JP2006086632A - Cdma receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of reception performance even if a delay profile update period is extended. <P>SOLUTION: When updating a delay profile, a finger allocator 103 detects a finger instructed by finger selection information from a Rake synthesis target finger selector 107 from paths where the paths are detected by a path detector 102, selects a path to be allocated, and stores the other candidate paths at a candidate path storage 104. Then, in a period where no delay profiles are updated, the Rake synthesis target finger selector 107 detects a finger having poor desired wave versus interference wave power ratio similarly, and the finger allocator 103 adds a finger in a candidate path stored in the candidate path storage 104 when updating the delay profile. More specifically, even in a period where no delay profiles are updated, finger allocation can be updated according to a propagation environment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a CDMA receiver provided in a base station or a mobile station in a CDMA (Code Division Multiple Access) mobile communication system, and more particularly to a CDMA receiver that receives radio signals from a plurality of propagation paths.

  Conventionally, in a CDMA receiver that receives radio signals from a plurality of propagation paths, even during reception, for the purpose of improving the quality of the received signal and preventing line disconnection during reception due to movement of the receiver, etc. A path search is performed (for example, Patent Document 1). Hereinafter, in order to facilitate understanding of the present invention, an outline thereof will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration example of a conventional CDMA receiver.

  The CDMA receiver illustrated in FIG. 5 includes a radio circuit 502 having an antenna 501, a finger circuit 503, a rake circuit 504, and a timing control circuit 505. The finger circuit 503 includes despreading circuits 506a to 506n and level measurement circuits 507a to 507n.

  In the above configuration, the reception signal output from the radio circuit 502 is input to the despreading circuits 506 a to 506 n and the timing control circuit 505 of the finger circuit 503. Outputs of the despreading circuits 506a to 506n become despread data via the level measurement circuits 507a to 507n and are input to the rake circuit 504 and the timing control circuit 505. The timing control circuit 505 outputs a reference timing pulse to the despreading circuits 506a to 506n of the finger circuit 503.

  Here, the finger circuit 503 performs despreading of the received signal output from the radio circuit 502 and measures the level of the desired wave to interference wave power ratio. When the level of the desired wave-to-interference wave power ratio falls below a certain threshold value, the path measurement information 507a to 507n of the finger circuit 503 notifies the timing control circuit 505 of the path valid / invalid information. The maximum number of path searches is changed according to the path valid / invalid information.

In such a CDMA receiving apparatus, the delay profile update period and the finger assignment update period are set to the same period, and the period is set so that the reception performance does not deteriorate.
JP 2001-186050 A

  However, in conventional CDMA receivers, finger allocation may not be able to keep up with changes in the propagation environment when the delay profile update period is increased in order to reduce power consumption and increase the number of channels accommodated in the base station apparatus. Therefore, there is a problem that the reception performance is deteriorated.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a CDMA receiver that can suppress deterioration in reception performance even when the delay profile update period is increased.

  In order to solve such a problem, a CDMA receiver according to the present invention includes a delay profile creating unit that creates a delay profile from a received signal, a path detecting unit that performs path detection from the delay profile, the path detection result, and a candidate path. Finger assignment unit for performing finger assignment based on candidate path information and finger selection information read from the storage unit, and storing candidate paths not assigned to fingers in the candidate path storage unit, and finger assignment information from the finger assignment unit A finger means for despreading the received signal based on the signal, a signal quality measuring means for measuring the signal quality based on the despreading result for each finger in the finger means, and a finger to be subjected to Rake synthesis based on the signal quality information for each finger And Rake synthesis target fingers And Rake combining target finger selecting means for outputting the finger selection information indicating each, and Rake combining means for performing Rake combining based on the despreading result in the finger means and the finger selection information. take.

  According to this configuration, when the delay profile is updated, the finger assigning unit detects a finger having good signal quality indicated by the finger selection information from the paths detected by the path detecting unit, and selects a path to be assigned. The other candidate paths are stored in the candidate path storage means. Then, during a period in which the delay profile is not updated, the finger having poor signal quality is detected and deleted in the same manner, and the finger is added using the candidate path stored in the candidate path storage means when the delay profile is updated. Therefore, finger allocation can be updated according to the propagation environment even during a period in which the delay profile is not updated, and degradation of reception performance can be suppressed.

  The CDMA receiver according to the present invention employs a configuration in which, in the above invention, the signal quality measuring unit is a desired wave to interference wave power ratio measuring unit that measures a desired wave to interference wave power ratio for each finger. .

  According to this configuration, it is possible to detect and delete a finger having a low desired wave to interference wave power ratio.

  The CDMA receiver according to the present invention employs a configuration in which, in the above invention, the signal quality measuring means is error bit number measuring means for measuring the number of error bits for each finger.

  According to this configuration, a finger having a large number of error bits can be detected and deleted.

  In the CDMA receiver according to the present invention, in the above invention, the signal quality measuring means is a reception level measuring means for measuring a reception level for each finger.

  According to this configuration, a finger having a low reception level can be detected and deleted.

  The mobile station apparatus according to the present invention employs a configuration including the CDMA receiver according to the present invention.

  According to this configuration, the mobile station apparatus can obtain the same operations and effects as the above invention.

  The base station apparatus according to the present invention employs a configuration including the CDMA receiver according to the present invention.

  According to this configuration, the base station apparatus can obtain the same operations and effects as the above invention.

  According to the present invention, it is possible to suppress the degradation of reception performance even when the delay profile is not updated. Therefore, it is possible to lengthen the delay profile update period to reduce power consumption and increase the accommodated channel in the base station apparatus.

  The essence of the present invention is that, even during a period when the delay profile is not updated, the finger having a poor signal quality is detected and deleted in the same manner as when the delay profile is updated, and the candidate path found when the delay profile is updated. In this case, the finger assignment is added so that the finger assignment can be updated according to the propagation environment, and the deterioration of the reception performance is suppressed. As the signal quality, any one of the desired wave to interference wave power ratio, the number of error bits, and the reception level is measured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a CDMA receiving apparatus according to Embodiment 1 of the present invention. 1 includes a delay profile creation unit 101, a path detection unit 102, a finger assignment unit 103, a candidate path storage unit 104, finger units 105-1 to 105-n, a desired wave pair, and the like. Interference wave power ratio measurement units 106-1 to 106-n, Rake synthesis target finger selection unit 107, and Rake synthesis unit 108 are provided.

  The received signal is input to delay profile creation section 101 and finger sections 105-1 to 105-n, respectively. The delay profile creation unit 101 creates a delay profile from the received signal and outputs it to the path detection unit 102. The path detection unit 102 detects a plurality of paths from the received delay profile and outputs each to the finger assignment unit 103.

  The finger assignment unit 103 assigns a finger based on the path detection result in the path detection unit 102, candidate path information read from the candidate path storage unit 104, and a plurality of finger selection information from the Rake synthesis target finger selection unit 107. The phase is determined and output to the finger sections 105-1 to 105-n. At this time, the finger assigning unit 103 outputs and stores the paths not assigned to the fingers as candidate paths in the candidate path storage unit 104.

  The finger units 105-1 to 105-n despread the received signal in the path phase assigned from the finger assigning unit 103, and use the despread results as the desired wave to interference wave power ratio measuring units 106-1 to 106-. n and Rake combiner 108 outputs the result.

  Desired wave-to-interference wave power ratio measuring units 106-1 to 106-n measure the desired wave-to-interference wave power ratio from the despread results in the respective finger units 105-1 to 105-n, and select the Rake combining target finger. Output to the unit 107.

  The Rake combining target finger selection unit 107 selects a finger to be subjected to Rake combining based on a desired wave-to-interference wave power ratio for each finger, and outputs the finger selection information to the finger assignment unit 103 and the Rake combining unit 108. .

  The rake combining unit 108 rake-combines the despreading results from the finger units 105-1 to 105-n based on the finger selection information from the rake combining target finger selecting unit 107, and outputs the result.

  Next, the operation of the CDMA receiver configured as described above will be described with reference to FIG. 1 and FIG. 2 is a time chart for explaining the operation of the CDMA receiver shown in FIG. In FIG. 2, time 0T, time 1T, time 2T, time 3T, time 4T, and time 5T are shown as operation timings. As shown in FIG. 2, the delay profile creation unit 101 and the path detection unit 102 operate every four operation cycles, while the other finger assignment unit 103, candidate path storage unit 104, and Rake composition target finger selection The unit 107 is shown to operate in each operation cycle.

  At time 0, the following operation is performed. The delay profile creation unit 101 creates a delay profile by calculating a sliding correlation between the received signal and the spread code, and updates the delay profile. Therefore, the path detection unit 102 detects the phase at which the correlation value peaks in the updated delay profile.

  In the finger assigning unit 103, based on the finger selection information at the previous time −T input from the Rake synthesis target finger selecting unit 107, the correlation value in the delay profile detected by the path detecting unit 102 is in order from the peak phase. Determine finger assignment. Specifically, if the finger selection information is “finger valid”, the finger assignment unit 103 assigns the peak phase at that time to the finger. Further, if the finger selection information is “finger invalid”, the peak phase at that time is not assigned to the finger. If the phase is not included in the finger selection information, a new path is found and assigned to the finger. After the finger assignment is determined in this way, the finger assignment unit 103 stores the peak phase that is not finally assigned to the finger in the candidate path storage unit 104.

  Each of the finger units 105-1 to 105-n despreads the received data with the path phase instructed from the finger assignment unit 103. Desired wave-to-interference wave power ratio measuring units 106-1 to 106-n calculate a ratio between desired wave power and interference wave power for each finger based on the despread result. Here, for example, the desired wave power is calculated by obtaining an average value of received pilot symbols and calculating the power value. The interference wave power is calculated by obtaining the dispersion of received pilot symbols and calculating the power value. The method for calculating the desired wave-to-interference wave power ratio is not limited to the above method, and a conventionally known method may be used.

  The rake composition target finger selection unit 107 compares the desired wave-to-interference wave power ratio for each finger with a predetermined desired wave-to-interference wave power ratio threshold value, and selects a finger that is equal to or greater than the threshold value as a rake composition target. The finger selection information “Finger valid” is selected as a finger to be selected, and the finger selection information “Finger invalid” is generated by selecting a finger smaller than the threshold as a finger not to be subjected to Rake synthesis. The Rake combining unit 108 performs Rake combining with the fingers whose finger selection information is “Finger valid”.

  Next, at times 1T, 2T, and 3T, the delay profile is not updated, and the finger assignment unit 103, the candidate path storage unit 104, the Rake synthesis target finger selection unit 107, and the like perform the following operations.

  The finger assigning unit 103 refers to the finger selection information of the past time only at the time −T, and deletes the finger that is “finger invalid” from the finger assignment. The deleted finger is newly assigned with the candidate path information read from the candidate path storage unit 104.

  Each of the finger units 105-1 to 105-n despreads received data at the path phase instructed from the finger assigning unit 103. Desired wave-to-interference wave power ratio measuring units 106-1 to 106-n calculate a ratio between desired wave power and interference wave power for each finger based on the despread result.

  The rake composition target finger selection unit 107 compares the desired wave-to-interference wave power ratio for each finger with a predetermined desired wave-to-interference wave power ratio threshold value, and selects a finger that is equal to or greater than the threshold value as a rake composition target. The finger selection information “Finger valid” is selected as a finger to be selected, and the finger selection information “Finger invalid” is generated by selecting a finger smaller than the threshold as a finger not to be subjected to Rake synthesis.

  The Rake combining unit 108 performs Rake combining with the fingers whose finger selection information is “Finger valid”. After time 4T, the operations from time 0T to 3T described above are repeated.

  As described above, according to the first embodiment, even when the delay profile is not updated, a finger having a low desired signal-to-interference signal power ratio is detected and deleted, and the finger is added using the candidate path found when the delay profile is updated. Therefore, the finger assignment can be updated according to the propagation environment, and the deterioration of the reception performance can be suppressed.

(Embodiment 2)
FIG. 3 is a block diagram showing a configuration of a CDMA receiving apparatus according to Embodiment 2 of the present invention. In FIG. 3, the same reference numerals are assigned to the same or equivalent components as those shown in FIG. 1 (Embodiment 1). Here, the description will be focused on the portion related to the second embodiment.

  That is, as shown in FIG. 3, in CDMA receiving apparatus 200 according to Embodiment 2, in the configuration shown in FIG. 1 (Embodiment 1), desired wave to interference wave power ratio measuring sections 106-1 to 106-106. Error bit number measuring units 206-1 to 206-n are provided instead of -n, and a Rake synthesis target finger selection unit 207 is provided instead of the Rake synthesis target finger selection unit 107.

  In the above configuration, error bit number measuring sections 206-1 to 206-n receive the despread results from finger sections 105-1 to 105-n, demodulate received pilot symbols, and compare with pilot patterns. The number of error bits is measured and output to the Rake composition target finger selection unit 207.

  The Rake combining target finger selection unit 207 compares the number of error bits for each finger with a predetermined error bit number threshold value, selects a finger that is equal to or less than the threshold value as a finger to be Rake combining target, and selects “finger valid” , The finger selection information “finger invalid” is created by selecting a finger larger than the threshold value as a finger not to be subjected to Rake synthesis, and the created finger selection information is used as a finger assignment unit 103 and a Rake. The data is output to the combining unit 108.

  As described above, according to the second embodiment, even when the delay profile is not updated, the finger having a large number of error bits is detected and deleted, and the finger is added by the candidate path found when the delay profile is updated. It is possible to update the finger assignment according to the environment, and to suppress the degradation of reception performance.

(Embodiment 3)
FIG. 4 is a block diagram showing a configuration of a CDMA receiving apparatus according to Embodiment 3 of the present invention.
In FIG. 4, the same or equivalent components as those shown in FIG. 1 (Embodiment 1) are denoted by the same reference numerals. Here, the description will be focused on the portion related to the third embodiment.

  That is, CDMA receiving apparatus 300 shown in FIG. 4 has a reception level measuring unit in place of desired wave-to-interference wave power ratio measuring units 106-1 to 106-n in the configuration shown in FIG. 1 (Embodiment 1). 306-1 to 306-n are provided, and a Rake composition target finger selection unit 307 is provided instead of the Rake composition target finger selection unit 107.

  In the above configuration, reception level measurement sections 306-1 to 306-n receive the despread outputs from finger sections 105-1 to 105-n, respectively, and measure the reception level by taking the average of the power values of the received symbols. And output to the Rake composition target finger selection unit 307.

  The rake composition target finger selection unit 307 compares the reception level for each finger with a predetermined reception level threshold value, selects a finger that is equal to or greater than the threshold value as a finger that is a rake composition target, and becomes “finger valid”. While creating finger selection information, a finger smaller than the threshold value is selected as a finger that is not to be subjected to Rake synthesis, finger selection information that is “invalid for finger” is created, and the created finger selection information is assigned to a finger assignment unit 103 and a Rake synthesis unit. And 108.

  As described above, according to the third embodiment, even when the delay profile is not updated, the finger having a low reception level is detected and deleted, and the finger is added using the candidate path found when the delay profile is updated. The finger allocation can be updated according to the reception performance, and the deterioration of the reception performance can be suppressed.

  In the first to third embodiments, the finger assignment unit 103 has been described as a configuration in which the finger assignment unit 103 is deleted from the finger assignment only once as “finger invalid” is determined. However, the finger assignment unit 103 is deleted after being determined as “finger invalid” multiple times. The structure to do may be sufficient.

  The present invention is suitable when it is desired to lengthen the delay profile update period in order to reduce power consumption and increase the number of channels accommodated in the base station apparatus.

FIG. 1 is a block diagram showing a configuration of a CDMA receiving apparatus according to Embodiment 1 of the present invention. Time chart for explaining the operation of the CDMA receiver shown in FIG. A block diagram showing a configuration of a CDMA receiver according to Embodiment 2 of the present invention. Block diagram showing a configuration of a CDMA receiving apparatus according to Embodiment 3 of the present invention. Block diagram showing a configuration example of a conventional CDMA receiver

Explanation of symbols

100, 200, 300 CDMA receiver 101 Delay profile creation unit 102 Path detection unit 103 Finger assignment unit 104 Candidate path storage unit 105-1 to 105-n Finger unit 106-1 to 106-n Measurement of desired wave to interference wave power ratio Unit 107, 207, 307 Rake synthesis target finger selection unit 108 Rake synthesis unit 206-1 to 206-n Error bit number measurement unit 306-1 to 306-n Reception level measurement unit

Claims (6)

  Finger assignment based on delay profile creation means for creating a delay profile from the received signal, path detection means for path detection from the delay profile, path detection result, candidate path information read from candidate path storage means and finger selection information A finger assigning means for storing candidate paths not assigned to fingers in the candidate path storage means, a finger means for despreading a received signal based on finger assignment information from the finger assigning means, and the finger means The signal quality measuring means for measuring the signal quality based on the despreading result for each finger, and the finger to be Rake combined and the finger not to be Rake combined are selected based on the signal quality information for each finger, R to output finger selection information And ke synthesis target finger selecting unit, CDMA receiving apparatus characterized by comprising a Rake combining means, for performing Rake combining based on the despreading results and said finger selection information in the finger means.   2. The CDMA receiver according to claim 1, wherein the signal quality measuring means is a desired wave to interference wave power ratio measuring means for measuring a desired wave to interference wave power ratio for each finger.   2. The CDMA receiver according to claim 1, wherein said signal quality measuring means is error bit number measuring means for measuring the number of error bits for each finger.   2. The CDMA receiver according to claim 1, wherein the signal quality measuring means is reception level measuring means for measuring a reception level for each finger.   A mobile station apparatus comprising the CDMA receiver according to any one of claims 1 to 4.   A base station apparatus comprising the CDMA receiver according to any one of claims 1 to 4.

Images