Patent Publication Number: US-2007110006-A1

Title: Burst detector

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      The application is a continuation of U.S. patent application Ser. No. 10/196,857, filed Jul. 16, 2002, which in turn claims priority from Provisional Patent Application Ser. No. 60/325,692, filed Sep. 28, 2001, which is incorporated by reference as if fully set forth. 
    
    
     BACKGROUND  
      The present invention relates to the field of wireless communications. More specifically, the present invention relates to detecting codes in a communication signal in order to activate the receiver to process the signal.  
      Spread spectrum TDD systems carry multiple communications over the same spectrum. The multiple signals are distinguished by their respective chip code sequences (codes). Referring to  FIG. 1 , TDD systems use repeating transmission time intervals (TTIs), which are divided into frames  34 , further divided into a number of timeslots  37   1 - 37   n , such as fifteen timeslots. In such systems, a communication is sent in a selected timeslot out of the plurality of timeslots  37   1 - 37   n  using selected codes. Accordingly, one frame  34  is capable of carrying multiple communications distinguished by both timeslot and code. The combination of a single code in a single timeslot is referred to as a physical channel. A coded composite transport channel (CCTrCh) is mapped into a collection of physical channels, which comprise the combined units of data, known as resource units (RUs), for transmission over the radio interface to and from the user equipment (UE) or base station. Based on the bandwidth required to support such a communication, one or multiple CCTrChs are assigned to that communication.  
      The allocated set of physical channels for each CCTrCh holds the maximum number of RUs that would need to be transmitted during a TTI. The actual number of physical channels that are transmitted during a TTI is signaled to the receiver via the Transport Format Combination Index (TFCI). During normal operation, the first timeslot allocated to a CCTrCh will contain the required physical channels to transmit the RUs and the TFCI. After the receiver demodulates and decodes the TFCI it would know how many RUs are transmitted in a TTI, including those in the first timeslot. The TFCI conveys information about the number of RUs.  
       FIG. 1  also illustrates a single CCTrCh in a TTI. Frames  1 ,  2 ,  9  and  10  show normal CCTrCh transmission, wherein each row of the CCTrCh is a physical channel comprising the RUs and one row in each CCTrCh contains the TFCI. Frames  3 - 8  represent frames in which no data is being transmitted in the CCTrCh, indicating that the CCTrCh is in the discontinuous transmission state (DTX). Although only one CCTrCh is illustrated in  FIG. 1 , in general there can be multiple CCTrChs in each slot, directed towards one or more receivers, that can be independently switched in and out of DTX.  
      DTX can be classified into two categories : 1) partial DTX; and 2) full DTX. During partial DTX, a CCTrCh is active but less than the maximum number of RUs are filled with data and some physical channels are not transmitted. The first timeslot allocated to the CCTrCh will contain at least one physical channel to transmit one RU and the TFCI word, where the TFCI word signals that less than the maximum number of physical channels allocated for the transmission, but greater than zero (0), have been transmitted.  
      During full DTX, no data is provided to a CCTrCh and therefore, there are no RUs at all to transmit. Special bursts are periodically transmitted during full DTX and identified by a zero (0) valued TFCI in the first physical channel of the first timeslot allocated to the CCTrCh. The first special burst received in a CCTrCh after a normal CCTrCh transmission or a CCTrCh in the partial DTX state indicates the start of full DTX. Subsequent special bursts are transmitted every Special Burst Scheduling Parameter (SBSP) frames, wherein the SBSP is a predetermined interval. Frames  3  and  7  illustrate the CCTrCh comprising this special burst. Frames  4 - 6  and  8  illustrate frames between special bursts for a CCTrCh in full DTX.  
      As shown in Frame  9  of  FIG. 1 , transmission of one or more RUs can resume at any time, not just at the anticipated arrival time of a special burst. Since DTX can end at any time within a TTI, the receiver must process the CCTrCh in each frame, even those frames comprising the CCTrCh with no data transmitted, as illustrated by Frames  4 - 6  and  8 . This requires that the receiver operate at high power in order to process the CCTrCh for each frame, regardless of its state.  
      Receivers are able to utilize the receipt of subsequent special bursts to indicate that the CCTrCh is still in the full DTX state. Detection of the special burst, though, does not provide any information as to whether the CCTrCh will be in the partial DTX state or normal transmission state during the next frame.  
      Support for DTX has implications to several receiver functions, notably code detection. If no codes are sent in the particular CCTrCh in one of its frames, the code detector may declare that multiple codes are present, resulting in a Multi-User Detector (MUD) executing and including codes that were not transmitted, reducing the performance of other CCTrChs that are also processed with the MUD. Reliable detection of full DTX will prevent the declaring of the presence of codes when a CCTrCh is inactive. Also, full DTX detection can result in reduced power dissipation that can be realized by processing only those codes that have been transmitted and not processing empty timeslots.  
      Accordingly, there exists a need for an improved receiver.  
     SUMMARY  
      The present invention is a receiver for receiving a communication signal divided into a plurality of timeslots, wherein the timeslots include a plurality of channels, including a burst detector for detecting when a selected one of the plurality of channels of the communication is received. The burst detector comprises a noise estimation device for determining a scaled noise power estimate of the selected one of the timeslots, a matched filter for detecting signal power of the selected one of the channels of the timeslots and a signal power estimation device, responsive to the matched filter, for generating a signal power estimate of the selected one of the channels of the timeslots. A comparator, responsive to the scaled noise power estimate and the signal power estimate, for generating a burst detection signal when the signal power estimate is greater than the scaled noise power estimate, and a data estimation device, responsive to the burst detection signal, for decoding the plurality of channels are also included in the burst detector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING(S)  
       FIG. 1  illustrates an exemplary repeating transmission time interval (TTI) of a TDD system and a CCTrCh.  
       FIG. 2  is a block diagram of a receiver in accordance with the preferred embodiment of the present invention.  
       FIG. 3  is a block diagram of the burst detector in accordance with the preferred embodiment of the present invention.  
       FIGS. 4A and 4B  are a flow diagram of the operation of the receiver in activating and deactivating the burst detector of the present invention.  
       FIG. 5  is a block diagram of a first alternative embodiment of the burst detector of the present invention.  
       FIG. 6  is a second alternative embodiment of the burst detector of the present invention.  
       FIG. 7  is a third alternative embodiment of the burst detector of the present invention.  
       FIG. 8  is a fourth alternative embodiment of the burst detector of the present invention.  
       FIG. 9  is a fifth alternative embodiment of the burst detector of the present invention.  
       FIG. 10  is a sixth alternative embodiment of the burst detector of the present invention.  
       FIG. 11  is a block diagram of an application of the burst detector of the present invention.  
       FIG. 12  is a block diagram of an alternate use for the burst detector of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
      The preferred embodiments will be described with reference to the drawing figures where like numerals represent like elements throughout.  
      Referring to  FIG. 2 , a receiver, preferably at a user equipment (UE)  19 , mobile or fixed, comprises an antenna  5 , an isolator or switch  6 , a demodulator  8 , a channel estimation device  7 , a data estimation device  2 , a burst detector  10 , and demultiplexing and decoding device  4 . Although the receiver will be disclosed at a UE, the receiver may also be located at a base station.  
      The receiver  19  receives various radio frequency (RF) signals including communications over the wireless radio channel using the antenna  5 , or alternatively an antenna array. The received signals are passed through a transmit/receive (T/R) switch  6  to a demodulator  8  to produce a baseband signal. The baseband signal is processed, such as by the channel estimation device  7  and the data estimation device  2 , in the timeslots and with the appropriate codes assigned to the receiver  19 . The channel estimation device  7  commonly uses the training sequence component in the baseband signal to provide channel information, such as channel impulse responses. The channel information is used by the data estimation device  2  and the burst detector  10 . The data estimation device  2  recovers data from the channel by estimating soft symbols using the channel information.  FIG. 2  shows one burst detector, however, a receiver may have multiple burst detectors to detect the reception of more than one code. Multiple burst detectors would be used, for example, when multiple CCTrChs are directed towards one receiver.  
       FIG. 3  is a block diagram of the burst detector  10  in accordance with the preferred embodiment of the present invention. The burst detector  10  comprises a noise estimator  11 , a matched filter  12 , a signal power estimator  13 , and a comparator  14 . The received and demodulated communication is forwarded to the matched filter  12  and the noise estimator  11 . The noise estimator  11  estimates the noise power of the received signal. The noise power estimate may use a predetermined statistic, such as the root-mean square value of the input samples, or other methods to approximate noise, interference, or total power. The noise power estimate is scaled by a predetermined scaling factor, generating a threshold value, which is forwarded to the comparator  14 .  
      The received and demodulated communication is also forwarded to the matched filter  12 , as well as, the channel impulse response from the channel estimation device  7 . The matched filter  12  is coupled to a signal power estimator  13  and a channel estimation device  7 . Although a matched filter  12  is shown in  FIG. 3  and described herein, any device which demodulates a particular code in the received signal can be utilized, such as a rake receiver  19 . The matched filter  12  also receives the code for the physical channel carrying the TFCI for the particular CCTrCh. Utilizing the three inputs, the matched filter  12  computes soft bit or symbol decisions for the physical channel carrying the TFCI for the CCTrCh. The soft decisions are then forwarded to the signal power estimator  13 .  
      The signal power estimator  13 , coupled to the matched filter  12  and the comparator  14 , receives the output of the matched filter  12  and estimates the signal power of the soft decisions in the received communication. As those skilled in the art know, a method of estimating the signal power is to separate the real and imaginary parts of the outputs of matched filter  12  and calculate the power therefrom. Any method of signal power estimation, though, may be used by the signal power estimator  13 . Once the signal power estimator  13  determines the signal power of the soft decisions in the received communication, it is forwarded to the comparator  14 .  
      The comparator  14  is coupled at its inputs to the signal power estimator  13  and the noise power estimator  11 , and at its output to the data estimation device  2 . The comparator  14  compares the scaled noise power and the signal power and the result of the comparison is used to indicate whether the particular CCTrCh is still in full DTX. For purposes of this disclosure, DTX will be indicative of the full DTX state discussed hereinabove. If the scaled estimated noise power is greater than the estimated signal power for the particular code carrying the TFCI in the first timeslot allocated to the CCTrCh in a frame, the comparator  14  outputs a signal to the data estimation device  2  indicating that no data was sent for the particular CCTrCh. This results is in the data estimation device  2  not operating to demodulate the particular CCTrCh.  
      If the estimated signal power for the particular code carrying the TFCI in the first timeslot allocated to the CCTrCh in a frame is greater than the scaled estimated noise power, the comparator  14  outputs a signal, to the data estimation device  2  indicating that the end of DTX has been detected, which results in the data estimation device activating the CCTrCh.  
      In the description above, the comparison between the scaled noise power and the estimated signal power is limited to the particular code carrying the TFCI since if any codes are transmitted then the code carrying the TFCI will be among them. As those skilled in the art know, the comparison can use other received codes allocated to the CCTrCh. If the estimated signal power is greater than the scaled noise power for any particular code, the comparator  14  outputs a signal to the data estimation device  2 . The data estimation device  2  can then activate demodulation of the code. Alternatively, it can be activated to demodulate the CCTrCh.  
      The data estimation device  2 , coupled to the demodulator  8 , burst detector  10 , the channel estimation device  7 , and the data demultiplexing and decoding device  4 , comprises a code detection device (CDD)  15 , a MUD  16 , and a TFCI decoder  17 . The MUD  16  decodes the received data using the channel impulse responses from the channel estimation device  7  and a set of channelization codes, spreading codes, and channel offsets from the CDD. As those skilled in the art know, the MUD  16  may utilize any multi-user detection method to estimate the data symbols of the received communication, a minimum mean square error block linear equalizer (MMSE-BLE), a zero-forcing block linear equalizer (ZF-BLE) or the use of a plurality of joint detectors, each for detecting one of the plurality of receivable CCTrChs associated with the UE  19 .  
      The CDD  15 , coupled to the MUD  16  and the burst detector  10 , provides the MUD  16  with the set of codes for each of the plurality of received CCTrChs associated with the receiver  19 . If the burst detector  10  indicates that the end of DTX state has been detected, the CDD  15  generates the code information and forwards it to the MUD  16  for decoding of the data. Otherwise, the CDD  15  does nothing with the particular CCTrCh.  
      Once the MUD  16  has decoded the received data, the data is forwarded to the TFCI decoder  17  and the data demultiplexing and decoding device  4 . As those skilled in the art know, the TFCI decoder  17  outputs the maximum-likelihood set of TFCI information bits given the received information. When the value of the TFCI decoder  17  is equal to zero (0), a special burst has been detected, indicating the CCTrCh is beginning DTX or remains in the DTX state.  
      As stated above, the data estimation device  2  forwards the estimated data to the data demultiplexing and decoding device  4 . The demultiplexing and decoding device  4 , coupled to the data estimation device  2 , detects the received signal to interference ratio (SIR) of the particular CCTrCh or the code carrying the TFCI in the CCTrCh. If the value of the SIR is greater than a predetermined threshold, the end of DTX detected by the burst detector  10  is validated. If the SIR is below the threshold, then a false detection has occurred, indicating that the particular CCTrCh is still in the DTX state. The data demultiplexing and decoding may include error detection on the data which acts as a sanity check for the burst detector  10 , reducing the effect of false detections by the UE receiver  19 .  
      The flow diagram of the operation of the receiver in accordance with the preferred embodiment of the present invention is illustrated in  FIGS. 4A and 4B . After synchronization of the UE to a base station and assuming the previous received frame included a special burst, the UE receiver  19  receives a plurality of communications in a RF signal (Step  401 ) and demodulates the received signal, producing a baseband signal (Step  402 ). For each of the CCTrChs associated with the UE, the burst detector  10  determines whether there are any symbols within a particular CCTrCh by comparing the estimated noise power to the estimated signal power (Step  403 ).  
      If the burst detector  10  indicates to the CDD  15  that the CCTrCh is in the DTX state, the burst detector  10  continues to monitor the CCTrCh (Step  409 ). Otherwise, the burst detector indicates to the CDD  15  that the CCTrCh is not in the DTX state (Step  404 ). The CDD  15  then provides the MUD  16  with the code information for the particular CCTrChs associated with the UE (Step  405 ). The MUD  16  processes the received CCTrCh and forwards the data symbols to the TFCI decoder  17  and the data demultiplexing and decoding device  4  (Step  406 ). The TFCI decoder  17  processes the received data symbols to determine the TFCI value (Step  407 ). If the TFCI value is zero (0), the special burst has been detected and a signal is then sent to the burst detector  10  to continue to monitor the CCTrCh (Step  409 ), indicating that the CCTrCh is in, or still in, the full DTX state.  
      If the TFCI value is greater than zero (0), and a CCTrCh is currently in the full DTX state, then the UE performs a sanity check on the received data using information provided by the data demultiplexing and decoding device  4  (Step  408 ). Referring to  FIG. 4B , when conducting the sanity check the UE first determines whether at least one transport block has been received in the associated CCTrCh (Step  408   a ). If there are no transport blocks received, the UE remains in full DTX (Step  408   b ). If there is at least one transport block, the data demultiplexing and decoding device  4  determines whether at least one of the detected transport blocks has a CRC attached. If not, then the data in the CCTrCh is accepted as valid and utilized by the UE (Step  410 ). If there is a CRC attached, then the data demultiplexing and decoding device  4  determines whether at least one transport block has passed the CRC check. If at least one has passed, then the data in the CCTrCh is accepted as valid and utilized by the UE (Step  410 ). Otherwise, the UE determines that the particular CCTrCh remains in the full DTX state (Step  408   b ).  
      If the sanity check determines that a CCTrCh is in the full DTX state, then an output signal is sent to the burst detector  10  indicating that the burst detector  10  should continue to monitor the CCTrCh to determine when full DTX ends and supply an output to the code detection device  15 . If the DTX control logic determines that a CCTrCh is not in the full DTX state then it outputs a signal to the burst detector  10  indicating that it should not monitor the CCTrCh and the decoded data is utilized by the UEs (Step  410 ).  
      An alternative embodiment of the burst detector  50  of the present invention is illustrated in  FIG. 5 . This alternative detector  50  comprises a matched filter  51 , a preliminary TFCI decoder  52 , a noise estimator  53 , and a comparator  54 . This detector  50  operates similar to the detector  10  disclosed in the preferred embodiment. The matched filter  51  receives the demodulated received signal from the demodulator  8  and forwards the soft symbol decisions to the preliminary TFCI decoder  52 . Similar to the TFCI decoder  17  disclosed hereinabove, the preliminary TFCI decoder  52 , coupled to the comparator  54  and the noise estimator  53 , computes power estimates for each possible TFCI word. The largest TFCI power estimate is then forwarded to the comparator  54  and all power estimates are forwarded to the noise estimator  53 .  
      The noise estimator  53 , coupled to the TFCI decoder  52 , and the comparator  54 , receives the decoded TFCI power and the largest TFCI power and calculates a predetermined statistic, such as the root-mean-square of all inputs. The statistic provides an estimate of the noise that the TFCI decoder  52  is subject to. The noise estimate is scaled and forwarded to the comparator  54  for comparison to the largest TFCI power from the TFCI decoder  52 .  
      The comparator  54 , coupled to the TFCI decoder  52  and the noise estimator  53 , receives the largest TFCI power and the scaled noise estimate and determines the greater of the two values. Similar to the preferred embodiment, if the estimated TFCI power is greater than the scaled noise estimate, the burst detector  50  signals to the data estimation device  2 , which activates the CCTrCh demodulation of the particular CCTrCh associated with the UE. Otherwise, the burst detector  50  signals to the data estimation device  2  that the CCTrCh remains in the DTX state.  
      A second alternative embodiment of the burst detector is illustrated in  FIG. 6 . Similar to the detector  50  illustrated in  FIG. 5  and disclosed above, this alternative burst detector  60  comprises a matched filter  61 , a preliminary TFCI decoder  63 , a noise estimator  62 , and a comparator  64 . The difference between this embodiment and the previous embodiment is that the noise estimator  62  receives the demodulated received signal before the matched filter  61  determines the soft symbols. The noise estimator  62 , coupled to the demodulator  8  and the comparator  64 , receives the demodulated received signal and calculates a noise estimate as in the preferred embodiment  11  shown in  FIG. 3 . The calculated statistic is then the noise estimate of the received signal.  
      The operation of this second alternative is the same as the previous alternative. The matched filter  61  receives the demodulated received signal, determines the soft symbols of the CCTrCh using the first code for the particular CCTrCh and forwards the soft symbols to the TFCI decoder  63 . The TFCI decoder  63  decodes the received soft symbols to produce a decoded TFCI word. An estimate of the power of the decoded TFCI word is then generated by the decoder and forwarded to the comparator  64 . The comparator  64  receives the power estimate for the decoded TFCI word and a scaled noise estimate from the noise estimator  62  and determines which of the two values is greater. Again, if the estimated power of the TFCI word is greater than the scaled noise estimate, the burst detector  60  signals to the data estimation device  2  that data has been transmitted in the particular CCTrCh associated with the receiver  19 , indicative of the end of DTX state or the transmission of the special burst.  
      A third alternative embodiment of the burst detector is illustrated in  FIG. 7 . As shown, this alternative detector  70  is the same as the second alternative except that an additional Decision Feedback Accumulation loop  75  is added. This loop  75  is coupled to the matched filter  71  and an adder  79  and comprises a data demodulator  76 , a conjugator  77 , and a symbol power estimator  78 . The soft symbols output from the matched filter  71  are forwarded to the demodulator  76  of the loop  75 , which generates symbol decisions with low latency. Each of the low latency symbol decisions are conjugated by the conjugator  77  and combined with the soft symbols output by the matched filter  71 . The combined symbols are then forwarded to the symbol power estimator  78  where a power estimate of the combined symbols is generated and scaled by a predetermined factor and forwarded to the adder  79 .  
      The adder  79 , coupled to the symbol power estimator  78 , the TFCI decoder  73  and the comparator  74 , adds a scaled TFCI power estimate from the TFCI decoder  73  and the scaled symbol power estimate from the symbol power estimator  78 , then forwards the summed power estimate to the comparator  74  for comparison to the noise estimate. A determination is then made as to whether data has been transmitted in the CCTrCh. This third alternative embodiment improves the performance of the burst detector  70  with a TFCI detector in those cases where the power estimate of the TFCI word is too low for a reliable determination of the state of the CCTrCh.  
      A fourth alternative embodiment of the burst detector of the present invention is illustrated in  FIG. 8 . This alternative detector  80  eliminates the TFCI decoder  73  of the alternative illustrated in  FIG. 7 . The advantage of eliminating the TFCI decoder  73  is that the burst detector  80  requires less signal processing. The comparator  84  for this alternative, then, compares the noise estimate to the symbol power estimate to determine whether the particular CCTrCh associated with the UE comprises data.  
      A fifth alternative embodiment of the burst detector of the present invention is illustrated in  FIG. 9 . This alternative burst detector  90  comprises a first and second matched filter  91 ,  92 , a TFCI decoder  93  and a comparator  94 . As shown in  FIG. 9 , the burst detector  90  is similar to the alternative detector  60  illustrated in  FIG. 6 . The TFCI decoder  93  generates an energy estimate of the decoded TFCI word from the soft symbols output by the first matched filter  91 . This energy estimate is forwarded to the comparator  94  for comparison to a scaled noise estimate. The noise estimate in this alternative burst detector  90  is generated by the second matched filter  92 .  
      The second matched filter  92 , coupled to the demodulator  8  and the comparator  94 , receives the demodulated received signal and generates a noise estimate using a ‘nearly’ orthogonal code. The ‘nearly’ orthogonal codes are determined by selecting codes that have low cross correlation with the subset of orthogonal codes used in a particular timeslot where the associated CCTrCh is located. For those systems that do not use all of their orthogonal codes in a timeslot, the ‘nearly’ orthogonal code could be one of the unused orthogonal codes. For example, in a 3GPP TDD or TD-SCDMA system there are 16 OVSF codes. If less than all 16 OVSF codes are used in a timeslot, then the ‘nearly’ orthogonal code would equal one of the unused OVSF codes. The noise estimate generated by the second matched filter  92  is scaled by a predetermined factor and forwarded to the comparator  94 .  
      A sixth alternative embodiment of the burst detector of the present invention is illustrated in  FIG. 10 . Again, this alternative burst detector  100  is similar to that which is disclosed in  FIG. 6 . Similar to the fifth alternative burst detector  60 , an alternate method of generating a noise estimate is disclosed. In this alternative, a symbol combiner  102 , coupled to the matched filter  101 , TFCI decoder  103  and statistic combiner  105 , is used to generate the noise estimate. The soft symbols from the matched filter  101  are forwarded to the symbol combiner  102 , as well as, the TFCI word generated by the TFCI decoder  103 . The symbol combiner  102  generates a set of statistics by combining the soft symbols, excluding from the set a statistic provided by the TFCI decoder  103  representing the decoded TFCI word, and forwards the set to the statistic combiner  105 . The statistic combiner  105  combines the statistics from the symbol combiner  102 , resulting in a noise estimate. The noise estimate is then scaled and forwarded to the comparator  104  for comparison against the power estimate of the TFCI word from the TFCI decoder  103 .  
       FIG. 11  is a block diagram of a receiver  110  comprising a CDD  111  which uses a plurality of burst detectors  112   1 . . .  112   n ,  113   1 , . . .  113   n  to generate the codes to be forwarded to the MUD  114 . Each burst detector  112   1 . . .  112   n ,  113   1 , . . .  113   n  outputs a signal to the CDD  111  indicating whether the code has been received in the burst. The CDD  111  uses these inputs to provide the MUD  114  with the set of codes associated with the received signal. It should be noted that the burst detector of any of the embodiments of the present invention can be used to detect the presence of codes in general. The burst detector is not limited to only detecting the end of DTX state of a particular CCTrCh.  
       FIG. 12  illustrates an alternate use for the burst detector of the present invention. As shown in  FIG. 12 , the burst detector may be used to monitor power, signal to noise ratio (SNR) and the presence of codes at a receiver that is not intended to have access to the underlying transmitted information. For example, this information can be used for cell monitoring applications. The output of the noise estimator  11  and the signal power estimator  13  are output from the burst detector for each code that is tested. The database maintains a history of the measurements and can compute and store the signal to noise ratio (SNR). This data can then be used to determine which, if any, codes are active in a cell.  
      The burst detector of the present invention provides a receiver with the ability to monitor the received signal to determine if a particular CCTrCh associated with the UE has reached the end of full DTX state. In particular, this ability is provided before the data estimation, avoiding the need for the data estimation device to process a large number of codes that may not have been transmitted. This results in a reduction in unnecessary power dissipation during full DTX by not operating the MUD (or other data estimation device) on the particular CCTrCh in the full DTX state. In the case where a CCTrCh is allocated physical channels in multiple timeslots in a frame, and the burst detector has indicated that DTX has not ended, the full receiver chain can remain off during the second and subsequent timeslots in a frame saving significantly more power.  
      The burst detector also results in better performance by eliminating the occurrence of the filling of the MUD with codes that were not transmitted, which reduces the performance of the CCTrChs associated with the UE. To simplify implementation, code detection devices often assume that at least one code has been transmitted and employ relative power tests to select the set of codes to output to the MUD. If no codes are transmitted for CCTrCh, such as during full DTX, a code detection device may erroneously identify codes as having been transmitted leading to poor performance. By determining whether full DTX is continuing and providing the information to the code detection device, the burst detector allows use of simpler code detection algorithms. Multiple burst detectors can be used in parallel ( FIG. 11 ) to provide further input to a code detection device enabling further simplifications therein.  
      While the present invention has been described in terms of the preferred embodiment, other variations which are within the scope of the invention as outlined in the claims below will be apparent to those skilled in the art.