JP4661560B2 - Synchronous tracking circuit and CDMA receiver - Google Patents

Description

  The present invention relates to a CDMA (Code Division Multiple Access) receiver, and more particularly, to a synchronization tracking circuit and a receiving apparatus including the synchronization tracking circuit.

  In a CDMA communication system used in a mobile communication system or the like, a transmitting side spreads and transmits a user signal to be transmitted using a spreading code, and a receiving side performs despreading using the same spreading code as the spreading code. The original user signal is obtained. First, a CDMA receiver will be described with reference to FIG. 3A and 3B are diagrams described in Patent Document 1. FIG.

  Referring to FIG. 3A, the CDMA receiver includes an antenna 1, an RF unit 2, an AD (Analog-to-Digital Converter) unit 3, a delay profile unit 4, a finger assignment unit 8, and a plurality of units. It is comprised from the finger part 9 and the RAKE synthetic | combination part 7 (refer FIG. 2 of patent document 1).

  The RF unit 2 converts the synthesized wave received by the antenna 1 into an analog baseband signal, and the AD unit 3 converts the analog baseband signal converted by the RF unit 2 into a digital baseband signal. The delay profile unit 4 obtains transmitted data by performing despreading using the digital baseband signal converted by the AD unit 3, but creates a delay profile to search for multipath components. To do. The finger assigning unit 8 assigns path timings (reference timings) corresponding to the respective peak positions of the plurality of radio waves detected by the delay profile unit 4 to different finger units 9. Each finger unit 9 reproduces received data by despreading the digital baseband signal converted by the AD unit 3 at each path timing assigned by the finger assigning unit, and the RAKE combining unit 7 The data reproduced by each finger unit 9 is RAKE-combined to output demodulated data.

  FIG. 3B is a diagram showing a configuration example of each finger portion 9 (FIG. 5 of Patent Document 1). Referring to FIG. 3B, the finger unit 9 includes a despreading unit 101, a power calculation unit 102, a selector unit 103, and a maximum value detection unit 107.

  The despreading unit 101 converts the digital baseband signal converted by the AD unit 3 into data by despreading (correlating with the pseudo-spread signal). The despreading unit 101 performs despreading within a predetermined section (hereinafter referred to as a path tracking range) among sections before and after the path timing allocated by the finger allocation unit 8. For example, when despreading is performed within the path tracking range of the n-point interval before and after the path timing, the despreading unit 101 outputs symbol data of the n-point interval, that is, n symbol data.

  The power calculator 102 calculates the average power value of each of the n pieces of symbol data output from the despreading unit 101. The maximum value detection unit 107 detects the maximum value among the n average power values calculated by the power calculation unit 102. The selector unit 103 selects and outputs only the symbol data of the maximum power value detected by the maximum value detection unit 107 from the n symbol data calculated by the despreading unit 101.

  As described above, the finger unit 9 obtains data by performing despreading within a predetermined path tracking range in the sections before and after the path timing instructed from the finger assigning unit 8, and obtains the maximum from the data. By searching for the power value, subtle fluctuations in the path are followed.

  As a path selection technique based on reception quality in a CDMA receiver, for example, in Patent Document 2, an interference wave level measurement unit measures an interference wave level included in a correlation value obtained by a despreader, and an interference wave level is measured. A configuration for controlling whether or not to output a correlation value to a detection unit subsequent to the path selection unit by obtaining reception quality (SIR) from the correlation value by the SIR calculator and controlling the path selection unit according to the reception quality A CDMA receiver configured to compare the reception quality of each correlation value, select a correlation value indicating the best reception quality by a path switching unit, and detect by the detection unit is disclosed. Patent Document 3 discloses a configuration for selecting the output of a correlator having the best reception quality among the outputs of a plurality of correlators. As a determination of the reception quality, a pilot signal or a pilot signal and data is disclosed. When the pilot signal is composed of multiple symbols depending on the signal reception level, the data part is tentatively determined based on the ratio of the estimated value of the signal power and the estimated value of the noise power, and the received data is demodulated to demodulate all data After the phase is aligned with the carrier phase, determination based on the ratio between the estimated value of signal power and the estimated value of noise power is described.

JP 2002-118500 A JP 2000-68981 A Japanese Patent Laid-Open No. 10-173630

  In Patent Document 1 described above, since the path tracking is performed by the finger portion, the point where the power is maximum in the path tracking range is selected as the data used for the RAKE combining.

  On the other hand, when the reception characteristics are considered, it is desirable that the ratio of received signal power to interference power (SIR; signal-to-interference ratio) is large. However, at the point where the power is maximum, the SIR may not be maximum.

  For this reason, in the technique described in Patent Document 1 (selecting symbol data with the maximum power), there is a possibility that an optimum point cannot be selected as the reception characteristic.

  In addition, in a receiving apparatus that requires a reduction in power consumption, an increase in power consumption due to SIR calculation may be a problem.

  Therefore, an object of the present invention is to provide a synchronous tracking circuit and a CDMA receiver that can select an optimum point as a reception characteristic.

  In order to solve the above problems, the invention disclosed in the present application is generally configured as follows.

  A finger unit (synchronous tracking circuit) according to one aspect of the present invention includes a despreading unit that performs despreading of sampling points within a path tracking range, and n pieces (n is a predetermined number) despread by the despreading unit. A positive integer) power calculation unit for calculating the average power per symbol of the symbol data, n despread data despread by the despreading unit, and n calculated by the power calculation unit The interference power calculation unit that calculates the average power of the interference component from the average power of n, n average powers calculated by the power calculation unit, and n interference powers calculated by the interference power calculation unit When the condition that the difference between the n average powers calculated by the power calculation unit and the SIR calculation unit for calculating the SIR is within a predetermined value is calculated, the calculation is performed by the SIR calculation unit. N SIRs In the case where the maximum value is detected from inside and the condition is not met, the maximum value detecting unit for detecting the maximum value among the n average powers calculated by the power calculating unit, and the despreading unit A selector unit that selects and outputs the maximum symbol data detected by the maximum value detection unit among the calculated plurality of symbol data.

  An apparatus according to another aspect of the present invention includes a despreading unit that despreads sampling points within a path tracking range, and n (where n is a predetermined positive integer) symbol data despread by the despreading unit. A power calculator that calculates an average power per symbol of each of the power, n despread data despread by the despreader, and n average power calculated by the power calculator, An interference power calculation unit that calculates the average power of the interference component, an SIR that calculates n SIRs from the n average powers calculated by the power calculation unit and the interference powers calculated by the interference power calculation unit Of the n symbol data calculated by the calculation unit, the maximum value detection unit for detecting the maximum value from the n SIRs calculated by the SIR calculation unit, and the despreading unit, the maximum value Maximum SI detected by the detector It includes a selector unit, a for selecting and outputting symbol data.

  A CDMA receiver according to another aspect of the present invention includes a plurality of finger units that reproduce received data by despreading each of a plurality of received radio waves that have arrived via a plurality of paths by a despreading unit; A finger assigning unit that assigns a path timing corresponding to each peak position of the received radio wave to each of the plurality of finger units, and the paths respectively assigned by the finger assigning unit in the plurality of finger units In the CDMA receiver in which the plurality of received radio waves are despread within a path tracking range in a section before and after the timing, each of the plurality of finger units is a plurality of symbol data despread by the despreading unit The maximum SIR value calculated from the average power per symbol of each power and the interference power, The SIR or average power comprises means for selecting and outputting a maximum symbol data.

  According to the present invention, the reception characteristic is improved by selecting the point with the maximum SIR as the optimum point for despreading.

  The above-described present invention will be described below with reference to the accompanying drawings in order to explain in more detail. FIG. 1 is a diagram illustrating a configuration of a finger portion according to an embodiment of the present invention. Referring to FIG. 1, the finger unit includes a despreading unit 101, a power calculation unit 102, a selector unit 103, an interference power calculation unit 104, an SIR calculation unit 105, and a maximum value detection unit 106. Yes. The finger unit of the embodiment of the present invention shown in FIG. 1 is mounted on the CDMA receiver as the finger unit 9 in FIG. 3A, for example, and is instructed by the finger assignment unit 8 in FIG. Within the path tracking range determined before and after the path timing, despreading is performed to obtain data, and the SIR maximum value is searched from the data to follow the path fluctuation.

  The despreading unit 101 performs despreading of sampling points within the path tracking range. A description will be given assuming that n sampling points are within the tracking range.

  The power calculation unit 102 calculates the average power per symbol of the power of each of the n pieces of symbol data despread by the despreading unit 101.

  The interference power calculation unit 104 calculates the average power of the interference component from the n despread data despread by the despreading unit 101 and the n average power calculated by the power calculation unit 102.

  The SIR calculation unit 105 calculates the SIR from the n powers calculated by the power calculation unit 102 and the interference power calculation unit 104 and the interference power.

  The maximum value detection unit 106 detects the maximum value from the n SIRs calculated by the SIR calculation unit 105.

  The selector unit 103 selects and outputs the maximum SIR symbol data detected by the maximum value detection unit 106 among the n pieces of symbol data calculated by the despreading unit 101. According to the present invention having such a configuration, it is possible to improve reception characteristics by selecting a point having the maximum SIR as the optimum point for despreading.

  FIG. 2 is a diagram illustrating a configuration of a finger portion according to the second embodiment of the present invention. Referring to FIG. 2, this embodiment includes a despreading unit 101, a power calculation unit 102, a selector unit 103, an interference power calculation unit 104, an SIR calculation unit 105, and a maximum value detection unit 106A. Yes.

  This embodiment is different from the first embodiment in the control of the maximum value detection unit 106A.

  Maximum value detection section 106A receives the output of power calculation section 102 and the output of SIR calculation section 105, and the difference between the average powers of n symbols calculated by power calculation section 102 is within a predetermined range. If it is within the range, the maximum point is detected from the n SIRs by detecting the maximum point of the SIR. The selector unit 103 selects and outputs the maximum SIR symbol data detected by the maximum value detection unit 106A among the n pieces of symbol data calculated by the despreading unit 101.

  On the other hand, in other cases (when the difference between the average powers of the n symbols calculated by the power calculation unit 102 is not within a certain range), the maximum value detection unit 106A uses the n calculated by the power calculation unit 102. The maximum point of average power of each symbol is detected, and the selector 103 is notified of the symbol data to be selected.

  The selector unit 103 selects and outputs the maximum SIR or maximum power symbol data detected by the maximum value detection unit 106A among the n pieces of symbol data calculated by the despreading unit 101.

  In the present embodiment, since it is not necessary to calculate interference power and SIR unless the power difference is within a certain range, the power consumption is kept low compared to the first embodiment. be able to. Further, when the power difference is within a certain range, the symbol data having the maximum SIR is selected, so that the reception characteristics can be improved as compared with the configuration of Patent Document 1.

  The present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the configurations of the above-described embodiments, and various modifications that can be made by those skilled in the art within the scope of the present invention. Of course, it includes deformation and correction.

It is a figure which shows the structure of the 1st Example of this invention. It is a figure which shows the structure of the 2nd Example of this invention. (A) is a figure which shows the structure of the conventional CDMA receiver and (B) is a finger part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 RF part 3 AD part 4 Delay profile part 7 RAKE combining part 8 Finger assignment part 9 Finger part 101 Despreading part 102 Power calculation part 103 Selector part 104 Interference power calculation part 105 SIR calculation part 106, 106A, 107 Maximum value Detection unit

Claims (3)

A despreading unit that despreads sampling points within the path tracking range;
A power calculator that calculates an average power of each of n (where n is a predetermined positive integer) symbol data despread by the despreader;
An interference power calculation unit for calculating an average power of an interference component from n despread data despread by the despreading unit and n average power calculated by the power calculation unit;
A SIR calculation unit that calculates n SIRs from the n average powers calculated by the power calculation unit and the interference powers calculated by the interference power calculation unit;
When satisfying the condition that the difference between the n average powers calculated by the power calculation unit is within a predetermined range , the maximum value is selected from the n SIRs calculated by the SIR calculation unit. When the above condition is not satisfied, a maximum value detection unit that detects a maximum value from the n average powers calculated by the power calculation unit;
A selector unit that selects and outputs the maximum symbol data detected by the maximum value detection unit among the plurality of symbol data calculated by the despreading unit;
A synchronous tracking circuit comprising:   A CDMA receiver comprising the synchronization tracking circuit according to claim 1 as a finger unit. A plurality of finger units that reproduce received data by despreading each of a plurality of received radio waves that have reached through a plurality of paths by a despreading unit;
A finger assignment unit that assigns a path timing corresponding to each peak position of the plurality of received radio waves to each of the plurality of finger units;
Have
A CDMA receiver that despreads the plurality of received radio waves within a path tracking range in a section before and after the path timing respectively assigned by the finger assignment unit in the plurality of finger units;
Each of the plurality of finger units includes a power calculation unit that calculates an average power of n (where n is a predetermined positive integer) symbol data despread by the despreading unit;
An interference power calculation unit for calculating an average power of an interference component from n despread data despread by the despreading unit and n average power calculated by the power calculation unit;
A SIR calculation unit that calculates n SIRs from the n average powers calculated by the power calculation unit and the interference powers calculated by the interference power calculation unit;
When satisfying the condition that the difference between the n average powers calculated by the power calculation unit is within a predetermined range, the maximum of the n SIRs calculated by the SIR calculation unit is selected. If the value is detected and the condition is not met, a maximum value detection unit that detects a maximum value among the n average powers calculated by the power calculation unit;
A CDMA receiving apparatus , comprising: a selector unit that selects and outputs the maximum symbol data detected by the maximum value detection unit among the plurality of symbol data calculated by the despreading unit .

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