HK1082627B

HK1082627B - Improved feedback system using dynamic decoding

Info

Publication number: HK1082627B
Application number: HK06102607.5A
Authority: HK
Inventors: S．A．伦比
Original assignee: 高通股份有限公司
Priority date: 2002-07-08
Filing date: 2003-07-08
Publication date: 2008-11-07

Description

Improved feedback system using dynamic decoding

Background

Technical Field

The present invention relates generally to packet data communications and, more particularly, to improving feedback systems using acknowledgement signals.

Background

The field of wireless communications has many applications including, for example, cordless telephones, paging, wireless local loops, Personal Digital Assistants (PDAs), internet telephony, and satellite communication systems. A particularly important application is cellular telephone systems for mobile subscribers. The term "cellular" as used herein encompasses both cellular and Personal Communications Services (PCS) services. Various air interfaces have been developed for such cellular telephone systems including, for example, Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA). Various national and international standards have been established in connection with them, including, for example, Advanced Mobile Phone Service (AMPS), IS-95 and its derivatives IS-95A, IS-95B, ANSI J-STD-008 (generally referred to herein collectively as IS-95), and the proposed high data rate systems are promulgated by the Telecommunications Industry Association (TIA) and other well known standard entities.

Cellular telephone systems configured pursuant to use of the IS-95 standard employ CDMA signal processing techniques to provide efficient and robust cellular telephone service. Exemplary cellular telephone systems configured substantially in accordance with the use of the IS-95 standard are described in U.S. patent nos. 5,103,459 and 4,901,307, both assigned to the assignee of the present invention and incorporated herein by reference. An exemplary system that utilizes CDMA techniques is the CDMA2000 ITU-R Radio Transmission Technology (RTT) candidate proposal (referred to herein as CDMA2000) promulgated by the TIA. The standard for Cdma2000 IS given in the draft of IS-2000 and IS acknowledged by the TIA. Another CDMA standard is the W-CDMA standard, embodied in the third generation partnership project "3 GPP" under document nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214.

The telecommunication standards cited above are only examples of the various communication systems that can be implemented. Some of these various communication systems are configured to allow transmission of data traffic between a subscriber unit and a base station. In systems designed to carry data traffic, optimizing the data throughput of the system is always the ultimate goal. Furthermore, it is desirable to ensure reliable reception of transmitted information. Embodiments described herein provide for a reliable feedback mechanism that will improve the reliable reception of transmitted data, which will further improve the data throughput of the communication system.

Disclosure of Invention

The method and apparatus presented herein addresses the above-mentioned needs. In one aspect, an apparatus for dynamically decoding an extended acknowledgement signal from a destination is presented, comprising: at least one memory element; and at least one processing element configured to execute a set of instructions held within the at least one memory element, the set of instructions for: receiving the extended acknowledgement signal in parallel and monitoring the received signal quality of the extended acknowledgement signal; comparing a received signal quality of a portion of the extended acknowledgment signal to a threshold; and if the received signal quality is greater than or equal to the threshold, decoding a portion of the extended acknowledgement signal and discarding a remaining portion of the extended acknowledgement signal.

In another aspect, a method is presented for: receiving the extended acknowledgement signal in parallel and monitoring the received signal quality of the extended acknowledgement signal; comparing a received signal quality of a portion of the extended acknowledgment signal to a threshold; and if the received signal quality is greater than or equal to the threshold, decoding the portion of the extended acknowledgement signal and discarding the remaining portion of the extended acknowledgement signal.

Drawings

Fig. 1 is a schematic diagram of a wireless communication network.

Fig. 2 shows a slotted timeline for performing a prior art fast acknowledgment method.

Fig. 3 is a timeline for decoding an acknowledgment signal.

Fig. 4 is a flow chart for fast decoding of an acknowledgment signal.

Fig. 5 is a flow chart for performing a new rapid acknowledgment method.

Fig. 6 shows a slotted timeline for performing the new fast acknowledgement method.

Detailed Description

As shown in fig. 1, a wireless communication network 100 generally includes a plurality of mobile stations (also referred to as subscriber units or user equipment or remote stations) 12a-12d, a plurality of base stations (also referred to as Base Transceiver Stations (BTSs) or node bs) 14a-14c, Base Station Controllers (BSCs) (also referred to as radio network controllers or packet control functions 16), a Mobile Switching Center (MSC) or switch 18, a packet data serving node (PSTN) or interworking function (IWF)20, and a Public Switched Telephone Network (PSTN)22 (typically a telephone company). And an Internet Protocol (IP) network 24 (typically the internet). For simplicity, four mobile stations 12a-12d, three base stations 14a-14c, one BSC 16, one MSC18, and one PDSN20 are shown. Those skilled in the art will appreciate that there may be any number of mobile stations 12, base stations 14, BSCs 16, MSCs 18, and PDSNs 20.

In one embodiment, the wireless communication network 10 is a packet data service network. The mobile stations 12a-12d may be any of a number of different types of wireless communication device such as a portable telephone, a cellular telephone that is connected to a laptop computer running an IP-based Web browser application, a cellular telephone with an associated hands-free car kit, a Personal Digital Assistant (PDA) running an IP-based Web browser application, a wireless communication module incorporated into a portable computer, or a fixed location communication module as might be found in a wireless local loop or meter reading system. In the most general embodiment, the mobile station may be any type of communication unit.

The mobile stations 12a-12d are preferably configured to implement one or more packet data protocols such as those described in the EIA/TIA/IS-707 standard. In a particular embodiment, the mobile stations 12a-12d generate IP packets that are directed to the IP network 24 and encapsulate the IP packets into frames using a Point-to-Point protocol (PPP).

In one embodiment, the IP network 24 is coupled to a PDSN20, the PDSN20 is coupled to a MSC18, the MSC is coupled to a BSC 16, which is coupled to the base stations 14a-14c, and the BSC is coupled to the BSCs 16, which are each implemented via lines configured for voice and/or data packet transmission in accordance with any known protocol, including, for example, E1, T1, Asynchronous Transfer Mode (ATM), IP, PPP, frame Relay, HDSL, ADSL, or xDSL. In another embodiment, the BSC 16 is coupled directly to the PDSN20, and the MSC18 is not coupled to the PDSN 20.

During normal operation of the wireless communication network 10, the base stations 14a-14c receive and demodulate sets of reverse signals arriving from the mobile stations 12a-12d involved in a telephone call, Web browsing, or other data communication. Each reverse signal received by a given base station 14a-14c is processed within that base station 14a-14 c. Each base station 14a-14c may communicate with a plurality of mobile stations 12a-12d by modulating sets of forward signals and transmitting them to the mobile stations 12a-12 d. For example, as shown in fig. 1, the base station 14a communicates with first and second mobile stations 12a, 12b simultaneously, and the base station 14c communicates with third and fourth mobile stations 12c, 12d simultaneously. The resulting packets are forwarded to the BSC 16, and the BSC 16 provides call resource allocation and mobility management functions, including orchestrating soft handoffs of calls for a particular mobile station 12a-12d from one base station 14a-14c to another base station 14a-14 c. For example, the mobile station 12c is communicating with two base stations 14b, 14c simultaneously. Finally, when the mobile station 12c moves far enough away from one of the base stations 14c, the call is handed off to the other base station 14 b.

If the transmission is a conventional telephone call, the BSC 16 will route the received data to the MSC18, which 18 provides additional routing services for interfacing with the PSTN 22. If the transmission is a packet-based transmission, such as a data call directed to the IP network 24, the MSC18 will route the data packet to the PDSN20, and the PDSN20 will send the packet to the IP network 24. Alternatively, the BSC 16 may route the packets directly to the PDSN20, and the PDSN20 may send the packets to the IP network 24.

In some communication systems, packets with data traffic are divided into subpackets, which occupy multiple slots of a transmission channel. For simplicity of explanation, the nomenclature of a cdma2000 system is used herein. Such use is not intended to limit the embodiments herein to cdma2000 systems. These embodiments may be implemented in other systems, such as WCDMA, without affecting the scope of the embodiments described herein.

The forward link from a base station to a remote station operating within range of the base station may include multiple channels. Some channels of the forward link may include, but are not limited to: a pilot channel, a synchronization channel, a paging channel, a quick paging channel, a broadcast channel, a power control channel, an assignment channel, a control channel, a dedicated control channel, a Medium Access Control (MAC) channel, a fundamental channel, a supplemental code channel, a packet data channel, and an acknowledgement channel.

The reverse link from the remote station to the base station also includes multiple channels. Some channels of the reverse link may include, but are not limited to: a pilot channel, a fundamental channel, a dedicated control channel, a supplemental channel, a packet data channel, an access channel, a channel quality feedback channel, and an acknowledgement channel.

Each channel carries a different type of information to the destination. Generally, voice data is transmitted on the fundamental channel and data traffic is transmitted on the supplemental channel or the packet data channel. Supplemental channels are typically enabled for durations on the order of seconds and rarely change modulation and coding formats, while packet data channels typically change from one 20ms interval to another 20ms interval. For purposes of describing the embodiments herein, the supplemental channels and the packet data channels are collectively referred to as data traffic channels.

Voice traffic and data traffic are typically encoded, modulated, and spread before being transmitted on the forward or reverse links. The coding, modulation, and spreading may be implemented in various formats. In a CDMA system, the transmission format ultimately depends on the type of channel over which voice traffic and data traffic are being transmitted, as well as the condition of the channel, which can be described in terms of fading and interference.

The predetermined transmission format corresponds to a combination of various transmission parameters, which may be used to simplify the selection of the transmission format. In an embodiment, the transmission format corresponds to a combination of any or all of the following transmission parameters: the modulation scheme used by the system, the number of orthogonal or quasi-orthogonal codes, the data payload size in bits, the duration of the message frame, and/or details about the coding scheme. Some examples of modulation schemes used within communication systems are the quadrature phase shift keying scheme (QPSK), the 8-ary phase shift keying scheme (8-PSK), and the 16-ary quadrature amplitude modulation (16-QAM). Some of the various coding schemes that can be selectively implemented are convolutional coding schemes, which are implemented at various rates, and turbo coding, which includes multiple coding steps separated by interleaving steps.

Orthogonal and quasi-orthogonal codes, such as Walsh code sequences, are used to channelize the information sent to each remote station on the forward link. In other words, the use of Walsh code sequences on the forward link enables the system to cover multiple users, each of which can be assigned a different orthogonal or quasi-orthogonal code at the same frequency for the same duration. Orthogonal codes, such as Walsh code sequences, are used to channelize separate, distinct information streams on the reverse link, such as dedicated control channels, supplemental channels, fundamental channels, and acknowledgment channels.

For the embodiments described below, the term "source" is used to refer to the party that is transmitting data seeking acknowledgement, and the term "destination" is used to refer to the party that is transmitting acknowledgement. The source is either a base station transmitting on the forward link or a mobile station transmitting on the reverse link. The destination station may be a mobile station receiving on the forward link or a base station receiving on the reverse link. In other words, embodiments may be extended to be implemented on either the forward or reverse links.

Furthermore, for ease of explanation, the term "data information" is used herein to describe information to be transmitted between a source and the information. The term "data packet" is used to describe data information that has been encoded and modulated according to a transmission format.

The transmission format and power on the data traffic channel are typically adjusted by a source to ensure a high probability of successful reception at the destination. Successful decoding may be confirmed by one or a combination of several methods known in the art, such as determining whether a Cyclic Redundancy Check (CRC) bit of a data packet passes or fails, calculating a re-encoded error rate, or calculating a Yamamoto metric for a viterbi decoder.

Due to unpredictable variations in channel quality and interference levels at the destination receiver, the source cannot directly determine whether a transmission has been successfully received by the destination. In a typical packet data system, an acknowledgement signal indicating the success or failure of a data transmission is sent back from the destination to the source. In some packet data systems, an acknowledgement signal is sent on an acknowledgement channel shortly after the destination station receives the data packet. Furthermore, in some packet data systems, the acknowledgement signal is time division multiplexed with additional information, which is then transmitted on the designated channel.

If the source receives a negative acknowledgement signal, the source may decide to retransmit the data packet. To ensure the eventual successful reception of the data, the source may decide to retransmit the data packet in a different coding or transmission format. Alternatively, the source may decide to interrupt the transmission of a data packet for various reasons after several unsuccessful transmission attempts, one thing that is originally the data information within the data packet becomes obsolete and useless after a period of time.

If the data packet is retransmitted by the source and subsequently received by the destination, the destination combines the portion of the newly received data packet with the stored copy of the previous data packet to further increase the probability of successful decoding. It should be noted that although the previously transmitted data packet may not be successfully decoded, the destination station may save the previous unsuccessfully decoded data packet and use the information about the unsuccessfully decoded data packet to decode the newly received data packet.

While waiting for an acknowledgement signal to be received for a transmitted data packet, the source may transmit a packet of new data information to another destination station, which may also need to be stored before receiving an acknowledgement of the new data packet. The process continues by sending several more packets to several more destination stations before receiving an acknowledgement for the first packet from the first destination station, thereby requiring the source to have undesirably large memory to hold all packets waiting for an acknowledgement. Alternatively, the source has a limited amount of memory and will stop sending new packets when the memory is full. Dead time occurs if the source stops sending new packets, which reduces the overall throughput of the source.

Similarly, the destination needs to store the packet that is waiting for retransmission. As described above, the destination may use portions of previously received data packets to decode subsequently received data packets. The destination station may therefore have a large memory to hold all packets waiting to be retransmitted from the source or sacrifice its throughput by not being able to receive packets continuously. Both of these options are undesirable.

One solution to the above problem is to use an acknowledgement signal that requires the shortest amount of time possible to be received by the source. The feedback time between packet transmission and acknowledgment reception is reduced if the acknowledgment signal is received faster by the source. The reduction in feedback time proportionally reduces the amount of packets waiting for transmission, which reduces memory requirements and data stall times. Therefore, to minimize the amount of memory required to store a packet for later retransmission, current high data rate transmission systems are configured to send a fast acknowledgment so that the source can quickly send the next data packet.

However, transmission of fast acknowledgements can also be problematic. A positive acknowledgement misinterpreted by the source as a negative acknowledgement may result in unnecessary retransmission of the packet, thereby reducing the effective throughput of the system. A negative acknowledgement misinterpreted as a positive acknowledgement may cause a packet to be lost and never retransmitted. Therefore, it is desirable that the acknowledgment be accurately received by the source. To address this problem, various upper layer protocols have been designed to ensure reliable transfer of data between parties, such as the Radio Link Protocol (RLP) and the Transmission Control Protocol (TCP). However, since these are upper layer protocols, a large processing overhead is necessary to retransmit any lost data segments, which results in significant delays in transmitting the data segments to the final destination. If such an upper layer protocol is not present in the system, the loss of this data segment will directly affect the destination.

Fig. 2 includes two timelines illustrating a rapid acknowledgment method that does not use upper layer protocols. Source in time slot s₁The first packet 200 is sent to a destination station in time slot d₁A first packet 200 is received. At the destination, the receiver of the destination needs at least two time slots d₂And d₃To decode the first packet 200. Destination in time slot d₄The first acknowledgement 210 is sent to the source. The destination then transmits in time slot d₅A second acknowledgement 220 is sent to the source to acknowledge the first acknowledgement 210. In time slot s₇The source determines that the information carried by the first packet 200 was not successfully decoded and transmits the information in the second packet 230. Alternatively, the source determines that the information carried by the first packet 200 was successfully decoded and transmits the new information in the second packet 230. In either case, there are at least 5 time slots(s)₂、s₃、s₄、s₅And s₆) The source does not transmit to the destination during these time slots. It should be noted that time slot s_iAnd d_iAre set to equal durations.

In addition to the above method of repeating the acknowledgement signal, another method of increasing the probability of accurately receiving the acknowledgement signal is to increase the transmission power of the acknowledgement signal. In general, the transmit power is limited due to transmitter design limitations, such as high power amplifiers that are constructed to comply with limits set by local, national, or international regulatory entities. Moreover, large transmit powers can cause large bursts of interference to users in the same coverage area or in different coverage areas, thereby degrading system capacity or even creating occasional communication losses. Therefore, increasing the transmission power is not a desirable solution.

Another way to increase the probability of accurately receiving an acknowledgment signal is to increase the transmission duration of the acknowledgment signal. However, as mentioned above, one skilled in the art would forego this approach because it contradicts the purpose of a fast acknowledgment that enables the source to quickly transmit the next packet and minimizes the storage space required for the retransmission.

Embodiments herein are directed to improving the accurate reception of acknowledgment signals, minimizing the memory space required for retransmissions, and improving the data throughput of a communication system. The described embodiments achieve these goals by using dynamic decoding of extended acknowledgement signals.

In one embodiment, the confirmation signal is a signal transmitted using simple modulation, such as an uncoded Binary Phase Shift Keying (BPSK) signal, which is orthogonalized by orthogonal Walsh code sequences. The probability of successfully decoding the acknowledgment signal may be related to the received energy per bit to noise (Eb/N) ratio. The Eb/N ratio is a function of parameters that cannot be directly controlled by the system, such as channel path loss, fast fading, shadowing, and interference level upon reception. A high Eb/N ratio indicates that the acknowledgment signal is likely to be decoded correctly, while a low Eb/N ratio indicates that the acknowledgment signal is unlikely to be decoded correctly. Therefore, it is desirable to maintain the highest Eb/N ratio possible for the acknowledgement signal. The Eb/N ratio may be changed either by increasing the transmit power of the acknowledgement signal or by increasing the transmission duration of the acknowledgement signal.

Although increasing the duration of the acknowledgment signal affects the latency of receiving the acknowledgment signal, the current embodiment is used to configure a source that can dynamically decode the extended acknowledgment signal using the Eb/N ratio. Once the source has enough information from the Eb/N ratio to confidently decode the extended length acknowledgment signal, the source decodes the portion of the extended length acknowledgment signal corresponding to the Eb/N ratio and stops decoding the remainder of the extended length acknowledgment signal.

In one embodiment, the duration of the acknowledgment signal is fixed to a long duration, e.g., 4 slots. The receiver of the source processes the acknowledgment signal and the corresponding Eb/N ratio. The source stops decoding the rest of the acknowledgment signal as long as the Eb/N ratio reaches a value such that a sufficient reception probability is ensured.

In one aspect of this embodiment, the determination of the Eb/N ratio is made by comparing the accumulated pilot channel signal-to-noise ratio from the start of the transmission of the acknowledgment signal to a threshold T. As long as the accumulated signal-to-noise ratio is greater than or equal to T, it is assumed that the acknowledgement signal received so far is sufficiently reliable. As long as the received signal quality is reliable, the source will decode the acknowledgment signal before receiving the entire acknowledgment signal. Thus, the feedback delay associated with decoding the entire extended acknowledgment signal is reduced.

Fig. 3 illustrates the decoding of the length extended acknowledgement signal as described above. Hardware within the source, such as memory elements and processing elements, may be configured to perform the following method. At time t₀The starting point of the extended length acknowledgment signal 300 is received by a source (not shown). Source from time t₀The accumulation of the Eb/N ratio is started. At time t₂The source determines that the accumulated Eb/N ratio is equal to the threshold T. Then, the source starts from time t₂Refraining from decoding the remainder of the extended acknowledgment signal is initiated. Source usage at t₀And t₂Information contained in the partial length extended acknowledgment signal received indirectly determines whether the data packet was successfully received at the destination station (not shown).

Fig. 4 is a flow chart further illustrating the above-described method steps. In step 400, the source transmits a data packet. At step 410, the source begins receiving an acknowledgment signal. In step 412, the source monitors the Eb/N ratio while receiving an acknowledgment signal. In step 414, the source compares the value of the accumulated Eb/N ratio to a threshold T. If the value of the accumulated Eb/N ratio is equal to or greater than the threshold T, flow proceeds to step 416 where the signal source decodes the portion of the acknowledgment signal that has been received up to the accumulated Eb/N ratio of T and disregards the remainder of the acknowledgment signal.

If the accumulated value of the Eb/N ratio is less than the threshold T, flow proceeds to step 418 where a determination is made as to whether the extended length acknowledgment signal has been fully received. If the length extended acknowledgment signal is fully received, the source decodes the entire length extended acknowledgment signal, step 420. If the extended length acknowledgment signal is not fully received, flow returns to step 412.

Thus, in the above embodiment, the source can transmit the next data packet with confidence that it will occur before the end of the acknowledgment signal.

Additional feedback improvements

The above embodiments can be implemented independently or in combination with other feedback improvements. In other feedback improvements, the processing elements in the source that control the scheduling and transmission format of the data packets and the processing elements in the destination that control the scheduling and transmission format of the acknowledgment signals may be reconfigured to minimize feedback delay between data packet transmissions.

Referring again to fig. 2, the prior art feedback system operates with a delay of at least 5 time slots between the transmission of the first data packet and the transmission of the second data packet, wherein the delay occurs due to waiting for an acknowledgement signal. In one embodiment, the processing element is configured to completely eliminate the feedback delay if the source has determined that the optimal feedback channel condition exists between the source and the destination. The elimination of feedback delay can be accomplished by the source "overwriting" the acknowledgment signal repetition parameters, which are typically controlled at the destination. In the prior art, the processing element within the destination station controls the scheduling of the acknowledgment signals, necessarily accompanied by the control of the retransmission of the acknowledgment signals. The retransmission is a repetition of the first acknowledgement signal expressed in the appropriate transmission format. As mentioned above, the repetition is to ensure correct decoding of the acknowledgment signal at the source. The embodiments described herein are directed to enabling a source capable of dynamically controlling the repetition parameters of an acknowledgment signal.

Fig. 5 is a flow diagram of a fast data packet transmission scheme. Hardware within the source and destination stations, such as memory elements and processing elements, may be configured to perform the following method steps. In step 500, the source is in time slot s₁A first data packet is transmitted. At step 510, the source determines that the channel conditions are ideal, i.e., that the transmission is likely to be received and correctly decoded. There are many ways for the source to determine whether the channel conditions are ideal, but the choice of which method to use is not relevant to understanding the embodiment, and therefore these methods are not described in detail here. An ideal channel condition is said to exist if the channel is reliable enough or of sufficient quality that the source can decode the acknowledgment signal without using repetition.

In step 520, the source is in slot s₂Transmitting a second data packet, time slot s₂Following a time slot s₁Thereafter, and prior to the receipt of any acknowledgment signals. Since the channel conditions are ideal, the second data packet will have a different data load than the data load of the first data packet.

In step 530, the destination station is in time slot d₁Receiving a first data packet in time slot d₂A second data packet is received. In step 540, the destination station is in time slot d₂And d₃During which the first data packet is decoded, in time slot d₃And d₄During which the second data packet is decoded.

In step 550, the destination station is in time slot d₄An acknowledgement signal (ACK1) associated with the first data packet is sent. At step 560, the destination preempts the slot with an acknowledgement signal ACK2, ACK2 being associated with the second data packet sent by the source, instead of at slot d₅Sending anda second ACK1 associated with the first data packet. Thus, the destination station is configured to overwrite the repetition of the previous acknowledgement in order to send a new acknowledgement. In prior art systems, the source avoids scheduling transmissions if a data packet transmission would result in an overwritten acknowledgement signal, i.e. if the acknowledgement signal of a new data packet is repeated with an acknowledgement signal of an old data packet.

Thus, this embodiment is directed to a source that manages the retransmission decisions of the destination by forcing overwrites over the retransmissions. By using this embodiment the total feedback delay is reduced by almost half. This section is illustrated in FIG. 6, which FIG. 6 shows a slotted timeline illustrating the above-described embodiment.

If the repetitions of the acknowledgment signal can be overwritten as in the above embodiments, the source will use the known ideal channel conditions to dynamically determine the number of acknowledgment repetitions that the destination will transmit. The source can directly change the number of acknowledgment repetitions by controlling the speed at which data packets are transmitted to the destination.

For example, if the source determines that no repetition is required, the source may transmit a data packet as shown in fig. 6. However, if the source has determined that a repetition is required to accurately decode the acknowledgment signal, the source will pass through slot s₁Transmitting a first packet in a time slot s₂Is halted and then in time slot s₃A second packet is transmitted. The destination station will be in time slot d₁Receiving a first data packet in time slot d₂And d₃Decoding a first data packet in time slot d₄Sending an acknowledgement of the second data packet, and in slot d₅A repetition of the first acknowledgement is sent. At the same time, the destination station will be in time slot d₃Receiving a second data packet in time slot d₄And d₅Decoding the second data packet and in time slot d₆A first acknowledgement of the second data packet is sent.

In the above example, any overwriting does not occur due to the transmission timing of the source. In yet another example, if the destination has decided to be in time slot d₅And d₆Determining the first data packetThe acknowledgement signal is repeated twice, but the source has decided that only the first data packet acknowledgement needs to be repeated once, and the source will pass through in slot s₃Up-timing the second data packet transmission to occur at time slot d₆One overwrite was forced on.

In one aspect of this embodiment, the source may set a transmission speed that is based on previous measurements of the feedback link. For example, the source may determine whether the feedback link quality is stable over a period of time, the source may determine whether the acknowledgment signal is consistently decoded without repetition (or with repetition), or the source may use some other method to determine the quality of the feedback link. Depending on the channel conditions, the source may dynamically change the number of repetitions transmitted by the destination, rather than waiting for a fixed number of repetitions set by the system parameters.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. The skilled person will recognize the interactivity of the hardware and software in these cases and how best to implement the described functionality for each particular application. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The implementation or execution of the various illustrative logical blocks, modules, and algorithm steps described in connection with the embodiments described herein may be implemented or performed with: a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP 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 the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for dynamically decoding an extended acknowledgement signal from a destination, comprising:

at least one memory element; and

at least one processing element configured to execute a set of instructions within the at least one memory element, the set of instructions for:

simultaneously receiving the extended acknowledgement signal and monitoring a received signal quality of the extended acknowledgement signal;

comparing a received signal quality of a portion of the extended acknowledgment signal to a threshold; and

if the received signal quality is greater than or equal to the threshold, then the portion of the extended acknowledgement signal is decoded and the remainder of the extended acknowledgement signal is disregarded.

2. The apparatus of claim 1, wherein the received signal quality is an accumulated energy per bit to noise ratio.

3. The apparatus of claim 2, wherein the energy-per-bit to noise ratio is based on an accumulated signal-to-noise ratio of a pilot channel.

4. A method for dynamically decoding an extended acknowledgement signal from a destination station, comprising:

5. The method of claim 4, wherein the received signal quality is an accumulated energy per bit to noise ratio.

6. The method of claim 5, wherein the energy-per-bit to noise ratio is based on an accumulated signal-to-noise ratio of a pilot channel.

7. An apparatus for dynamically decoding an extended acknowledgement signal from a destination, comprising:

means for receiving an extended acknowledgement signal;

means for monitoring received signal quality of the extended acknowledgement signal;

means for comparing a received signal quality of a portion of the extended acknowledgment signal to a threshold; and

means for decoding the portion of the extended acknowledgment signal if the received signal quality is greater than or equal to the threshold, wherein the means also disregards the remaining portion of the extended acknowledgment signal.

8. A method for decoding an acknowledgment signal, comprising:

receiving an acknowledgement signal;

monitoring an energy value of the acknowledgement signal;

decoding a portion of the acknowledgement signal having an energy value exceeding a predetermined threshold without decoding a remaining portion of the acknowledgement signal if the energy value exceeds the predetermined threshold before an end of the acknowledgement signal is received; and

decoding the entire acknowledgement signal if the energy value does not exceed a predetermined threshold before the end of the acknowledgement signal is received.

9. An apparatus for decoding an acknowledgement signal, comprising:

means for receiving an acknowledgement signal;

means for monitoring an energy value of the acknowledgement signal;

means for decoding a portion of the acknowledgment signal if the energy value exceeds a predetermined threshold before the end of receipt of the acknowledgment signal, wherein the means is further for disregarding the remainder of the acknowledgment signal if the energy of the portion exceeds a predetermined threshold; and decoding the entire acknowledgment signal if the energy value does not exceed a predetermined threshold before the end of the acknowledgment signal is received.