HK1157968B - Increasing capacity in wireless communications - Google Patents

Description

Increasing capacity of wireless communications

RELATED APPLICATIONS

This application claims priority to the following U.S. provisional applications:

U.S. provisional application No. 61/060,119 entitled "Apparatus and Methods for improving Capacity in Wireless Communications", filed on 9.6.2008;

U.S. provisional application No. 61/060,408 entitled "Apparatus and Methods for improving Capacity in Wireless Communications", filed on 10.6.2008;

U.S. provisional application No. 61/061,546 entitled "Apparatus and Methods for improving Capacity in Wireless Communications", filed 13.6.2008. The entire contents of these provisional applications are hereby incorporated by reference into the present application.

This application is a continuation-in-part of a U.S. patent application No. 12/389,211, entitled "Frame Termination", filed on 19.2.2009, which claims priority to a U.S. provisional application No. 61/030,215 filed on 20.2.2008, both of which are assigned to the assignee of the present application and are hereby incorporated by reference in their entirety.

Technical Field

The present disclosure relates generally to digital communications, and more specifically to techniques for reducing transmit power and increasing capacity in a wireless digital communication system.

Background

Wireless communication systems are widely deployed today to provide various types of communication such as voice, packet data, and so on. These systems may be based on Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), or other multiple access techniques. For example, these systems may conform to standards such as third generation partnership project 2(3GPP2, or "CDMA 2000"), third generation partnership project (3GPP or "W-CDMA"), or long term evolution ("LTE"). In the design of these communication systems, it is desirable to maximize the capacity, or number of users that these systems can reliably support, given the available resources. Several factors affect the capacity of the wireless communication system, some of which are described below.

For example, in a speech communication system, a speech synthesizer typically encodes speech transmissions using one of a plurality of variable coding rates. The coding rate may be selected based on, for example, the amount of voice activity detected during a particular time interval. For example, in a vocoder of a CDMA2000 wireless communication system, voice transmissions may be sent using Full Rate (FR), Half Rate (HR), Quarter Rate (QR), or Eighth Rate (ER) frames, where a full rate frame includes a maximum number of traffic bits and an eighth rate frame includes a minimum number of traffic bits. Eighth rate frames are typically transmitted during silent periods and generally correspond to the lowest rate transmission that can be achieved by a voice communication system.

Although the eighth rate frame represents a reduced rate transmission in a CDMA2000 system, the eighth rate still contains a non-zero number of traffic bits. Even eighth rate frame transmissions unnecessarily consume significant transmit power levels in the system during certain time intervals, e.g., relatively long periods of time when no voice activity and background noise remains constant. This may increase the level of interference caused to other users, thereby reducing system capacity, which is undesirable.

It would be desirable to provide techniques for further reducing the transmission rate of a voice communication system, with minimum rate frame transmissions such as eighth rate frame transmissions given below.

In another aspect of a wireless communication system, transmissions between two units typically use some redundancy to guard against errors in the received signal. For example, in Forward Link (FL) transmissions from a Base Station (BS) to a Mobile Station (MS) in a CDMA2000 wireless communication system, redundancy such as partial rate symbol coding and symbol repetition may be used. In a CDMA2000 system, the coded symbols are grouped into a number of sub-segments known as Power Control Groups (PCGs) and transmitted over the air, where a fixed number of PCGs define a frame.

While the use of symbol redundancy techniques, such as those used in CDMA2000, may allow the transmitted signal to be accurately recovered in the presence of errors, these techniques also represent additional consumption in overall system transmit power when signal reception conditions are good, which also reduces system capacity, which is also undesirable.

It would also be desirable to provide efficient techniques for terminating the transmission of a frame, for example, when it is determined that the receiver has accurately recovered information associated with the frame, thereby saving transmit power and increasing system capacity. It would also be desirable to provide improved power control schemes to accommodate these techniques.

Disclosure of Invention

One aspect of the present invention provides a method for early termination of consecutive frame transmissions on a communication channel, the method comprising: continuously transmitting a first frame to a receiver; receiving an acknowledgement message from the receiver during transmission of the first frame; ceasing transmission of the first frame after receiving the acknowledgement message.

Another aspect of the present invention provides a method for early termination of consecutive frame transmissions on a communication channel, the method comprising: continuously receiving a first frame from a transmitter; attempting to decode the first frame before receiving the entire first frame; determining whether frame decoding is successfully performed according to a result of the attempt; transmitting an acknowledgement message to the transmitter upon determining that frame decoding was successful, wherein the acknowledgement message is operable to cease transmitting the first frame.

Another aspect of the present invention provides an apparatus for early termination of consecutive frame transmissions on a communication channel, the apparatus comprising: a transmitter for continuously transmitting first frames to a receiver; a receiver module to receive an acknowledgement message from the receiver during transmission of the first frame; the transmitter is configured to: ceasing transmission of the first frame after receiving the acknowledgement message.

Another aspect of the present invention provides an apparatus for early termination of consecutive frame transmissions on a communication channel, the apparatus comprising: a receiver for continuously receiving a first frame from a transmitter; a processor to: attempting to decode the first frame before receiving the entire first frame; determining whether frame decoding is successfully performed according to a result of the attempt; a transmitter module configured to transmit an acknowledgement message to the transmitter upon determining that frame decoding was successful, wherein the acknowledgement message is operable to stop transmitting the first frame.

Another aspect of the present invention provides an apparatus for early termination of frame transmissions on a communication channel, the apparatus comprising: means for receiving a continuously transmitted frame from a transmitter; means for terminating transmission by the transmitter before receiving an entire frame.

Another aspect of the present invention provides an apparatus for early termination of frame transmissions on a communication channel, the apparatus comprising: means for continuously transmitting first frames; means for terminating the continuous transmission based on successful decoding of the at least one transmitted sub-segment by the receiver.

Another aspect of the invention provides a computer-readable storage medium storing instructions for causing a computer to prematurely terminate a frame transmission over a communication channel, the medium storing instructions for causing a computer to: receiving continuously transmitted frames from a transmitter; attempting to decode an entire frame of a continuous transmission before receiving the frame; determining whether the frame is successfully decoded according to a result of the attempt; transmitting an acknowledgement message to the transmitter upon determining that the frame was successfully decoded, wherein the acknowledgement message is operable to terminate transmission of a remaining portion of the continuously transmitted frame.

Another aspect of the invention provides a computer-readable storage medium storing instructions for causing a computer to prematurely terminate transmission of frames over a communication channel, each frame being allocated a fixed time interval for transmission, the medium storing instructions for causing a computer to: continuously transmitting first frames; receiving an acknowledgement message from a receiver during transmission of the first frame; ceasing transmission of the first frame after receiving the acknowledgement message; beginning transmission of a second frame after a fixed time interval of the first frame has elapsed.

Another aspect of the present invention provides a method for early termination of consecutive frame transmissions on a communication channel, the method comprising: continuously transmitting a first frame to at least one receiver; receiving at least one acknowledgement message from the at least one receiver during transmission of the first frame; ceasing transmission of the first frame after receiving a first one of the at least one acknowledgement message.

Another aspect of the present invention provides a method for early termination of consecutive frame transmissions on a communication channel, the method comprising: continuously receiving first frames from at least one transmitter; attempting to decode the first frame before receiving the entire first frame; determining whether frame decoding is successfully performed according to a result of the attempt; transmitting an acknowledgement message upon determining that frame decoding was successful, wherein the acknowledgement message is operable to cease transmission of the first frame by each of the at least one transmitter.

Drawings

Fig. 1 depicts a wireless communication system in the prior art.

Fig. 2 depicts a signal transmission path for voice in the prior art.

Fig. 3 depicts an exemplary embodiment of a signal transmission path for speech according to the present invention.

Fig. 4 depicts an exemplary embodiment of an algorithm that may be applied by the system blanking module.

Fig. 5 and 5A depict exemplary frame transmission sequences processed by a speech synthesizer and system blanking module.

Fig. 6 depicts an exemplary embodiment of a receive algorithm for processing a system blanked signal generated by a voice signal transmission path such as that shown in fig. 3.

Fig. 7 depicts another exemplary embodiment of a signal transmission path for speech according to the present invention.

Fig. 8 depicts an exemplary embodiment of an algorithm that may be applied by the system blanking module.

Fig. 9 and 9A depict exemplary frame transmission sequences processed by a speech synthesizer and system blanking module.

Fig. 10 depicts an exemplary embodiment of a method for system blanking according to the present invention.

Fig. 11 depicts an exemplary embodiment of a pilot gating scheme in accordance with the present invention.

Fig. 12 depicts an exemplary embodiment of a rate reduced power control scheme for controlling the power of Forward Link (FL) transmissions in accordance with the present invention.

Fig. 13 depicts an exemplary embodiment of a rate reduced power control scheme for controlling the power of Reverse Link (RL) continuous pilot transmissions in accordance with the present invention.

Fig. 14 depicts an exemplary embodiment of a rate reduced power control scheme for controlling the power of Reverse Link (RL) gated pilot transmissions in accordance with the present invention.

Fig. 15 depicts a power control method according to the present invention.

Fig. 16 depicts a prior art frame processing scheme for processing information bits by a transmitter in a communication system.

Fig. 17 depicts a prior art timing diagram associated with a forward link signaling scheme for CDMA 2000.

Fig. 18 depicts a prior art method for recovering estimated information bits b' from received symbols y.

Fig. 19 depicts an exemplary embodiment of a scheme for early termination of forward link transmissions for system operation according to the CDMA2000 standard.

Fig. 20 depicts an exemplary embodiment of a per sub-segment decoding scheme in accordance with the present invention.

Fig. 21 depicts a prior art implementation of a forward link symbol path for radio configuration 4(RC4) in accordance with the CDMA2000 standard, and an exemplary embodiment of a forward link symbol path in accordance with the present invention.

Fig. 22 depicts an exemplary embodiment of a signaling scheme for sending an ACK message on the reverse link to prematurely terminate the modulator.

Fig. 23 depicts an exemplary embodiment of a scheme for early termination of reverse link transmissions for system operation in accordance with the CDMA2000 standard.

Fig. 24 depicts an implementation of a reverse link symbol path in the prior art and an exemplary embodiment of a reverse link symbol path in accordance with the present invention.

Fig. 25 depicts an exemplary embodiment of a signaling scheme for transmitting an ACK message on the reverse link to prematurely terminate the forward fundamental channel (F-FCH) and/or up to two forward supplemental channels (F-SCH1 and F-SCH 2).

Fig. 26 depicts an exemplary embodiment of a method according to the present invention.

Detailed Description

The description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The term "exemplary" used throughout this specification means "serving as an example, instance, or illustration," and should not be construed as preferred or advantageous over other exemplary embodiments. The description includes specific details for the purpose of providing a thorough understanding of exemplary embodiments of the invention. It will be apparent, however, to one skilled in the art that the embodiments of the invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the novelty of the exemplary embodiments presented herein.

In the present specification and claims, it will be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected to" or "directly coupled to" another element, there are no intervening elements present.

The communication system may use a single carrier frequency or a multi-carrier frequency. Referring to fig. 1, in the wireless cellular communication system 100, reference numerals 102A to 102G denote cells, reference numerals 160A to 160G denote base stations, and reference numerals 106A to 106G denote Access Terminals (ATs). The communication channels include a Forward Link (FL) (also known as the downlink) for transmissions from AN Access Network (AN)160 to AN Access Terminal (AT)106 and a Reverse Link (RL) (also known as the uplink) for transmissions from the AT 106 to the AN 160. The AT 106 is also referred to as a remote station, mobile station, or subscriber station. An Access Terminal (AT)106 may be mobile or stationary. Each link includes a different number of carrier frequencies. Further, an access terminal 106 may be any data device that communicates through a wireless channel or through a wired channel (e.g., using fiber optic or coaxial cables). The access terminal 106 may also be any of a number of types of devices including, but not limited to: PC card, compact flash, external or internal modem, or wireless or wireline phone.

Modern communication systems are designed to allow multiple users to access a common communication medium. Numerous multiple-access techniques are known in the art, such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), space division multiple access, polarization division multiple access, Code Division Multiple Access (CDMA), and other similar multiple-access techniques. The multiple access concept is a channel allocation method that allows multiple users to access a common communication link. Depending on the particular multiple access technology, the channel allocation may take different forms. For example, in an FDMA system, the entire frequency spectrum is divided into a number of smaller sub-bands, with each user being allocated one sub-band to access the communication link. Alternatively, in TDMA systems, each user is allocated the full spectrum during a periodically recurring time slot. In CDMA systems, each user is allocated the full spectrum at all times, where the transmissions are distinguished by the use of codes.

Although certain exemplary embodiments of the present invention are described below with respect to operation in accordance with the CDMA2000 standard, those of ordinary skill in the art will appreciate that these techniques may be readily applied to other digital communication systems as well. For example, the techniques of this disclosure may also be applied to systems based on the W-CDMA (or 3GPP) wireless communication standard and/or any other communication standard. It is contemplated that these alternative exemplary embodiments also fall within the scope of the present invention.

Fig. 2 depicts a prior art signal transmission path 200 for speech. In fig. 2, a speech signal 200a is input to a speech synthesizer 210, the speech synthesizer 210 being configured to encode the speech signal for transmission. The speech frames 210a output by the speech synthesizer 210 may have one of a plurality of rates, depending on the speech content of the speech signal 200a at any time. In fig. 2, the plurality of rates include Full Rate (FR), Half Rate (HR), Quarter Rate (QR), and Eighth Rate (ER). The speech frames 210a are provided to a physical layer processing module 220 which prepares the speech frame data for transmission in accordance with the physical layer protocol of the system. Those of ordinary skill in the art will appreciate that these protocols may include, for example, encoding, repeating, puncturing, interleaving, and/or modulating data. The output of the physical layer processing module 220 is provided to the TX module 230 for transmission. TX module 230 may perform Radio Frequency (RF) operations such as up-converting a signal to a carrier frequency, amplifying the signal for transmission on an antenna (not shown).

Generally speaking, the rate at which the speech synthesizer 210 selects at any time to encode speech frames 210a of the speech signal 200a depends on the level of speech activity detected in the speech signal 200 a. For example, a Full Rate (FR) may be selected for frames of speech signal 200a containing active speech, while an Eighth Rate (ER) may be selected for frames of speech signal 200a containing silence. During such a silence period, the ER frame may include parameters for characterizing "background noise" related to the silence. While ER frames include significantly fewer bits than FR frames, silence periods occur frequently during normal sessions, making the total transmission bandwidth for transmitting ER frames significant.

It is desirable to further reduce the transmission bandwidth required to transmit the speech signal 200a to the receiver.

Fig. 3 depicts an exemplary embodiment of a signal transmission path 300 for speech according to the present invention. In fig. 3, a speech signal 200a is input to a speech synthesizer 310, which speech synthesizer 310 generates a frame of speech 310a for transmission. The speech frame 310a may have one of a plurality of rates including Full Rate (FR), Half Rate (HR), Quarter Rate (QR), Eighth Rate (ER), and critical eighth rate (ER-C). In an exemplary embodiment, the speech synthesizer 310 may designate eighth-rate frames as "critical" eighth-rate frames for those frames that contain parameters, such as parameters corresponding to changes in background noise detected in silence intervals.

The speech frame 310a is provided to a system blanking module 315, and the system blanking module 315 then provides the processed speech frame 315a to the physical layer processing module 220. As described further below, the system blanking module 315 minimizes the transmission bit rate of the vocoder output 310a by selectively "blanking" the vocoder output (i.e., replacing some frames in the vocoder output 310a with zero rate (NR) frames having a smaller data rate than eighth rate frames). In an exemplary embodiment, the NR frames have zero traffic content, i.e., a traffic bit rate of 0 bits per second (bps).

Fig. 4 depicts an exemplary embodiment 400 of an algorithm that may be applied by the system blanking module 315.

In step 410, the system blanking module 315 receives the frame 310a from the speech synthesizer 310.

At step 420, frame 310a is evaluated to determine whether it is FR, HR, QR, or ER-C. These rates are considered critical to the transmission and may also be referred to as critical frame types. If the frame 310a includes one of these critical rates, the frame 310a is provided directly to the physical layer processing module 220 for transmission. If not, the frame is considered to include a non-critical rate and the algorithm proceeds to step 430.

It should be noted that the exemplary designation of FR, HR, QR, and ER-C as "critical" is for illustrative purposes only, and is not meant to limit the scope of the invention to only those embodiments in which these frame types are designated as critical. In alternative exemplary embodiments, other sets of frame types may be designated as critical for transmission by the system blanking module. It is contemplated that these alternative exemplary embodiments also fall within the scope of the present invention.

At step 430, the algorithm evaluates the frame number of the current frame to be transmitted to determine whether transmission of the current frame is warranted. In one exemplary embodiment, the guaranteed transmission may comprise a non-zero rate (e.g., non-NR) transmission. In one exemplary embodiment, the frame number may be a number assigned to each frame that is repeated consecutively for each successive frame. In the exemplary embodiment shown, the current frame number "is added to the current frame offset", and the modulo operation (mod) is performed with the non-blanking interval parameter N and the result (frame number + frame offset). If the result of the modulo operation is 0, the algorithm proceeds to step 440. Otherwise, the algorithm goes to step 450.

It will be appreciated by those of ordinary skill in the art that other techniques than the particular evaluation shown in step 430 may be readily applied to specify which frames are guaranteed to be transmitted. These alternative techniques may use, for example, parameters other than the current frame number or current frame offset, or other operations other than the modulo operation described.

In step 450, the system blanking module 315 provides the zero rate (NR) frame to the physical layer processing module 220 for transmission. In an exemplary embodiment, the zero-rate frame has a traffic data rate of 0bps (bits/second), thus consuming minimal signaling bandwidth. After sending the zero-rate frame, the algorithm returns to step 410 to receive the next speech frame 310a from the speech synthesizer 310.

From the foregoing, it will be appreciated by those of ordinary skill in the art that the non-blanking interval N controls how often non-key frames are transmitted, where N-1 corresponds to the transmission of all non-key frames, and a larger value of N corresponds to less frequent transmission of non-key frames. In an exemplary embodiment, the value of N may take the form of 1, a default of 4, 8, or other predetermined value specified (e.g., by external signaling (not shown)).

Fig. 5 and 5A depict exemplary frame transmission sequences 310a processed by speech synthesizer 310 and system blanking module 315, respectively^*And 315a^*。

In FIG. 5, frame sequence 310a^*Including eighth-rate frames labeled "ER" and eighth-rate key frames labeled "ER-C". Such a sequence of frames may occur during a voice session, for example, during a silent period on the part of the session.

In FIG. 5A, a frame transmission sequence 315A^*And to transmission sequence 310a^*The result of applying a selective blanking algorithm such as 400 corresponds to where a non-blanking interval N-4 is used. In FIG. 5A, frame sequence 315A^*Including eighth rate frames ER and zero rate frames NR. Frame number 0 is transmitted directly as a frame (i.e., ER frame) received from the vocoder 310. The frame numbers 1 and 3 are transmitted as NR frames according to the non-blanking interval N-4. Frame number 2 of the eighth-rate frame ER-C specified by the vocoder as critical is transmitted as the ER frame. As shown, frame numbers 4 through 13 are similarly processed. It should be noted that in fig. 5A, a frame corresponding to (frame number + frame offset mod N) ═ 0 is marked.

Fig. 6 depicts an exemplary embodiment of a receive algorithm 600 for processing signals generated by a voice transmission signal path using a system blanking module such as 315 shown in fig. 3.

In fig. 6, at step 610, the transmitted signals are Received (RX) and processed using, for example, operations complementary to the TX operations 230 shown in fig. 3. Such RX operations may include: such as RF amplification, down conversion, filtering, etc.

At step 620, physical layer Receive (RX) processing is performed using, for example, operations complementary to the physical layer TX operations 220 shown in fig. 3. Such physical layer reception processing may include: e.g., decoding, deinterleaving, symbol combining, etc.

At step 630, the algorithm 600 evaluates whether the currently received frame is an NR frame. If so, the algorithm returns to step 610 to begin receiving the next frame since there is no traffic data to process for the NR frame. If not, the algorithm proceeds to step 640.

It will be appreciated by those of ordinary skill in the art that various techniques may be used to evaluate whether a currently received frame is an NR frame. In an exemplary embodiment, energy in the traffic portion of the received frame may be detected using an energy estimation algorithm. For example, the energy corresponding to the traffic portion of the received frame may be measured and compared to an appropriately scaled energy threshold. If the measured energy is less than the threshold, then it may be declared to be an NR frame because, in one exemplary embodiment, the transmitter does not expect to transmit a signal in the traffic portion of the NR frame. Such an energy estimation algorithm may also use information about the system blanking algorithm and the non-blanking interval N used by the transmitter to further aid in the detection of NR frames.

It should be noted that the description of possible NR detection algorithms given above is for illustrative purposes only and is not meant to limit the scope of the present invention to any particular NR detection algorithm.

At step 640, the parameters of the received non-NR frame may be used to update an Outer Loop Power Control (OLPC) algorithm at the receiver. In one exemplary embodiment, the parameters of the received non-NR frame may include: for example, whether a Frame Quality Indicator (FQI) (e.g., CRC for the received frame) passes the results of the quality check. It will be appreciated by those skilled in the art that the OLPC algorithm may be used, for example, to calculate an appropriate signal-to-interference ratio (SIR) setpoint for a received frame, which may be used to guide a power control feedback mechanism between the transmitter and receiver for the transmitted speech frames. By excluding the quality check results derived from the NR frames, the OLPC algorithm can be correctly updated, for example, using only frames with significant transmit energy for the traffic segment.

At step 650, the speech frame is decoded to obtain speech output 650a, and algorithm 600 returns to step 610 to receive the next frame.

Fig. 7 depicts an alternative exemplary embodiment of a signal transmission path 700 for speech in accordance with the present invention. In fig. 7, a speech signal 200a is input to a speech synthesizer 710, where the speech synthesizer 710 generates a frame of speech 710a for transmission. The speech frame 710a may have one of a plurality of rates including Full Rate (FR), Half Rate (HR), Quarter Rate (QR), Eighth Rate (ER), and vocoder zero rate (VNR). When the vocoder 710 has no new information to send, it generates VNR frames (also referred to as vocoder zero-rate frames or vocoder null frames). In an exemplary embodiment, the VNR frame may simply be a blank frame that does not contain data.

The speech frame 710a is provided to a system blanking module 715, and the system blanking module 715 then provides the processed speech frame 715a to the physical layer processing module 220. As described further below, the system blanking module 715 minimizes the transmission bit rate of the vocoder output 710a by selectively replacing certain frames in the vocoder output 710a with zero rate (NR) or zero rate indicator (NRID) frames having little or no data content.

Fig. 8 depicts one exemplary embodiment 800 of an algorithm that may be applied by the system blanking module 715.

In step 810, the system blanking module 715 receives the frame 710a from the vocoder 710.

At step 820, frame 710a is evaluated to determine whether it is FR, HR, QR, or ER. These rates are considered critical for transmission. If the frame 710a contains one of these critical rates, the frame 710a is provided to the physical layer processing module 220 for transmission at step 840. If not, the frame is deemed to contain a non-critical rate and the algorithm proceeds to step 830.

At step 830, the algorithm evaluates the current frame number of the transmission to determine if a non-zero transmission should be made. In the exemplary embodiment shown, the current frame number "is added to the current frame offset", and the modulo operation (mod) is performed with the non-blanking interval parameter N and the result (frame number + frame offset). If the result of the modulo operation is 0, the algorithm proceeds to step 835. Otherwise, the algorithm proceeds to step 850.

At step 835, a zero rate indicator (NRID) frame is transmitted. The frame corresponds to a predetermined frame or indicator recognizable by the receiver, and is also referred to as a frame including zero traffic data since the frame does not include new information. The null traffic data may include bit patterns that are not used by the receiving vocoder, and thus the receiving vocoder will discard the null traffic data. In one aspect, for example, the predetermined null frame or indicator may be a known 1.8-kbps frame with null traffic data. In another aspect, for example, the predetermined frame or indicator may repeat the last transmitted 1.8-kbps frame, thereby indicating zero traffic data.

In step 850, the system blanking module 715 provides the zero rate (NR) frame to the physical layer processing module 220 for transmission. In an exemplary embodiment, the zero-rate frame contains no traffic bits, and therefore consumes minimal signaling bandwidth. After transmitting the zero-rate frame, the algorithm returns to step 810 to receive the next speech frame 710a from the speech synthesizer 710.

Fig. 9 and 9A depict exemplary frame transmission sequences 710a processed by a speech synthesizer 710 and a system blanking module 715, respectively^*And 715a^*。

In FIG. 9, frame sequence 710a^*Including eighth-rate frames labeled "ER" and vocoder zero-rate frames labeled "VNR" generated by vocoder 710.

In FIG. 9A, frame transmission sequence 715a^*And to transmission sequence 710a^*Using a selective blanking algorithm such as 800The result corresponds to a non-blanking interval N of 4, where used. In FIG. 9A, frame sequence 715a^*Including eighth rate frames ER and zero rate frames NR. The frame number 0 is transmitted directly as a frame (i.e., ER frame) received from the vocoder 710. According to the non-blanking interval N-4, the frame numbers 1 to 3 are transmitted as NR frames, and the frame number 4 is transmitted as an NRID frame. It should be noted that NRID frames are transmitted to guarantee periodic non-zero rate frame transmission, as described with reference to algorithm 800. The processing of frame numbers 5 through 13 can be readily understood by one of ordinary skill in the art in light of the above description.

Fig. 10 depicts an exemplary embodiment of a method 1000 for system blanking according to the present invention. It should be noted that the method 1000 is shown for illustrative purposes only and is not meant to limit the scope of the present invention to any particular method shown.

In fig. 10, at step 1010, a determination is made as to whether new traffic information is present, wherein the new traffic information is included in a frame for transmission over the wireless communication link.

In step 1020, the decision module determines the result of the determination of step 1010.

In step 1030, if new service information exists, a service part including data representing the new service information is added to the frame.

In step 1040, if no new traffic information exists, no new frame is transmitted unless the frames correspond to frames for which transmission is guaranteed. In this case, a frame guaranteed for transmission is generated that includes zero traffic data, which the receiving vocoder can recognize as a zero data rate.

Fig. 11 depicts an exemplary embodiment of a pilot gating scheme for identifying zero-rate frame transmissions in accordance with the present invention. It should be noted that the pilot gating scheme is presented for illustrative purposes only and is not meant to limit the scope of the present invention to systems where gated pilot transmission must accompany zero-rate frame transmission.

In fig. 11, a traffic portion 1110 of a TX transmission is shown along with a pilot portion 1120. It can be observed that pilot portion 1120 has a different pattern during transmission of zero-rate frames than during transmission of non-zero-rate frames. For example, as shown in fig. 11, the pilot gating pattern for the zero frame corresponds to 2 subsegments or PCGs for the on pilot (indicated by "P" in fig. 11) alternating with 2 subsegments or PCGs for the off pilot. The use of different pilot gating patterns during the transmission of null frames may further assist the receiver in determining whether a currently received frame is a null frame. This may be used, for example, during the zero rate decision step 630 in fig. 6.

It will be appreciated by those of ordinary skill in the art that alternative pilot gating patterns can be readily derived in accordance with the present invention to signal the presence of a null frame. For example, the pilot gating pattern may include pilot transmission of every other sub-segment or PCG or use any other pattern. It is contemplated that these alternative techniques also fall within the scope of the present invention.

In another aspect of the invention, the power control rate of the forward link and/or reverse link of the system may be reduced in order to further reduce the signal transmission of the system. In one exemplary embodiment, the mobile station may reduce the number of forward link power control commands it sends to the base station, for example, by sending only forward link power control commands during the PCG corresponding to gated reverse link pilot transmission, even in frames where the reverse link pilot portion is continuous (i.e., ungated). In another exemplary embodiment, the base station may transmit reverse link power control commands at a reduced rate (e.g., every other power control group). In addition, mobile stations receiving these reverse link power control commands may use each command to control the transmission of non-zero frames. For null frames, for example, when the reverse link pilot portion is gated as described above, a reduced number (e.g., less than all) of the power control commands received from the base station may be used to control the null frame transmission by the mobile station. These exemplary power control techniques are further described with reference to fig. 12-14.

Fig. 12 depicts an exemplary embodiment 1200 of a rate reduction power control scheme for controlling the power of Forward Link (FL) transmissions in accordance with the present invention.

In fig. 12, a Base Station Transmission (BSTX)1210 is shown along with a mobile station transmission (MS TX) 1220. The PCG transmitted by the mobile station containing Forward Link (FL) Power Control (PC) commands is shown as the PCG with shading in 1220. The upper right arrow originates from each shaded PCG pointing to the forward link PCG transmitted by the base stations that applied the received FL PC commands when transmitting the forward link PCG. For example, the base station applies the FL PC command or the like transmitted by the mobile station in RL PCG #3 when transmitting FL PCG # 4.

It should be noted that in fig. 12, the shaded PCGs in 1220 correspond to the RL PCGs that turn on the RL TX pilot according to the gated pilot scheme 1100 shown in fig. 11. Meanwhile, the mobile station transmits only FL PC commands in the RL PCGs corresponding to the PCGs with the shading as indicated by 1220. The mobile station does not send FL PC commands in the unshaded RL PCGs. Thus, these FL PC commands are transmitted only in those RL PCGs that are also transmitted during the gated pilot scheme, regardless of whether the gated pilot pattern is used for a particular frame (e.g., regardless of whether the particular frame is a zero-rate frame or a non-zero-rate frame). Those of ordinary skill in the art will appreciate that while this reduces the complexity of FL PC processing, it also reduces the overall FL PC rate.

Fig. 13 depicts an exemplary embodiment of a rate reduction power control scheme for controlling the power of Reverse Link (RL) continuous pilot transmissions in accordance with the present invention.

In fig. 13, the PCG transmitted by the base station containing forward link (RL) Power Control (PC) commands is shown as the shaded PCG in 1310. The lower right arrow originates from each shaded PCG pointing to the reverse link PCG transmitted by the mobile station using the corresponding received RL PC command. For example, the mobile station applies the RL PC command or the like transmitted by the base station in the FL PCG #3 when transmitting the RL PCG # 4.

In fig. 13, the base station transmits RL PC commands only in the FL PCGs corresponding to the PCGs with shading, as shown at 1310. The base station does not send RL PC commands in the unshaded PCGs.

Fig. 14 depicts an exemplary embodiment of a rate reduction power control scheme for controlling the power of Reverse Link (RL) gated pilot transmissions in accordance with the present invention.

In fig. 14, the PCGs transmitted by the base station containing forward link (RL) Power Control (PC) commands are shown as the shaded PCGs in 1410. The solid lower right arrow originates from the shaded PCG, which points to the reverse link PCG transmitted by the mobile station using the corresponding received RL PC command. On the other hand, the dashed arrow originating from the shaded PCGs indicates the RLPC commands transmitted by the base station, wherein the MS to which the corresponding RL PCG points does not apply this RL PC command transmitted by the base station. The base station transmits the RL PC command only in the FL PCGs corresponding to the PCGs with the shading. The base station does not send RL PC commands in the unshaded PCGs.

For example, the mobile station applies the RL PC command or the like transmitted by the base station in the FL PCG #1 when transmitting the RLPCG # 3. On the other hand, the mobile station does not apply the RL PC command transmitted by the base station in the FL PCG #2 when transmitting the RL PCG # 4. Alternatively, in one exemplary embodiment, the mobile station may maintain the same power level as used for the previous PCG (e.g., RL PCG #3 in the described example). In one aspect of the invention, this can be used to simplify the handling of RL PC commands by the mobile station.

Fig. 15 depicts a power control method 1500 in accordance with the present invention. It should be noted that the method 1500 is shown for illustrative purposes only and is not meant to limit the scope of the present invention

At step 1510, a current frame is received, wherein the frame is formatted into a plurality of sub-segments.

At step 1520, the received frame is processed according to the physical layer protocol.

At step 1530, power control commands received in the sub-segments designated for transmission according to the first gated pilot pattern are received.

In step 1540, the transmit power of the TX sub-segment following the designated sub-segment is adjusted based on the received power control command, where the TX sub-segment transmits according to the second gated pilot pattern.

In accordance with another aspect of the present invention, techniques are provided for early termination of forward link and/or reverse link transmissions in a wireless communication system to conserve power and increase capacity.

Fig. 16 depicts a prior art frame processing scheme for processing information bits 1600b by a transmitter in a communication system. In some exemplary embodiments, the illustrated frame processing scheme may be used in a forward link or reverse link transmission in a wireless communication system. Fig. 16A depicts the state of data processing by the operation shown in fig. 16.

It should be noted that the frame processing scheme shown is for illustrative purposes only and is not meant to limit the scope of the present invention to any particular processing scheme shown. Alternative exemplary embodiments of the present invention may employ alternative frame processing schemes that may, for example, reorder the steps of the scheme shown in fig. 16 and/or add or delete steps to or from the scheme shown. It is contemplated that these alternative exemplary embodiments also fall within the scope of the present invention.

In fig. 16, the information source generates information bits 1600b at a selected rate R. The number of information bits 1600b generated per frame depends on the selected rate R. For example, in a CDMA2000 system, there may be 172 bits of information per 20 millisecond frame ("full rate"), 80 bits per frame ("half rate"), 40 bits per frame ("quarter rate"), or 16 bits per frame ("eighth rate"). In fig. 16A, the information bits 1600b of one frame are collectively represented by a variable b.

At step 1600, a Frame Quality Indicator (FQI) may be generated and added to the information bits 1600b of the frame. For example, the FQI may be a Cyclic Redundancy Check (CRC) as known to those of ordinary skill in the art. As also shown in fig. 16A, signal 1600a represents a combination of information bits 1600b and FQI.

At step 1610, encoder tail (tail) bits may be added to signal 1600 a. For example, the encoder tail bits represent a fixed number of zero-valued tail bits for a convolutional encoder. As also shown in fig. 16A, signal 1610a represents the combination of signal 1600a and the encoder tail bits.

At step 1620, signal 1610a is encoded and repeated (or punctured). As previously described, the coding may include convolutional coding and Turbo coding, and the repetition may be used to further increase (or decrease in the case of puncturing) the transmit energy associated with each symbol. It should be noted that the encoding may use other techniques known to those of ordinary skill in the art, such as block encoding or other types of encoding, and the encoding techniques are not limited to the encoding explicitly described in the present invention. As also shown in fig. 16A, signal 1620a represents an encoded and repeated (or punctured) version of signal 1610 a.

At step 1630, signal 1620a is interleaved, e.g., to improve the diversity of the encoded symbols along the selected signal dimension. In one exemplary implementation, the symbols may be interleaved over time. As also shown in fig. 16A, signal 1630a represents an interleaved version of signal 1620 a.

At step 1640, the interleaved symbols of signal 1630a are mapped to a predefined frame format, as also shown in fig. 16A. The frame format may specify a frame to be composed of a plurality of sub-segments. In an exemplary embodiment, a sub-segment may be any portion of a frame that is adjacent along a given dimension (e.g., time, frequency, code, or any other dimension). A frame may include a fixed number of multiple sub-segments, each sub-segment including a portion of the total number of symbols allocated to the frame. For example, in an exemplary embodiment according to the W-CDMA standard, one sub-segment may be defined as one slot. In an exemplary embodiment according to the CDMA2000 standard, one sub-segment may be defined as one Power Control Group (PCG).

In some example embodiments, the interleaved symbols may be mapped into time, frequency, code, or any other dimension for signal transmission. The frame format may also specify interleaved symbols including, for example, control symbols (not shown) and signal 1630 a. These control symbols may include, for example, power control symbols, frame format information symbols, and the like. As also shown in fig. 16A, signal 1640a represents the output of step 1640 of symbol to frame mapping.

At step 1650, the signal 1640a is modulated onto, for example, one or more carrier waveforms. In some exemplary embodiments, the modulation may employ, for example, QAM (quadrature amplitude modulation), QPSK (quadrature phase shift keying), and the like. As also shown in fig. 16A, signal 1650a represents a modulated version of signal 1640 a. In fig. 16A, the signal 1650a is also represented by the variable x.

At step 1660, the modulated signal 1650a is further processed, transmitted over the air, and received by a receiver. Step 1660 generates the received symbol 1700a, which is represented in FIG. 16A by the variable y. It should be noted that techniques for processing signals 1650a transmitted and received over the air are well known and not further described in this application, as will be appreciated by those of ordinary skill in the art. The symbols contained in y may be further processed as described below.

Fig. 17 depicts a prior art timing diagram associated with a forward link signaling scheme for CDMA 2000.

In fig. 17, a Base Station (BS) transmits a series of frames to a Mobile Station (MS) on a forward fundamental channel (F-FCH TX) at 1700. In the illustrated exemplary embodiment, the subsegments correspond to Power Control Groups (PCGs), and each frame is composed of 16 PCGs (numbered 0 through 15). After transmitting all 16 PCGs corresponding to the first frame TX frame #0, the BS starts transmitting the next frame TX frame # 1. In an exemplary embodiment, the transmitted data may be processed as previously described herein with reference to fig. 16 and 16A.

On the MS side, the MS receives the transmitted PCG at 1710. After receiving the last PCG (i.e., PCG #15) of RX frame #0 corresponding to TX frame #0, the MS starts decoding RX frame #0 using all the received PCGs. The decoded information is available after a decoding time TD. In an exemplary embodiment, decoding may be performed as described below with reference to FIG. 18. It should be noted that while the MS is decoding TX frame #0, the PCG of TX frame #1 is received at the same time.

Fig. 18 depicts a prior art method 1800 for recovering an estimated information bit b' from a received symbol y.

At step 1805, symbol y or 1700a of the entire frame is received.

At step 1810, the symbol y or 1700a is demodulated, parsed, and deinterleaved to generate a symbol y', which is also represented as signal 1810 a. Those of ordinary skill in the art will appreciate that the operations performed at step 1810 may correspond to the inverse of the operations performed by the transmitter shown, for example, in fig. 16.

At step 1820, symbol y' is decoded and combined assuming that the rate R is known. In one implementation, the rate R may indicate how many bits are present in a received frame, which may be used by, for example, a decoder to determine at which point in a received symbol sequence to terminate decoding and/or to remove tail bits from the decoded sequence. At step 1820, tail bits of the decoded sequence may also be removed (e.g., as added at step 1610 of fig. 16). The result of step 1820 is output signal 1820 a.

At step 1830, the FQI is checked (e.g., as added at step 1600 of fig. 16) and also removed from the information bits. In one implementation, the result of the FQI check may identify whether the decoding was successful or failed. Step 1830 generates the recovered information bits (denoted b') along with the FQI result indicating success or failure.

At step 1840, the method can proceed to the next frame and repeat the steps described above for the next frame.

In accordance with the present invention, the early frame decoding and termination techniques as described below may allow the overall communication system 100 to operate more efficiently and save transmit power, thereby increasing cellular capacity.

Fig. 19 depicts an exemplary embodiment of a scheme for early termination of forward link transmissions for system operation according to the CDMA2000 standard. It should be noted that this exemplary embodiment is shown for illustrative purposes only and is not meant to limit the scope of the present invention to CDMA 2000-based systems. It will also be understood by those of ordinary skill in the art that the particular PCGs and frame numbers referred to herein are for illustrative purposes only and are not meant to limit the scope of the present invention.

In fig. 19, a Base Station (BS) transmits a series of frames to a Mobile Station (MS) at 1900. In an exemplary embodiment, these transmissions may be made on a fundamental forward channel (F-FCH TX). As described above, each of the subsegments shown in fig. 19 may correspond to a Power Control Group (PCG) in CDMA 2000. The BS starts transmission with PCG #0 of TX frame #0, continuously transmitting PCGs until receiving ACK signal 1945 from the MS after PCG # 8. The MS transmits an ACK signal to inform the BS that the MS successfully decoded the entire TX frame #0 from the received PCG.

After receiving ACK 1945, the BS stops transmission of the PCG corresponding to TX frame #0, and waits until the next frame (TX frame #1) starts before transmitting the PCG of new frame TX frame # 1. It should be noted that the BS has begun transmitting PCG #9 of TX frame #0 during the limited time period associated with receiving and processing ACK signal 1945.

Markers 1910 through 1940 depict the times of actions taken by the MS that the MS performs to generate an ACK signal 1945 to the BS to cause the BS to prematurely terminate the TX frame transmission.

At 1910, the MS receives PCGs of TX frame #0 and TX frame #1 as RX frame #0 and RX frame #1, respectively.

At 1920, upon receiving each PCG of RX frame #0, the MS attempts to decode RX frame #0 without waiting for receipt of all 16 PCGs assigned to RX frame # 0. In an exemplary embodiment, to accomplish such decoding on a per PCG basis, the MS may use a per sub-segment decoding algorithm such as 2000, described later below with reference to fig. 20.

At 1925, after receiving PCG #7, the MS successfully decodes RX frame #0 as determined by, for example, checking the CRC associated with the received bits. The MS declares the decoding success and proceeds to ACK transmission 1930.

At 1930, after declaring a successful decode at 1925, the MS transmits to the BS an MSACK signal 1945 during the transmission portion associated with PCG #8 of the reverse link.

In an exemplary embodiment, the MS may only transmit the ACK signal during the PCG immediately following the PCG for which decoding was determined to be successful or any PCG following the PCG for which decoding was determined to be successful. In an alternative exemplary embodiment, such as that shown in fig. 19, ACK mask 1940 may control the time at which ACK signal 1945 is transmitted. The ACK mask is used to specify when an ACK signal may or may not be transmitted. Providing such an ACK mask may limit the communication link capacity used to send the acknowledgement message.

In fig. 19, the ACK mask is characterized by a time interval designated as "1" during which ACK transmission is allowed on the reverse link. ACK transmission is not allowed during the time interval designated "0". In an exemplary embodiment, by limiting ACK transmission to a time interval only after a threshold PCG, the ACK mask may ensure that decoding is attempted when a sufficient portion of the received frame is processed. According to the present invention, the MS can transmit the ACK message in the next time period designated as "1" by the ACK mask immediately after successful decoding.

It should be noted that the particular ACK mask configuration shown herein is for illustrative purposes only and is not meant to limit the scope of the present invention to any ACK mask shown. It will be appreciated by those of ordinary skill in the art that alternative ACK mask configurations may be readily provided to allow ACK transmission during different sub-segments or PCG portions than those shown. It is contemplated that these alternative exemplary embodiments also fall within the scope of the present invention.

In one exemplary embodiment, the PCG specified by the ACK mask pattern may overlap with the same PCG specified by the pattern of RL gated pilot pattern used to signal the NR frame transmission (e.g., as described previously herein with reference to fig. 11).

In an exemplary embodiment, the BS TX may also include pilot transmission (not shown) that may transition from a continuously transmitted pilot signal to a gated pilot signal after receiving the MS ACK 1945, where the gated pilot signal is transmitted according to a gated pilot pattern.

Fig. 20 depicts an exemplary embodiment of a per sub-segment decoding scheme in accordance with the present invention. It should be noted that the method 2000 is shown for illustrative purposes only and is not intended to limit the scope of the present invention to any particular exemplary embodiment shown.

In fig. 20, in step 2001, the sub-segment index n is initialized to n-0.

In step 2005, the method receives a symbol y for a sub-segment n_n。

In step 2010, the method applies all received symbols y for up to and including the current frame sub-segment n_∑nDemodulation, parsing and deinterleaving are performed. y is_∑nThe method can comprise the following steps: e.g., all traffic symbols received from the included sub-segment 0 through sub-segment n. The result of step 2010 is denoted as y'_∑n。

At step 2020, the method pairs the symbol y'_∑nDecoding and combining are performed. Those of ordinary skill in the art will understand that although symbol y'_∑nTypically corresponding only to a portion of all symbols x allocated by the transmitter for the entire frame, but still by using only symbols y'_∑nTo attempt to decode the entire frame "ahead of time". Such an early decoding attempt has a good chance of successful decoding due to, for example, redundancy in symbols x introduced by partial rate coding and/or repetition (e.g., step 1620 of fig. 16) and/or time or other dimensional diversity achieved by interleaving at step 1630 of fig. 16.

The encoded tail bits may also be removed from the decoded bit sequence at step 2020 to generate signal 2020 a.

At step 2030, the method checks the FQI from signal 2020a and generates a FQI result 2030a from the accumulated received subsegments for the current frame up to n.

At step 2035, the method evaluates whether the FQI result indicates success. If so, the method proceeds to step 2040 where a successful decode is declared and the method performs ACK message generation to enable early termination of the forward link transmission in step 2040. The next available opportunity may be specified, for example, by the ACK mask described with reference to fig. 5. If not, the method proceeds to step 2037.

At step 2037, the method increments n by 1 and determines if there are more remaining sub-segments to receive in the frame. If so, the method returns to step 2005. If not, the method proceeds to step 2060, declaring the decoding for the frame unsuccessful.

At step 2070, the decoder continues to evaluate the next frame.

Fig. 21 depicts a prior art implementation 2100 of a forward link symbol path for wireless configuration 4(RC4) according to the CDMA2000 standard and an exemplary embodiment 2110 of a forward link symbol path according to the present invention. In implementation 2100, the frame quality indicator includes a CRC of length 6, 8, or 12 added to the bits of the frame according to the frame symbol rate. In the exemplary embodiment 2110 according to the present invention, the frame quality indicator includes a CRC having an increased length of 12, 12 or 12 added to bits of the frame. The use of increased length CRCs improves the performance of the early decoding scheme according to the present invention, enabling, for example, more accurate detection of decoding success for the early decoding technique according to the present invention. It should be noted that the particular CRC lengths shown herein are for illustrative purposes only and are not meant to limit the scope of the present invention to any particular CRC lengths shown.

As further shown in implementation 2100, the symbol puncturing rate is 1/5, 1/9, none, and none, depending on the frame symbol rate. In the exemplary embodiment 2110 according to the present invention, the symbol puncturing rate is 1/3, 1/5, 1/25 and none according to the frame symbol rate. It will be appreciated by those of ordinary skill in the art that the enhanced puncturing in the exemplary embodiment 2110 may be used to accommodate the increased length of CRC required by the exemplary embodiment 2110.

Fig. 22 depicts an exemplary embodiment of a signaling scheme 2200 for sending an ACK message on the reverse link to prematurely terminate forward link transmissions. In fig. 22, a reverse ACK channel (R-ACKCH)2210 is modulated onto walsh code W (64, 16)2212 using on-off keying (OOK) by a modulator 2214. The resulting signal is applied with a relative channel gain 2216 and the result is provided to an adder 2218.

In fig. 22, a reverse fundamental channel (R-FCH)2220 having a rate of 1536 symbols every 20 msec is modulated onto a walsh function W (16, 4)2222 using a modulator 2224. The resulting signal is applied with a relative channel gain 2226 and the result is provided to an adder 2218. The output of the summer may be provided on a quadrature (Q) channel 2228 for reverse link transmission to the BS. In the illustrated exemplary embodiment, an in-phase (I) channel 2234 is also provided that includes a reverse pilot channel (R-PICH) 2230.

It should be noted that the exemplary embodiment of the reverse link ACK transmission scheme shown with reference to fig. 22 is presented for illustrative purposes only and is not meant to limit the scope of the present invention to any particular embodiment of an ACK transmission scheme. Those of ordinary skill in the art will appreciate that alternative techniques for sending an ACK on the reverse link may be readily derived in accordance with the present invention, including applying different forms of modulation and sending an ACK message on alternative channels other than the one shown. It is contemplated that these alternative exemplary embodiments also fall within the scope of the present invention.

Fig. 23 depicts an exemplary embodiment of a scheme 2300 for early termination of reverse link transmissions for system operation in accordance with the CDMA2000 standard. It should be noted that the exemplary embodiments shown are for illustrative purposes only and are not meant to limit the scope of the present invention to any particular reverse link early termination scheme shown. It will be understood by those of ordinary skill in the art that the particular PCGs and frame numbers referred to herein are for illustration purposes only.

In fig. 23, at 2300, a Mobile Station (MS) transmits a series of frames to a Base Station (BS). In an exemplary embodiment, the frames may be transmitted on a reverse fundamental channel (R-FCH TX). In fig. 23, each of the subsegments is shown to correspond to a Power Control Group (PCG). The MS starts transmitting TX frame #0 at PCG #0, continues transmitting PCGs until an ACK signal 2345 is received from the BS after PCG # 8. After receiving ACK 2345, the MS stops transmitting the PCG corresponding to TX frame #0, waits until the next frame (TX frame #1) starts, so as to start transmitting the PCG corresponding to TX frame # 1.

Markers 2310 through 2340 depict the times of actions taken by the BS, which the BS performs to generate an ACK signal 2345 to the MS to allow the MS to prematurely terminate the reverse link frame transmission.

At 2310, the BS receives the PCGs of TX frame #0 and TX frame #1 as RX frame #0 and RX frame #1, respectively.

At 2320, upon receiving each individual PCG, the BS attempts to decode RX frame #0 without waiting for all 16 PCGs allocated to RX frame #0 to be received. In an exemplary embodiment, to accomplish such decoding on a per PCG basis, the BS may use a per sub-segment decoding algorithm such as 2000 described previously with reference to fig. 20.

At 2325, after receiving PCG #5, the BS declares decoding success and goes to ACK transmission step 2330 to generate a BS ACK TX signal.

At 2330, after declaring a successful decode at 2325, the BS transmits an ACK signal 2345 during the transmit portion associated with PCG #8 of the forward link. The portion of the transmission during which ACK signal 2345 is sent may be specified by a corresponding ACK mask 2340.

In one exemplary embodiment, the ACK mask pattern enables ACK transmission only during some PCGs in which power control commands are sent on the Forward Link (FL) to control Reverse Link (RL) power transmission, as previously described herein with reference to fig. 19.

In fig. 23, 2350 also depicts transmission of reverse link pilot signals by the MS in accordance with an exemplary embodiment of a reverse link early termination scheme. At step 2350, after the MS receives ACK signal 2345 from the BS at PCG #8, the MS stops transmitting RL pilot signals at any PCG. As shown, RL pilot signal transmission may be gated off more suitably for selected PCGs. This may be used to reserve RL pilot signal transmit power for the remaining PCGs and provide additional ACK transmission mechanisms to the BS. In one exemplary embodiment, the RL gated pilot pattern for the remaining PCGs may correspond to the pattern used to signal the NR frame transmission (e.g., as previously described with reference to fig. 11).

In the exemplary embodiment shown, the RL pilot signal is gated off during PCGs 9, 10, 13, and 14. Typically, the RL pilot signal is gated off in alternate two PCG groups after the ACK signal is transmitted until the end of the early terminated frame. It should also be noted that because pilot gating of NR frames is used, various schemes may be used for pilot gating for early terminated frames, such as: one power control group is turned on followed by one power control group being turned off; the two power control groups are turned on and then turned off; any other mode that can be used to reduce the transmit power.

Fig. 24 depicts an implementation 2400 of a reverse link symbol path in the prior art and an exemplary embodiment 2410 of a reverse link symbol path in the present invention. In implementation 2400, a CRC of length 6, 8, or 12 is added to the bits of the frame, depending on the frame symbol rate. In an exemplary embodiment 2410 according to the present invention, a CRC having an increased length of 12, 12 or 12 is added to the bits of the frame. As in the case of forward link processing shown in fig. 21, the use of increased length CRCs improves the performance of the early decoding scheme according to the present invention, such that decoding success is more accurately detected, for example, for early decoding techniques. It should be noted that the particular CRC lengths shown herein are for illustrative purposes only and are not meant to limit the scope of the present invention to any particular CRC lengths shown.

As further shown in implementation 2400, the symbol puncturing rate is 1/5, 1/9, none, and none, depending on the frame symbol rate. In the exemplary embodiment 2410 according to the present invention, the symbol puncturing rate is 1/3, 1/5, 1/25 and none, according to the frame symbol rate. It will be appreciated by one of ordinary skill in the art that the use of increased puncturing in the exemplary embodiment 2410 may accommodate CRCs of increased length that are also present in the exemplary embodiment 2410.

In an exemplary embodiment, an ACK signal sent by the BS to the MS may be provided by replacing (puncturing) a bit having a predetermined position on the forward link traffic channel and/or using on-off keying (OOK) at the predetermined position to send an ACK or NAK (negative acknowledgement) signal to the MS. In one exemplary embodiment, the predetermined position may vary on a per frame basis according to a predetermined pseudo-random bit pattern. In one exemplary embodiment, the ACK bits may be Time Domain (TDM) multiplexed with the reverse link power control bits.

It should be noted that the frame early termination scheme described above is applicable not only to the fundamental channel of a CDMA2000 communication link, but also to the "high data rate" supplemental channel. For example, in an alternative exemplary embodiment (not shown), an ACK signaling mechanism on the forward link may be used to enable one or more MSs to prematurely terminate transmissions on one or more corresponding reverse supplemental channels.

For example, in one exemplary embodiment (not shown), one or more MSs may transmit frames on the corresponding reverse supplemental channels simultaneously. If the BS successfully receives a frame from the MS on the reverse supplemental channel, the BS transmits ACKs on corresponding forward common acknowledgement subchannels of forward common acknowledgement channels, one subchannel of each of which is designated for controlling one reverse supplemental channel. Accordingly, forward common acknowledgement subchannels from multiple MSs may be multiplexed on a single forward common acknowledgement channel. For example, in one exemplary embodiment, multiple subchannels may be time-multiplexed on a single common acknowledgement channel according to a predetermined pattern known to both the BS and one or more MSs. Such a predetermined pattern may be indicated by an external signaling form (not shown).

The BS may support operation on one or more forward common acknowledgement channels. In one exemplary embodiment, the sub-segments or PCGs for which a forward common acknowledgement channel may be transmitted for the reverse supplemental channel may be indicated by an ACK mask, as previously described herein.

In an alternative exemplary embodiment, for system operation according to the CDMA2000 standard, an ACK signaling mechanism on the reverse link is provided to control transmission on the forward fundamental channel and one or more forward supplemental channels. Fig. 25 depicts an exemplary embodiment of a signaling scheme 2500 for signaling an ACK message on the reverse link to prematurely terminate the forward fundamental channel (F-FCH) and/or up to two forward supplemental channels (F-SCH1 and F-SCH 2).

In fig. 25, the reverse ACK channel (R-ACKCH)2520 is modulated using Binary Phase Shift Keying (BPSK) onto a walsh function W (64, 16)2522 by a modulator 2524. In an exemplary embodiment, R-ACKCH 2520 may signal the BS to terminate transmission on the forward fundamental channel (F-FCH). The relative channel gain 2526 is applied to the resultant signal, and the result thereof is supplied to the adder 2518.

In fig. 25, a second reverse ACK channel (R-ACKCH)2510 is modulated onto a walsh function W (16, 12)2512 using Binary Phase Shift Keying (BPSK) by a modulator 2514. In an exemplary embodiment, ACKCH 2510 can signal the BS to terminate transmission on the first forward supplemental channel (F-SCH 1). A relative channel gain 2516 is applied to the resultant signal, and the result thereof is supplied to an adder 2518.

As further shown in FIG. 25, two R-ACK channels and a reverse fundamental channel (R-FCH) may be combined onto the quadrature (Q) component of the RL signal. The R-FCH has a rate of 1536 symbols every 20 ms and is also modulated onto walsh function W (16, 4)2532 using modulator 2534. A relative channel gain 2536 is applied to the resultant signal and the result is provided to the adder 2518. The output of the summer may be provided to the BS on a quadrature (Q) channel 2528 for reverse link transmission.

As further shown in fig. 25, a third reverse ACK channel (R-ACKCH)2550 is modulated onto a walsh function W (16, 8)2552 using on-off keying (OOK) by a modulator 2554. In an exemplary embodiment, the ACKCH 2550 may signal the BS to terminate transmission on the second forward supplemental channel (F-SCH 2). A relative channel gain 2556 is applied to the resulting signal and the result is provided to an adder 2548. An adder 2548 may be used to combine the R-ACKCH 2550 with a reverse pilot channel (R-PICH)2540 to generate an in-phase (I) reverse link signal 2544.

It will be appreciated by those of ordinary skill in the art that the above examples of a particular ACK signaling scheme for the forward link are given for illustrative purposes only and are not meant to limit the scope of the present invention to any particular ACK signaling scheme for the forward channel and the reverse channel.

FIG. 26 depicts an exemplary embodiment of a method 2600 in accordance with the present invention. It should be noted that the method 2600 is shown for illustrative purposes only and is not meant to limit the scope of the present invention to any particular method.

At step 2610, a speech frame is received.

At step 2620, the method attempts to decode the received speech frame in advance. In an exemplary embodiment, early decoding may be attempted before all sub-segments of the frame are received.

In step 2630, the method determines whether the attempted speech frame decoding was successful. In an exemplary embodiment, a frame quality indicator, such as a CRC, may be checked to determine whether the frame decoding was successful.

At step 2640, an acknowledgement signal (ACK) is transmitted to terminate the voice frame transmission.

The early termination technique of the present invention can be readily applied in situations where the mobile station is in "soft handoff", i.e.: in soft handoff, the MS communicates with multiple BSs simultaneously on the forward link and/or reverse link.

For example, when the MS is in soft handoff between two BSs, each of the two BSs may receive reverse link transmissions by the MS, and either or both of the two BSs may send an ACK signal back to the MS (not necessarily simultaneously) to stop the MS transmission. In one exemplary embodiment, in response to receiving more than one ACK signal within a reverse link frame transmission, the MS stops transmission of the current frame after receiving the first ACK signal. Furthermore, early termination may similarly be applied to control forward link transmissions by two BSs to one MS. For example, in response to successful early decoding of frames received simultaneously from two BSs, the MS may transmit an ACK signal to stop transmission on the forward link by both BSs. It is contemplated that these alternative exemplary embodiments also fall within the scope of the present invention.

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, circuits, and algorithm steps described in connection with the exemplary 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. 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 exemplary embodiments of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the exemplary embodiments disclosed 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 thereof 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.

Furthermore, the steps of a method or algorithm described in connection with the exemplary 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 Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable PROM (EEPROM), 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. Of course, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary embodiments, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

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

Claims (42)

1. A method for early termination of consecutive frame transmissions on a communication channel, the method comprising:

continuously transmitting a first frame to a receiver, each frame formatted into a plurality of consecutive sub-segments, the continuously transmitting comprising sequentially and continuously transmitting sub-segments of the first frame to the receiver;

receiving an acknowledgement message from the receiver during transmission of the first frame;

ceasing transmission of the first frame after receiving the acknowledgement message,

the acknowledgement message is received according to an acknowledgement mask specifying when the acknowledgement message can be transmitted or when the acknowledgement message cannot be transmitted.

2. The method of claim 1, each frame being allocated a fixed time interval for transmission, the method further comprising:

after a fixed time interval of the first frame has elapsed, transmission of a second frame is started, wherein the second frame immediately follows the first frame in a sequence of frames.

3. The method of claim 1, further comprising:

adjusting a transmit power of the first frame in response to receiving a power control message from the receiver.

4. The method of claim 1, each frame comprising: partially encoded bits interleaved in time.

5. A method for early termination of consecutive frame transmissions on a communication channel, the method comprising:

receiving continuously from a transmitter a first frame, each frame formatted into a plurality of consecutive subsegments, said continuously receiving comprising receiving consecutively in sequence subsegments of said first frame from said transmitter;

attempting to decode the first frame before receiving the entire first frame;

determining whether frame decoding is successfully performed according to a result of the attempt;

transmitting an acknowledgement message to the transmitter upon determining that frame decoding was successful, wherein the acknowledgement message is to cease transmitting the first frame,

wherein transmitting the acknowledgement message further comprises transmitting according to an acknowledgement mask, and wherein the acknowledgement mask is to specify when the acknowledgement message can be transmitted or when the acknowledgement message cannot be transmitted.

6. The method of claim 5, each frame being allocated a fixed time interval for transmission, the method further comprising:

beginning to receive a second frame after a fixed time interval of the first frame has elapsed, wherein the second frame immediately follows the first frame in a sequence of frames.

7. The method of claim 5, further comprising:

transmitting a power control message to the transmitter to adjust a transmit power of the first frame.

8. The method of claim 5, wherein transmitting the acknowledgement message further comprises:

transmission is only performed at a plurality of predetermined times.

9. The method of claim 5, the acknowledgement mask specifying a time interval having a smaller duration than a full sub-segment used to transmit the acknowledgement message.

10. The method of claim 9, further comprising:

receiving the acknowledgement mask from the transmitter.

11. The method of claim 5, transmitting an acknowledgement message comprising:

applying a non-zero gain to an acknowledgment signal comprising a walsh function associated with the acknowledgment message;

and combining the acknowledgement signal and the service signal for transmission.

12. The method of claim 5, the consecutively received frames being received on a first channel, the acknowledgement messages being transmitted on a first acknowledgement channel, the method further comprising:

continuously receiving second frames from the transmitter on a second channel;

attempting to decode the second frame before receiving the entire second frame;

determining whether frame decoding is successfully performed according to a result of attempting to decode the second frame;

transmitting an acknowledgement message to the transmitter upon determining that the second frame was successfully frame decoded, wherein the acknowledgement message is to cease transmitting the second frame.

13. The method of claim 5, further comprising:

continuously receiving continuously transmitted second frames from a second transmitter;

attempting to decode the second frame before receiving the entire second frame;

determining whether the second frame is successfully decoded according to a result of the attempt;

transmitting an acknowledgement message to the second transmitter upon determining that the second frame was successfully frame decoded, wherein the acknowledgement message is to terminate transmission of a remaining portion of the second frame, wherein transmitting the acknowledgement message to the transmitter comprises modulating at least one bit on a common acknowledgement channel, and wherein transmitting the acknowledgement message to the second transmitter comprises modulating at least one other bit on the same common acknowledgement channel.

14. The method of claim 13, further comprising:

the common acknowledgement channel is spread using a single walsh function.

15. The method of claim 13, time multiplexing at least one bit corresponding to an acknowledgement message sent to the transmitter with at least one other bit corresponding to an acknowledgement message sent to the second transmitter on the same common acknowledgement channel.

16. The method of claim 5, the transmitting an acknowledgement message comprising: on-off keying is used to modulate the signal on different walsh codes.

17. The method of claim 5, the transmitting an acknowledgement message comprising: modulating at least one ACK bit on a traffic channel, wherein the at least one ACK bit replaces at least one traffic bit on the traffic channel.

18. The method of claim 17, wherein the location of ACK bits in the traffic channel varies on a per frame basis.

19. An apparatus for early termination of consecutive frame transmissions on a communication channel, the apparatus comprising:

a transmitter to: continuously transmitting a first frame to a receiver, each frame formatted into a plurality of consecutive sub-segments, the transmitter further configured to continuously transmit by sequentially continuously transmitting sub-segments of the first frame to the receiver;

a receiver module to: receiving an acknowledgement message from the receiver during transmission of the first frame;

the transmitter is further configured to: ceasing transmission of the first frame after receiving the acknowledgement message,

the acknowledgement message is received according to an acknowledgement mask specifying when the acknowledgement message can be transmitted or when the acknowledgement message cannot be transmitted.

20. The apparatus of claim 19, each frame is allocated a fixed time interval for transmission, the transmitter is further configured to:

beginning transmission of a second frame after a fixed time interval of the first frame has elapsed, wherein the second frame immediately follows the first frame in a sequence of frames.

21. The apparatus of claim 19, the transmitter further configured to:

adjusting a transmit power of the first frame in response to receiving a power control message from the receiver.

22. The device of claim 19, each frame comprising: partially encoded bits interleaved in time.

23. An apparatus for early termination of consecutive frame transmissions on a communication channel, the apparatus comprising:

a receiver to: continuously receiving a first frame from a transmitter, each frame formatted into a plurality of consecutive sub-segments, the receiver for continuously receiving by sequentially continuously receiving sub-segments of the first frame from the transmitter;

a processor to:

attempting to decode the first frame before receiving the entire first frame;

determining whether frame decoding is successfully performed according to a result of the attempt;

a transmitter module to: transmitting an acknowledgement message to the transmitter upon determining that frame decoding was successful, wherein the acknowledgement message is to cease transmitting the first frame,

wherein the transmitter module is further configured to transmit the acknowledgement message according to an acknowledgement mask, and wherein the acknowledgement mask is configured to specify when the acknowledgement message can be transmitted or when the acknowledgement message cannot be transmitted.

24. The apparatus of claim 23, each frame is allocated a fixed time interval for transmission, the processor is further configured to:

beginning to receive a second frame after a fixed time interval of the first frame has elapsed, wherein the second frame immediately follows the first frame in a sequence of frames.

25. The apparatus of claim 23, the transmitter module further to:

transmitting a power control message to the transmitter to adjust a transmit power of the first frame.

26. The apparatus of claim 23, the transmitter module further to:

the acknowledgement message is transmitted only at a plurality of predetermined times.

27. The apparatus of claim 23, the acknowledgement mask specifies time intervals having a smaller duration than full sub-segments used to transmit the acknowledgement message.

28. The apparatus of claim 23, the receiver further configured to:

receiving the acknowledgement mask from the transmitter.

29. The apparatus of claim 23, the transmitter module for transmitting the acknowledgement message by:

applying a non-zero gain to an acknowledgment signal comprising a walsh function associated with the acknowledgment message;

and combining the acknowledgement signal and the service signal for transmission.

30. The apparatus of claim 23, the consecutive received frames are received on a first channel,

the transmitter module is further configured to:

transmitting the acknowledgement message on a first acknowledgement channel;

the receiver is further configured to:

continuously receiving second frames from the transmitter on a second channel;

the processor is further configured to:

attempting to decode the second frame before receiving the entire second frame;

determining whether frame decoding is successfully performed according to a result of attempting to decode the second frame;

the transmitter module is further configured to:

transmitting an acknowledgement message to the transmitter upon determining that the second frame was successfully frame decoded, wherein the acknowledgement message is to cease transmitting the second frame.

31. The apparatus as set forth in claim 23, wherein,

the receiver is further configured to:

continuously receiving continuously transmitted second frames from a second transmitter;

the processor is further configured to:

attempting to decode the second frame before receiving the entire second frame;

determining whether the second frame is successfully decoded according to a result of the attempt;

the transmitter module is further configured to:

transmitting an acknowledgement message to the second transmitter upon determining that the second frame was successfully decoded, wherein the acknowledgement message is to terminate transmission of a remaining portion of the second frame;

transmitting the acknowledgement message to the transmitter by modulating at least one bit on a common acknowledgement channel;

transmitting the acknowledgement message to the second transmitter by modulating at least one other bit on the same common acknowledgement channel.

32. The apparatus of claim 31, the transmitter module further configured to:

the common acknowledgement channel is spread using a single walsh function.

33. The apparatus of claim 31, at least one bit corresponding to an acknowledgement message sent to the transmitter is time multiplexed with at least one other bit corresponding to an acknowledgement message sent to the second transmitter on the same common acknowledgement channel.

34. The apparatus of claim 23, the transmitter module further to:

the signal is modulated on different walsh codes using on-off keying to transmit the acknowledgment message.

35. The apparatus of claim 23, the transmitter module further to:

transmitting an acknowledgement message by modulating at least one ACK bit on a traffic channel in place of at least one traffic bit on the traffic channel.

36. The apparatus of claim 35, the location of ACK bits in the traffic channel varies on a per frame basis.

37. An apparatus for early termination of frame transmissions on a communication channel, the apparatus comprising:

means for receiving continuously transmitted frames from a transmitter, each frame formatted into a plurality of consecutive subsegments, the receiving comprising sequentially receiving subsegments of the frame from the transmitter;

means for attempting to decode an entire frame before the frame is received;

means for determining a successful frame decode based on a result of the attempt; and

means for transmitting an acknowledgement message to the transmitter based on the determination of the successful frame decoding, wherein the acknowledgement message is to cease transmitting the frame, wherein transmitting the acknowledgement message further comprises transmitting according to an acknowledgement mask, and wherein the acknowledgement mask is to specify when an acknowledgement message can be transmitted or when an acknowledgement message cannot be transmitted.

38. An apparatus for early termination of frame transmissions on a communication channel, the apparatus comprising:

means for successively transmitting first frames, each frame formatted into a plurality of successive subsegments, said successively transmitting comprising successively transmitting subsegments of said first frame in sequence;

means for receiving an acknowledgement message from the receiver during transmission of the first frame; and

means for ceasing transmission of the first frame after receiving the acknowledgement message,

the acknowledgement message is received according to an acknowledgement mask specifying when the acknowledgement message can be transmitted or when the acknowledgement message cannot be transmitted.

39. A method for early termination of consecutive frame transmissions on a communication channel, the method comprising:

continuously transmitting a first frame to at least one receiver, each frame formatted into a plurality of consecutive sub-segments, the continuously transmitting comprising sequentially and continuously transmitting sub-segments of the first frame to the at least one receiver;

receiving at least one acknowledgement message from the at least one receiver during transmission of the first frame;

ceasing transmission of the first frame after receiving a first one of the at least one acknowledgement message,

each of the at least one acknowledgement message is received according to an acknowledgement mask specifying when an acknowledgement message can be transmitted or when an acknowledgement message cannot be transmitted.

40. The method of claim 39, the at least one receiver comprising a first receiver and a second receiver, the receiving the at least one acknowledgement message from the at least one receiver comprising: receiving an acknowledgement message from the first receiver and receiving an acknowledgement message from the second receiver.

41. A method for early termination of consecutive frame transmissions on a communication channel, the method comprising:

receiving consecutively from at least one transmitter a first frame, each frame formatted into a plurality of consecutive subsegments, said consecutively receiving comprising receiving consecutively in sequence subsegments of said first frame from said at least one transmitter;

attempting to decode the first frame before receiving the entire first frame;

determining whether frame decoding is successfully performed according to a result of the attempt;

transmitting an acknowledgement message upon determining that frame decoding was successful, wherein the acknowledgement message is to cease transmission of the first frame by each of the at least one transmitter,

wherein transmitting the acknowledgement message further comprises transmitting according to an acknowledgement mask, and wherein the acknowledgement mask is to specify when the acknowledgement message can be transmitted or when the acknowledgement message cannot be transmitted.

42. The method of claim 41, the at least one transmitter comprising a first transmitter and a second transmitter, the transmitting the acknowledgement message comprising transmitting the acknowledgement message to both the first transmitter and the second transmitter.