JP2004187019A - Path search instrument of cdma receiver, its method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change ratio of a correlator dynamically assigned to a user from receiving conditions or a search range. <P>SOLUTION: A correlator control unit 10 of a searcher 16 decides assignment of the correlator 4 for each user from window information of a window control unit 9, receiving quality information (BER, BLER, SIR, etc.) from a receiving quality monitor 15, and user number information obtained from a higher rank instrument which is not shown, and dynamically changes ratio of the using correlator 4 by controlling the correlator 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a path search apparatus, a method, and a program for a CDMA (code division multiple access) receiver, and more particularly to an improvement in a path search method.
[0002]
[Prior art]
A receiver of a spread spectrum communication system used for a CDMA system or the like has a finger unit for despreading a received signal converted into a baseband signal, and usually includes a plurality of finger units. A rake combining unit for rake combining the output despread signal at a predetermined timing; a delay profile calculated from the received signal; a valid peak as a reception timing is detected from the obtained delay profile; And a path searcher unit that notifies timing information and valid finger information to the rake combining unit.
[0003]
An example of a conventional receiver used for this type of spread spectrum communication system is disclosed in Patent Document 1. According to Patent Document 1, in order to improve reception identification, a target signal is extracted by applying forward protection and rearward protection by a path capture holding unit 150 based on a search path detected by a searcher unit 120 and a tracking path tracked by a searcher, It describes that a path to be demodulated is selected by a correlation demodulation path selection unit 160 excluding a path of a signal other than a target signal, and then combined by a rake unit 140.
[0004]
Further, as another example, Japanese Patent Application Laid-Open No. H10-163,873 discloses that a sequence of measured values is read from a multipath profile, a timing offset having a resolution higher than a predetermined timing resolution of a searcher unit is derived, and the finger processing element is used as a best candidate path. Are described.
[0005]
[Patent Document 1]
Japanese Patent No. 2853705 (paragraph 0052, FIG. 2)
[0006]
[Patent Document 2]
JP-A-11-261528 (paragraph 0029, FIG. 1)
[0007]
[Problems to be solved by the invention]
However, in such a conventional configuration, the correlator assigned to the user is fixedly determined, and a user who has poor reception conditions and wants to improve the accuracy of the path, or a user who wants to detect the path quickly, etc. There is a problem that the extra correlator cannot be used. Further, there is a problem that it is necessary to have more correlators than necessary.
[0008]
Accordingly, it is an object of the present invention to provide a path search device of a CDMA receiver that can dynamically change the proportion of correlators to be assigned to a user based on a reception state, a search range, and the like, and a method and a program therefor. .
[0009]
[Means for Solving the Problems]
A path search device of a CDMA receiver according to the present invention includes a plurality of correlators for calculating a correlation value between each of reception signals from a plurality of users and an ideal reception signal prepared in advance, and based on the correlation values. A path search apparatus of a CDMA receiver for detecting a desired path, comprising: correlator control means for controlling the number of the correlators to be assigned to each user based on information on the reception state of the received signal. .
[0010]
The path search method for a CDMA receiver according to the present invention includes a plurality of correlators for calculating a correlation value between each of reception signals from a plurality of users and an ideal reception signal prepared in advance. A path search method for a CDMA receiver that detects a desired path based on a received signal, the method including a correlator control step of controlling the number of the correlators allocated to each user based on information on a reception state of the received signal. And
[0011]
Further, the program according to the present invention includes a plurality of correlators for calculating a correlation value between each of reception signals from a plurality of users and an ideal reception signal prepared in advance, and determines a desired path based on the correlation value. A program for causing a computer to execute a path search method of a CDMA receiver to be detected, comprising a correlator control step of controlling the number of the correlators to be assigned to each user based on information on a reception state of the received signal. It is characterized by.
[0012]
The path search apparatus, method, and program for a CDMA receiver according to the present invention improve path detection accuracy, shorten path detection time, and reduce necessary minimum by dynamically changing the ratio of correlators allocated to users. The number of correlators (1) to (2) is to keep the reception state of many users good.
[0013]
This is assigned to each user from window information, reception quality information (BER (bit error rate), BLER (block error rate), SIR (signal-to-interference power ratio), etc.), and information on the number of users. A correlator control unit that determines the number of correlators can assign a correlator preferentially to a user having poor reception quality, etc., and improve the accuracy of path detection.
[0014]
Further, when the number of users is small, a large number of correlators can be allocated to each user, so that it is possible to improve reception quality and shorten the path detection time.
[0015]
FIG. 1 shows a configuration of a system to which the present invention is applied. The correlator control 10 determines the ratio of the correlator 4 to each user. According to the present invention, the correlator control unit 10 uses the window information from the window control unit 9, the reception quality information (BER, BLER, SIR, etc.) from the reception quality monitoring unit 15 and the number-of-users information obtained from a higher-level device (not shown). By determining the allocation of the correlator 4 for each user and controlling the correlator 4, the ratio of the correlator 4 to be used is dynamically changed.
[0016]
As a result, more correlators 4 are allocated to users with low reception quality, and the accuracy of path detection is improved, and as a result, reception quality is also improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, a first embodiment will be described. FIG. 1 is a configuration diagram of a first embodiment of a path search device of a CDMA receiver according to the present invention. In the first embodiment, the present invention is applied to an example of a CDMA mobile communication system base station apparatus. Here, only the reception function part of the base station apparatus is shown.
[0018]
Referring to FIG. 1, a base station apparatus receiving function unit 17 includes an antenna 1 for receiving a transmission signal spread by a CDMA system transmitted from a mobile terminal (not shown), and an interface function for a signal received by the antenna 1. A high-frequency receiving circuit section 2 for demodulating a received signal and an A / D (analog / digital) converting section 3 for converting an analog signal output from the high-frequency receiving circuit section 2 into a digital signal.
[0019]
Further, the base station apparatus reception function unit 17 measures the reception quality using the searcher unit 16, the finger unit 18, a CRC (cyclic redundancy check) added to a pilot signal transmitted from the mobile terminal or received data, or the like. And a reception quality monitoring unit 15 for performing the reception.
[0020]
The searcher unit 16 generates a spread code of the allocated communication channel by a code generator 7, and multiplies the spread code generated by the code generator 7 by a predetermined pilot signal to perform ideal reception. A plurality of correlators 4 which are hardware capable of operating in parallel to calculate a correlation value between the signal and a pilot signal portion added to the head position of each time slot of the input signal; For the I signal and the Q signal, which are orthogonal signal components, an in-phase addition unit 5 for performing a certain number of in-phase additions “I + I” or “Q + Q” and a power addition unit 6 for performing a certain number of power additions “I ² + Q ² ”. A path control unit 8 for detecting a path based on a calculation result from the power adding unit 6; a path information storing path information; Window control unit 9 for controlling the position to open a window based on the information, path information from path control unit 8, window information from window control unit 9, reception quality information from reception quality monitor 15 (BER, BLER, A correlator control unit 10 for determining a ratio of the correlator 4 to be assigned to each user from user information from an SIR or the like and a higher-level device (for example, a radio network controller (RNC)); And a recording medium 19 on which recording is performed.
[0021]
The finger unit 18 extracts a specific path corresponding to the delay time notified from the searcher unit 16 and a code generator 11 that generates a spread code of the allocated communication channel. The apparatus includes a despreading unit 12 for despreading using a code, a detection unit 13 for estimating a channel and a channel to remove the influence of fading, and a rake (RAKE) synthesis unit 14 for synthesizing the detected signals.
[0022]
Next, the operation of the present embodiment will be described. A transmitting mobile terminal (not shown) transmits a framed transmission signal having a plurality of time slots. FIG. 2 shows an example of a transmission signal from the mobile terminal. Referring to FIG. 1, a transmission signal is composed of a dedicated physical data channel (DPDCH) and a dedicated physical control channel (DPCCH). These signals are transmitted in each time slot (slot # 0- # 14).
[0023]
The DPDCH is composed of transmission data (Data), and the DPCCH is composed of a pilot signal (Pilot), a transport format combination indicator (TFCI), a feedback information (FBI), and a transmit power composed of a TPC (transmitted power). Note that these signals are not directly related to the present invention, and thus description thereof is omitted.
[0024]
A pilot signal, which is a fixed pattern known in advance on both sides of transmission and reception, is added to the head position of each time slot, and orthogonally modulated together with transmission data. After orthogonal modulation, spectrum spreading is performed using a spreading code unique to each communication channel.
[0025]
Hereinafter, a description will be given with reference to FIGS. FIG. 3 is a flowchart showing an operation procedure of the antenna 1, the high-frequency reception circuit section 2, and the A / D conversion section 3 of the base station apparatus reception function section 17, and FIGS. 4 and 5 are flowcharts showing an operation procedure of the searcher section 16. 6 is a flowchart showing the operation procedure of the finger unit 18.
[0026]
The antenna 1 of the base station apparatus reception function unit 17 receives a transmission signal spread by using a spreading code unique to the CDMA system (S1 in FIG. 3). This received signal is amplified by the high-frequency receiving circuit unit 2 (S2 in FIG. 3), and further converted from an analog signal to digital data by the A / D conversion unit 3 (S3 in FIG. 3). The digital data is input to the searcher unit 16 and the finger unit 18.
[0027]
The searcher section 16 determines in advance the pilot signal portion added to the head position of each time slot of the digital data output from the A / D conversion section 3 by the correlator 4 and the spread code generated by the code generator 7. A correlation value with an ideal received signal obtained by multiplying and spreading the obtained pilot signal is calculated (S11 in FIG. 4). The assignment of the user and the window position to each correlator 4 is controlled by the correlator control unit 10.
[0028]
The in-phase addition unit 5 performs in-phase addition of the correlation value calculated by the correlator 4 a predetermined number of times (S12 in FIG. 4), and performs power addition using the in-phase addition result obtained from the in-phase addition unit 5 in the power addition unit 6. (S13 in FIG. 4). From the result of the power addition, the path control unit 8 detects a path having a level higher than a threshold obtained from a noise level or the like (S14 in FIG. 4), and outputs the path information to the finger unit 18 and the window control unit 9. . The window control unit 9 obtains a position for opening the window from the path information and outputs it to the correlator control unit 10 (S15 in FIG. 4).
[0029]
The finger unit 18 extracts a specific path corresponding to the delay time notified from the searcher unit 16 from the digital data from the A / D conversion unit 3 and uses the spreading code generated by the code generator 11 to perform despreading. In step 12, despreading is performed (S31 in FIG. 6). Thereafter, the detection unit 13 performs channel estimation to remove the effect of fading (S32 in FIG. 6), and RAKE-combines the detected signal in the RAKE combining unit 14 (S33 in FIG. 6) to generate demodulated data.
[0030]
The reception quality monitor 15 to which the output of the finger unit 18 is input measures the reception quality using a pilot signal on the demodulated data or a CRC added to the data, and receives reception quality information (BER, BLER, SIR, etc.). Is output to the correlator control unit 10 (S34 in FIG. 6).
[0031]
In the present invention, the correlator control unit 10 uses the correlator 4 without waste by dynamically changing the ratio of the correlator 4 allocated to each user based on the current number of users, window information, and reception quality information. As a result, the path detection accuracy can be improved, the path detection time can be reduced, and the search processing can be performed with the minimum number of correlators.
[0032]
For example, when only the users A and B in the process are being processed (Y in S21 of FIG. 5), the paths and window positions are stable for both users, and the reception quality is almost the same (S22 in FIG. 5). In the case of “approximately” in FIG. 7, that is, in the reception state at the time (1) in the reception state versus time characteristic diagram of FIG. 7, as shown in the diagram showing the use ratio of the correlator in FIG. The correlators 4 are assigned to the users A and B at substantially the same ratio (for example, 50%: 50%) (S23 in FIG. 5).
[0033]
On the other hand, if the user B starts moving and the reception quality of only the user B decreases (in the case of “the reception quality of the user B decreases” in S22 of FIG. 5), that is, the reception state versus time characteristic diagram of FIG. In the case where the reception state changes at the time (2), the usage rate of the correlator 4 is reduced from 50% as an example, as shown in FIG. 9 showing the usage rate of the correlator. It is increased to 70% (S24 in FIG. 5). Thereafter, when the reception quality of the user B becomes substantially equal to that of the user A again (in the case of “same level” in S22 of FIG. 5), that is, the reception state at the time (3) in the reception state versus time characteristic diagram of FIG. If it has changed, the usage rate of the correlator 4 returns to the rate shown in FIG. 8 (S23 in FIG. 5).
[0034]
In another example, when a new user is set while processing of a plurality of users is already being performed (in the case of “N: new user is set” in S21 of FIG. 5), processing is basically already in progress. Is expected to be stable, the correlator 4 is 40% for new users and 40% for existing users A, as shown in FIG. B is allocated 30% each (S25 in FIG. 5). This makes it possible to improve the path detection accuracy and shorten the detection time, thereby shortening the time until the reception quality is stabilized.
[0035]
Next, a second embodiment will be described. FIG. 11 is a configuration diagram of a second embodiment of the path search device of the CDMA receiver according to the present invention. In FIG. 11, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The configuration is the same as that of FIG. 1 except that a function of directly outputting path information from the path control unit 8 to the correlator control unit 10 in FIG. 11 is added. In this embodiment, the correlator control unit 10 dynamically changes the number of correlators 4 assigned to each user based on the current number of users, window information, path information, and reception quality information. Thus, it is possible to improve and maintain the reception quality of many users by using the correlator 4 without waste.
[0036]
Next, a third embodiment will be described. The third embodiment relates to a program for causing a computer to execute a path search method. As described above, the path search device shown in FIG. The same applies to the path search device shown in FIG. The recording medium 19 stores the program shown in the flowchart of FIG. The correlator control unit 10 in the searcher unit 16 reads out this program from the recording medium 19 and controls the correlator 4 according to this program. Since the contents of the control have already been described, the description is omitted here.
[0037]
[Explanation of effects]
As described above, the present invention is configured to dynamically change the ratio of the correlator to be assigned to the user based on the reception state, the search range, etc., thereby improving the path detection accuracy, shortening the path detection time, and With a limited number of correlators, it is possible to maintain a good reception state for a large number of users.
[0038]
Specifically, the first effect of the present invention is that the correlator 4 required for the device can be minimized. The second effect is that when the number of users is small, path detection accuracy and reception quality are improved. The third effect is that the path detection time is shortened by allocating a large number of correlators to newly added users. Furthermore, the fourth effect is that in a path search device that performs a wide area search using a time-division search window, even when a wide area search is requested by a user, a large number of correlators 4 are assigned to the wide area search at a high speed. It is possible to perform a simple search.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of a path search device of a CDMA receiver according to the present invention.
FIG. 2 is a configuration diagram of an example of a transmission signal from a mobile terminal.
FIG. 3 is a flowchart illustrating an operation procedure of the antenna 1, the high-frequency reception circuit unit 2, and the A / D conversion unit 3 of the base station device reception function unit 17.
FIG. 4 is a flowchart illustrating an operation procedure of the searcher unit 16;
FIG. 5 is a flowchart showing an operation procedure of the searcher unit 16;
FIG. 6 is a flowchart showing an operation procedure of the finger unit 18.
FIG. 7 is a graph showing a reception state versus time characteristic.
FIG. 8 is a diagram showing a use ratio of a correlator.
FIG. 9 is a diagram showing a use ratio of a correlator.
FIG. 10 is a diagram showing a use ratio of a correlator.
FIG. 11 is a configuration diagram of a second embodiment of the path search device of the CDMA receiver according to the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 antenna 2 high-frequency reception circuit unit 3 A / D conversion unit 4 correlator 5 in-phase addition unit 6 power addition unit 7 code generator 8 path control unit 9 window control unit 10 correlator control unit 11 code generator 12 despreading unit 13 Detecting unit 14 Rake combining unit 15 Reception quality monitoring unit 16 Searcher unit 17 Base station apparatus receiving function unit 18 Finger unit 19 Recording medium

Claims (18)

A path search of a CDMA receiver including a plurality of correlators for calculating correlation values between each of received signals from a plurality of users and an ideal received signal prepared in advance, and detecting a desired path based on the correlation values A device,
A path search apparatus for a CDMA receiver, comprising: correlator control means for controlling the number of correlators allocated to each user based on information on the reception state of the received signal. 2. The path search device for a CDMA receiver according to claim 1, wherein the correlator control means controls the number of the correlators based on reception quality information of the received signal. 2. The path search device for a CDMA receiver according to claim 1, wherein said correlator control means controls the number of said correlators based on information on a position at which a window is opened. 2. The path search device for a CDMA receiver according to claim 1, wherein said correlator control means controls the number of said correlators based on path information having a level higher than a threshold obtained from a noise level or the like. 2. The path search device for a CDMA receiver according to claim 1, wherein said correlator control means controls the number of said correlators based on information on the number of users from a host device. The CDMA receiver according to claim 2, wherein the reception quality information is at least one of a bit error rate (BER), a block error rate (BLER), and a signal-to-interference power ratio (SIR). Path search device. A path search of a CDMA receiver including a plurality of correlators for calculating correlation values between each of received signals from a plurality of users and an ideal received signal prepared in advance, and detecting a desired path based on the correlation values The method,
A path search method for a CDMA receiver, comprising a correlator control step of controlling a number of the correlators allocated to each user based on information on a reception state of the received signal. The method according to claim 7, wherein the correlator control step controls the number of the correlators based on reception quality information of the received signal. 8. The method according to claim 7, wherein the correlator control step controls the number of the correlators based on information on a window opening position. 9. The path search method for a CDMA receiver according to claim 7, wherein said correlator control step controls the number of said correlators based on path information having a level higher than a threshold obtained from a noise level or the like. 8. The path search method for a CDMA receiver according to claim 7, wherein the correlator control step controls the number of the correlators based on information on the number of users from a higher-level device. 9. The CDMA receiver according to claim 8, wherein the reception quality information is at least any one of a bit error rate (BER), a block error rate (BLER), and a signal-to-interference power ratio (SIR). Path search method. A path search of a CDMA receiver including a plurality of correlators for calculating correlation values between each of received signals from a plurality of users and an ideal received signal prepared in advance, and detecting a desired path based on the correlation values A program for causing a computer to execute the method,
A program comprising a correlator control step of controlling the number of correlators allocated to each user based on information on a reception state of the reception signal. 14. The program according to claim 13, wherein the correlator control step controls the number of the correlators based on reception quality information of the received signal. 14. The program according to claim 13, wherein the correlator control step controls the number of the correlators based on information about a position at which a window is opened. 14. The program according to claim 13, wherein the correlator control step controls the number of the correlators based on path information having a level higher than a threshold obtained from a noise level or the like. 14. The program according to claim 13, wherein the correlator control step controls the number of the correlators based on information on the number of users from a host device. 15. The program according to claim 14, wherein the reception quality information is at least one of a bit error rate (BER), a block error rate (BLER), and a signal-to-interference power ratio (SIR).

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