RU2470464C2 - System and method of in-band modem for data transmission over digital wireless communication networks - Google Patents

Abstract

FIELD: physics, communications.

SUBSTANCE: invention relates to data transmission over a voice channel, particularly transmission of non-speech information through a speech codec (within the bandwidth) over a communication network. The method of obtaining non-speech data embedded in a vocoder packet involves receiving and decoding the vocoder packet; filtering the decoded vocoder packet until a synchronisation signal is detected; calculating a timing offset based on the synchronisation signal; and extracting the non-speech data embedded in the decoded vocoder packet based on the timing offset. Filtering involves steps of correlating the decoded vocoder packet with a pseudorandom noise sequence to generate a plurality of correlation peaks and comparing the plurality of correlation peaks with an expected pattern. Correlation includes a step for correlating one of the non-overlapping or overlapping composite preamble sequence of the decoded vocoder packet with the pseudorandom noise sequence. The expected pattern is based on a combination of negative and positive correlation peaks. The comparison employs a certain number from the plurality of correlation peaks, which is matched with the expected pattern, and determining whether said number exceeds a predetermined value.

EFFECT: high efficiency of in-band data transmission through a speech codec in a wireless communication system.

28 cl, 41 dwg, 6 tbl

Description

PRIORITY REQUEST

Priority is claimed for the following provisional patent applications: No. 61/059,179, entitled "ROBUST SIGNAL FOR DATA TRANSMISSION OVER IN-BAND VOICE MODEM IN DIGITAL CELLULAR SYSTEMS", filed June 5, 2008, transferred to the assignee of this and therefore expressly included in this document by reference; and No. 61 / 087,923, entitled “SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS”, filed on August 11, 2008 and referred to this assignee and therefore expressly incorporated herein by reference link; and No. 61/093,657, entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS", filed September 2, 2008, transferred to the assignee of this and thus explicitly incorporated herein by link; and No. 61/122,997, entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS", filed December 16, 2008 and transferred to the assignee of this and thus explicitly included in this document according to link; and No. 61/151,457, entitled "SYSTEM AND METHOD FOR PROVIDING GENERAL BI-DIRECTIONAL IN-BAND MODEM FUNCTIONALITY", filed February 10, 2009, transferred to the assignee of this and thus explicitly incorporated herein by reference; and No. 61/166,904, entitled "SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS (OR CELLULAR) COMMUNICATION NETWORKS", filed April 6, 2009, submitted to this assignee and thus explicitly incorporated herein by link.

LINKS TO RELATED APPLICATIONS

Related US patent applications pending include:

"SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has in the register of patent attorney No. 081226U1, filed simultaneously with this document, transferred to this successor and explicitly included in this document by reference;

"SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has in the register of patent attorney No. 081226U2, filed simultaneously with this document, transferred to this successor and explicitly included in this document by reference;

"SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has in the register of patent attorney No. 081226U4, filed simultaneously with this document, transferred to this successor and explicitly included in this document by reference;

"SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has in the register of patent attorney No. 081226U5, filed simultaneously with this document, transferred to this successor and explicitly included in this document by reference;

"SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS", which has in the register of patent attorney No. 081226U6, filed simultaneously with this document, transferred to this successor and explicitly included in this document by reference.

FIELD OF TECHNOLOGY

The present disclosure generally relates to data transmission over a voice channel. In particular, the present disclosure relates to the transmission of non-speech information through a speech codec (within a bandwidth) in a communication network.

BACKGROUND OF THE INVENTION

Voice transmission continues to be the main component in communication systems since the invention of the telephone with a fixed communication line and wireless radio. Advances in the study and design of communication systems have advanced the industry in the direction of digital-based systems. One advantage of a digital communication system is its ability to reduce the required transmission bandwidth by compressing data intended for transmission. As a result, much research and development has been devoted to compression techniques, especially in the field of speech coding. A common speech compression device is a “vocoder”, which is also interchangeably referred to as a “speech codec” or “speech encoder”. A vocoder receives digitized speech samples and compiles data bits known as “speech packets”. To support various digital communication systems requiring voice communication, there are several standardized voice coding algorithms, and, in fact, today voice support is the minimum and necessary requirement in most communication systems. The 3rd Generation Partnership Project 2 (3GPP2) is an example of a standardization organization that specifies the IS-95 communication system, 1xRTT (1x radio transmission technology) CDMA2000, EV-DO (optimized data transfer development) CDMA, and EV-DV (transmission development data / voice) CDMA. The Third Generation Partnership Project (3GPP) is another example of a standardization organization specifying GSM (Global System for Mobile Communications), UMTS (Universal Mobile Communications System), HSDPA (High Speed Downlink Packet Access System), HSUPA (High Speed Packet Access System) uplink), HSPA + (high-speed packet access development system), and LTE (long-term development system). VoIP (Voice over Internet Protocol) is an example of a protocol used in a communication system defined by 3GPP and 3GPP2, as well as other standards. Examples of vocoders used in such communication systems as well as protocols include G.729 ITU-T (International Telecommunication Union), AMR (adaptive multi-speed speech codec), and EVRC (advanced variable speed codec with voice options 3, 68, 70 )

Information sharing is the primary goal of today's communications systems in supporting the demand for instant and ubiquitous connectivity. Users of today's communication systems transmit video, text messages and other data in connection mode. Newly developed applications tend to outpace network development and may require updating modulation schemes and communication system protocols. In some remote geographical areas, only voice services may be available due to the lack of infrastructure support for advanced data services in the system. Alternatively, users can choose to use only voice services on their communication device for economic reasons. In some countries, communications services are authorized to support public services, such as 911 emergency services (E911) or in-vehicle emergency calls (eCall). In these emergency applications, fast data transfer is a priority, but not always real, especially in a situation where advanced data services are not available at the user terminal. Previous methods provided solutions for transmitting data through a voice codec, but these solutions are able to support only low-speed data transfers due to coding imperfections introduced when trying to encode a non-speech signal using a vocoder.

The speech compression algorithms implemented by most vocoders use “analysis through synthesis” methods to model the human voice path using parameter sets. These parameter sets typically include functions of digital filtering coefficients, gains, and stored signals, known as codebooks, for example. The search for parameters that are most closely consistent with the characteristics of the input speech signal is performed on the vocoder encoder. The parameters are then used at the vocoder decoder to evaluate the input speech. The sets of parameters available to the vocoder for the purpose of coding signals are tuned to the best speech modeling, characterized by voiced periodic segments, as well as unvoiced segments having noise-like characteristics. Signals that do not contain periodic or noise-like characteristics are not efficiently encoded by the vocoder and may, in some cases, result in serious distortion in the decoded output signal. Examples of signals that do not exhibit speech characteristics include rapidly changing single frequency “tonal” signals or dual-tone multi-frequency “DTMF” signals. Most vocoders are not able to efficiently and effectively encode such signals.

Data transmission by means of a speech codec is usually considered as data transmission “within the bandwidth”, in which data is embedded in one or more speech packets leaving the speech codec. Several methods for presenting data use audio tones at predetermined frequencies within the speech frequency band. Using predefined frequency tones to transmit data through speech codecs, especially with higher data rates, is unreliable due to the vocoders used in the systems. Vocoders are configured to simulate speech signals using a limited number of parameters. These limited parameters are insufficient for effective modeling of tonal signals. The ability of vocoders to model tones is further impaired by trying to increase the data rate by quickly changing tones. This affects the accuracy of detection and results in the need to add complex circuits in order to minimize data errors, which, in turn, further reduces the overall data rate of the communication system. Thus, the need arises for efficient and effective data transmission through a speech codec in a communication network.

Accordingly, it would be advantageous to provide an improved system for transmitting and receiving information by means of a speech codec in a communication network.

SUMMARY OF THE INVENTION

The embodiments disclosed in the present invention meet the above needs by using an in-band modem to reliably transmit and receive non-speech information through a speech codec.

In one embodiment, a method for sending non-speech information by means of a speech codec comprises processing a plurality of input data symbols to produce a plurality of signals of a first pulse; generating a given set of signals of the first pulse in order to produce a plurality of generated signals of the first pulse; and encoding a given set of generated signals of the first pulse.

In another embodiment, the device comprises a processor configured to process a plurality of input data symbols to produce a plurality of signals of the first pulse; a driver configured to generate a given plurality of signals of the first pulse in order to produce a plurality of generated signals of the first pulse; and a speech codec configured to encode a given set of generated signals of the first pulse.

In another embodiment, the device comprises means for processing a plurality of input data symbols to produce a plurality of signals of the first pulse; means for generating a given plurality of signals of the first pulse in order to produce a plurality of generated signals of the first pulse; and means for encoding a given set of generated signals of the first pulse.

In another embodiment, a method for synchronizing non-speech frames by means of a speech codec comprises generating a predetermined sequence having noise-like characteristics and being robust against speech frame errors; and sending the given predetermined sequence through the speech codec.

In another embodiment, the device comprises a generator configured to generate a predetermined sequence having noise-like characteristics and being resistant to speech frame errors; and a speech codec configured to process a given predetermined sequence to produce a speech packet.

In another embodiment, the device comprises means for generating a predetermined sequence having noise-like characteristics and being resistant to speech frame errors; and means for sending the given predetermined sequence through the speech codec.

In another embodiment, a method for obtaining non-speech data embedded in a vocoder package comprises receiving and decoding a vocoder package; filtering this decoded vocoder packet until a synchronization signal is detected; calculating a time offset based on a given synchronization signal; and extracting non-speech data embedded in a decoded vocoder package based on a time offset.

In another embodiment, the device comprises a receiver configured to receive and decode a vocoder packet; a filter configured to filter this decoded vocoder packet until a synchronization signal is detected; a calculator configured to calculate a time offset based on a given synchronization signal; and an extractor configured to extract non-speech data embedded in a decoded vocoder package based on a time offset.

In another embodiment, the device comprises means for receiving and decoding a vocoder packet; means for filtering a given decoded vocoder packet before detecting a synchronization signal; means for calculating a time offset based on a given synchronization signal; and means for extracting non-speech data embedded in a decoded packet of a vocoder based on a time offset.

In another embodiment, a method for controlling transmissions of a source terminal from a destination terminal in an in-band communication system comprises transmitting a start signal from a destination terminal; interruption of the transmission of the start signal upon detection of the first received signal; transmitting a NACK signal from a destination terminal; interruption of NACK signal transmission upon detection of a successfully received data terminal message of the source terminal; transmitting the ACK signal from the destination terminal; and interrupting the transmission of the ACK signal after a predetermined number of ACK signals have been transmitted.

In another embodiment, the device comprises a processor, a memory in electronic communication with the processor, instructions stored in the memory, these instructions being able to carry out the steps of transmitting a start signal from a destination terminal; interruption of the transmission of the start signal upon detection of the first received signal; transmitting a NACK signal from a destination terminal; interrupting NACK signal transmission upon detection of a successfully received data terminal message of the source terminal; transmitting the ACK signal from the destination terminal; and interrupting the transmission of the ACK signal after a predetermined number of ACK signals have been transmitted.

In another embodiment, an apparatus for controlling transmissions of a source terminal from a destination terminal in an in-band communication system comprises means for transmitting a start signal from a destination terminal; means for interrupting the transmission of the start signal upon detection of the first received signal; means for transmitting a NACK signal from a destination terminal; means for interrupting the transmission of the NACK signal upon detection of a successfully received data message of the source terminal; means for transmitting the ACK signal from the destination terminal; and means for interrupting the transmission of the ACK signal after a predetermined number of ACK signals have been transmitted.

In another embodiment, a method for controlling transmissions of a source terminal from a source terminal in an in-band communication system comprises detecting a request signal at a source terminal; transmitting a synchronization signal from a source terminal upon detection of a given request signal; transmitting a user data segment from a source terminal using a first modulation scheme; and interrupting the transmission of a given segment of user data upon detection of the first received signal.

In another embodiment, the device comprises a processor, a memory in electronic communication with the processor, instructions stored in the memory, and these instructions are capable of performing steps of detecting a request signal at a source terminal; transmitting a synchronization signal from a source terminal upon detection of a given request signal; transmitting a user data segment from the source terminal using the first modulation scheme; and interrupting the transmission of this user data segment upon detection of the first received signal.

In another embodiment, an apparatus for controlling transmissions of a source terminal from a source terminal in an in-band communication system comprises means for detecting a request signal at a source terminal; means for transmitting a synchronization signal from a source terminal upon detection of a given request signal; means for transmitting the user data segment from the source terminal using the first modulation scheme; and means for interrupting the transmission of this user data segment upon detection of the first received signal.

In another embodiment, an apparatus for controlling bidirectional data transmissions from a destination terminal in an in-band communication system comprises transmitting a send signal from a destination terminal; interruption of the transmission of the send signal upon detection of the first received signal; transmitting a synchronization signal from a destination terminal; transmitting a user data segment from the destination terminal using the first modulation scheme; and interrupting the transmission of a given segment of user data upon detection of a second received signal.

In another embodiment, the device comprises a processor, a memory in electronic communication with the processor, instructions stored in the memory, these instructions being able to carry out the steps of transmitting a send signal from the destination terminal; interrupting the transmission of the send signal upon detection of the first received signal; transmitting a synchronization signal from a destination terminal; transmitting the user data segment from the destination terminal using the first modulation scheme and interrupting the transmission of this user data segment upon detection of the second received signal.

In another embodiment, an apparatus for controlling bidirectional data transmissions from a destination terminal in an in-band communication system comprises means for transmitting a send signal from a destination terminal; means for interrupting the transmission of the send signal upon detection of the first received signal; means for transmitting a synchronization signal from a destination terminal; means for transmitting the user data segment from the destination terminal using the first modulation scheme; and means for interrupting the transmission of this user data segment upon detection of the second received signal.

In another embodiment, a system for transmitting data via an in-band communication system from a vehicle containing a vehicle integrated system (IVS) to a public safety reference point (PSAP) comprises one or more sensors located in the IVS to provide IVS sensor data IVS transmitter located in IVS for transmitting IVS sensor data, PSAP receiver located in PSAP for receiving IVS sensor data; PSAP transmitter located in PSAP for transmitting PSAP control data; IVS receiver; located in the IVS for receiving PSAP control data; wherein the IVS transmitter comprises an IVS message formatter (formatter) for formatting the IVS sensor data and producing an IVS message, an IVS processor for processing an IVS message and producing a plurality of generated IVS pulse signals, an IVS speech encoder for encoding data of the generated IVS pulse signals and producing an encoded IVS signal an IVS clock generator for generating an IVS clock; an IVS transmission controller for transmitting a sequence of IVS clocks and IVS messages; moreover, the PSAP receiver includes a PSAP detector for detecting the IVS synchronization signal and producing a PSAP synchronization flag, a PSAP demodulator for demodulating the IVS message and producing the received IVS message; wherein the PSAP transmitter comprises a PSAP message formatter for formatting the PSAP control data and generating the PSAP control message, a PSAP processor for processing the PSAP control message and producing a plurality of generated PSAP pulse signals, a PSAP speech encoder for encoding data of the generated PSAP pulse signals and producing the encoded PSAP signal, a PSAP synchronization generator for generating a PSAP synchronization signal, and a PSAP transmission controller for transmitting a sequence of PSAP synchronization signals and PSAP fragmenting messages; wherein the IVS receiver comprises an IVS detector for detecting a PSAP synchronization signal and producing an IVS synchronization flag, and an IVS demodulator for demodulating the PSAP messages and producing the received PSAP message.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and related advantages of the embodiments described herein will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram of an embodiment of source and destination terminals using an in-band modem for transmitting data via a speech codec in a wireless communication network;

2 is a diagram of an embodiment of a data modem used in an in-band communication system;

3A is a diagram of an embodiment of a signal clock generator;

3B is a diagram of another embodiment of a signal clock generator;

Fig. 3C is a diagram of another another embodiment of a signal synchronization generator;

4 is a diagram of an embodiment of a burst pulse generator;

5 is a diagram of an embodiment of a sequence of a burst of synchronization pulses;

6A is a diagram of an embodiment of a sequence of synchronization preamble;

6B is a diagram of an embodiment of a sequence of a synchronization preamble with non-overlapping reference sequences;

figa is a graph of the correlation output of the synchronization preamble, where the preamble is composed of non-overlapping reference sequences;

figv is a graph of the correlation output of the synchronization preamble, where the preamble is composed of overlapping reference sequences;

Fig. 8A is a diagram of an embodiment of a synchronization message format;

8B is a diagram of another embodiment of a synchronization message format;

figs is a diagram of another another variant implementation of the format of the synchronization message;

9 is a diagram of an embodiment of a data message format for transmission;

10 is a diagram of an embodiment of a composite message format of synchronization and transmission data;

11A is a graph of a power spectral density of an in-band signal based on a pulse in comparison with a frequency;

11B is a graph of a power spectral density of an in-band signal based on a tone versus frequency;

12 is a diagram of an embodiment of a data modulator using scattered pulses;

13 is a diagram of an embodiment of a representation of a scattered pulse data symbol;

figa is a diagram of a variant of implementation of the placement of the generated pulses within the modulation frame using the transfer method;

FIG. 14B is a diagram of an embodiment of arranging generated pulses within a modulation frame for a typical example in the art;

15A is a diagram of an embodiment of a synchronization signal detector and a receiver controller;

15B is a diagram of another embodiment of a synchronization signal detector and a receiver controller;

FIG. 16 is a diagram of an embodiment of a burst pulse detector; FIG.

17A is a diagram of an embodiment of a synchronization preamble detector;

17B is a diagram of another embodiment of a synchronization preamble detector;

FIG. 18A is a diagram of an embodiment of a controller of a synchronization detector; FIG.

Fig. 18B is a diagram of another embodiment of a synchronization detector controller;

FIG. 19 is a diagram of an embodiment of a reception time controller; FIG.

20 is a diagram of an embodiment of a reception data modem used in an in-band communication system;

21 is a diagram of an embodiment of an emergency call system within a vehicle;

FIG. 22 is a diagram of an embodiment of an interaction of a data request sequence transmitted on a downlink in a destination communication terminal and a data response sequence transmitted on an uplink in a communication source terminal, wherein this interaction is initiated by a destination terminal;

23A is a diagram of an embodiment of an interaction of a data request sequence transmitted on a downlink in a destination communication terminal and a data response sequence transmitted on an uplink in a communication source terminal, wherein this interaction is initiated by a source terminal;

23B is a diagram of another embodiment of an interaction of a data request sequence transmitted on a downlink in a destination communication terminal and a data response sequence transmitted on an uplink in a communication source terminal, wherein this interaction is initiated by a source terminal;

24A is a diagram of an embodiment of an interaction of a bidirectional data request sequence and a data response sequence transmitted both in a downlink and an uplink;

24B is a diagram of another embodiment of a bi-directional data request sequence and a data response sequence transmitted both in a downlink and an uplink;

FIG. 25 is a diagram of an embodiment of a user data packet format, where the length of the user data length is less than the transmission packet size;

FIG. 26 is a diagram of an embodiment of a user data packet format, where the length of the user data is longer than the transmission packet size;

FIG. 27A is a diagram of an embodiment of an interaction of a data request sequence for transmission and a data response sequence for transmission in which a user data length is larger than a transmission packet size;

FIG. 27B is a diagram of another embodiment of an interaction of a data request sequence for transmission and a data response sequence for transmission in which a user data length is greater than a transmission packet size;

FIG. 27C is a diagram of yet another embodiment of an interaction of a data request sequence for transmission and a data response sequence for transmission in which a user data length is greater than a transmission packet size;

Fig. 27D is a diagram of yet another embodiment of an interaction of a data request sequence for transmission and a data response sequence for transmission in which the user data length is larger than the transmission packet size.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows an embodiment of an in-band communication system for transmitting data as possible to be implemented within the wireless source terminal 100. This source terminal 100 communicates with the destination terminal 600 via communication channels 501 and 502, network 500, and communication channel 503. Examples of relevant wireless communication systems include cellular telephone systems operating in accordance with the Global System for Mobile Communications (GSM) standards, the third generation universal mobile telecommunications system of the Partnership Project (3GPP UMTS), and the third-generation partnership code multiple access standards of the third generation 2 partnership (3GPP2) CDMA), synchronous multiple access and time division multiple access (TD-SCDMA) standards, and microwave worldwide compatibility standards of Access (WiMAX). One skilled in the art will appreciate that the methods described herein may equally apply to an in-band data communication system that does not use a wireless channel. Communication network 500 includes any combination of routing and / or switching equipment, a communication line, and other infrastructure suitable for establishing a communication line between a source terminal 100 and a destination terminal 600. For example, communication channel 503 may not be a wireless line. The source terminal 100 typically functions as a voice communication device.

TRANSMITTER

The main transmission band 200 typically routes user speech through a vocoder, but is also capable of routing non-speech data through a vocoder in response to a request from a source terminal or communication network. Routing non-speech data through a vocoder is advantageous because it eliminates the need for a source terminal to request and transmit data over a separate communication channel. Non-speech data is formatted into messages. Message data, still in digital form, is converted into a noise-like signal consisting of generated pulses. Information with message data is embedded in the pulse position of the noise-like signal. The noise-like signal is encoded using a vocoder. The vocoder is not configured perfectly depending on whether the input data is user speech or non-speech data, so it is advantageous to convert the message data into a signal that can be efficiently encoded by a set of transmission parameters assigned to the vocoder. A coded noise-like signal is transmitted within the bandwidth of the communication line. Since the transmitted information is embedded in the pulse positions of the noise-like signal, reliable detection depends on the restoration of the temporal distribution of the pulses relative to the speech boundaries of the codec frame. To assist the receiver in detecting in-band transmission before transmitting the message data via the vocoder, a predetermined synchronization signal is generated and encoded. The sequence of synchronization, control, and message protocols is transmitted to ensure reliable detection and demodulation of non-speech data at the receiver.

Regarding the main transmission band 200, an input signal sound S210 is input into a microphone and an audio input processor 215 and transmitted through a multiplexer 220 to a vocoder encoder 270 where compressed voice packets are generated. A suitable audio input processor typically includes a circuit for converting the input signal into a digital signal and a signal conditioner for generating a digital signal, such as a low-pass filter. Examples of suitable vocoders include vocoders described by the following reference standards: GSM-FR, GSM-HR, GSM-EFR, EVRC, EVRC-B, SMV, QCELP13K, IS-54, AMR, G.723.1, G.728, G. 729, G.729.1, G.729a, G.718, G.722.1, AMR-WB, EVRC-WB, VMR-WB. A vocoder encoder 270 delivers voice packets to a transmitter 295 and an antenna 296, and voice packets are transmitted over a communication channel 501.

A data request may be initiated through a source terminal or through a communication network. The data transfer request S215 turns off the voice path through the multiplexer 220 and turns on the data path. The input data S200 is pre-processed by the data message formatter 210 and output as S220 TX to the TX data modem 230. Input data S200 may include user interface (UI) information, user position / location information, time stamps, equipment sensor information, or other relevant data. An example of a suitable data message formatter 210 includes a circuit for computing and applying cyclic redundancy check (CRC) bits to input data, providing retransmission of buffer memory, implementing error control coding such as hybrid automatic repeat request (HARQ), and interleaving input data. The TX data modem 230 converts the TX message S220 to the TX data signal S230, which is routed through the multiplexer 220 to the vocoder encoder 270. When the data transfer is completed, the voice path can be re-enabled through the multiplexer 220.

Figure 2 is a corresponding exemplary structural diagram of a TX data modem 230 shown in Figure 1. Through the multiplexer 259, three signals can be time-multiplexed into the output signal S230 of the TX data: synchronization output signal S245, muted output signal S240, and Tx modulation output signal S235. It will be appreciated that various orders or combinations of synchronization output signal S245, muted output signal S240, and modulation output signal S235 Sx5 may be output to Tx data output S230. For example, the synchronization output signal S245 may be sent before each data segment of the TX modulation output signal S235. Or, the synchronization output signal S245 may be sent once before the full TX modulation output signal S235, with muted output signals S240 sent between each data segment of the TX modulation output signal S235.

The synchronization output signal S245 is a synchronization signal used to establish a timing distribution at the receiving terminal. The synchronization signals are required to establish a time distribution for the transmitted in-band data, since the data information is embedded in the pulse positions of the noise-like signal. FIG. 3A shows a corresponding exemplary structural diagram of a synchronization generator 240 shown in FIG. 2. Three signals can be multiplexed in time through the multiplexer 247 into the synchronization output signal S245 in time: the synchronization pulse train signal S241, the activation output signal S236, and the synchronization preamble output signal S242. It will be appreciated that various orders or combinations of synchronization pulse train signal S241, activation output signal S236, and synchronization preamble output signal S242 may be output to the synchronization output signal S245. For example, FIG. 3B shows a synchronization generator 240 consisting of an activation output signal S236 and a synchronization preamble output signal S242, where an activation output signal S236 may be sent before each synchronization preamble output signal S242. Alternatively, FIG. 3C shows a synchronization generator 240 consisting of a synchronization pulse burst signal S241 and a synchronization preamble output signal S242, where a synchronization pulse burst signal S241 may be sent before each synchronization preamble output signal S242.

Returning to FIG. 3A, the sync pulse burst signal S241 is used to establish a rough time distribution at the receiver and consists of at least one sinusoidal frequency signal having a predetermined sampling rate, sequence and duration, and is generated by a burst of 250 sync pulses shown figure 4. Sinusoidal frequency 1 251 represents binary data +1, and frequency 2 252 represents binary data -1. Examples of suitable signals include constant frequency sinusoids in the band of a voice signal, such as 395 Hz, 540 Hz and 512 Hz for one sinusoidal signal, and 558 Hz, 1035 Hz and 724 Hz for another sinusoidal signal. The sequence 253 of the burst of synchronization pulses determines which frequency signal is multiplexed by multiplexer 254. The information sequence modulated into the burst of synchronization pulses should be a sequence with good autocorrelation characteristics. An example of a corresponding sequence 253 of a burst of synchronization pulses is a Barker code with a length of 7, shown in Fig.5. For each symbol “+”, a sine wave of frequency 1 is output to the signal S241 of the burst of synchronization pulses, and for each symbol “-” a sinusoid of frequency 2 is output.

Turning back to FIG. 3A, the output of the synchronization preamble S242 is used to establish an accurate (based on samples) time distribution at the receiver and consists of a predetermined data transmission scheme known in the receiver. A corresponding example of a predetermined data transmission scheme of the synchronization preamble output signal S242 is the synchronization preamble sequence 241 shown in FIG. 6A. A composite preamble sequence 245 is generated by connecting several periods of the pseudo-random noise (PN) sequence 242 in series with the overlapping and added result of the PN sequence 242 and the inverse of the PN sequence 244. The symbols “+” in the composite sequence 245 of the preamble represent binary data +1, and the symbols “-” represent binary data -1. Another relevant example inserts zero-value samples between the data bits of a PN sequence. This provides a time gap between the data bits to account for the effects of “blurring” caused by the characteristics of the channel bandwidth filter, which tends to distribute the energy of the data bits over several bit transmission time intervals.

The previously described synchronization preamble configuration, using series-connected PN sequence periods with overlapping segments of the reverse PN sequence options, provides benefits in reduced transmission time, improved correlation characteristics, and improved detection characteristics. These benefits result in a preamble that is robust against speech frame errors.

By overlapping PN segments, the resulting composite synchronization preamble consists of fewer bits in the sequence compared to the non-overlapping version, thereby reducing the total time required to transmit the composite preamble sequence 245.

To illustrate the improvements in the correlation characteristics of the overlapping synchronization sequence of FIGS. 7A and 7B, a comparison is made between the correlation of the PN sequence 242 with the non-overlapping preamble compound sequence 245b shown in FIG. 6B and the correlation of the PN sequence 242 with the overlapping synchronization preamble sequence 245 shown on figa. Fig. 7A shows the main correlation peaks, both positive and negative, as well as the secondary correlation peaks located between the main peaks for the non-overlapping composite synchronization preamble sequence 245b. A negative peak 1010 is obtained from the correlation of the PN sequence 242 with the first inverse segment of the non-overlapping composite preamble sequence 245b. The positive correlation peaks 1011, 1012, 1013 are obtained from the correlation of the PN sequence 242 with three series-connected segments of the PN sequence 242 constituting the middle portion of the non-overlapping composite preamble sequence 245b. A negative peak 1014 is obtained from the correlation of the PN sequence 242 with the second inverse segment of the non-overlapping composite preamble sequence 245b. 7A, the minor correlation peak 1015 corresponding to the offset of 3 samples from the first positive correlation peak 1011 shows a value of approximately 5 (1/3 of the magnitude of the main peaks). FIG. 7B shows several major correlation peaks, both positive and negative, as well as secondary correlation peaks located between the main peaks for the overlapping composite sequence 245 of the synchronization preamble. 7B, the minor correlation peak 1016 corresponding to the offset of 3 PN samples from the first positive correlation peak 1011 shows a value of approximately 3 (1/5 of the magnitude of the main peaks). The smaller background correlation peak 1016 for the overlapping preamble shown in FIG. 7B results in less false detection of the main correlation peaks of the preamble compared to the non-overlapping background peak 1015 shown in FIG. 7B.

As shown in FIG. 7B, when the PN sequence 242 is correlated with the composite sequence 245 of the synchronization preamble, five main peaks are generated. The demonstrated scheme (1 negative peak, 3 positive peaks and 1 negative peak) provides the possibility of temporal distribution of the frame based on any three detected peaks and the corresponding time intervals between the peaks. The combination of the three detected peaks with the corresponding time interval is always unique. A similar image of the correlation peak pattern is shown in Table 1, where the correlation peaks are shown as “-” for the negative peak and “+” for the positive peak. The method of using a unique correlation peak scheme is beneficial for in-band systems because this unique scheme compensates for possible loss of speech frame, for example, due to poor channel conditions. The loss of a speech frame can also result in a loss of a correlation peak. By possessing a unique correlation peak pattern separated by predetermined time intervals, the receiver can reliably detect a synchronization preamble even when speech frames are lost, resulting in loss of correlation peaks. Several examples are shown in Table 2 for combinations of the three detected peaks in the circuit (two peaks are lost in each example). Each entry in table 2 represents a unique pattern of peaks and time intervals between peaks. Example 1 in Table 2 shows the detected peaks 3, 4, and 5 (peaks 1 and 2 were lost), resulting in a “++ -” pattern with one predetermined gap between each peak. Examples 2 and 3 in table 2 also show the scheme "++ -", however, the gaps are different. Example 2 has two predefined gaps between the detected peak 2 and peak 4, while example 3 has two predefined gaps between the detected peak 3 and peak 5. Thus, examples 1, 2 and 3 each represent a unique pattern, from which a temporary frame allocation may be output. It should be borne in mind that these detected peaks may extend beyond the boundaries of the frame, but that these unique patterns and preset intervals are nevertheless applied.

One skilled in the art will appreciate that a different preamble sequence may be used, resulting in a different correlation peak pattern other than that shown in FIG. 7B and table 1. One skilled in the art will also take into account that to determine of various operating modes or transmission of information bits, a plurality of correlation peak schemes may be used. An example of an alternative correlation peak scheme is shown in Table 3. The correlation peak scheme shown in Table 3 supports a unique scheme from which the temporal distribution of the frame can be derived, as described previously. Having a plurality of correlation peak patterns is advantageous for defining various transmitter configurations at the receiver, such as message formats or modulation schemes.

Referring again to FIG. 3A, an activation output signal S236 is used to initiate activation of a vocoder encoder 270 from a sleep state, a slow transmission rate state, or a discontinuous transmission state. The activation output S236 can also be used to prevent the vocoder encoder 270 from entering a sleep state, slow transmission, or intermittent transmission state. The activation output S236 is generated by the activation generator 256. Activation signals are advantageous when transmitting in-band data through vocoders that perform sleep functions, discontinuous transmission (DTX) functions or operate at a slower transmission rate during inactive voice segments, in order to minimize the launch delay that may occur during the transition from an inactive voice state to a state of active voice. Activation signals can also be used to determine the characteristics of the transmission mode, for example, the type of modulation scheme used. A first example of a corresponding activation output signal S236 is a constant frequency sinusoidal signal in a band of a voice signal, such as 395 Hz. In this first example, the activation signal inhibits the input of the vocoder encoder 270 to a sleep state, DTX, or a state of slow transmission speed. In this first example, the receiver ignores the transmitted activation output signal S236. A second example of a corresponding activation output signal S236 is a signal consisting of a plurality of sinusoidal signals, where each signal defines a specific data modulation scheme, for example, 500 Hz for a modulation scheme 1 and 800 Hz for a modulation scheme 1. In this second example, the activation signal performs an input ban the vocoder encoder 270 into a sleep state, DTX, or slow bit rate state. In this second example, the receiver uses the transmitted activation output signal S236 to determine a data modulation scheme.

An example of a composite synchronization output signal S245 is a signal consisting of a multiplexed synchronization pulse train signal S241 and a synchronization preamble output signal S242, as shown in FIG. 8A. Tsb 701 and Tsp 702 represent the time duration when each signal is transmitted. An example of an appropriate range for Tsb is 120-140 milliseconds, and for Tsp is 40-200 milliseconds. Another example of a composite synchronization output signal S245 is a signal consisting of a multiplexed activation output signal S236 and a synchronization preamble output signal S242, as shown in FIG. Twu 711 and Tsp 702 represent the time duration when each signal is transmitted. An example of an appropriate range for Twu is 10-60 milliseconds, and for Tsp is 40-200 milliseconds. Another example of a composite synchronization output signal S245 is a signal consisting of a multiplexed activation output signal S236, a synchronization pulse train signal S241, and a synchronization preamble output signal S242, as shown in FIG. 8C. Twu 711, Tsp1 721, Tsb 701, Tsp2 722 represent the time duration when each signal is transmitted. An example of an appropriate range for Twu is 20-80 milliseconds, for Tsp1 it is 40-200 milliseconds, for Tsb it is 120-140 milliseconds, and for Tsp2 it is 40-200 milliseconds.

Turning back to FIG. 2, a corresponding example of the Tx modulation output signal S235 is a signal generated by a phase pulse modulation (PPM) modulator 235 with special forms of modulation pulses. This modulation method results in low distortion in coding and decoding by means of various types of vocoders. Additionally, this method results in good autocorrelation characteristics and can be easily detected by a receiver consistent with the waveform. Additionally, the generated pulses do not have a tonal structure; instead, the signals appear noise-like in the frequency spectrum region and also retain a noise-like sound response. An example of a power spectral density of a signal based on generated pulses is shown in FIG. 11A. As can be seen in FIG. 11A, the power spectral density exhibits a noise-like characteristic in the in-band frequency range (constant energy in the frequency range). In contrast, an example of a power spectral density of a signal with a tonal structure is shown in FIG. 11B, where data is represented by tones at frequencies of approximately 400 Hz, 600 Hz, and 1000 Hz. As can be seen in FIG. 11B, the power spectral density shows “bursts” of significant energy in the in-band frequency range in tonal frequencies and in its harmonics.

FIG. 12 is a structural diagram of a modulator 235 shown in FIG. 2. The scattered pulse generator 238 produces pulses corresponding to the input message S220 Tx using phase-pulse modulation, and then the pulse shaper 239 generates pulses in order to create a signal for better encoding quality in the vocoder encoder. A corresponding example of a scattered pulse is shown in FIG. 13. The time axis is divided into modulation frames of duration T _MF . Within each such modulation frame, relative to the boundaries of the modulation frame, a certain number of time instants t ₀ , t ₁ , ..., t _m-1 are determined that determine the potential positions of the main pulse p (t). For example, a pulse 237 at position t _{3 is} denoted as p (tt ₃ ) . The information bits of the S220 TX message input to the modulator 235 are converted into symbols with a corresponding translation into pulse positions in accordance with the conversion table. An impulse can also be formed by changing the polarity, + p (t) . Symbols can thus be represented by one of the distinct signals of type 2m within the modulation frame, where m is the number of times determined for the modulation frame, and the multiplication factor, 2 , is a positive or negative polarity.

An example of the corresponding pulse-phase conversion is shown in Table 4. In this example, the modulator converts a 4-bit symbol for each modulation frame. Each symbol is represented through the position k of the pulse shape p (nk) and the sign of the pulse. In this example, T _MF is four milliseconds, resulting in 32 possible positions for an 8 kHz sampling interval. The pulses are separated by four points in time, resulting in the assignment of 16 different positions of the pulses and combinations of polarity. In this example, the effective data rate is 4 bits per character in a period of 4 milliseconds or 1000 bits / second.

Table 4 Symbol Pulse Decimal Binary 0 0000 p (n-0) one 0001 p (n-4) 2 0010 p (n-8) 3 0011 p (n-12) four 0100 p (n-16) 5 0101 p (n-20) 6 0110 p (n-24) 7 0111 p (n-28) 8 1000 -p (n-28) 9 1001 -p (n-24) 10 1010 -p (n-20) eleven 1011 -p (n-16) 12 1100 -p (n-12) 13 1101 -p (n-8) fourteen 1110 -p (n-4) fifteen 1111 -p (n-0)

Another example of the corresponding pulse-phase conversion is shown in Table 5. In this example, the modulator converts a 3-bit symbol for each modulation frame. Each symbol is represented through the position k of the pulse shape p (nk) and the sign of the pulse. In this example, T _MF is two milliseconds, resulting in 16 possible positions for a sampling interval of 8 kHz. The pulses are separated by four points in time, resulting in the appointment of 8 different positions of the pulses and combinations of polarity. In this example, the effective data rate is 3 bits per character in a period of 2 milliseconds or 1500 bits / second.

Table 5 Symbol Pulse Decimal Binary 0 000 p (n) one 001 p (n-4) 2 010 p (n-8) 3 011 p (n-12) four one hundred -p (n-12) 5 101 -p (n-8) 6 110 -p (n-4) 7 111 -p (n)

In order to increase stability under poor channel conditions, the modulator 235 can increase the duration of the modulation frame T _MF , while maintaining a constant number of time instants t ₀ , t ₁ , ..., t _m-1 . This method serves to accommodate a longer time interval between pulses, resulting in more reliable detection. An example of an appropriate pulse-phase conversion includes a T _MF of four milliseconds, resulting in 32 possible positions for a sampling interval of 8 kHz. As in the previous example, if the pulses are separated by four points in time, the conversion results in the assignment of 16 different positions of the pulses and combinations of polarity. However, in this example, the separation between times is increased by a factor of 2 relative to the previous example, resulting in 8 different pulse positions and polarity combinations. In a corresponding example, the modulator 235 may switch between different phase-pulse transformations or durations of the modulation frame depending on the feedback signal indicating channel conditions or transmission success. For example, modulator 235 may start transmitting data using T _MF in two milliseconds, then switch to T _MF in four milliseconds if channel conditions are determined to be bad.

In order to increase stability for certain vocoders, the modulator 235 can change the initial time offset in the phase-pulse transformation. An example of the corresponding pulse-phase conversion is shown in Table 6. In this example, the modulator converts a 3-bit symbol to a modulation frame. Each symbol is represented through the position k of the pulse shape p (nk) and the sign of the pulse. In this example, T _MF is two milliseconds, resulting in 16 possible positions for a sampling interval of 8 kHz. The initial offset is set to 1 point in time, and the pulses are separated by four points in time, resulting in the appointment of 8 different positions of the pulses and combinations of polarity, as shown in the table.

Table 6 Symbol Pulse Decimal Binary 0 000 p (n-1) one 001 p (n-5) 2 010 p (n-9) 3 011 p (n-13) four one hundred -p (n-13) 5 101 -p (n-9) 6 110 -p (n-5) 7 111 -p (n-1)

It will be appreciated that a decrease in the number of split times may result in an increased number of bits per symbol and thus higher data rates. For example, if T _MF is four milliseconds, the resulting number of possible positions for a sampling interval of 8 KHz is 32 with plus or minus polarity for each, resulting in 64 different signals if no separation is turned on. To convert 64 positions, the number of supported bits per character is 6, and the resulting effective data rate is 1500 bits per second. It should also be noted that various combinations of T _MF and sampling rates can be used to achieve the desired effective bit rate.

An example of the corresponding pulse shaper 239 is the cosine transformation of the form elevated to the root:

where β represents the selectivity coefficient, 1 / T _s represents the maximum symbol rate, and t represents a selective point in time.

For the previous example with 32 possible positions of the pulses (time instants), the following transformation generates the cosine form of the pulse raised to the root, where the number of zeros to the first nonzero element of the pulse determines the exact position of the pulse within the frame.

It should be borne in mind that the transformation can be shortened or extended for various options for the size of the modulation frame.

14A is an example of placing a pulse within a modulation frame to generate a specific entry in the modulation alphabet. On figa the pulse is represented by 13 samples, shown as P0-P12, where each sample is a nonzero elements r (n), shown in the previous example. Figv is an example of a conventional implementation in the field of technology. On figv pulse is located at offset 7 within the frame 1003 modulation T _MF (n), and the "end" portion of the pulse goes to the next frame 1004 modulation T _MF (n + 1) for 4 samples (P9-P12). Samples from T _MF modulation frame 1003 (n) that go to the next T _MF modulation frame 1004 (n + 1), as shown in FIG. 14B, may result in intersymbol interference if pulse samples for the T _MF frame (n + 1) are located in any of the first 4 samples of the frame T _MF (n + 1), since overlapping samples may occur. Alternatively, in the “transfer” method illustrated in FIG. 14A, end samples that could go to the next modulation frame, frame 1004 T _MF (n + 1), are placed at the beginning of the current modulation frame, frame 1003 T _MF (n ) Samples (P9-P12) are transferred to the beginning of the frame T _MF (n) in samples 0-3. Using the transfer method to generate the modulation alphabet eliminates the cases when the generated pulse samples go to the next modulation frame. This transfer method is advantageous because it results in reduced intersymbol interference, which can occur if the generated pulse samples in the current frame go to the next frame and overlap with the generated pulse samples in the next frame. One skilled in the art will be able to take into account that the transfer method can be used for any position of the pulse in the modulation frame, which may result in the output of the samples in the next modulation frame. For example, a pulse located at offset 8 within the modulation frame 1003 T _MF (n) may carry samples (P8-P12).

Another example of a corresponding pulse shaper 239 is a shape amplitude transformation signal

r (n) p (nt)

An example of an amplitude transformation signal of a 32nd sample is a waveform

Another example of a corresponding pulse shaper 239 is a linear prediction synthesizing filter. The response of an exemplary (illustrative) recursive synthesizing LPC filter is determined by its impulse response

and coefficients: a (i) = {- 6312, 5677, -2377, 1234, -2418, 3519, -2839, 1927, -629, 96} / 4096, i = 1, ..., 10. Linear prediction filters are well known in the art. The residual signal r (n) is first created by input signal symbols in accordance with the pulse conversion tables indicated above. The actual shape of the modulation pulse is then obtained by filtering the modulated signal r (n) with h (n) .

One skilled in the art will understand that the methods described herein may equally be applicable to other pulse shapes and transformations. The waveform lengths and modulation schemes applied to these waveforms can also vary. Moreover, the waveforms can use fully uncorrelated (or orthogonal) waveforms to represent different symbols. In addition to the polarity of the generated pulse, the amplitude of the generated pulse can also be used to carry information.

Returning again to FIG. 2, the muted audio output signal S240 represents a signal used to separate the Tx message transmissions and is generated by the mute generator 255. An example of a corresponding composite TX data signal S230 consisting of a multiplexed TX modulation output signal S235 and a muted output signal S240 is shown in FIG. Tmu1 731, Td1 732, Tmu2 733, Td2 734, Tmu3 735, Td3 736 and Tmu4 737 represent the time duration when each signal is transmitted. An example of the corresponding range for Tmu1, Tmu2, Tmu3 and Tmu4 is 10-60 milliseconds, and for Td1, Td2 and Td3 it is 300-320 milliseconds for normal operation and 600-640 milliseconds for stable operation. Examples of the appropriate sequence of the mute generator can be: a signal with a sequence of all zeros or a sinusoidal frequency signal. Another relevant example of a signal used to separate Tx message transmissions is illustrated in FIG. 10. In this example, the activation output signal S236 and the synchronization preamble output signal S242 precede each transmission of the TX modulation output signal S235. One skilled in the art will appreciate that other combinations of the sync preamble output signal S242, muted output signal S240, and TX modulation output signal S235 can equally be applied. For example, the Tx modulation output signal S235 in FIG. 10 may follow after or before the muted sound output signal S240.

RECEIVER

Referring to FIG. 1, a main reception band 400 typically routes decoded voice packets from a vocoder to an audio processor, but is also capable of routing decoded packets through a data demodulator. Since non-speech data has been converted into a noise-like signal and encoded by a vocoder in the transmitter, the receiver vocoder is able to efficiently decode the data with minimal distortion. Decoded packets are continuously monitored for in-band clock. If a synchronization signal is detected, the temporal distribution of the frame is restored, and the decoded packet data is routed to the data demodulator. Decoded packet data is demodulated into messages. These messages are deformed and issued. The sequence of protocols containing synchronization, control and messages, provides reliable detection and demodulation of non-speech data.

Voice packets are received via communication channel 502 at receiver 495 and input to a vocoder decoder 390, where a decoded voice is generated and then routed through demultiplexer 320 to an audio output processor and speaker 315, generating an output sound S310.

When a synchronization signal is detected by the synchronization detector 350 in the output signal S370 of the vocoder decoder, the demultiplexer Rx control signal S360 is switched to the Rx data path in the Rx demultiplexer 320. The vocoder packets are decoded by the vocoder decoder 390 and routed by the Rx demultiplexer 320 to the Rx time distribution unit 380, and then to the Rx data modem 330. The Rx data is demodulated by the Rx data modem 330 and transmitted to the data formatting device (deformer) 301, where the S300 output is made available to the user or the equipment connected via the interface.

An example of a corresponding data message deformer 301 includes a circuit for eliminating data interleaving of an S320 Rx message, performing error control decoding such as hybrid automatic repeat request (HARQ), and computing and checking cyclic redundancy check (CRC) bits. Corresponding input to the S300 may include user interface (UI) information, user position / location information, time stamps, equipment sensor information, or other relevant data.

FIG. 15A is a corresponding exemplary structural diagram of a synchronization detector and receiver controller 350 shown in FIG. The output signal S370 of the vocoder decoder is input to a sync pulse burst detector 360 and a sync preamble detector 351. The sync pulse burst detector 360 detects the transmitted sync burst signal in the output signal S370 of the vocoder decoder and generates the burst pulse synchronization index S351. The sync pulse burst detector 351 detects the transmitted synchronization preamble output signal in the output signal S370 of the vocoder decoder and generates a preamble synchronization index S353. The signals of the pulse train synchronization index S351 and the preamble synchronization index S353 are input to the synchronization detector controller 370. The synchronization detector controller 370 generates output signals: Rx demultiplexer control S360, which routes the output signal S370 of the vocoder decoder to the data path S326 or the sound path S325, the mute control signal S365 that turns the sound output signal S310 on or off, and the time offset signal S350, which provides information on the temporal allocation of bits to the Rx time allocation unit 380 in order to align the S326 Rx data for demodulation.

Another example of a corresponding synchronization detector 350 is shown in FIG. The output signal S370 of the vocoder decoder is input into the memory 352 and the synchronization preamble detector 351. A memory 352 is used to store the last samples of the output signal S370 of the vocoder decoder including the received activation output signal. A relevant example of memory 352 is a sequential service (first-in, first-out) memory (FIFO), or random access memory (RAM). The synchronization preamble detector 351 detects the transmitted synchronization preamble output signal in the output signal S370 of the vocoder decoder and outputs a synchronization flag signal S305. A modulation type signal S306 and a synchronization flag signal S305 are input to the synchronization detector controller 370. The synchronization detector controller 370 generates a modulation search signal S307 used to access the memory 352, find the received activation output signal based on the time offset signal S350, and evaluate the activation output signal to determine the type of modulation used in the transmission. The resulting modulation type is output from the memory 352 as a modulation type signal S306. The synchronization detector controller 370 also generates output signals: an Rx demultiplexer control S360, which routes the output of the vocoder decoder S370 to the data path or the sound path, a mute control signal S365 that turns the sound output signal S310 on or off, and a time offset signal S350, which provides temporal bit allocation information to Rx time allocation block 380 in order to equalize S326 Rx data for demodulation.

An example of a corresponding sync pulse burst detector 360 is illustrated in FIG. The output signal S370 of the vocoder decoder is input to a power calculator 361. Examples of the corresponding power calculator 361 include an input squaring function or an absolute value function calculated in the input signal. The output signal S370 of the vocoder decoder is also input to a mixer 362 of the functions, where it is multiplied by the in-phase and quadrature components of the reference frequency sinusoid 1 363 and frequency sinusoid 2 364 in order to generate down-converted signal components with a frequency of 0 Hz. The output of the mixer 362 is filtered from low frequencies by means of a 365 LPF filter to eliminate the results of the high frequency multiplier in the mixed output. An example of the transfer function of the corresponding 365 LPF filter takes the form:

where c = 0.0554, a ₁ = 2, a ₂ = 1, b ₁ = -1.9742, b ₂ = 0.9744. The magnitude of the common-mode and quadrature output data of the 365 LPF filter is calculated by the magnitude calculating unit 366 and added to the adder 367. The output of the adder 367 is input to a matched filter 368 that matches the transmitted sequence of the burst of synchronization pulses. Consistent filters are well known in the art. The output of the matched filter 368 is scanned for maximum peak search in maximum search block 369. When a maximum is detected in the maximum search block 369, an index corresponding to the maximum offset time is output in the pulse train synchronization index signal S351.

An example of a corresponding synchronization preamble detector 351 is shown in FIG. The output signal S370 of the vocoder decoder is processed by a matched filter 368, which is matched with the sequence of the synchronization preamble. The output of the matched filter 368 is then provided to the maximum search unit 369, which searches for the maximum peak. When a maximum is detected in the maximum search block 369, an index corresponding to the maximum offset time is output in the preamble synchronization index signal S353.

Another example of a corresponding synchronization preamble detector 351 is shown in FIG. The output signal S370 of the vocoder decoder is processed by the filter in step 452. A corresponding example of the filter in step 452 is a scattered signal filter with coefficients based on an impulse response with a filtered passband of a synchronization preamble sequence. The scattered signal filter has a finite impulse response structure with some coefficients set to zero, and results in a reduction in the computational complexity based on the smaller number of required factors due to zero coefficients. Scattered signal filters are well known in the art. At step 453, the filter output is scanned to find the maximum positive and negative correlation peaks consistent with the expected pattern based on the gap between the negative and positive correlation peaks. For example, 5 peaks should be detected in step 453 based on a sequence 245 of a synchronization preamble, 3 positive peaks corresponding to correlations with a pseudo-random noise (PN) sequence 243, and 2 negative peaks corresponding to correlations with an inverse version of a PN 244 sequence. In a corresponding example, the synchronization detector must detect at least 2 peaks to announce that the synchronization preamble is detected. At step 461, the number of peaks detected is counted, and if most peaks are detected, then the synchronization indicator flag is set to “True” at step 460, indicating that preamble synchronization has been detected. A relevant example of most peaks detected is 4 out of 5 peaks consistent with the expected pattern. If most peaks are not detected, then control proceeds to step 454, where the time span between the positive peaks detected in step 453 is compared with the expected span, PeakDistT1. PeakDistT1 is set as a function of the period of the PN sequence 242, since filtering the received preamble with respect to the PN sequence 242 should produce a time span between the correlation peaks equal to a multiple of the period. If the time interval between the positive peaks is detected to be in the range PeakDistT1, at step 455 then the amplitudes of the positive peaks are checked against the threshold value PeakAmpT1. The suitable range for PeakDistT1 is plus or minus 2 samples. PeakAmpT1 is a function of the amplitudes of the previously detected peaks. In the corresponding example, PeakAmpT1 is set so that the peaks detected in step 453 do not differ in amplitude by more than a factor of 3, and the average peak amplitude does not exceed half of the maximum peak amplitude observed so far. If any of the verification of the time interval between the positive peaks at step 454 or the verification of the amplitude at step 455 fails, then at step 456, the time interval of the negative peaks is checked. If the time interval between the negative peaks is in the range of PeakDistT2, then at step 457 the amplitudes of the negative peaks are then checked against the threshold value of PeakAmpT2. The suitable range for PeakDistT2 is plus or minus 2 samples. PeakDistT2 is set as a function of the period period of the 242 PN, and PeakAmpT2 is set as a function of the amplitudes of the previously detected peaks. If any of the verification of the time span of the positive peaks at step 454 or the verification of the amplitude of the positive peaks at step 455, or the verification of the time span of the negative peaks at step 456 or the verification of the amplitude of the negative peaks at step 457, then the synchronization indicator flag is set to “True "At step 460, indicating that preamble synchronization has been detected. If any of the verification of the time interval of the negative peaks in step 456 or the verification of the amplitude of the negative peaks in step 457 fails, then the synchronization indicator flag is set to “False” in step 458, indicating that no preamble synchronization has been detected. Keep in mind that other orders and combinations of steps will achieve the same result. For example, the detection of multiple peaks in step 461 may be performed after checking the positive peaks of steps 454 and 455.

An example of a corresponding synchronization detector controller 370 is shown in FIG. 18A. Step 407 is the entry point to the controller, initializing the memory buffers and configuring the initial state of the receiver. At 406, a synchronization search type is checked, indicating whether the synchronization signal is searched in the data path Rx or the sound path Rx. Go to step 372 if synchronization is currently being searched in the sound path Rx. By using the burst synchronization index S351, in step 372, in a number of processed frames, N1, a maximum burst and pulse index are searched. Step 373 determines whether the maximum burst of synchronization pulses and the index searched at step 372 satisfy the criterion of successful search. An example of an appropriate search decision criterion in step 373 takes the form

where s _{max max} is the maximum number of bursts of synchronization pulses detected in N1 the number of processed frames, Th _SB is the threshold for detecting bursts of synchronization pulses, i _smax is the index of the maximum bursts of synchronization pulses, N _sync is the number of processed frames in which a search is performed, and N _guard is the lag time period in the frames being processed. If a burst of pulses is not detected, control returns to step 406, and the search starts again. If a burst of pulses is detected, control proceeds to step 374, where a mute control signal S365 is generated to prevent the sound path from being output to the speaker. At step 375, by using the preamble synchronization index S353, in a number of processed frames, N2, a maximum of the synchronization preambles and the index are searched. Step 376 determines whether the maximum synchronization preamble and index searched for in step 375 satisfy the criterion of successful search. An example of an appropriate search decision criterion in step 376 takes the form

where s _{max max} represents the maximum number of bursts of synchronization pulses detected in N1 the number of processed frames, c ₁ and c ₂ are the scaling factors, z _{max max} represents the maximum data outputs of the matched filter 368 in the synchronization preamble detector 351, P (i _smax ) represents the maximum input of power to the maximum search unit 369 in the detector 360 of the burst of synchronization pulses with the maximum index of the burst of synchronization pulses, i _smax . If the synchronization preamble is not detected at step 376, control returns to step 406, and the search starts again. If the synchronization preamble is detected, at step 378, the Rx demultiplexer control signal S360 is generated to switch to the Rx data path in the demultiplexer 320. The control then proceeds to step 377 where the time offset signal S350 is calculated. An example of a corresponding calculation of the time offset has the form:

where i _zmax is the index of the maximum data outputs of the matched filter 368 in the sync preamble detector 351 per frame, N _sync is the number of processed frames to be searched, N _samp is the number of samples in one frame, and k _max is the phase the maximum data output of the matched filter 368 in the sync preamble detector 351 per frame. The control then proceeds to step 418, where the Rx modem 330 is turned on by the Rx modem enable signal S354, then finally proceeds back to step 406, and the search starts again. Step 372a proceeds if synchronization is currently being searched in the Rx data path. Steps 372a, 373a, 375a, and 376a function in the same way as steps 372, 373, 375, and 376, respectively; the main difference is that the sound path is not turned off and the demultiplexer does not switch from Rx sound to Rx data when the synchronization search type checked in step 406 is Rx data.

Another example of a corresponding synchronization detector controller 370 is illustrated in FIG. Step 407 is the entry point to the controller, initializing the memory buffers and configuring the initial state of the receiver. At 406, a synchronization search type is checked, indicating whether the synchronization signal is searched in the data path Rx or the sound path Rx. Control then proceeds to step 411, where the preamble detector 351 is turned on. Step 412 checks the synchronization flag signal S305, indicating that a synchronization preamble has been detected, then confirms this by cyclically checking the synchronization flag signal S305 a total N number of times. The corresponding value for N is 1 (that is, only 1 preamble is detected without confirmation) for destination terminal 600 and 3 for source terminal 100. If a synchronization preamble is detected, a mute control signal S365 is generated to prevent the sound path from being output to the speaker. Then, in step 378, the control signal R3 of the demultiplexer Rx is generated to switch from the audio path Rx to the data path Rx in the demultiplexer 320. The control then proceeds to step 377, in which the time offset signal S350 is calculated. An example of a corresponding calculation of the time offset has the form

Temporal Displacement = Pulse Position + Interval Between Peaks

The Impulse position represents the time interval from the positive correlation peak to the first reference point in time and can have both positive and negative polarity. The Peak Gap is the time span between the positive correlation peak and the negative correlation peak. An example of a corresponding first reference point in time may be the position of a particular sample relative to the current received speech frame. Another example of a corresponding calculation of the time offset has the form:

Temporal Displacement = Pulse Position

The Impulse position represents the time interval from the negative correlation peak to the second reference point in time, and can have both positive and negative polarity. An example of a corresponding second reference point in time may be the position of a particular sample relative to the current received speech frame. The control then proceeds to step 414, where, using the modulation search signal S307, the modulation type is determined by searching the memory 352 at a predetermined position where the received activation output signal should be stored. Control then proceeds to step 418 where the Rx modem 330 is turned on by the Rx modem enable signal S354. The demodulation scheme used in the Rx modem enable signal S354 is determined in step 418 by a modulation type input signal S306. Finally, control moves back to step 406, and the search starts again. Step 411a proceeds if synchronization is currently being searched in the Rx data path. Steps 411a and 412a function in the same way as steps 411 and 412, respectively; the main difference is that the sound path is not turned off and the demultiplexer does not switch from Rx sound to Rx data when the synchronization search type checked in step 406 is Rx data. Keep in mind that other orders and combinations of steps will achieve the same result. For example, steps 374 of the mute path and steps 378 of the path switching can be swapped without any effect for the overall detection of synchronization.

Fig. 19 is an exemplary structural diagram of the Rx distribution of 380 over time shown in Fig. 1. The Rx time distribution 380 is used to align the boundaries of the modulation frame when data is output from the vocoder decoder 390, so that demodulation can occur in the Rx data modem 330. An Rx data signal S326 is input to a buffer 381, where several samples are stored. Relevant examples of buffer 381 include first-in-first out (FIFO) memory, or random access memory (RAM). Samples from buffer 381 are input to adjustable delay unit 382, where a time delay is applied to align the boundaries of the modulation frame in accordance with the time offset control signal S350. The corresponding delay used in block 382 adjustable delay, can be any number of samples from zero to frame size -1. The delayed signal is output as the adjusted Rx data signal S330.

FIG. 20 is a corresponding exemplary structural diagram of an Rx data modem 330 shown in FIG. Two signals can be demultiplexed in time through the demultiplexer 331 of the Rx data modem from the adjusted Rx data input signal S330: the demultiplexer muted signal S332 and the demultiplexer data signal S333. The demultiplexer mute signal S332 is a split or mute period that may exist between consecutive received messages, and which is removed from the adjusted Rx data signal S330 if this split or mute signal was applied to the transmitter. The demultiplexer Rx data signal S333 is a received modulated message signal input to the demodulator 335. The demodulator 335 demodulates the received message information bits from the adjusted Rx data signal S330. The Rx data modem 330 uses the demodulation frame boundaries determined by the Rx time distribution 380 and the demodulation type indicator determined by the synchronization detector controller 370 to determine the position of the data signal pulse and calculate the output data symbol based on the given position of the data signal pulse. An example of a suitable demodulator is a matched filter correlator, consistent with all allowed cyclic deviations of the modulation pulse shape used by the data modulator for transmission. Another example of a suitable demodulator is a matched filter correlator, consistent with the filtered pulse bandwidth used by the data modulator for transmission, this bandwidth filter representing channel transmission characteristics.

SYSTEM

21 is a case of exemplary (illustrative) use of the system and methods disclosed herein. The diagram represents a typical example of an emergency call system inside a vehicle (eCall). Vehicle accident 950 is shown as an accident with two vehicles. Other relevant examples for vehicle accident 950 include multiple vehicle accidents, single vehicle accidents, a flat tire on one vehicle, engine failure on one vehicle, or other situations in which the vehicle breaks down or when the user needs help. The Vehicle Integrated System (IVS) 951 is located in one or more vehicles involved in the accident 950, or may be located on the user. The vehicle system 951 may be comprised of a source terminal 100 described herein. The vehicle integrated system 951 communicates over a wireless channel, which may consist of an uplink channel 501 and a downlink channel 502. The request for data transmission may be received by means of a system integrated in the vehicle via a communication channel, or may be automatic or manually generated in a system built into the vehicle. Wireless tower 955 receives transmission from a vehicle system 951 and communicates via an interface with a wired network consisting of a wired uplink 962 and a wired downlink 961. A suitable example of a wireless tower 955 is a cellular telephone tower consisting of antennas, transceivers and relay equipment, all well known in the art, for communicating via an interface with a wireless uplink 501 and a downlink 502. The wired network communicates via an interface with a public safety reference point 960 (PSAP), where emergency information transmitted by the vehicle's integrated system 951 can be received and control and data transferred. The public security reference point 960 may consist of a destination terminal 600 described herein. The connection between the vehicle system 951 and the public safety reference point 960 is made using the interaction diagrams described in the following paragraphs.

FIG. 22 is an example (illustrative) diagram of the interaction of synchronization and data transmission sequences between a source terminal 100 and a destination terminal 600. In this example, the uplink sequence 810 is initiated by the destination terminal 600. The downlink sequence 800 is the transmission of synchronization and data messages from the destination terminal 600 to the source terminal 100, and the uplink sequence 810 is the transmission of synchronization and data messages from the source terminal 100 to the destination terminal 600. The downlink sequence 800 is initiated at time t0 850 via the destination terminal 600 using the synchronization sequence 801. Relevant examples of synchronization sequence 801 are the examples described in FIG. 8A, FIG. 8B and FIG. 8C. Following the synchronization sequence 801, the destination terminal 600 transmits a Start message 802 to instruct the source terminal 100 to begin transmitting its uplink sequence 810. Destination terminal 600 continues to transmit alternating: synchronization 801 and “Start” message 802 and is awaiting a response from source terminal 100. At time 851, t1, the source terminal 100, having received the “Start” message 802 from the destination terminal 600, starts transmitting its own synchronization sequence 811. Relevant examples of synchronization sequence 811 are those described in FIG. 8A, FIG. 8B and FIG. 8C. Following the synchronization sequence 811, the source terminal 100 transmits a minimum data set or an “MSD” message 812 to the destination terminal 600. A corresponding example of data containing the “MSD” message 812 includes touch data or user data formatted by the data message formatter 210. At time 852 t2, the destination terminal 600, having received the synchronization message 811 from the source terminal 100, starts transmitting a negative acknowledgment or “NACK” message 803 to the source terminal 100. Destination terminal 600 continues to transmit alternating: synchronizations 801 and NACK messages 803 until it successfully receives MSD message 812 from source terminal 100. A corresponding example of the successful reception of the MSD message 812 includes confirmation of the cyclic redundancy check performed in the MSD message 812. At time 853, time t3, the destination terminal 600, having successfully received the MSD message, starts transmitting alternating synchronizations 801 and confirmation message 804 or “ACK”. The source terminal 100 may attempt to send an MSD message multiple times (813, 814) until it receives an ACK message 804. In a corresponding example, if the source terminal 100 attempts to send an MSD message more than 8 times, each attempt being a different redundancy option, it switches to a more stable modulation scheme determined by the activation signal S236. A corresponding example of a more robust modulation scheme includes increasing the duration of the TMF modulation frame while maintaining a constant number of times, as described previously. At time 854 t4, the source terminal 100, having received the ACK message 804 from the destination terminal 600, interrupts the transmission of the MSD message 814. In a corresponding example, the destination terminal 600 again sends a retransmission request by sending start messages 802, after a predetermined number of ACK messages 804 have been sent by the destination terminal 600.

23A is another exemplary (illustrative) diagram of the interaction of synchronization and data transmission sequences between the source terminal 100 and the destination terminal 600. In this example, the uplink sequence 810 is initiated by the source terminal 100. The uplink sequence 810 is triggered at time t0 850a by the source terminal 100 using voice data 815 by configuring the transmission band 200 of the transmission of the source terminal 100 to the Tx audio path S225. At time 851a, t1, the source terminal 100 configures the transmission bandwidth 200 to the Tx data path S230 and starts transmitting its synchronization sequence 811, followed by the MSD message 812. At time 852a time t2, the destination terminal 600, having received the synchronization message 811 from the source terminal 100, starts transmitting alternating: synchronizations 801 and “NACK” messages 803 to the source terminal 100. Destination terminal 600 continues to transmit alternating: synchronizations 801 and NACK messages 803 until it successfully receives MSD message 812 from source terminal 100. At time 853, time t3, the destination terminal 600, having successfully received the MSD message, starts transmitting alternating synchronizations 801 and confirmation message 804 or “ACK”. The source terminal 100 may attempt to send an MSD message multiple times until it receives an ACK message 804, each attempt being a different redundancy option. At time 854 t4, the source terminal 100, having received the ACK message 804 from the destination terminal 600, interrupts the transmission of the MSD message 814.

23B is another exemplary (illustrative) diagram of the interaction of synchronization and data transmission sequences between the source terminal 100 and the destination terminal 600. In this case, the uplink sequence 810 is initiated by the source terminal 100. Instead of transmitting voice data on the uplink in order to initiate the transfer, the source terminal 100 transmits the following: synchronization 811 and the message “Sending” 805 at time t0 850b. At time tb 851b t1, the destination terminal 600, having received the “Send” message 805 from the source terminal 100, transmits alternating: synchronization 801 and the “Start” message 802. At time t2 852b t2, the source terminal 100, having received the Start message 802 from the destination terminal 600, transmits a synchronization sequence 811, followed by the MSD message 812, to the destination terminal 600. At time 853b time t3, the destination terminal 600, having successfully received the synchronization message 811 from the source terminal 100, transmits the alternating: synchronization 801 and the "NACK" message 803 to the source terminal 100. At time t4 854b t4, the destination terminal 600, having successfully received the MSD message, transmits alternating: synchronization 801 and the ACK message 804. Upon receipt of the ACK message 804 from the destination terminal 600, the source terminal 100 interrupts the transmission of the MSD message.

24A is an example (illustrative) diagram of the interaction of synchronization and data transmission sequences between the source terminal 100 and the destination terminal 600. In this case, data is requested and transmitted by both the source terminal 100 and the destination terminal 600 on the uplink and downlink, respectively, in support of bidirectional data transmission. The downlink sequence 800 is triggered at time t0 by the destination terminal 600 using alternating: synchronization sequences 801 and the “Start” message 802. At the time 851 at time t1, the source terminal 100, having received the “Start” message 802 from the destination terminal 600, starts transmitting its own synchronization sequence 811, followed by the data 812. At the time 852 t2, the destination terminal 600 transmits alternating: synchronization 801 and message 803 “NACK” until it successfully receives data 812 from the source terminal 100, after which the destination terminal 600 then transmits alternating: synchronization sequence 801 and an “ACK” message 804. At time 854 t4, the source terminal 100, having received the ACK message 804 from the destination terminal 600, interrupts the transmission of its data. At time 855, t5, the destination terminal 600 transmits alternating: a synchronization sequence 801 and a “send” message 805, indicating a request for data transmission in a downlink. At time 856 time t6, the source terminal 100, upon detecting the “Send” message 805, responds using alternating: synchronization sequences 811 and the “Start” message 816. At time 857 t7, the destination terminal 600, upon detecting the “Start” message 816, responds with a synchronization sequence 801, followed by data 806. At time 858 t8, the source terminal 100 transmits alternating: synchronization sequence 811 and “NACK” message 817 to until it successfully receives the data 806 from the destination terminal 600, after which, at time t9, t9, the source terminal 100 sends alternating: synchronization sequence 811 and “ACK” message 818. At time 860 t10, the destination terminal 600, having received the ACK message 818 from the source terminal 100, stops transmitting its data. The data specialist will appreciate that the interactions described herein are symmetrical and can be triggered by the source terminal 100. One of ordinary skill in the art will also appreciate that a synchronization sequence, a start message, a NACK message, and an ACK message can each be the same or different sequence between those transmitted on the downlink and uplink.

24B is another example (illustrative) diagram of the interaction of synchronization and data transmission sequences between a source terminal 100 and a destination terminal 600, in which data is requested and transmitted by both the source terminal 100 and the destination terminal 600 on the uplink and downlink, respectively. The difference between the interactions in FIG. 24B and the interactions in FIG. 24A occurs at time t3. In this example, instead of alternating: synchronizations and ACK messages, alternating: synchronization 801 and message 805 “Send” are transmitted via the destination terminal 600. In this example, a “Send” message 805 is used to indicate that the destination terminal 600 has successfully received the data 812 of the source terminal 100, and results in the terminal 100 terminating its data transmission at time 854 t4. The message “Sending” also means a request from the destination terminal 600 to send data on the downlink.

25 is an example (illustrative) diagram of compiling a data packet for transmission in which a user data length is less than a data packet length for transmission. The user data segment 900 is compiled into a data packet 806 or 812 for transmission simultaneously with a prefix length indicator 910 and a subsequent sequence of filler bits 911 serving to fill the data to the end of the data packet for transmission. A suitable example for a length indicator 910 is a value from 1 to 3 bytes indicating the length of a user data segment 900. A suitable example of a length of 806 or 812 data packets for transmission may be a length of 100-200 bytes. A corresponding example of filler bits 911 includes a binary value of “0”. One skilled in the art will appreciate that the filler bits 911 may consist of a binary value of “1”, or may consist of a binary value circuit of “1” and “0”.

26 is an example (illustrative) diagram of compiling a data packet for transmission in which the length of user data is greater than the length of the data packet for transmission. The user data 900 is divided into many segments, so that the first segment plus the length indicator is equal to the length of the data packet for transmission, and subsequent segments are equal to the length of the data packet for transmission. If the user data is not an integer multiple of the length of the data packet to transmit, then the last segment contains a placeholder. In the example of FIG. 26, user data is divided into two segments. The first user data segment 901 is assembled into a data packet 806 or 812 for transmission along with a preliminary length indicator 910. The second user data segment 902 is arranged in a data packet 806 or 812 for transmission, and since the segment is shorter than the length of the data packet for transmission, a placeholder 911 is used to fill the data to the end of the data packet for transmission.

27A is an example (illustrative) diagram of an interaction of a data transmission request sequence and a data transmission response sequence in which a user data length is larger than a data packet size for transmission. Initiated by the “Start” messages of the requesting terminal, either in the downlink transmission 800 or in the uplink transmission 810, at time t70 870, the first data packet 806 or 812 for transmission consisting of the length indicator 910 and the first is transmitted by the responding terminal user data segment 901. At time 871, time t21, since the responding terminal has not yet received the ACK message, it starts sending user data again in the second attempt 903. At time 872 t22, the responding terminal, having received the message “ACK”, interrupts the transmission of the first data packet 806 or 812 . At time 873 of time t23, the requesting terminal, after evaluating the length indicator 910 to determine how many segments are expected, requests the next data packet 806 or 812 for transmission by sending “Start” messages to the responding terminal. At time 874 t24, the responding terminal, having received the “Start” message from the requesting terminal, starts transmitting the next data packet 806 or 812 for transmission, consisting of the next user data segment 902 and placeholder 911 (in this example, the next data packet for transmission is the last packet data). At time 875, t25, the responding terminal, having received the “ACK” message, interrupts its data transmission. One skilled in the art will appreciate that the interactions described herein are symmetrical, with the requesting and responding terminals being either the source terminal 100 or the destination terminal 600. One skilled in the art will also appreciate that user data may span more than two data packets 806 or 812 for transmission.

Figv is another exemplary (illustrative) diagram of the interaction of the sequence of the request for data transmission and the sequence of the response to the transmission of data in which the data length of the user is greater than the size of the packet for transmission. In this example, after the first data packet 806 or 812 for transmission is requested via “Start” messages transmitted by the requesting terminal, subsequent data packets 806 or 812 for transmission are automatically transmitted by the responding terminal based on the receipt of the “ACK” message from the requesting terminal. In this example, the requesting terminal does not send a Start message to initiate the transmission of a subsequent data packet 806 or 812 for transmission from the responding terminal. At time 881, t31, the answering terminal, having received the “ACK” message, interrupts the transmission of the first data packet, then immediately starts transmitting the next data packet 806 or 812 for transmission, separated only by the synchronization sequence. At time 882, t32, the requesting terminal, having received the synchronization sequence, starts transmitting “NACK” messages until it successfully receives a data packet 806 or 812 for transmission. At time 883, t33, having successfully received the data packet 806 or 812 for transmission, the requesting terminal starts transmitting “ACK” messages. At time 884, t34, the responding terminal, having received the ACK message, interrupts the transmission of the data packet 806 or 812 for transmission.

FIG. 27C is another other exemplary (illustrative) diagram of the interaction of a data transfer request sequence and a data transfer response sequence in which a user data length is larger than a packet size for transmission. In this example, after the first data packet 806 or 812 for transmission is requested via “Start” messages transmitted by the requesting terminal, subsequent data packets 806 or 812 for transmission are automatically transmitted by the responding terminal based on the receipt of the “ACK” message from the requesting terminal. In this example, the requesting terminal does not transmit “Start” messages in order to initiate the transmission of a data packet 806 or 812 for transmission from the responding terminal, the requesting terminal does not transmit “NACK” messages either. At time tl 891, the responding terminal, having received the “ACK” message, interrupts the transmission of the first data packet, then immediately starts transmitting the next data packet 806 or 812 for transmission, separated only by the synchronization sequence. At time 892, t42, having successfully received the data packet 806 or 812 for transmission, the requesting terminal starts transmitting “ACK” messages. When the responding terminal receives the ACK messages, it interrupts the transmission of the data packet 806 or 812 for transmission.

Fig. 27D is another another exemplary (illustrative) diagram of the interaction of the sequence of the request for data transmission and the sequence of the response to the transmission of data in which the data length of the user is greater than the size of the packet for transmission. FIG. 27D is an alternative to the example (illustrative) interaction diagram shown in FIG. 27B. In the example of FIG. 27D, a time gap is closed at time 882 of time t32 between the “ACK” message of the requesting terminal on the first user data segment 903 and the “NACK” message on the next user data segment 902. This helps maintain time distribution in the responding terminal so that it does not need to be re-synchronized with the synchronization sequence of the requesting terminal.

One skilled in the art will understand that the responding terminals can automatically transmit data packets following the first data packet without transmitting a synchronization sequence separator. In this case, the synchronization sequence is sent once before the first data packet 806 or 812 for transmission, then upon receipt of the “ACK” messages, the answering terminal automatically transmits the next data packet without sending synchronization. The person skilled in the art will also be able to take into account that the length indicator 910 can also be transmitted with other data segments in addition to the first.

The interaction diagrams disclosed herein may exhibit failure situations that must be received and processed in a predetermined manner. The following paragraphs provide examples of handling failure situations corresponding to the interaction diagrams disclosed herein. In each example, a failure situation is recorded along with a description of the corresponding response. One of skill in the art will appreciate that the failure processing described herein can equally be applied to a source terminal or a destination terminal in both unidirectional and bidirectional embodiments.

An exemplary failure condition occurs when the source terminal does not detect a transmitted synchronization preamble. As an example of a response, the source terminal delays the transmission of the MSD message until a predetermined number of synchronization preambles is detected.

Another exemplary failure condition occurs when the source terminal incorrectly detects the synchronization preamble. As an example of a response, the source terminal delays the transmission of the MSD message until a predetermined number of synchronization preambles produces the same sample offset.

Another exemplary failure condition occurs when the source terminal falsely detects a synchronization preamble, although in reality none have been transmitted. As an example of a response, the source terminal ignores falsely detected synchronization preambles. The source terminal initiates the MSD transmission only if a predetermined number of detected synchronization preambles produces the same estimate of the sample offset.

Another exemplary failure condition occurs when the destination terminal does not detect a transmitted synchronization preamble. As an example of a response, the destination terminal does not start decoding the MSD message, but continues to transmit “Start” messages to prompt the source terminal to re-initiate the MSD transmission after a predetermined number of “Start” messages have been received (including the sequence of synchronization preamble).

Another exemplary failure condition occurs when the destination terminal incorrectly detects the synchronization preamble. As an example of the response, the destination terminal decodes the received MSD data incorrectly during all redundancy options. Based on incorrectly decoded data, the destination terminal can re-initiate the MSD transmission by sending “Start” messages to the source terminal.

Another exemplary failure condition occurs when the destination terminal falsely detects a synchronization preamble, although in reality none have been transmitted. There is no response, since the likelihood of this incident is very small. The destination terminal does not start tracking its received signal until it waits for the synchronization preamble from the source terminal.

Another exemplary failure condition occurs when the source terminal erroneously interprets the “Start” message as a “NACK” message. As an example of a response, if the MSD transmission has not yet begun, the source terminal delays the transmission of the MSD until it receives the “Start” message. As another example of a response, if the MSD transmission is already ongoing, the source terminal delays the reinitialization of the transmission.

Another exemplary failure condition occurs when the source terminal erroneously interprets the “Start” message as the “ACK” message. As an example of a response, if the MSD transmission has not yet begun, the source terminal ignores any “ACK” message. As another example of a response, the source terminal ignores “ACK” if previous messages were interpreted as a “Start” message. As another other example of a response, if the previous messages were “NACK” messages, the source terminal puts itself on hold and ends the MSD transmission if the next message is also interpreted as “ACK”. As another other example of a response, if the previous message was interpreted as “ACK”, the source terminal fails to transmit the MSD erroneously. The probability of this event is low, however, if it occurs, the destination terminal can re-initiate the transmission again by sending a request along with the Start message.

Another exemplary failure condition occurs when the source terminal erroneously interprets the “NACK” message as the “Start” message. As an example of the response, a single "NACK", interpreted as "Start", does not have any effect on the transmission of MSD. As another example of a response, a series of “NACK” messages, each of which is interpreted as a “Start” message, may cause the source terminal transmitter to re-initiate the MSD. The destination terminal will not expect this and will not be able to receive incoming data, as a result it will produce incorrectly decoded data. Based on incorrectly decoded data, the destination terminal can request the source terminal to re-initiate the transmission by sending “Start” messages.

Another exemplary failure condition occurs when the source terminal erroneously interprets the “NACK” message as the “ACK” message. As an example of a response, if the previous message was interpreted as a “Start” message, the source terminal ignores any “ACK” message. As another example of a response, if the previous message was interpreted as a “NACK” message, the source terminal expects another “ACK”. If the next message is not another “ACK”, the current “ACK” is ignored. As another other example of a response, if the previous message was also erroneously detected as an “ACK” message, the source terminal may end the MSD transmission, although the destination terminal has not yet received the MSD correctly. The probability of this event is low, however, if it occurs, the destination terminal can re-initiate the transmission again by sending a request along with the Start message.

Another exemplary failure condition occurs when the source terminal erroneously interprets the “ACK” message as a “Start” message. As an example of the response, the source terminal will not interrupt the transmission of additional MSD redundancy options, since a typical interruption situation is the reception of a predetermined number of “ACK” messages. If more subsequent messages are interpreted as “Start” messages, the source terminal may re-initiate the MSD transmission. As a result, the destination terminal will stop transmitting messages. The source terminal will ultimately determine that the destination terminal is no longer transmitting synchronization frames, and will reset itself, thereby stopping additional transmissions.

Another exemplary failure condition occurs when the source terminal erroneously interprets the “ACK” message as the “NACK” message. As an example of the response, the source terminal will continue to transmit redundancy options until the ACK messages are correctly detected. As a result, the destination terminal will stop sending messages. The source terminal will ultimately determine that the destination terminal is no longer transmitting synchronization frames, and will reset itself, thereby stopping additional transmissions.

Another exemplary failure condition occurs when the source terminal determines that the received message is not reliable. As an example of a response, if the received messages are “Start” messages, the source terminal continues to count unreliable messages, but with a lower significance coefficient than if the messages were received using a reliable determination. Subsequent triggering of an event based on counting received messages will require a larger predefined number of received untrusted messages as to if the messages would have been received with a reliable determination. As another example of a response, if the unreliable received messages are “NACK” messages or “ACK” messages, the source terminal may ignore the message data.

Another exemplary failure condition occurs when the destination terminal is not able to detect the transmitted MSD due to noise or other channel distortion. As an example of the response after trying to decode a predetermined number of redundancy options, the destination terminal may request the source terminal to re-initiate the transmission by sending “Start” messages. In a re-triggered transmission, the source terminal may use a fault tolerant modulator, less susceptible to noise and other channel distortions.

Another exemplary failure condition occurs when the destination terminal cannot correctly evaluate the activation signal. As an example of a response, if the destination terminal considers the activation signal detection unreliable, it selects the fast (or normal) modulation mode for the first attempt to demodulate MSD data. For any other set of predetermined number of received MSD data redundancy options, the destination terminal may use stable modulation mode to demodulate the data.

Thus, an apparatus and method for reliable and efficient data transmission within a bandwidth by means of a speech codec in a wireless communication system are disclosed herein. Those skilled in the art will understand that information and signals can be represented using any of a variety of technologies and methods. For example, data, instructions, commands, information, signals, bits, symbols and chips that can be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or a combination. Also, although embodiments are described primarily from the point of view of a wireless communication system, the described methods can be applied to other communication systems for transmitting data within a bandwidth that is fixed (non-portable) or does not use a wireless channel.

Those skilled in the art will further fully appreciate that the various illustrative logical blocks, modules, circuits, and algorithmic steps described in connection with the embodiments of the present disclosed invention can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been generally described above in terms of their functionality. Whether such functionality will be in the form of hardware or software depends on the particular implementation and design constraints imposed on the entire system. Skilled artisans may perform the described functionality in varying ways for each particular embodiment, but such implementation decisions should not be construed as falling outside the scope of the present disclosed invention.

The various illustrative logical blocks, modules, and circuits described in connection with embodiments of the present disclosed invention may be implemented or produced by a general purpose processor, a digital signal processor (DSP), specialized to solve a specific task of an integrated circuit (ASIC) programmable by a valve user matrix (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components or any combat their combination, made with the ability to perform the functions described in the present invention. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state determination mechanism. A processor may also be a combination of computing devices, for example, a combination of a DSP processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with embodiments of the present disclosed invention may be implemented directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module can reside (stored) in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, on a hard disk, a removable disk, a CD-ROM, and any other form of storage medium (storage medium), known in the art. The storage medium is connected to the processor so that the processor can read information from this storage medium and write information to the storage medium. Alternatively, the storage medium may be integrated in the processor. The processor and the storage medium may reside within the ASIC. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal.

The above description of the disclosed embodiments is intended to provide a specialist in the field of technology the ability to perform or use the present invention. Various modifications to these embodiments will be readily apparent to such specialists, and the general principles described herein can be applied to other exemplary embodiments without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited by the embodiments shown in the present invention, but should be consistent with the broadest scope consistent with the principles and new features disclosed in the present invention.

Claims (28)

1. A method of obtaining non-speech data embedded in a vocoder package comprising the steps of:
receive and decode a vocoder packet;
filtering the decoded vocoder packet until a synchronization signal is detected, the filtering comprising the steps of correlating the decoded packet of the vocoder with a predetermined sequence to generate a plurality of correlation peaks, and comparing the plurality of correlation peaks with the expected pattern, the predetermined sequence being pseudo-random noise sequence, and moreover, the correlation contains the stage at which one of the non-overlapping or ne an uncovered composite preamble sequence of a decoded vocoder packet with a pseudo-random noise sequence, wherein the expected pattern is based on a combination of negative and positive correlation peaks, and the comparison uses a number of the plurality of correlation peaks consistent with the expected pattern and determining whether the said quantity exceeds a predetermined value ;
calculating a time offset based on a synchronization signal; and
extracting non-speech data embedded in a decoded vocoder packet based on a time offset. 2. The method according to claim 1, in which the correlation further comprises the step of applying a sparse signal filter, the coefficients of which are the impulse response of a predefined sequence. 3. The method according to claim 1, in which the predefined value is 80% of the maximum number of positive correlation peaks and negative correlation peaks detected in the synchronization signal corresponding to the expected pattern. 4. The method according to claim 1, in which the comparison comprises the steps in which:
identify the number of positive correlation peaks in the synchronization signal;
determining whether the time interval between the positive correlation peaks is within the first predetermined range; and
determining whether the amplitude of the positive correlation peaks is greater than the first predetermined threshold value. 5. The method according to claim 1, in which the comparison comprises the steps in which:
identify the number of negative correlation peaks in the synchronization signal;
determining whether the time interval between the negative correlation peaks is within the second predetermined range; and
determining whether the amplitude of the negative correlation peaks is greater than the second predetermined threshold value. 6. The method according to claim 1, wherein the calculation comprises adding a time interval between a positive correlation peak and a reference point in time to a time interval between a positive correlation peak and a negative correlation peak. 7. The method according to claim 1, in which the calculation comprises the step of adding a time interval between the negative peak of the correlation and the reference point in time. 8. The method according to claim 1, in which the extraction contains stages in which:
determining a demodulation frame boundary based on a time offset;
determining a demodulation type based on a demodulation type indicator;
determining the position of the pulse of the data signal using the border of the demodulation frame and the type of demodulation; and
calculating an output symbol based on the position of the pulse of the data signal. 9. The method of claim 8, wherein the demodulation type indicator is a predefined signal. 10. The method according to claim 9, in which the predefined signal is a sinusoidal signal. 11. The method according to claim 9, in which the predefined signal is stored in memory at a position determined by the time offset. 12. Memory storing a computer program, which, when executed, instructs the computer to perform the following actions:
receive and decode a vocoder packet;
filtering the decoded vocoder packet until a synchronization signal is detected, the filtering comprising correlating the decoded vocoder packet with a predetermined sequence to generate a plurality of correlation peaks and comparing the plurality of correlation peaks with the expected pattern, the predetermined sequence being a pseudo-random noise sequence, and moreover, the correlation contains the correlation of one of the non-overlapping or overlapping composite sequence the preamble sequence of the decoded vocoder packet with a pseudo-random noise sequence, wherein the expected pattern is based on a combination of negative and positive correlation peaks, and the comparison uses a certain number of multiple correlation peaks consistent with the expected pattern, and determining whether said amount exceeds a predetermined value;
calculate the time offset based on the synchronization signal; and
extract non-speech data embedded in a decoded vocoder package based on a time offset. 13. A device for obtaining non-speech data embedded in a vocoder package, comprising:
a receiver configured to receive and decode a vocoder packet;
a filter configured to filter the decoded vocoder packet until a synchronization signal is detected, the filter comprising a correlator for correlating the decoded vocoder packet with a predetermined sequence to generate a plurality of correlation peaks and a comparator for comparing said plural correlation peaks with the expected pattern, moreover, the predetermined sequence is a pseudo-random noise sequence, and moreover, the correlator it solves one of the non-overlapping or overlapping composite preamble sequence of the decoded vocoder packet with a pseudo-random noise sequence, wherein the expected pattern is based on a combination of negative and positive correlation peaks, and the comparison uses some of the many correlation peaks consistent with the expected pattern, and determining if said amount is a predetermined value;
a calculator configured to calculate a time offset based on a synchronization signal; and
an extractor configured to extract non-speech data embedded in a decoded vocoder package based on a time offset. 14. The device according to item 13, in which the correlator is a sparse signal filter, the coefficients of which are the impulse response of a predefined sequence. 15. The device according to item 13, in which the predefined value is 80% of the maximum number of positive correlation peaks and negative correlation peaks detected in the synchronization signal corresponding to the expected pattern. 16. The device according to item 13, in which the filter contains:
a positive peak detector for identifying the number of positive correlation peaks in the synchronization signal;
a positive peak time comparator for determining whether the time interval between the positive correlation peaks is within the first predetermined range; and
a positive peak amplitude comparator for determining whether the amplitude of the positive correlation peaks is greater than the first predetermined threshold value. 17. The device according to item 13, in which the filter contains:
a negative peak detector for identifying the number of negative correlation peaks in the synchronization signal;
a negative peak time comparator for determining whether the time interval between the negative correlation peaks is within the second predetermined range; and
a negative peak amplitude comparator for determining whether the amplitude of the negative correlation peaks is greater than the second predetermined threshold value. 18. The device according to item 13, in which the calculator comprises an adder for adding a time interval between a positive correlation peak and a reference point in time to a time interval between a positive correlation peak and a negative correlation peak. 19. The device according to item 13, in which the calculator comprises an adder for adding a time interval between the negative correlation peak and the reference time. 20. The device according to item 13, in which the extractor contains a processor for:
determining a demodulation frame boundary based on a time offset;
determining the type of demodulation based on the indicator of the type of demodulation;
determining the position of the pulse of the data signal using the border of the demodulation frame and the type of demodulation; and
computing an output symbol based on the position of the pulse of the data signal. 21. A device for receiving non-speech data embedded in a vocoder package, comprising:
means for receiving and decoding a vocoder packet;
means for filtering the decoded vocoder packet until a synchronization signal is detected, the filtering means comprising means for correlating the decoded packet of the vocoder with a predetermined sequence for generating a plurality of correlation peaks and means for comparing the plurality of correlation peaks with the expected pattern, the given sequence is a pseudo-random noise sequence, and moreover, the means for correlation correlates one of an overlapping or overlapping composite preamble sequence of the decoded pseudo-random noise vocoder packet, the expected pattern being based on a combination of negative and positive correlation peaks, and the comparison using a number of multiple correlation peaks consistent with the expected pattern, and determining if the said number exceeds the previously mentioned amount set value;
means for calculating a time offset based on a synchronization signal; and
means for extracting non-speech data embedded in a decoded vocoder package based on a time offset. 22. The device according to item 21, in which the means for correlation is further configured to use a sparse signal filter, the coefficients of which are the impulse response of a predefined sequence. 23. The device according to item 21, in which the predefined value is 80% of the maximum number of positive correlation peaks and negative correlation peaks detected in the synchronization signal corresponding to the expected pattern. 24. The device according to item 21, in which the filtering tool is further configured to:
identification of the number of positive correlation peaks in the synchronization signal;
determining whether the time span between the positive correlation peaks is within the first predetermined range; and
determining whether the amplitude of the positive correlation peaks is greater than the first predetermined threshold value. 25. The device according to item 21, in which the means for filtering is further configured to:
identification of the number of negative correlation peaks in the synchronization signal;
determining whether the time interval between the negative correlation peaks is within the second predetermined range; and
determining whether the amplitude of the negative correlation peaks is greater than the second predetermined threshold value. 26. The device according to item 21, in which the means for calculating comprises means for adding a time interval between a positive correlation peak and a reference point in time to a time interval between a positive correlation peak and a negative correlation peak. 27. The device according to item 21, in which the means for calculating contains means for adding a time interval between the negative peak of the correlation and the reference point in time. 28. The device according to item 21, in which the means for extracting contains:
means for determining a demodulation frame boundary based on a time offset;
means for determining a demodulation type based on a demodulation type indicator;
means for determining the position of the pulse of the data signal using the border of the demodulation frame and the type of demodulation; and
means for calculating the output symbol based on the position of the pulse of the data signal.

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