer 144, demodulator and decoder 146 are hereinafter referred to as demultiplexer/demodulator (D/D) 148. D/D is preferably implemented using high speed digital techniques that demultiplex the uplink carrier 21 by known polyphase techniques. The QPSK demodulator is preferably a serial shared digital demodulator for recovering baseband dibit symbols. The symbols 144 recovered from the individual PRC carriers 110 are sequentially differentially decoded to recover the original PRC symbols 108 provided at the input encoders of the broadcast station 23, i.e., the channel distributors 82 and 98 of fig. 3. The satellite 25 payload preferably includes 6 digitally 48-carrier D/D148. In addition, two spare D/ds are provided in the satellite payload to replace any failed processing units.

With continued reference to fig. 6, the processor 116 is programmed in accordance with software modules shown at 150 to synchronize and rate align the time-division multiplexed symbol streams produced at the outputs of the QPSK demodulator and differential decoder 146. The software and hardware components (e.g., digital memory buffers and oscillators) of the rate alignment module 150 in fig. 6 are described in more detail with reference to fig. 7. The rate alignment module 150 compensates for the clock rate difference between the on-board clock 152 and the clock of the symbols conveyed by the single uplink PRC carrier 138 received at the satellite 25. The clock rates differ by different clock rates at different broadcast stations 23 and by different doppler rates resulting from different positions due to satellite movement. The clock rate difference due to the broadcast station 23 may occur at a broadcast station's own clock or at a remote clock, where the clock rate is communicated over a terrestrial link between a broadcast studio and a broadcast station 23.

The rate alignment module 150 adds or removes a "0" value symbol in the PRC header portion 112 of each 432ms recovery frame 100, or does nothing. A "0" value symbol is a symbol that includes a bit value of 0 on both the I and Q channels of the QPSK modulation symbol. The PRC header 112 includes 48 symbols under normal operating conditions and consists of an initial symbol of "0" value followed by 47 other symbols. When the symbol timing of the uplink clock recovered by the QPSK demodulator 146 in cooperation with the uplink carrier frequency is synchronized with the timing of the on-satellite clock 152, the PRC preamble 112 of the PRC 110 is not changed. When the timing of the arriving uplink symbol lags the on-board clock 152 by one symbol, a "0" symbol is added at the beginning of the PRC preamble 112 of the currently processed PRC, resulting in a length of 49 symbols. When the timing of the arriving uplink symbol leads the on-board clock 152 by one symbol, a "0" symbol is removed from the beginning of the PRC preamble 112 of the currently processed PRC, resulting in a length of 47 symbols.

As described above, the input signal to the rate alignment module 150 comprises the recovered baseband dibit symbol streams for each uplink PRC received at its individual original symbol rate. 288 such symbol streams are generated from the D/ds 148 corresponding to the 6 active processors 116. Actions are described herein that involve only one D/D148 and one rate alignment module 150, although it is understood that the other 5 active processors 116 on the satellite perform similar functions.

To rate align the uplink PRC symbols with the on-board clock 152, three steps are performed. In a first step, symbols are combined in respective buffers 149 and 151 of a ping-pong buffer 153 according to their initial 8208 dibit symbol PRC frame 110. This requires correlation of the PRC header 112 (containing a 47 symbol word) using a locally stored unique word in a correlator shown at 155 to locate the symbols in the buffer. Second, the number of on-board clock 152 beats between correlated spikes is determined and used to adjust the length of the PRC head 112 to compensate for the rate difference. The third step is to clock the PRC frame with the modified header to a corresponding location in a switching and routing memory arrangement 156 (fig. 8) at the on-satellite rate.

The PRC symbols enter the ping-pong buffer pair 153 from the left. The ping-pong action causes one buffer 149 or 151 to fill at the uplink clock rate while the other buffer is emptied at the on-board clock rate. The two buffers exchange roles on a frame-by-frame basis and create a continuous flow between the input and output of buffers 149 and 151. The newly arrived symbol is written to the buffer 149 or 151 that is being connected. The write operation continues to fill the buffer 149 or 151 until a correlation spike occurs. Then, the writing is stopped, and the input and output switches 161 and 163 are switched to the inverted state. This operation captures an uplink PRC frame such that its 48 header symbols stay in 48 symbol slots, one of which is not filled on the output of the buffer and 8160 data symbols are filled in the first 8160 slots. The contents of the main buffer are read immediately onto its output at the on-board clock rate. The number of symbols read is such that the PRC header contains 47, 48 or 49 symbols. A "0" value symbol is cleared or added at the beginning of the PRC header to make this adjustment. The header length is controlled by a signal from a frame symbol counter 159 which records the number of on-satellite clock rate symbols that will fall within one PRC frame period to determine the header length. And the reciprocating exchange action is used for exchanging the role of the buffer area.

To count, frame correlation spikes from the buffer correlator 155 are smoothed by a sync pulse oscillator (SPC)157 as PRC frames fill the buffers 149 and 151. The smoothed synchronization pulse is used to record the number of symbol occurrences in each frame. This number may be 8207, 8208 or 8209, indicating whether the PRC head should have a symbol length of 47, 48 or 49, respectively. This information causes the frame buffer to generate the correct number of symbols to maintain a symbol stream that is synchronized to the on-board clock and independent of the ground terminal starting point.

The run time between preamble 112 modifications is relatively long for rate differences expected to occur on system 10. For example, 10^-6The difference in clock rates of (a) will produce a PRC preamble correlation on average every 123 PRC frames. The final rate adjustment results in accurate synchronization of the symbol rate of the PRC 110 with the on-board clock 152. This allows the baseband bit symbols to be routed to the correct location in the TDM frame. The PRC to which synchronization is derived is indicated generally at 154 in fig. 6. On-satellite routing and intersection of these PRCs 154 to TDM frames is now described with reference to FIG. 8And (4) changing.

Fig. 6 illustrates the PRC process by a single D/D148. The other five active D/ds on the star perform similar processing. PRCs that emanate from one of the 6D/ds 148 and are already synchronized and aligned occur in a serial stream having a symbol rate of 48 x 19,000, i.e., equal to 921,000 symbols per second in each D/D148. As shown in fig. 7, the serial stream from each D/D148 may be demultiplexed into 48 parallel PRC streams with a rate of 19,000 symbols per second. There are 288 PRC streams from all 6D/ds 148 on satellite 25, with each D/D148 delivering a symbol stream of 19,000 symbols per second. The symbol thus has an epoch or period of 1/19,000 seconds, approximately equal to a period of 52.63 milliseconds.

As shown in fig. 8, for each occurrence of an uplink PRC symbol, 8, 288 symbols appear at the output of six D/ds 148a, 148b, 148c, 148D, 148e, 148 f. Once a PRC symbol has occurred, 288 symbol values are written into a switch and route memory 156. The contents of the buffer 156 are read into three downlink TDM frame assemblers 160, 162, and 164. The contents of the 288 memory locations are read into the three TDM frames in the assemblers 160, 162 and 164 in 2622 groups of 96 symbols using the routing and switching elements shown at 172 with an epoch of 136.8ms, which implies that a read-in occurs once per TDM frame period or 138 ms. Thus the scan rate or 136.8/2622 is faster than the duration of one symbol. The routing switch and modulator 124 includes a ping-pong switch memory structure, generally designated 156, which includes buffers 156a and 156b, respectively. The 288 uplink PRCs shown at 154 are provided as inputs to routing switch and modulator 124. The symbols for each PRC occur at a rate of 19,000 symbols per second corrected to the on-board clock 152 timing. The PRC symbols are written as input to 288 locations in the ping-pong memory 156a or 156b in parallel at a clock rate of 19,000 Hz. At the same time, the memory used as output 156b or 156a, respectively, reads the symbols stored in the previous frame into three TDM frames at a read rate of 3 × 1.84 MHz. The rate is sufficient to simultaneously generate three TDM parallel streams, each connected to one of the three beams. The routing of symbols to their designated beams is controlled by a symbol routing switch 172. This switch can route a symbol into any one, two or three TDM streams. Each TDM stream appears at a rate of 1.84 Msym/s. The output memory is timed to an interval of 136.8ms and a stop of 1.2 ms to allow insertion of the 96 symbol MFP and 2112 symbol TSCC. Note that for each symbol read into more than one TDM stream, there is one unused and skipped offset uplink FDM PRC channel. The swap memory buffers 156a, 156b switch roles frame by frame through switch components 158a, 158 b.

With continued reference to fig. 8, the 96 symbol groups are passed into 2622 corresponding timeslots in each TDM frame. The corresponding symbols (i.e., the ith symbol) of all 96 uplink PRCs are combined together into the same TDM frame slot as shown by slot 166 for symbol 1. The contents of 2622 slots of each TDM frame are scrambled by adding a pseudorandom bit pattern over the entire 136.8ms epoch. In addition, a 1.2 ms epoch is appended to the beginning of each TDM frame to insert a 96 symbol Main Frame Preamble (MFP) and a 211 symbol TSCC as shown at 168 and 170, respectively. The sum of the 2622 time slots each conveying 96 symbols and the symbols for the MFP and TSCC is 253, 920 symbols per TDM frame, thus yielding a downlink symbol rate of 1.84 Msym/s.

The PRC symbol routing between the outputs of the six D/ds 148A, 148B, 148C, 148D, 148E, 148F and the inputs of the TDM frame assemblers 160, 162, 164 is controlled by an on-board switching sequence unit 172 which stores instructions sent to it from the SCC238 (fig. 12) on the surface over the command link. Each symbol emanating from a selected uplink PRC symbol stream may be routed onto a slot in a TDM frame to be transmitted to a desired destination beam 27. The routing method is independent of the relationship between the symbol occurrence time in the respective uplink PRC and the symbol occurrence time in the downlink TDM stream. This reduces the complexity of the satellite 25 payload. And symbols transmitted from the selected uplink PRC may be routed to two or three destination beams through switch 158.

Operation of a wireless receiver

The wireless receiver 29 used in the system 10 will now be described with reference to fig. 9. The wireless receiver 29 includes a Radio Frequency (RF) section 176 having an L-band electromagnetic wave receiving antenna 176 and is pre-filtered to select the receiver's operating band (e.g., 1452 to 1492 MHz). The RF section 176 also includes a low noise amplifier 180 that is capable of amplifying the received signal with minimal self-induced noise and countering interfering signals that may come from another service sharing the operating band of the receiver 29. A mixer 182 is provided to down-convert the received spectrum to an Intermediate Frequency (IF). A high performance IF filter 184 selects the desired TDM carrier bandwidth from the outputs of the mixer 182 and a local oscillator synthesizer 186 that generates the mixing input frequency required to down-convert the desired signal to the center frequency of the IF filter. The TDM carriers are located at a center frequency distributed on a grid with 460kHz spacing. The bandwidth of the IF filter 184 is close to 2.5 MHz. The carrier spacing is preferably at least seven or eight steps, or approximately 3.3 MHz. The RF section 176 is designed to pick out the desired TDM carrier bandwidth with minimal mutual interference and distortion and to discard undesired carriers that may be present in the 152 to 192 MHz operating band. In most regions of the world, the level of the undesired signal is weak and typically an undesired signal-to-desired signal ratio of 30 to 40 dB provides adequate protection. In some areas, it is desirable that the previous design be able to have a better protection ratio if it is to operate near a high power transmitter, such as near a public switched telephone network or other broadcast audio service terrestrial microwave transmitter. The desired TDM carrier bandwidth derived from the downlink signal using the RF section 176 is provided to an a/D converter 188 and then to a QPSK demodulator 190. QPSK demodulator 190 is designated to recover the TDM bit stream transmitted from satellite 25, i.e., via on-board processor payload 121 or on-board transparent payload 133, at the selected carrier frequency.

QPSK demodulator 190 is preferably implemented to first convert the IF signal from RF section 176 to digital form using a/D converter 188 and then QPSK demodulate using a known digital processing method. Demodulation preferably uses symbol timing and carrier frequency recovery and decision circuitry that samples and decodes the QPSK modulated signal into a baseband TDM bit stream.

The a/D converter 188 and QPSK demodulator 190 are preferably provided on a channel recovery chip 187 that recovers the broadcast channel digital baseband signal from the IF signal recovered by the RFIF board 176. The channel recovery circuit 187 includes a TDM synchronizer and predictor module 192, a TDM demultiplexer 194, and a PRC synchronizer alignment and multiplexer 196, the operation of which will be described in more detail below in conjunction with fig. 10. The TDM bit stream on the output of the QPSK demodulator 190 is provided to an MFP synchronization correlator 200 in a TDM synchronizer and predictor module 192. Correlator 200 compares bits in the received stream to a stored pattern. When no signal is present at the receiver before, correlator 200 first enters a search mode in which it searches for the desired MFP correlation mode without any time gating or window (aperturing) restriction on its output. When the correlator finds a correlation event, the correlator enters a mode in which a gate is opened for a time interval during which the next correlation event is expected. If a related event occurs again within the predetermined time gate open time, the time gating process is repeated. If correlation occurs in five consecutive time periods, it indicates that the software has determined synchronization. But the synchronization threshold may be changed. If no correlation occurs before the minimum number of consecutive time periods reaches the synchronization threshold, the correlator continues to search for a correlation pattern.

Assuming synchronization occurs, the correlator enters a synchronization mode in which the correlator adjusts its parameters so that the probability of continuous synchronization lock is maximized. If correlation is lost, the correlator enters a special predictor mode where the correlator continues to maintain synchronization by predicting the arrival of the next correlation event. For short signal losses (e.g., 10 seconds), the correlator can maintain sufficiently accurate synchronization to complete a virtually instantaneous recovery when the signal returns. This fast recovery is advantageous since it is important in mobile reception conditions. If correlation is not re-established after a certain period, the correlator 200 returns to the search mode. The TDM demultiplexer 194 can restore the TSCC when synchronizing with the MFP of the TDM frame (block 202 in fig. 10). The TSCC contains information identifying the program provider conveyed by the TDM frame and information identifying where in the 96 PRCs the channel of the respective program provider can be found. Scrambling of the partial TDM frame conveying the PRC symbols is preferably removed before any PRCs can be demultiplexed from the TDM frame. This can be done by adding the same scrambling pattern to the receiver 29, which is added to the PRC portion of the TDM frame bit stream at the satellite 25. This scrambling pattern is synchronized with the TDM frame MFP.

The symbols of the PRC are not combined consecutively in the TDM frame, but rather are diffused into the frame. 2622 symbol groups are contained in the PRC portion of the TDM frame. In each symbol group, there is one symbol per PRC in a numbered position in ascending order of 1 to 96. Thus, as shown in block 204, all symbols belonging to PRC1 are in the first position of all 2622 symbol groups. All symbols belonging to PRC 2 are in the second position of all 2622 symbol groups, and so on. This arrangement of numbering and locating the symbols of the PRCs in the TDM frame, based on the present invention, minimizes the amount of memory used for switching and routing at the satellite and memory used for demultiplexing at the receiver. As shown in fig. 9, TSCC is recovered from TDM demultiplexer 194 and provided to controller 220 on receiver 29 to recover the n PRCs for a particular broadcast channel. The symbols for the n PRCs associated with the broadcast channel are extracted from the unscrambled TDM frame time slot positions identified in the TSCCs. This association is implemented by a controller included in the wireless receiver and is generally indicated by 205 in fig. 10. The controller 220 accepts the radio receiver operator's broadcast selection, mixes the selection with the PRC information contained in the TSCCs, extracts the PRC symbols from the TDM frame and reorders them to recover the n PRCs.

Referring to modules 196 and 206 in fig. 9 and 10, respectively, the symbols of all n PRCs (e.g., as indicated at 207) associated with one broadcast channel (e.g., as indicated at 209) selected by the wireless receiver operator are re-multiplexed into the FEC encoded Broadcast Channel (BC) format. The n PRCs of a broadcast channel are realigned before the re-multiplexing is completed. Realignment is useful because the clocks that determine the symbol timing encountered in demultiplexing and on-satellite rate alignment, re-determining the multiplexing that occurs while traversing the end-to-end link of system 10, can produce an offset of four symbols in the relative alignment of the recovered PRC frames. The n PRCs of a broadcast channel each have a 48 symbol preamble followed by 8160 coded PRC symbols. To remix the n PRCs into a broadcast channel, the 47, 48 or 49 symbol headers of the individual PRCs are synchronized. The head length depends on the timing alignment performed on the uplink PRC of the satellite 25. Synchronization is performed using a preamble correlator which operates on the 47 most recently received PRC header symbols for each of the n PRCs. The preamble correlator detects the correlation event and emits a single symbol during the occurrence of a correlation spike. The symbol content of the n PRCs can be precisely aligned and re-multiplexed to recover the FEC encoded broadcast channel, depending on the relative times at which correlation spikes occur on the n PRCs associated with the broadcast channel, and by operating in conjunction with an alignment buffer that is four symbols wide. The re-multiplexing of the n PRCs for the re-assembly of the FEC encoded broadcast channels preferably requires that the symbol spreading process for demultiplexing the FEC encoded broadcast channels into PRCs at the broadcast station 23, as shown by blocks 206 and 208 in fig. 10, be performed in reverse order.

Fig. 11 illustrates how a broadcast channel containing four PRCs is recovered at the receiver (block 196 in fig. 9). The four arriving demodulated PRCs are shown on the left side of fig. 11. Due to the variation in retiming and the different time delays experienced from the broadcast station to the radio receiver via the satellite, a relative shift of up to four symbols occurs in the n PRCs that make up a broadcast channel. The first step in the recovery process is to realign the symbol content of these PRCs. This is achieved by a set of FIFO buffers of equal length to the variation range. Each PRC has its own buffer 222. Each PRC is first provided to a PRC header correlator 226 which determines the arrival events of the PRC header. For purposes of illustration, one arrival event is shown by one correlation spike 224 for all four PRCs. Writing (W) to the respective buffers is started immediately after the occurrence of the relevant event and thereafter continued until the end of the frame. The symbols are aligned with the PRC and read out (R) from all buffers 222 is started when the last correlation event occurs. This results in the symbols of all PRCs being read out in parallel at the buffer 222 output (block 208). The length of the PRC header may be 47, 48 or 49 symbols due to the on-board clock 152 rate alignment. This variation is eliminated in the correlator 226 by detecting correlation events using only the most recently arrived 47 symbols. These 47 symbols are specifically chosen to produce optimal correlation detection.

Referring to blocks 198 and 210 in fig. 9 and 10, respectively, the FEC encoded broadcast channels are provided sequentially to FEC processing block 210. Most errors encountered in transmission between the encoder and decoder locations are corrected by the FEC process. The FEC process preferably uses a Viterbi network decoder followed by deinterleaving and then a Reed-Solomon decoder. The FEC process recovers the original broadcast channel, which includes the n x 16kbps channel delta and its n x 224 bit SCH (block 212).

The n x 16kbps segments of the broadcast channel are provided to a decoder, such as an MPEG2.5 layer 3 decoder 214, which converts the segments into an audio signal. Thus, the broadcast channel can be received from the satellite using an inexpensive wireless receiver. Since the broadcast programming transmission via satellite 25 is digital, system 10 supports a number of other services that are also represented in digital format. As described above, the SCH included in the broadcast channel provides a control channel for a large number of future service options. Thus, a chipset can be produced to implement these service options by making available the entire TDM bit stream and its original demodulation format, demultiplexing the TSCC information bits, and recovering the error correction broadcast channel. The wireless receivers 29 may also be provided with an identification code uniquely addressed to each wireless receiver. The identification code is accessible by a bit conveyed by one of the SCHs of the broadcast channel. For mobile operations using the wireless receiver 29 in accordance with the present invention, the wireless receiver is set to predict and substantially simultaneously find the location of the MFP correlation spike with an accuracy of 1/4 symbols for an interval of 10 seconds. It is desirable to install a symbol timing local oscillator in the radio receiver that is better than 100,000,000 times shorter and has accuracy, especially in a handheld radio receiver 29 b.

Satellite and broadcasting station management system

As described above, the system 10 may include one or more satellites 25. Fig. 12 depicts three satellites 25a, 25b, 25c for purposes of illustration. The system 10 with several satellites preferably includes a plurality of TCR stations 24a, 24b, 24c, 24d, 24e, two of which are able to directly see each satellite 25a, 25b, 25 c. The TCR stations are collectively represented by reference numeral 24 and are controlled by a Regional Broadcast Control Facility (RBCF)238a, 238b, 238 c. Each RBCF238a, 238b, 238c includes a Satellite Control Center (SCC)236a, 236b, 236c, a Mission Control Center (MCC)240a, 240b, 240c, and a Broadcast Control Center (BCC)244a, 244b, 244c, respectively. Each SCC controls the satellite bus and communication payload and is a location site for space segmentation command and control computers and human resources. The facility is preferably manually operated 24 hours a day by a group of technicians trained specifically for command and control of orbiting satellites. The SCCs 236a, 236b, 236c monitor the on-board components and manipulate the corresponding satellites 25a, 25b, 25 c. Each TCR station 24 is preferably directly connected to a corresponding SCC236a, 236b, 236c by a dedicated dual redundant PSTN circuit.

In each service area of a satellite 25a, 25b, 25c, the corresponding RBCF238a, 238b, 238c reserves broadcast channels for audio, data, video image services, allocates spatial segment channel routes through the Mission Control Center (MCC)240a, 240b, 240c, confirms service submissions, which are information needed to bill the broadcast service provider, and charges the service provider.

Each MCC is configured to program a spatial segment channel allocation comprising an uplink PRC frequency and a downlink PRC TDM time slot allocation. Each MCC is dynamically and statically controlled. Dynamic control involves controlling the time window allocated, i.e. allocating space segments used on a monthly, weekly and daily basis. Static control involves space segment allocation that does not change on a monthly, weekly, and daily basis. A sales department having personnel selling the capacity of a space segment on a specified RBCF provides MCC data indicating the available capacity and instructions to occupy the capacity that has been sold. The MCC formulates an overall plan that occupies the time and frequency space of the system 10. The plan is then converted to instructions for the on-satellite route switch 172 and sent to the SCC for transmission to the satellite. The schedule can preferably be updated and sent to the satellite every 12 hours. The MCCs 240a, 240b, 240c also monitor satellite TDM signals received by corresponding channel system monitoring devices (CSMEs) 242a, 242b, 242 c. CSME confirms that the broadcast station 23 is transmitting the broadcast channel on demand.

Each BCC 244a, 244b, 244c monitors whether the broadcast ground stations 23 within its area are operating properly within selected frequency, power and antenna pointing tolerances. The BCC can also be connected to a corresponding broadcast station in order to order a malfunctioning station to stop broadcasting. A central facility 246 is preferably provided for each SCC to provide technical support services and backup operations.

Signaling protocol

In accordance with a preferred embodiment of the present invention, the information broadcast to the radio receiver 29 is formatted into a waveform according to a signaling protocol that exhibits a number of advantages over existing broadcast systems. The information processing for broadcast transmission and reception is summarized in fig. 13, which illustrates a broadcast segment 250, a spatial segment 252 and a radio segment 254 of a satellite direct radio broadcast system 10 constructed in accordance with a preferred embodiment of the present invention. The service and transport layers of system 10 are described below.

For broadcast segment 250, some steps in the formatting process are similar to those described previously. For example, the steps of demultiplexing the encoded and interleaved broadcast channel bit stream (block 256), and adding the primary rate channel preamble (block 258) to produce the primary rate channel for transmission to the satellite 25 over the frequency division multiplexed uplink are similar to the process described above with reference to FIGS. 3 and 4. The process of generating a bit stream from different service components, such as service components 260 and 262, scrambling the bit stream 266, and Forward Error Correction (FEC) encoding the bit stream (block 268) by adding a Service Control Header (SCH)264 will now be described in connection with figures 13, 14 and 15, which illustrate a preferred embodiment of the present invention. Encryption is also discussed in conjunction with the SCH and table 1 (block 265).

According to the present invention, a broadcast service may include, but is not limited to, audio, data, still images, moving images, paging signals, text, messages and full image symbols. A service may consist of several service components submitted by one service provider as illustrated by service components 260 and 262 in fig. 13. For example, a first service component may be audio and a second service component may be text displayed on a wireless receiver screen or image data related to an audio broadcast. In addition, a service may be composed of a single service component or more than two service components. Service 261 is mixed with an SCH 264 to generate a service layer for one broadcast segment. The allocation of service components within service 261, such as service components 260 and 262, is dynamically controlled via the SCH in accordance with the present invention. As shown in fig. 4, a broadcast channel bit stream preferably has a frame period of 432 milliseconds. The SCH 102 in fig. 4 has n × 224 bits, and the service 104 includes n × 6912 bits, for a total of n × 7136 bits per frame 100. The number n is the total bit rate of service divided by 16,000 bits per second (bps).

As described above, the service component of service 261 may deliver an audio service or a digital service. The service component bit rate may preferably be divided into multiples of 8000 bps and between 8000 bps and 128,000 bps. When the sum of bit rates of all service components in service 261 is lower thanAt bit rate of service 261, the remaining bit rate is made up with a filler service component. Thus, the fill service component bit rate is

Wherein i is a group containing N_scI-th service component of a service of the service components, i ≦ 1 ≦ N_scN (i) equals the bit rate of the ith service component divided by 8000 bps and n equals the service bit rate divided by 16,000 bps.

Referring to fig. 14, the service component and the padding service component, if any, are preferably multiplexed within a 432 millisecond period of the frame 100. In contrast to the SCH 102, the portion 104 of the 432ms frame period that includes the service 261 is preferably divided into 432 data bit fields. Each bit field 270 is preferably provided with 8 bits from the service component N (1), N (2), …, N (N)_sc) And any bits filling the service component N (p), thereby multiplexing N_scThe individual service components and the filler service components thus constitute service 261. In this way, the bits of the respective service components are spread throughout the frame. It is advantageous to interleave the service components in each broadcast frame when burst errors occur. In the event of a burst error (bursterror), the service component, which is time-division multiplexed only within the broadcast channel frame and not interleaved, loses a large amount of data, while the interleaved component loses only a small portion.

The audio service component is preferably a digital audio signal compressed according to a Moving Picture Experts Group (MPEG) algorithm such as MPEG1, MPEG2, MPEG2.5 level 3, and subjected to low sampling frequency extension. MPEG2.5 layer 3 coding is well suited for high quality audio of 16 and 32 kbps. Level 3 coding incorporates higher spectral resolution and entropy coding. The digital audio signal preferably has a bit rate that is a multiple of 8000 bps and may be between 8000 and 128,000 bps. Possible sampling frequencies of the audio service component of the present invention are 48 kHz or 32 kHz defined by MPEG1, 24 kHz or 16 kHz defined by MPEG2, 12 kHz or 8 kHz defined by MPEG 2.5. The sampling frequency is preferably synchronized with the service component bit rate. The framing of the MPEG encoder is preferably synchronized to the SCH. Thus, the first bit of the audio service component within the broadcast channel frame 100 is the first bit in the MPEG header.

The digital service component contains other types of services other than audio services, such as pictures, audio services that do not conform to the features previously described in connection with the MPEG encoded audio service component, paging, file transfer data, and other digital data. The digital service component has a bit rate that is a multiple of 8000 bps and may be between 8000 and 128,000 bps. The digital service data is formatted to enable access to the service 261 using the data bit field defined in the SCH. The SCH data bit field is described below in connection with table 1.

The SCH includes four kinds of bit field groups, i.e., a service preamble, service control data, service component control data, and assistance data. According to the present invention, the contents of the SCH include the data shown in table 1.

Table 1-service control header
				Bit field group	Bit domain name	Length (position)	Content providing method and apparatus
Service preamble	Service preamble	20	0474B (hexadecimal)
				Service control data	Bit Rate Index (BRI) (BRI = n)	4	Service bit rate divided by kbps 0000: there is no legal data 0001: 16kbps 1000: 128 kbps 1001-1111: reserved for Future Use (RFU)
Service control data	Encryption control	4	0000: no encryption 0001: static key 0010: ES1, public key, predefined phase (subscriptionperiod) a (UC collection a shall be used) 0011: ES1, public key, predetermined stage B (UC set B should be used) 0100: ES1, public key, broadcast channel private key of predetermined phase a (UC set a should be used) 0101: ES1, public Key, broadcast channel private Key of predetermined stage B (UC set B shall be used)
				Service control data	Auxiliary bit field content indicator 1(ACI1)	5	00 (hexadecimal): unused or unknown 01 (hexadecimal): 16-bit encryption key selector 02 (hexadecimal): RDS PI code 03 (hexadecimal): associated broadcast channel index (PS flag and ASP)

			04 (hexadecimal) to 1F (hexadecimal): RFU
				Service control data	Auxiliary bit field content indicator 2(ACI2)	7	00 (hexadecimal): unused or unknown 01 (hexadecimal): 64-bit encryption key selector 02 (hexadecimal): a service tag; based onSequence 03 (hexadecimal) to 7F (hexadecimal) of ISO-latin 1: RFU
Service control data	Number of service components (N)sc)	3	000: one service component 001: two service components 111: eight service components
				Service control data	Auxiliary data bit field 1(ADF1)	16	Data fields, content defined by ACI1
Service control data	ADF2 Multi-frame Start Flag (SF)	1	1: first segment of multiframe or no multiframe 0: middle segmentation of multiframe
				Service control data	ADF2 segmentation offset and Length bit field (SOLF)	4	If SF =1 (first segment); SOLF includes multiple frame segmentsThe total number is reduced by one. 0000: one fragmented multiframe (or no multiframe) 0001: two-segment multiframe 1111: 16-segment multiframe if SF =0 (middle segment); SOLF contains segment offsets. SOLF value of 1, 2, …, multiframe division

			The total number of segments is-1.
				Service control data	Auxiliary data bit field 2(ADF2)	64	Data fields, content defined by ACI2
Service component control data	Service component control Domain (SCCF)	Nsc *32	Each service component hasAn SCCF; SCCF content see Table 3
				Auxiliary services	Dynamic label	The variable: n is*224-128-Nsc *32	Byte stream

The service preamble is preferably 20 bits long and is chosen to have good synchronization quality when implementing the autocorrelation technique. As shown in table 1, the service preamble is preferably 0474B in hexadecimal. The SCH also includes a Bit Rate Index (BRI), which is preferably 4 bits long and equal to the serving bit rate divided by kilobits per second. For example, "0000" may be used to indicate that no legitimate data (e.g., padding data that should be ignored) is being sent in the current frame. "0001" may be used to represent a BRI of 16kbps, and "000 (B)" may be used to represent a BRI of 128 kbps. Accordingly, BRI denotes the number of 16,000 bits per second components constituting one broadcast channel frame 100. The SCH preferably also includes a bit field for encryption control. For example, a 4-bit value may be used to indicate that the digital information in the portion of the current frame 100 corresponding to the service 104 of the SCH 102 is not encrypted. Other 4-bit binary values may be used to indicate that a certain key is used to encrypt the broadcast channel data. A public key and a private key that encrypts a particular broadcast channel may be used for encryption.

According to one aspect of the invention, the SCH 264 may be provided with an auxiliary data bit field (ADF1) and an auxiliary bit field content indicator (ACI1) to allow the service provider to control the specific functions associated with its service 261. The ADF1 and ACI1 between broadcast frames 100 may change at the discretion of the service provider. The ACI1 content is preferably an encryption key selector, a standardized radio data system or RDS code or data indexing an associated broadcast channel.

For encryption applications, two different keys may be used, one key being 16 bits in length for low security applications and the other key being 64 bits in length for high security applications. The actual 16-bit key is transferred in the ADF 1-bit field and the actual 64-bit key is transferred through another auxiliary data bit field referred to as "ADF 2" below, according to the key indicated by ACI 1. The use of a 16-bit key or a 64-bit key is chosen by the service provider. The key bit length between broadcast channel frames 100 may vary according to the desires of the service provider. The key selector in the ACI1 bit field may be an over-the-air (over-the-air) code of a decryption key that includes three parts: a user code indicating the user characteristics of the service, a hardware code uniquely identifying the wireless receiver and a wireless broadcast code or Key Selector (KS). Decryption of the encrypted service can only be done when all three parts are used. Radio data system codes (e.g., RDS PI codes) are currently used for frequency modulation or FM broadcasts. To prepare for simulcasting programs over FM wavelength frequencies, the service provider provides the RDS PI code in the ADF1 bit field.

According to one aspect of the invention, the service 261 in the broadcast channel may be designated as a primary service for a multi-broadcast channel service. Accordingly, the effective bandwidth of the service 261 can be extended by using the bandwidth of the secondary service related to the primary service. Other broadcast channels deliver the associated secondary services along with the primary service, which can be received by only requiring the wireless receiver 29 to be properly equipped (i.e., a receiver equipped with more than one channel recovery device). The ADF1 bit field is provided with information to distinguish primary and secondary services. The data preferably includes a primary/secondary flag or PS flag and an Associated Service Pointer (ASP) field. The PS flag is preferably set to 1(B) when the service 261 in the frame 100 belongs to a primary service and set to 0(B) when the service 261 is not a primary service. In other words, the primary service is delivered through a frame of another broadcast channel. The PS flag values and ASPs are shown in Table 2.

TABLE 2 auxiliary data bit field 1
			Assignment of value	Length (position)	Content providing method and apparatus
Is not used	4	0000
			Major/minor flag (PS flag)	1	1: main component 0: is not mainly
Correlation service pointer (SAP)	11	000 (hexadecimal): no other services are connected other: broadcast channel identification of related services (see time slot control channel)

Thus, if service 261 is a component of a secondary service or the primary and secondary services are not currently being transmitted, the PS flag in ADF1 of the SCH may be 0 (B). When a broadcast channel includes a primary service, a secondary service Broadcast Channel Identification (BCID) is provided to the ASP in the ADF1 bit field of the SCH of frame 100 in the broadcast channel. The BCID will be described in detail below. If more than two secondary services are associated with the primary service, the ASP domain in the ADF1 domain containing the SCH of the secondary service is provided with the BCID of the next secondary service. Otherwise, the BCID of the main service is provided for the ASP. And the PS flag in the ADF1 bit field of the SCH of frame 100 of the other broadcast channel containing the secondary service component is set to 0 (B). A wireless receiver 29 equipped with more than one channel recovery device may receive the primary and secondary channels. For example, these wireless receivers may play back audio programs received over a first channel and programs related to video received over another channel.

In accordance with another aspect of the present invention, another auxiliary data bit field, hereafter denoted ADF2, and an auxiliary bit field content indicator, hereafter denoted ACI2, are provided in the SCH 102 in each frame 100 of a single broadcast channel for transmitting the multi-frame information in the ADF2 through other broadcast channel frames 100. The segments comprising multiframe information need not be in consecutive broadcast channel frames. As described above, ACI2 includes bits indicating which of a plurality of 64-bit encryption keys is provided in ADF 2. ACI2 may also be provided with a service tag such as an international standards organization tag (e.g., an ISO-latin 1 based sequence). ADF2 includes a Start Flag (SF) and a segment offset and length bit field (SOLF) as shown in Table 1. The SF preferably has one bit and is set to a first value, such as "1," when the ADF2 includes a first segment of a sequence of multiple frames. ADF2 SF is set to "0" to indicate that the contents of ADF2 are middle segments of a multi-frame sequence. SOLF preferably has a length of 4 bits to indicate which of all the multi-frame segments is currently provided in the ADF2 bit field. SOLF may be used as a transition counter that indicates which of all of the multi-frame segments is currently being sent in ADF 2. The second auxiliary data field ADF2 is useful for sending text messages while sending wireless broadcasts. The text message may be displayed on a display device of the wireless receiver 29.

With continued reference to table 1, the service control header is also provided with information that controls the reception of the single service component within the broadcast channel frame at the radio receiver 29. The SCH is provided with a service component number bit field (N)_sc) To indicate the number of service components (e.g., service components 260 and 261 in fig. 13) that make up the service portion 104 (fig. 4) of the bitstream frame 100 produced at the broadcasting station 23. Preferably, 3 bits are used in the SCH to indicate the number of service components N_sc. Accordingly, according to the preferred embodiment, there may be eight service components in a frame. N on SCH_scPreferably, no padding bits, i.e. padding service components, are included in the parameters. The SCH is also provided with a service component control bit field, referred to as SCCF, which includes data for each component in the SCH. For each SCH, SCCF preferably has N_scx32 bits long. As illustrated in fig. 14, each broadcast channel frame 100 may include two or more service components multiplexed into each of a plurality of data bit fields 270. Referring to table 3, the SCCF includes data for each service component in the SCH so that the radio receiver 29 demultiplexes the service component. In other words, one SCCF is included for each service component SCH. According to the present embodiment, the SCCF is the only part of the SCH that is specific to each service component.

Table 3-service component control bit field
			Bit domain name	Length (position)	Content providing method and apparatus
SC Length	4	Service component bit rate divided by 8 kbps 0000: 8 kbps 0001: 16kbps 1111: 128 kbps
			Type SC	4	Service component type: 0000: MPEG encoded audio 0001: general data (no special format) 0100: JPEG encoded image (TBC) 0101: low bit rate video (h.263) 1111: illegal data other: RFU
Encryption flag	1	0: no encrypted service component 1: encrypting service components

		Note that: if ciphering control =0, the ciphering flag should be ignored
			Program type	15	Types of music, speech, etc
Language(s)	8	Service component language

As shown in table 3, each SCCF includes a 4-bit service component or SC-length bit field indicating the service component bit rate divided by 8000 bps. For example, "000 (B)" may represent an SC length of 1 × 8000 bps, and "111 (B)" may represent an SC length of 16 × 8000 bps or 128,000 bps. The SC length field is important for demultiplexing at the radio receiver 29 since the radio receiver 29 has no way of determining the location of the service component in the frame 100 other than the length of the data field 270 (fig. 14) without knowing the service component rate. Another bit field provided in the 32-bit SCCF is an SC-type bit field that is also preferably 4 bits in length. The SC type bit field identifies the type of service component. For example, "000 (B)" may indicate that the service component in the service portion 104 of the frame 100 is MPEG encoded audio. Other binary values may be used in the SC-type bit field to indicate that the service component is a JPEG encoded picture, low bit rate video (e.g., CCITT h.263 standard video), illegal data (i.e., data that should be ignored by wireless receiver 29), or other type of audio or data service. A 1-bit encryption flag is provided in the SCCF to indicate whether a particular service component is encrypted. The SCCF for each service component is also provided with a program type field including bits identifying the program type to which the service component belongs and a language field including bits identifying the language in which the program was generated. The program types may include music, voice, advertisements for prohibited products or services, and other programs. In this way, the country prohibited from drinking alcohol may use the program type bitfield to prevent the programming receiver 29 from receiving the alcohol-related advertisement transmitted by the broadcasting station 23, thereby ignoring the broadcast data having the specific program type bitfield code.

According to embodiments of the present invention described with reference to fig. 13-15 and tables 1-3, each broadcast channel of broadcast station 23 may have more than one service component (e.g., components 260 and 262). The waveforms and signaling protocols of the present invention are considered advantageous for a number of reasons. First, since each PRC is provided with a header that allows rate alignment on the satellite 25, the services 261 transmitted by different broadcast stations 23 do not have to be synchronized to the same unit rate reference. Thus, the broadcasting station 23 is less complex and less expensive, since it does not have to be able to synchronize with one single reference source. The bits of the individual service components are multiplexed, i.e. interleaved over the entire frame 100 in order to spread the service components over the entire frame 100. Thus, if a burst error occurs, only a small portion of the service component is lost.

As mentioned above, the SCH includes four different types of bit-field groups, three of which have been described. The set of auxiliary service type fields includes a variable length dynamic label byte stream. The length of the dynamic tag byte stream is preferably N × 224-128-N_scX 32. The dynamic tag byte stream is a serial byte stream used to transmit auxiliary information. The dynamic tag may include text and a wireless receiver screen and represent a universal serial byte stream. Changeable pipeIn other words, a dynamic tag byte appears on the entire broadcast channel as opposed to tuning to a particular service. For example, the dynamic tag byte stream may send a service menu that is displayed on the screen of the wireless receiver 29. Thus, the dynamic label byte stream represents another method of communicating with a wireless receiver, in accordance with the present invention, outside of the service portion 104 of each broadcast frame 100, and the auxiliary data fields ADF1 and ADF2 described above.

Fig. 15 provides a more detailed illustration of components 261, 264, 265, and 266 in the service layer of broadcast segment 250 of fig. 13. As shown in fig. 15, a broadcast channel includes one or more service components, generally designated 272, and these components are mixed as shown at 274. As shown at 276, the selected service components may be encrypted before a SCH 278 is appended to the service information. As shown in table 1, the SCH 278 includes a service preamble 280. The SCH 278 includes service component control data 282 containing an SCH bit field indicating the number of services in a frame and a service component control bit field or SCCF. The service control data 284 typically contains the SCH bit field with BRI and encryption control. Finally, SCH 278 provides secondary services 286, and secondary services 286 include secondary data fields ADF1, ADF2 and its associated fields ACI1, ACI2, and start flags and SOLF corresponding to data field ADF 2. The secondary services 286 also include a stream of dynamic tag bytes available in the SCH. The secondary service 286 provides a means of communicating with a wireless receiver over several frames within a broadcast channel when using the secondary data bit field ADF2, over frames within the SCH of two or more broadcast channels when using the secondary data bit field ADF1, and over the entire broadcast channel when using a dynamic tag byte stream. As shown in 288, the service information and the additional SCH are scrambled in order.

The data of the broadcast channel is preferably randomized using a Pseudo Random Sequence (PRS) generator or scrambler 290 as shown in fig. 16. It is preferable to use the scrambler 290 even when the service is encrypted. The scrambler generates a pseudo-random sequence that is applied to the broadcast channel in a bitwise modulo-2 fashionOver a sequence of frames. The pseudo-random sequence preferably has a generator polynomial X⁹+X⁵+1. The pseudo-random sequence is initialized in each frame 100 with the value 11111111 (binary), wherein the value 11111111111 (binary) is provided to the first bit of the frame 100. Thus, the scrambler 290 produces a reproducible random bit stream that is added to the broadcast bit stream at the broadcast station 23 to scramble or descramble bit strings having a 1 or 0 pattern that may cause demodulation failure at the wireless receiver 29. The same reproducible random bit stream is added a second time at the wireless receiver 29 to extract the bit stream from the received data.

Referring to fig. 13, the transport layer of the radio segment 254 has been described above in connection with fig. 10, as indicated at 292 and 294, which is required to extract symbols from the received TDM data stream and, as indicated at 296, to remix the symbols into corresponding broadcast channels. For the service layer of radio segment 254 (fig. 13), the service components and SCH 102 from the service portion 104 of one frame 100 are now described in connection with fig. 17.

As shown in fig. 16, a modulo-2 scrambler 290 is used to remove scrambling from the bit stream comprising the plurality of frames 100, thereby extracting the pseudo-random sequence from the input bit stream as shown at 298. The service control header 278 is then extracted before decrypting those service components encrypted at the broadcast station 23, as shown at 300. As shown in fig. 15 and 17, dynamic control, as shown by blocks 273 and 275 in fig. 15 and blocks 301 and 303 in fig. 17, is provided for each service to allow the service provider to selectively control the content of the SCH 278. In other words, the service provider can change the encryption control information in the SCH on a frame-by-frame basis, and even on a service component-by-service component basis. Similarly, a service provider may change the contents of the auxiliary data fields ADF1, ADF2, and their corresponding associated fields (i.e., ACI1 for ADF1, ACI2 for ADF2, SF, and SOLF). As described above, if a multi-frame information sequence can be transmitted using the bit-field ADF2 in addition to encryption control, the association between the primary broadcast service and one or more secondary broadcast services can be dynamically changed.

The transport layer of broadcast segment 256 will now be described in conjunction with fig. 18, with respect to the service layer previously described in conjunction with fig. 15. The transport layers of broadcast segment 250 preferably include an outer transport layer 306, a communication link transport layer 308, and an inner transport layer 310. The outer transport layer 306 may be remote from the inner transport layer 310. The communication line transport layer 308 contains all functions necessary for transmission over the communication line. Within the transport layer, the broadcast channel is preferably Forward Error Correction (FEC) encoded using a tandem Reed-Solomon coding and interleaving method, as shown at 312 and 314, before being demultiplexed into primary channels having a service rate equal to 16 kbits per second. Accordingly, as shown in fig. 18, the FEC encoded broadcast channel is sent as a protection broadcast channel between the outer transport layer 306 and the inner transport layer 310.

Fig. 19 illustrates a bit stream processed by the outer transport layer 306 and a bit stream processed by the inner transport layer 310. The broadcast channel 316 and the primary rate channel 318 are preferably derived from the same clock reference. And Reed-Solomon coding and interleaving is preferably synchronized with the SCH. The primary rate channel of a broadcast channel is preferably time synchronized such that the position of the service preamble described above in connection with table 1 is referred to as the primary rate channel preamble as shown in fig. 4.

Reed-Solomon (255, 223) encoding at the broadcasting station 23 (e.g., 80a in fig. 3) is preferably performed in 8-bit symbol fashion and is used as outer coding for the tandem coding process.

The code generator polynomial is preferably:

wherein α is F (x) = x⁸+x⁴+x³+x²+1 root.

Using a substrate {1, α¹，α²，α³，α⁴，α⁵，α⁶，α⁷And (6) coding is carried out.

The individual symbols are interpreted as:

{u₇，u₆，u₅，u₄，u₃，u₂，u₁，u₀}，u₇is the Most Significant Bit (MSB),

wherein u is_iIs alphaⁱRespectively, and accordingly:

u₇*α⁷+u₆*α⁷+u₅*α⁵+u₄*α⁴+u₃*α³+u₂*α²+u₁*α+u₀

the encoding is systematic, i.e. the first 223 symbols are information symbols. Before encoding, the first symbol and x are timed²²³Associating, last symbol with x⁰And (6) associating. The last 32 symbols are redundant symbols. After encoding, the first symbol and x are timed³¹Associating, last symbol with x⁰And (6) associating.

A block interleaver with a depth of preferably 4 Reed-Solomon (RS) blocks is used as interleaver 314 in the tandem coding process. The RS encoding 314 and interleaving 314 are preferably as follows:

set 1: sy (1), Sy (5), Sy (9),., Sy (1+ 4)^*m),.., Sy (889); m ranges from 0 to 222

Set 2: sy (2), Sy (6), Sy (10),., Sy (2+ 4)^*m),.., Sy (890); m ranges from 0 to 222

Set 3: sy (3), Sy (7), Sy (11),.., Sy (3+ 4)^*m),.., Sy (891); m ranges from 0 to 222

Set 4: sy (4), Sy (8), Sy (12),., Sy (4+ 4)^*m),.., Sy (892); m ranges from 0 to 222

As shown at 324, 326, 328 and 330 in fig. 20, each set is augmented with redundant data of the next 32 symbols (8 bits).

Set 1: r (1), R (2), R (3),.., R (32)

Set 2: r (33), R (34), R (35),.., R (64)

Set 3: r (65), R (66), R (67),.., R (96)

Set 4: r (97), R (98), R (99), R (128)

Accordingly, the output symbol stream 332 has the following content, Sy (1), Sy (2), Sy (3),. ann, Sy (892), R (1), R (33), R (65), R (97), R (2), R (34), R (66),. ann, R (j), R (j +32), R (j +64), R (j +96),. ann, R (32), R (64), R (96), R (128), j is from 1 to 32 as shown in fig. 20. Thus, as shown at 334 of FIG. 19, the guard broadcast channel frame receives 1024 bits per 7136 bits of broadcast channel 316 due to Reed-Solomon redundancy. The first bit of Sy (1) is preferably the first bit of the service preamble (table 1) of the broadcast channel.

As shown in fig. 21, for the interleaving 314 performed in the outer transmission layer 306 of the broadcasting station 23, a Viterbi convolutional code (rate 1/2, k =7) is preferably used as an inner code of the tandem coding process of the outer transmission layer 306. The generator polynomial is g₁=1111001 binary (B) and g₂=1011011 (B). Each block 336 in fig. 21 represents a unit delay. The modulo-2 adder shown at 338 and a transformer 340 are implemented such that the output of the encoder shown in fig. 21 is preferably g₁And g₂. For each input bit, a symbol is preferably generated with switch "Sw" in position 1, followed by a symbol with the switch in position 2.

The Viterbi encoder 342 shown in fig. 18 generates a bit stream that is sequentially demultiplexed in the inner transport layer 310. As shown in fig. 22, demultiplexer 344 preferably divides the encoded broadcast channel into primary rate channels, each having a bit rate of 38000 bps. Referring to fig. 19, the protection broadcast channel frame includes n × 8160 bits in total, i.e., n × 7136 bits of the broadcast channel and 1024 bits of Reed-Solomon redundancy as shown in 346 of fig. 22. For demultiplexing, the symbols S (1), S (2), etc. are all dibit symbols from the FEC encoded broadcast channel. S (1) is preferably inserted into the first symbol of the first primary rate channel as shown at 348 of fig. 22. Thus, as shown at 350 in FIG. 22, demultiplexing causes the content of the ith primary rate channel to become

S(i)，S(i+n)，S(i+2^*n)，...，S(i+p^*n)，...，S(i+8159^*n)

Where p is from 0 to 8159. The broadcast channel is preferably demultiplexed into n primary channels. The number of bits from the FEC encoded broadcast channel provided in the respective primary rate channel per frame period is preferably 16, 320. As shown at 352 in fig. 18, the primary rate channels are then each provided with a primary rate channel preamble. The primary rate channel preambles within a broadcast channel are preferably all time consistent. As illustrated in fig. 4, the primary rate channel preamble length is preferably 96 bits or 48 symbols. The primary rate channel preamble preferably has a value of 14C181EA649 (hexadecimal), where the most significant bit is the first bit to be transmitted. The primary rate channel preamble is preferably comprised of a 48-bit sequence generated at the same time on the I and Q components of QPSK modulation 86 (fig. 3).

When a protection broadcast channel is not available, it is preferable to generate an empty broadcast channel in the inner transport layer 310. The null guard broadcast channel has the same bit rate and frame period as the broadcast channel it replaces. The null guard broadcast channel contains a pseudo-random sequence and an SCH limited to a service preamble, and a BRI padded with 0. The pseudo-random sequence is generated using a generator such as the PRS generator 290 described in fig. 16 and the same generator polynomial described above.

As described above, the communication line transport layer 308 is preferably transparent to protect the broadcast channel digital format. This transport layer 308 establishes a connection between the inner and outer transport layers 310 and 306, which may be in different locations. Accordingly, the communication line transport layer 308 may contain communication lines. The outer transport layer 306 is used to protect the signal from communication line errors. A higher level of protection is possible if the communication line generates a lot of errors. For example, the protected broadcast channel may be protected with another FEC encoding, or the received protected broadcast channel may be Reed-Solomon decoded and error corrected and Reed-Solomon encoded before reaching the inner transport layer 310.

As described above, the system 10 of the present invention includes a processing task and a transparent task. The transport layers of the broadcast segment 250 of the transparent task preferably include a broadcast segment transport layer and a spatial segment transport layer that process the task. Since all broadcast channels are from a common hub, there is no need for extensive broadcast signal realignment (i.e., frame rate alignment at satellite 25) in the transparent task. Thus, there is no time difference between the plurality of broadcasting stations 23.

The transport layers of spatial segment 252 in fig. 13 are now described. As shown at 354 in fig. 13, the spatial segment transport layer receives a primary rate channel from the broadcasting station 23. A spatially segmented transport layer, generally indicated at 356, is illustrated in fig. 23. As shown in fig. 7, the primary rate channels are rate aligned before being routed to selected downlink beams and multiplexed for time division multiplexed downlink transmission. The rate alignment process is shown at 356 in fig. 23. Switching and routing is done on the satellite and shown in fig. 8 as 358, while time division multiplexing is shown as 360. A time slot control channel 362 is inserted into the time division multiplexed or TDM bit stream at the level of the spatial segment 252. The Slotted Control Channel (TSCC) is described in more detail below. The multiplexed primary rate channel and TSCC 362 is scrambled as shown at 364 before appending a main frame preamble as shown at 366, which is used for TDM synchronization at the wireless receiver 29. As shown in fig. 24, the TDM frame period is preferably 138 msec. The main frame preamble length is preferably 192 bits or 96 symbols. The slotted control channel preferably comprises 4224 bits.

The symbol rate alignment process performed on the satellite 25 and shown in fig. 7 is now described using fig. 25. Rate alignment is performed between the individual uplink channels received from the broadcast stations 23 to correct for time differences between the bit rate references of the various broadcast stations 23 and the satellite TDM rate references. The rate alignment procedure is advantageous since it is not necessary to synchronize all broadcast stations 23 to a single bit rate reference. In this way, the broadcast station can operate with less complex equipment, thereby reducing costs. As shown in fig. 7, the rate alignment procedure includes the step of adjusting the length of the primary rate channel by adding a bit at the beginning of a preamble, dropping a bit or neither adding nor dropping a bit. PRC bit stream 368 indicates when there is no delay between the satellite bit rate reference and the reference of the broadcast station 23 that transmitted the received primary rate bit channel or PRC bit stream. The PRC bit stream, shown as 370, illustrates the process of inserting a 0 into the preamble, which produces a 49 symbol preamble to be corrected when the broadcast station bit rate reference lags the reference of the satellite by one symbol. When the satellite bit rate reference lags the reference of the broadcast station by one symbol, a 0 is cleared from a 48 symbol PRC preamble, as shown at 372, resulting in a 47 symbol preamble.

With continued reference to fig. 23, TSCC 362 preferably includes a TDM identification 374 and a timeslot control word 376 for timeslots 1 through 96. TSCC 362 is shown in fig. 26. TSCC multiplex 362 preferably includes 233 8-bit symbols. The TDM identification 374 and the timeslot control word or TSCW 376 for 96 timeslots are preferably each 16 bits long. TSCC multiplex 362 also includes one set of 232 bits that make up rounding sequence 378. The rounding sequence 378 includes odd-numbered 0's and even-numbered 1's. The first bit sent is preferably the most significant bit and the slot control word, which is also 1.96 slots, includes a field of bits as shown in table 4.

TABLE 4 time Slot control words
				Bit field group	Bit domain name	Length (position)	Content providing method and apparatus
Broadcast Channel Identification (BCID)	BCID type	2	00: local BCID 01: regional BCID 11: BCID10 worldwide: extension to BCIDs worldwide
				BCID number	9	00000000: reserved 11111111 for unused channels: channel reservation for testing
	-	Last primary rate channel flag	1				0: non-final primary rate channel 1 of the broadcast channel: last primary rate channel of broadcast channel
-				Recognized format	2	00: WordStar 1 otherwise: RFU
	-	Broadcast audience	1				0: public audience 1: special audience
-				Retention	1	RFU

Each broadcast channel is preferably identified by a unique Broadcast Channel Identification (BCID) consisting of a BCID type and a BCID number. The BCID types preferably include a local BCID, a regional BCID, a world-wide BCID and an extension to the world-wide BCID. The BCIDs worldwide indicate that the BCID of a particular broadcast channel is legitimate for any time-division multiplexed bit stream within any geographic region. In other words, the BCID identifies a specific broadcast channel for a wireless receiver 29 located anywhere in the world and operating on any time division multiplexed carrier of any downlink beam. As mentioned above, each satellite 25 preferably transmits signals via three downlink beams, each beam having two differentially polarized TDM carriers. Regional BCIDs are legal for a particular geographic area where the same BCID can be used to uniquely identify another broadcast channel in another geographic area. Regional BCIDs are legal on any TDM downlink in a particular region. The local BCID is legal for only one specific TDM carrier in one specific area. As such, the same BCID may be used on another beam within the same geographic region, or may be used in another region to identify other broadcast channels.

With continued reference to FIG. 5, the contents of TDM identification 374 includes an area identification and a TDM number. The region identifier uniquely identifies a region of the received TDM bit stream. For example, an area may be a geographic region served by the downlink of a first satellite covering a substantial portion of the continental africa. The region identifier may uniquely identify the region served by the satellite covering asian and caribbean regions, respectively. The TDM number bit field in TDM id 374 defines a particular TDM bit stream. The odd TDM number is preferably used for left hand polarization (LHCP) TDM, and the even TDM number is preferably used for right hand polarization (RHCP) TDM.

TABLE 5 TDM identification
			Bit domain name	Length (position)	Content providing method and apparatus
Region identification	4	0000: reservation 0001: non-star 0010: asian 0100: caribbistat otherwise: RFU

TDM number	4	0000: reservation 0001: TDM1(LHCP) 0010: TDM2(RHCP) 0110: TDM6(RHCP) other: RFU notes: odd TDM numbers are used for left hand polarization (LHCP) TDM and even TDM numbers are used for right hand polarization (RHCP) TDM
			Retention	6	RFU

The TSCC multiplex is preferably encoded in 8-bit symbols using Reed-Solomon (255, 223) coding, as shown in block 380 of fig. 23. The code generator polynomial is preferably

Wherein α is F (x) = x⁸+x⁷+x²+ x + 1.

Using a substrate {1, α¹，α²，α³，α⁴，α⁵，α⁶，α⁷And (6) coding is carried out. The individual symbols are interpreted as:

{u₇，u₆，u₅，u₄，u₃，u₂，u₁，u₀}，u₇is MSB, where u_iIs alphaⁱRespectively, and accordingly:

u₇*α⁷+u₆*α⁷+u₅*α⁵+u₄*α⁴+u₃*α³+u₂*α²+u₁*α+u₀

Reed-Solomon coding is systematic, i.e., the first 223 symbols that make up the TSCC multiplex are information symbols before coding. Timing the first symbol and x²²²Associating, last symbol with x⁰And (6) associating. The last 32 symbols are the encoded redundancy symbols. Timing the first symbol and x³¹Associating, last symbol with x⁰And (6) associating.

As shown in fig. 23, interleaving is not performed before Viterbi encoding 382 is performed. A 72-bit rounding bit set is added after the 255-symbol Reed-Solomon block before Viterbi encoding. The 72-bit rounding bit group includes "0" for all odd bits and "1" for even bits. The first bit sent is preferably the MSB, which is a "1". The Viterbi codes with R =1/2 and k-7 are used with the same features as described above in connection with the Viterbi codes on the broadcasting station 23. The Viterbi encoding is synchronized with the main frame preamble such that the first bit following the main frame preamble is the first bit submitted by the Viterbi encoder, which is affected by the first bit of RS encoded data. During initialization of the Viterbi encoder, the register in the Viterbi encoder is set to 0, wherein initialization of the Viterbi encoder is performed after the preamble of the main frame and before the first bit of the multiplexed bit stream occurs.

As shown in block 366 of fig. 23, a main frame preamble is inserted into the serial symbol TDM stream. The main frame preamble comprises a unique word and is preferably composed of a sequence of 96 bits with the same time synchronization on the I and Q components of the QPSK modulated signal. The scrambling process (block 364) can be implemented using a PRS generator 384 as shown in fig. 27 and the data can be randomly spread across the TDM carrier. Scrambler 384 generates a pseudo-random sequence that is preferably modulo-2 added to the TDM frame sequence in symbol-by-symbol steps. A symbol of pseudo-random sequenceThe number consists of two consecutive bits from the descrambler 384. The pseudo-random sequence may have one such as x¹¹+x²A generator polynomial of + 1. The pseudo-random sequence may be initialized in each frame with a value such as 11111111 (binary), where the value 11111111111 (binary) is provided to the first bit of the I component after the preamble of the main frame.

The transport layer of the radio segment 254 is shown in fig. 28a, 28 b. The radio segment transport layer receives the TDM main frame preamble from the physical layer of the radio receiver 29 (block 386). The operations performed in the transport layer are the inverse of the operations performed in the spatial segment (fig. 23) and the broadcast segment (fig. 18). After descrambling (388), data from the time slot control channel (390) is used to identify and select TDM time slots belonging to the same broadcast channel to which the wireless receiver is tuned. A Viterbi decoder (block 392) is used to clear the encoding performed at the satellite and described above in connection with block 382 in fig. 23. Also, a Reed-Solomon decoder (block 394) decodes the encoding performed at the spatial station and described above in connection with block 380 of fig. 23. The TDM time slots belonging to a selected broadcast channel are then demultiplexed to obtain primary rate channels, as shown in block 396. Demultiplexing is illustrated by blocks 294, 296 in fig. 13 and in connection with fig. 10. Referring to blocks 398 and 400 in fig. 28b, the primary rate channels are rate aligned using the heads of the single primary rate channel, as previously shown in fig. 11. After primary rate channel synchronization and re-multiplexing (block 402), Viterbi decoding is performed (block 404) to clear the coding performed in the transport layer of the broadcast segment and described above in connection with block 342 in fig. 18. The symbol order is deinterleaved (block 406) and decoded using a Reed-Solomon decoder (block 408), which is performed at the outer transport layer 306 of the broadcast segment to obtain the inverse of the broadcast channel processing of the broadcast channel. Thus, a received time division multiplexed bit stream is descrambled to correct errors in the TDM transmission, decoded to recover the broadcast channel, and then descrambled to correct broadcast channel errors.

While the foregoing has been with a selection of certain advantageous embodiments for the purposes of illustration, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims (72)

1. A method of formatting a signal for broadcast transmission to a remote receiver, comprising the steps of:

receiving a service having at least a first service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols;

dynamically controlling reception of said service at said remote receiver by generating a broadcast channel bitstream frame by appending a service control header to said service, said service control header including service control data;

wherein said service comprises a total bit rate of K bits per second, said total bit rate corresponding to n times a minimum bit rate of L bits per second, said frame period being M seconds, said service having a rate of nxlxm = nxp bits per frame, said frame comprising nxp bits of said service and nxq bits of said service control header, wherein K, n, L, M, P and Q are numerical values, respectively.

2. The method of claim 1, further comprising the step of providing said service control header with first service component control data for dynamically controlling reception of said first service component at said remote receiver.

3. The method of claim 2 wherein said service comprises a second service component, and further comprising the step of providing said service control header with second service component control data for dynamically controlling reception of said second service component at said remote receiver.

4. The method of claim 3, wherein at least one of said first service component control data and said second service component control data comprises at least one of a plurality of bit fields including a service component length bit field, a service component type bit field, an encryption bit field, a program type bit field, and a language bit field, wherein said service component length bit field indicates a bit rate for a corresponding one of said first service component and said second service component, said service component type bit field indicates which of a plurality of signals is included in said corresponding one of said first service component and said second service component, said encryption bit field indicates which of a plurality of encryption methods was used to encrypt said corresponding one of said first service component and said second service component, the program type field indicates which of a plurality of programs is transmitted through a corresponding one of the first service component and the second service component, and the language field indicates in which of a plurality of languages the corresponding one of the first service component and the second service component is generated.

5. The method of claim 4 further comprising the step of providing said service component length bit field with n bits for indicating said bit rate of a corresponding one of said first service component and said second service component, said bit rate being a multiple of m bits per second, wherein 1 ≦ said multiple ≦ 2ⁿM bits per second is the minimum bit rate, n and m are values, the contents of said service component length bit field having values corresponding to said multiple between 0 and 2ⁿA binary number of values in between.

6. The method of claim 5, further comprising the steps of:

receiving said frame at said remote receiver;

demultiplexing a corresponding one of the first service component and the second service component from the frame using the service component length position.

7. The method of claim 5, wherein n =4 bits and m-8000 bits per second.

8. The method of claim 4, further comprising the step of providing said service component type field with one of a plurality of values corresponding to a corresponding one of said plurality of signals, said plurality of signals including Moving Picture Experts Group (MPEG) encoded audio, general purpose data without special formats, Joint Photographic Experts Group (JPEG) encoded image data, video and illegal data.

9. The method of claim 4, further comprising the step of providing a first value and a second value for said encrypted bit field when a corresponding one of said first service component and said second service component is encrypted and unencrypted, respectively.

10. The method of claim 4 further comprising the step of providing said program type field with one of a plurality of values corresponding to a respective one of said plurality of programs, said plurality of programs including music, talk show broadcasts, video, text, programs under review, advertisements and programs on a specified topic.

11. The method of claim 4, further comprising the step of providing said language bitfield with one of a plurality of values corresponding to a respective one of said plurality of languages.

12. The method of claim 1, wherein said service includes a second service component, and further comprising the steps of:

dividing at least a portion of said frame into data bit fields;

interleaving at least a portion of said first service component and said second service component into respective ones of said data bit fields.

13. The method of claim 12, wherein said first service component and said second service component have a bit rate that is a multiple of L/2 bits per second, said interleaving step comprising the step of adding padding bits to each data bit field when said multiple of L/2 bits per second is an odd number.

14. A signal comprising broadcast information transmitted in a carrier wave broadcast to a remote receiver, said signal comprising a broadcast channel bit stream frame generated by appending a service control header to a service, said service having at least a first service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said service control header comprising service control data for dynamically controlling reception of said service at said remote receiver, said service comprising a total bit rate of K bits per second, said total bit rate corresponding to n times the minimum bit rate of an L bit per second, said frame period being M seconds, said service having a rate of n x L x M = n x P bits per frame, said frame comprising n x P bits of said service and n x Q bits of said service control header, wherein K, n, L, M, P and Q are numerical values, respectively.

15. The signal of claim 14 wherein said total bit rate K for said service is between 16 kbits per second and 128 kbits per second, said minimum bit rate L for said service is 16 kbits per second, n is an integer of 1 ≦ n ≦ 8, said frame period M is 432 milliseconds, P is 6912, Q is 224, said frame includes n x 6912 bits for said service and n x 224 bits for said service control header for a total of n x 7136 bits.

16. A signal according to claim 15, wherein said service includes a first service component and a second service component, at least a portion of said frame being divided into 432 data fields of approximately 1 millisecond duration, each of said data fields having n x 16 bits, said first service component and said second service component being interleaved into each of said data fields.

17. A method of formatting a signal for broadcast transmission to a remote receiver, comprising the steps of:

receiving a service having at least a first service component selected from the group of service components consisting of a digitized audio signal, an analog audio signal and an analog signal;

digitizing said first service component if said first service component is an analog signal;

the first service component is compressed using a source coding method selected from the group of coding methods consisting of Moving Picture Experts Group (MPEG)1, MPEG2, MPEG2.5 and MPEG2.5 level 3.

18. The method of claim 17, wherein said compressing step comprises the step of sampling said first service component at a sampling frequency synchronized to a bit rate of said first service component.

19. The method of claim 18, further comprising the step of dynamically controlling reception of said service at said remote receiver by generating a broadcast channel bit stream frame by appending a service control header to said service, said service control header including service control data for dynamically controlling reception of said service at said remote receiver.

20. The method of claim 19, further comprising the step of synchronizing framing operations of an MPEG encoder to said service control header, said broadcast channel bitstream frames being capable of transmitting MPEG frames generated by said MPEG encoder as sub-frames thereof.

21. The method of claim 20, wherein said synchronizing step includes the step of aligning a first bit of said first service component with a first bit of a frame header generated by said MPEG encoder.

22. A signal comprising broadcast information transmitted in a carrier wave broadcast to a remote receiver, said signal comprising a broadcast channel bitstream frame generated by appending a service control header to a service, said service having at least one service component selected from the group of service components consisting of a digitized audio signal, an analog audio signal and an analog signal, said service component being digitized in the event that said service component is an analog signal and compressed using a source coding method selected from the group of coding methods consisting of Moving Picture Experts Group (MPEG)1, MPEG2, MPEG2.5 and MPEG2.5 layer 3, said service control header comprising service control data for dynamically controlling the reception of said service at said remote receiver, said source coding having framing operations synchronized with said service control header, the broadcast channel bitstream frame can transmit an MPEG frame generated by the source coding as a subframe thereof.

23. A method of formatting a signal for broadcast transmission to a remote receiver, comprising the steps of:

receiving a service having at least a first service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols;

dynamically controlling reception of said service at said remote receiver by adding a service control header to said service to generate a broadcast channel bit stream frame, said service control header comprising service control header data selected from the group of bits consisting of a preamble indicating the start of said frame, a bit rate index indicating the bit rate of said service, encryption control data, an auxiliary data bit field, an auxiliary bit field content indicator relating to the content of said auxiliary data bit field, data relating to the number of frames in said auxiliary data bit field when multiplexing said auxiliary data bit field, and data indicating the number of service components making up said frame.

24. The method of claim 23, wherein said preamble is one of a binary number and a hexadecimal number selected to effectively auto-correlate upon receipt of said frame and to enable synchronization of said frame.

25. The method of claim 24, wherein said preamble comprises 20 bits and corresponds to 0474B hexadecimal.

26. The method of claim 23, wherein said generating step comprises dividing said total rate of service into n rates that are multiples of a minimum bit rate of L bits per second, where n and L are numerical values, said bit rate index comprising one of a binary number and a hexadecimal number representing said numerical value n.

27. The method of claim 23 wherein L is 16000, said total rate for said service is n times 16 kbits per second, n is an integer of 1 ≦ n ≦ 8, said bit rate index comprises four bits, wherein binary 0000 indicates that said service is not transmitting legitimate data, and binary numbers 0001, 0010, 0011, 0100, 0101, 0111, and 1000 indicate that said total rate for said service is 16 kbits per second, 32 kbits per second, 48 kbits per second, 64 kbits per second, 80 kbits per second, 96 kbits per second, 112 kbits per second, and 128 kbits per second, respectively.

28. The method of claim 23, wherein the encryption control data includes encryption method data indicating which of a plurality of encryption methods is used to encrypt the service, the remote receiver being capable of decrypting the service using the encryption method data.

29. The method of claim 23, further comprising the step of encrypting a broadcast channel containing said service and said service control header, and a plurality of broadcast channels containing different services and corresponding service control headers, said encryption control data including bits instructing said remote receiver to decrypt a key type required for a corresponding one of said broadcast channels and said plurality of broadcast channels, said key type being selected from a key set consisting of a static key, a public key and a private key, said static key being used to encrypt said service in said broadcast channel and broadcast said service to a selected one of said remote receivers, said remote receivers decrypting using said static key, said public key being used to decrypt all of said plurality of broadcast channels at all of said remote receivers, wherein said plurality of broadcast channels are encrypted using the same encryption method, said private key being used to decrypt said broadcast channels at all of said remote receivers when said broadcast channels are encrypted using a selected encryption method.

30. The method of claim 23, further comprising the step of transmitting auxiliary data related to said service via said auxiliary data bit field of a service control header, said auxiliary bit field content indicator including bits indicating that said auxiliary data is encrypted and a key used to encrypt said auxiliary data.

31. The method of claim 23, further comprising the step of transmitting a Radio Data System (RDS) PI code for Frequency Modulation (FM) broadcasting through said auxiliary data bit field of the service control header, said auxiliary bit field content indicator including bits indicating that said auxiliary data bit field includes said RDS PI code.

32. The method of claim 23, wherein said service corresponds to a primary service transmitted to said broadcast remote receiver over a primary broadcast channel, the method further comprising the steps of:

receiving a second service having at least one service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said second service being transmitted to said remote receiver over a secondary broadcast channel;

generating a second broadcast channel bitstream frame by appending a second service control header to said second service, thereby dynamically controlling reception of said second service at said remote receiver;

providing a bit in the service control header corresponding to the primary broadcast channel indicating to the remote receiver that the primary broadcast channel relates to the secondary broadcast channel.

33. The method of claim 32, further comprising the steps of:

assigning an identification code to said primary broadcast channel and said secondary broadcast channel, said identification code uniquely identifying a corresponding one of said primary broadcast channel and said secondary broadcast channel;

providing the identification code corresponding to the second broadcast channel to the service control header of the primary broadcast channel.

34. The method of claim 33 wherein a third broadcast channel is transmitted, the third broadcast channel being related to said primary broadcast channel and having an identification code uniquely identifying said third broadcast channel, the method further comprising the steps of:

generating another of said broadcast channel bitstream frames;

modifying the service control header of the primary broadcast channel to include the identification code corresponding to the third broadcast channel to indicate that the third broadcast channel is associated with the primary broadcast channel in place of the secondary broadcast channel.

35. The method of claim 33 wherein a third broadcast channel is transmitted which is also related to said primary broadcast channel and has an identification code which uniquely identifies said third broadcast channel, the method further comprising the steps of:

generating another of said broadcast channel bitstream frames;

modifying said service control header of said secondary broadcast channel to include said identification code corresponding to said third broadcast channel to indicate that said third broadcast channel also relates to said primary broadcast channel.

36. The method of claim 35, wherein said providing step further comprises the steps of:

providing a bit in said service control header of said primary broadcast channel indicating that said primary broadcast channel is a primary broadcast channel related to other broadcast channels;

providing a bit in each of the service control headers corresponding to the secondary broadcast channel and the third broadcast channel indicating a relationship with the primary broadcast channel.

37. The method of claim 32, further comprising assigning a geographic-specific identification code to said primary broadcast channel and said secondary broadcast channel to uniquely distinguish said primary broadcast channel and said secondary broadcast channel from each other and among a plurality of broadcast channels received in a selected one of a plurality of geographic areas.

38. The method of claim 37 further comprising providing said service control header of said primary broadcast channel with at least one bit indicating which of a plurality of different identification code types corresponds to said geographic-specific identification code, said plurality of different identification code types corresponding to a respective one of said plurality of geographic regions.

39. The method of claim 32, further comprising the step of assigning identification codes to uniquely distinguish said primary broadcast channel and said secondary broadcast channel from each other and among a plurality of broadcast channels received in a local area, a regional area and throughout the world, and said providing step comprises the step of adding at least two bits to said service control header of said primary broadcast channel indicating which of a plurality of different identification code types corresponds to said identification codes, said code type being selected from the group of types consisting of a local code, a regional code and a worldwide code, said local code being used to uniquely identify a channel of said plurality of broadcast channels to which a spot beam of a satellite transmitter is transmitted to a geographic region, said regional code identification being transmitted over a predetermined continuous geographic region and a region of predetermined discontinuous geographic regions One of the plurality of broadcast channels, the world wide code being used to distinguish the second broadcast channel from others of the plurality of world wide transmitted broadcast channels.

40. The method of claim 32, wherein said providing step includes the step of providing a bit in said auxiliary bit field content indicator of said service control header indicating to said remote receiver that said primary broadcast channel relates to said secondary broadcast channel.

41. The method of claim 40, further comprising the steps of:

assigning an identification code to each of said primary broadcast channel and said secondary broadcast channel, said identification codes each being capable of uniquely distinguishing a corresponding one of said primary broadcast channel and said secondary broadcast channel;

inserting said identification code corresponding to said secondary broadcast channel into said secondary data bit field of said primary broadcast channel;

inserting the identification code corresponding to the primary broadcast channel into the secondary data bit field of the secondary broadcast channel.

42. The method of claim 40 further comprising the step of inserting broadcast channel identification data identifying said secondary broadcast channel in said ancillary data bit field.

43. The method of claim 42 wherein said broadcast channel identification data includes an identification code uniquely identifying said secondary broadcast channel, said inserting step further comprising the step of selecting said identification code uniquely distinguishing said secondary broadcast channel from a plurality of broadcast channels received in a selected one of a plurality of geographic regions.

44. The method of claim 32 wherein said secondary data field in each of said service control header and said second service control header includes a primary/secondary (PS) flag, the method further comprising the steps of:

setting said PS flag to a first value when said frame corresponding to one of said service control header and said second service control header is a component of said primary broadcast channel;

setting the PS flag to a first value when the frame corresponding to one of the service control header and the second service control header is a component of the secondary broadcast channel, the remote receiver being capable of identifying whether a receiving broadcast channel is a primary broadcast channel or a secondary broadcast channel using the PS flag.

45. The method of claim 32, further comprising the steps of:

assigning an identification code to each of said primary broadcast channel and said secondary broadcast channel, said identification codes each being capable of uniquely distinguishing a corresponding one of said primary broadcast channel and said secondary broadcast channel;

providing an associated service indicator (AS) corresponding to the identification code of the secondary broadcast channel for the auxiliary data bit field corresponding to the primary broadcast channel.

46. The method of claim 45, wherein a third broadcast channel is transmitted, the third broadcast channel being related to the primary broadcast channel, the method further comprising the steps of:

generating another of said broadcast channel bit stream frames of said primary broadcast channel;

modifying the service control header of the primary broadcast channel to include the identification code corresponding to the third broadcast channel to indicate that the third broadcast channel is associated with the primary broadcast channel in place of the secondary broadcast channel.

47. The method of claim 45, wherein a third broadcast channel is transmitted, the third broadcast channel also being related to said primary broadcast channel, the method further comprising the steps of:

generating another of said broadcast channel bit stream frames on said secondary broadcast channel;

modifying said service control header of said secondary broadcast channel to include said identification code corresponding to said third broadcast channel to indicate that said third broadcast channel also relates to said primary broadcast channel.

48. The method of claim 47 further comprising the step of providing said service control header of said third broadcast channel with an identification code corresponding to said primary broadcast channel.

49. The method of claim 48, wherein said providing step further comprises the steps of:

providing a bit in said service control header of said primary broadcast channel indicating that said primary broadcast channel is a primary broadcast channel and that other broadcast channels are associated therewith;

providing a bit in each of the service control headers corresponding to the secondary broadcast channel and the third broadcast channel indicating a relationship with the primary broadcast channel.

50. The method of claim 23, wherein said service control header is provided with bits that are displayed on a display device that is connected to at least one of said remote receivers.

51. The method of claim 50, wherein said providing step includes the step of providing said auxiliary bit field content indicator in said service control header with bits displayed on a display device connected to at least one of said remote receivers.

52. The method of claim 50, wherein said bits comprise a standard serial service tag displayed on said display device.

53. The method of claim 23, further comprising the step of providing data relating to said service to said ancillary data bit field for receipt at said remote receiver.

54. The method of claim 53, wherein said providing step includes the step of providing bits to said auxiliary bit field content indicator in said service control header indicating the encryption method used on the content of said auxiliary data bit field.

55. The method of claim 54, further comprising the steps of:

generating a second broadcast channel bitstream frame by appending a second service control header to one of said service and a second service, said second service having at least one service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said second service control header dynamically controlling reception at said remote receiver of a corresponding one of said service and a second service, each of said service control header and said second service control header including a start flag indicating when said auxiliary data fields in said service control header and said second service control header are a segment of a plurality of segments in a multi-frame signal;

setting said start flag in said service control header to a first value when said auxiliary data field in said service control header is the field of the first said segment in said multi-frame signal and an independent segment in the absence of said multi-frame signal;

when the auxiliary data field in the service control header is a first field of the segment in the multi-frame signal and the auxiliary data field in the second service control header is another field of the segment in the multi-frame signal, setting the start flag in the second service control header to a second value, wherein the frame corresponding to the service is not necessarily adjacent to the frame corresponding to the second service.

56. The method of claim 55, further comprising the step of providing a segment offset and length bit field (SOLF) to each of said service control header and said second service control header, said SOLF including bits relating to how many of said segments make up said multi-frame signal.

57. The method of claim 56 wherein said step of providing said SOLF includes the step of setting said SOLF to N-1 when said start flag is set to said first value, where N is the total number of said segments comprising said multi-frame signal.

58. The method of claim 55, further comprising the step of:

generating a third broadcast channel bitstream frame by appending a third service control header to one of said service, said second service and a third service, said third service having at least one service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said third service control header dynamically controlling reception of a corresponding one of said service, said second service and said third service at said remote receiver, each of said service control headers, said second service control header and said third service control header including a start flag indicating when said ancillary data field corresponding thereto is a segment of a multi-frame signal;

providing a segment offset and length bit field (SOLF) to each of said service control headers, said second service control header and said third service control header, said SOLF including bits relating to how many of said segments form said multi-frame signal.

59. The method of claim 58 further comprising the step of setting said SOLF in said service control header to N-1 when said start flag is set to said first value, wherein N corresponds to the total number of said segments comprising said multi-frame signal.

60. The method of claim 59 further comprising the step of setting said SOLF in said second service control header to N- (N-1) when said start flag is set to said second value.

61. The method of claim 60 further comprising the step of setting said SOLF in said third SCD header to N- (N-2) when said START flag is set to said second value and said frame including said third SCD header is transmitted after said frame including said second SCD header.

62. The method of claim 59, further comprising the steps of:

generating a plurality of frames comprising a service of a plurality of services and a service control header of a plurality of service control headers, the services including said service, said second service, said third service and others, said plurality of service control headers each comprising an ancillary data field and a start flag indicating when said ancillary data field corresponding thereto is a segment of a multi-frame signal;

setting said SOLF in said service control header to N-1 when said start flag is set to said first value, where N corresponds to the total number of said segments comprising said multi-frame signal;

when the corresponding start flag is set to the second value to indicate that the auxiliary data bit field corresponds to one of the N segments of the multi-frame signal, the SOLF in each of the second SCP header, the third SCP header, and the plurality of SCPs is set to 1, 2, 3, 4.

63. A signal comprising broadcast information transmitted in a carrier wave broadcast to a remote receiver, said signal comprising a broadcast channel bit stream frame, wherein said broadcast channel bit stream frame is generated by appending a service control header to a service, said service having at least one service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said service control header comprising service control data for dynamically controlling reception of said service at said remote receiver over a broadcast channel, said service control header comprising service control header data selected from the group of bits consisting of a preamble indicating the start of said frame, a bit rate index indicating the bit rate of said service, encrypted control data, an auxiliary data bit field, an auxiliary bit field content indicator relating to the content of said auxiliary data bit field, data relating to a plurality of frames in said auxiliary data bit field when multiplexing said auxiliary data bit field, and data indicating the number of service components constituting said frames.

64. The signal of claim 63, wherein a second broadcast channel bitstream frame is generated by appending a second service control header to a second service, said second service having at least one service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said second service control header including service control data for dynamically controlling reception of said second service at said remote receiver over a second broadcast channel, said service control header and said second service control header including data identifying which of said broadcast channel and said second broadcast channel is a primary broadcast channel and which is a secondary broadcast channel related to said primary broadcast channel.

65. The signal of claim 63, wherein said service control header and said second service control header each include data identifying which of local reception, regional reception and worldwide reception, respectively, reception of said broadcast channel and reception of said second broadcast channel.

66. The signal of claim 63, wherein a second broadcast channel bitstream frame is generated by appending a second service control header to a second service, said second service having at least one service component selected from the group of service components consisting of audio, data, still images, moving images, paging signals, text, messages and full image symbols, said second service control header including service control data for dynamically controlling reception of said second service at said remote receiver over a second broadcast channel, said service control header and said second service control header including a start flag and a fragment offset and length bit field (SOLF), wherein the start flag indicates when said auxiliary data bit field in each of said service control header and said second service control header is a fragment of a multi-frame signal, and SOLF indicates how many of the segments constitute the multi-frame signal.

67. A method of formatting a signal for broadcast transmission to a remote receiver, comprising the steps of:

receiving broadcast channels from at least one broadcast station, each of said broadcast channels comprising a plurality of primary rate channels, each primary rate channel comprising a plurality of symbols;

routing each of said plurality of primary rate channels to at least one link of a plurality of time division multiplexed downlinks, each of said plurality of time division multiplexed downlinks comprising a plurality of time slots;

multiplexing said symbols corresponding to each of said primary rate channels and routed to the same one of said plurality of time division multiplexed downlinks into said time slots in said same downlink to thereby generate a corresponding plurality of serial, time division multiplexed or TDM frame bit streams;

appending a time slot control word to each of said TDM frame bit streams to control recovery of said primary rate channel corresponding to a selected one of said broadcast channels of at least one of said remote receivers, said time slot control word including at least one bit field selected from a group of bit fields consisting of a broadcast channel identification type bit field, a broadcast channel identification number bit field, a last primary rate channel flag, a format identification bit field and a broadcast audience bit field.

68. The method of claim 67 wherein said time slot control word includes said broadcast channel identification type field and said appending step includes the step of providing said broadcast channel identification type field with at least one bit indicating which of a plurality of different identification code types corresponds to said selected said broadcast channel, said plurality of different identification code types corresponding to respective ones of said plurality of geographic regions.

69. The method of claim 68, wherein said appending step includes the step of adding to said time slot control word at least two bits indicating which of a plurality of different identification code types corresponds to said identification code of said selected one of said broadcast channels, said code type being selected from the group consisting of a local code, a regional code and a world wide code, the local code is used to uniquely identify one of a plurality of broadcast channels transmitted to a geographic area by a point transmission from a satellite transmitter, the regional code identifies one of a plurality of broadcast channels transmitted to one of a predetermined contiguous geographic area and a predetermined non-contiguous geographic area, the world wide code is used to distinguish the second broadcast channel from other ones of the plurality of broadcast channels transmitted worldwide.

70. The method of claim 67 further comprising the step of assigning identification codes to uniquely distinguish said selected ones of said broadcast channels from each other and among a plurality of broadcast channels received in a selected one of a plurality of geographic regions.

71. The method of claim 70, further comprising the step of providing said time slot control word with at least one bit indicating which of a plurality of different identifier types corresponds to said identifier code of said selected one of said broadcast channels, said plurality of different identifier types corresponding to respective ones of said plurality of geographic regions.

72. A signal comprising broadcast information conveyed in a carrier wave broadcast for transmission to remote receivers, said signal corresponding to one of a plurality of time division multiplexed downlinks having broadcast channels routed from at least one broadcast station and comprising a plurality of time slots, each of said broadcast channels comprising a plurality of primary rate channels, each of said primary rate channels comprising symbols corresponding to said primary rate channel routed to said time division multiplexed downlink, said time division multiplexed downlink being multiplexed in corresponding said time slots to produce a serial, Time Division Multiplexed (TDM) frame bit stream, said TDM frame bit stream comprising a time slot control word to control recovery of said primary rate channel corresponding to a selected one of said broadcast channels of at least one of said remote receivers, the slot control word includes at least one bit field selected from a group of bit fields consisting of a broadcast channel identification type bit field, a broadcast channel identification number bit field, a last primary rate channel flag, a format identification bit field and a broadcast audience bit field, wherein the broadcast channel identification type bit field indicates a corresponding one of a plurality of geographical areas for receiving the broadcast channel.