JP2003198428A - Receiver and receiving path timing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To exactly detect the path timing to be received even on the condition that the receiving status is deteriorated in a multi-path phasing environment. <P>SOLUTION: The receiver of a mobile machine or the like has a receiving means for receiving a radio signal, measuring means 201 and 202 for measuring the error rate and the receiving quality of the received signal and control means 203 and 204 for controlling a cycle to detect and update the path timing to be received corresponding to these measured error rate and receiving quality. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving path timing control method used in a receiving device such as a mobile device or a base station device of a code division multiple access system.

[0002]

2. Description of the Related Art Code division multiple access (CDMA)
division multiple access) system using digital car phone / mobile phone system (cellular system)
Then, in order to perform high-quality reception in a multipath fading environment in a base station device or a mobile device as a communication device, a rake / diversity reception technique, a transmission power control technique, etc. are indispensable. There is.
Above all, the technique for detecting the reception path timing is an important element, and the accuracy of the detection of the reception path timing affects the characteristics at the time of rake / diversity reception in the CDMA cellular system.

In this specification, "detection of reception path timing" means "detection of (reception) timing of a path to be received". That is, in a cellular system using the CDMA system, the reception environment is observed as a plurality of received waves (multipath) due to diffraction and reflection, and when receiving these, each received wave is separated as appropriately as possible. , It is required to receive each reception wave (“path to be received”) at “reception timing” which is as appropriate as possible. In this way, the function of detecting and determining the reception timing of the path to be received is generally implemented as a multipath search unit (multipath searcher) both as a base station device and as a mobile device.

As a means for realizing a conventional receiving path timing control method, for example, Japanese Patent Application Laid-Open No. 10-173629 discloses a receiving apparatus using a code division multiplexing method using spread spectrum, and rake combining (passes through several paths). In order to stably extract the path timing to be combined, the output of the searcher circuit is set to the spread code. If the value is within the upper and lower thresholds, which is the autocorrelation value of the replica of the error plus the error range, it is considered as an invalid correlation value due to the autocorrelation, and if it is outside that range, it is considered as a valid path timing to be combined. A device is disclosed.

Further, in Japanese Laid-Open Patent Publication No. 10-173630, a CDMA chip synchronizing circuit of a receiver of a mobile communication system using a direct spread code division multiple access system is used to receive a plurality of multipath components included in a received signal. Search means for measuring timing, and a plurality of receiving means for performing reception at a plurality of timings with a time interval shorter than one chip cycle before and after the reception timing with respect to the reception timing measured by the search means. And a memory for temporarily storing the outputs of the plurality of receiving means, and a selecting means for selecting a received signal having the best reception quality among a plurality of received signals received by the plurality of receiving means at a constant time interval. , A technique that enables reliable multipath reception timing is disclosed.

Further, in Japanese Patent Laid-Open No. 10-271034, a moving average time determining means for determining a moving average time by measuring timing fluctuation of a selected path in a mobile communication receiving apparatus using CDMA, and this moving method are provided. Delay profile calculating means for calculating a delay profile by moving averaging correlation values according to the moving average time designated by the average time control means, the moving average time determining means is provided when the timing variation of the selected path is large. By shortening the moving average time and increasing it when the fluctuation is small, and controlling the moving average time of the delay profile in this way, the path movement can follow the rapid timing fluctuation of the selected path due to the high speed movement of the communication device. Such a technique is disclosed.

Further, in Japanese Patent Laid-Open No. 11-251962, even if the reception level fluctuates or deteriorates due to multipath fading or the like, the reception level is detected from the reception signal in order to perform accurate synchronization acquisition and tracking. A reception level measuring unit for comparing with a predetermined threshold value, a plurality of despreading units for multiplying a received signal by a spread code, an internal memory for taking in correlation signals from the plurality of despreading units, and the internal A reception path timing generation unit that detects a reception path from the output of the memory and generates a path timing, and outputs the correlation signal of the internal memory to the reception path timing generation unit according to the result of the comparison judgment of the reception level measurement unit. There is disclosed a cellular system using a CDMA system in which whether or not to output the signal is selected.

[0008]

As a conventional method for detecting and controlling the reception path timing, a so-called sliding correlation calculation is performed according to a preset detection path timing detection and update cycle. However, in such a method, even when the reception environment fluctuates and deteriorates due to multipath fading or the like,
Since the reception path timing is detected and controlled according to the preset reception path timing detection and update cycle, the reception path timing is erroneously detected, the reception accuracy is deteriorated, and as a result, a stable communication state cannot be maintained. There was a problem. The present invention has been made to solve the above problems, and a code division multiple access system capable of accurately detecting the path timing to be received even in a situation where the reception state deteriorates under a multipath fading environment. An object is to provide a receiving apparatus and a receiving path timing control method.

[0009]

The receiving apparatus of the present invention is a receiving means (101 to 1) for receiving a radio signal as a reception signal.
04), measuring means (201, 202) for measuring the error rate and the reception quality of the received signal, and the cycle of detection and update of the path timing to be received according to the measured error rate and reception quality. Control means (203, 20)
4) and. As described above, the present invention provides a digital mobile telephone using the code division multiple access system.
In a receiver of a mobile phone system (cellular system), the error rate and the reception quality of the received signal are measured, and the path timing information is periodically replaced with the latest path timing information. Can be prepared for deterioration. This makes it possible to adaptively control the reception path timing according to the reception environment. In one configuration example of the receiving device of the present invention,
If the error rate is below a preset error rate threshold and the reception quality is above a preset reception quality threshold, the control means sets a preset candidate value T.
1, T2, T3, T4 (T1>T2>T3> T4) is selected as the maximum candidate value T1 as the cycle for detecting and updating the path timing, and the error rate exceeds the error rate threshold value. And, if the reception quality is lower than the reception quality threshold, the minimum candidate value T4 is selected as a cycle for detecting and updating the path timing, and the error rate is lower than the error rate threshold, and If the reception quality is lower than the reception quality threshold, a candidate value T3 that is larger than the minimum value T4 and smaller than the maximum value T1 is selected as a cycle for detecting and updating the path timing, and the error rate is set to the error rate threshold value. , And the reception quality exceeds the reception quality threshold value, the maximum value T is larger than T3.
A candidate value T2 smaller than 1 is selected as the cycle for detecting and updating the path timing.

Further, the receiving path timing control method of the present invention comprises a receiving procedure for receiving a radio signal as a received signal, a measuring procedure for measuring an error rate and a receiving quality of the received signal, and the measured error rate. And according to the reception quality
A control procedure for controlling the cycle of detection and update of the path timing to be received is executed. In one configuration example of the receiving path timing control method of the present invention, the control procedure is such that the error rate is below a preset error rate threshold and the reception quality is a preset reception quality. If the threshold value is exceeded, preset candidate values T1, T2, T3, T4 (T1>T2>T3>
The maximum candidate value T1 is selected from among T4) as the cycle for detecting and updating the path timing, the error rate exceeds the error rate threshold, and the reception quality falls below the reception quality threshold. In this case, the smallest candidate value T4 is selected as the cycle for detecting and updating the path timing, and if the error rate is below the error rate threshold and the reception quality is below the reception quality threshold, the minimum A candidate value T3 that is larger than the value T4 and smaller than the maximum value T1 is selected as the cycle for detecting and updating the path timing, the error rate exceeds the error rate threshold, and the reception quality is the reception quality threshold. If the value exceeds T3, a candidate value T2 that is larger than T3 and smaller than the maximum value T1 is selected as the cycle for detecting and updating the path timing.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile device according to an embodiment of the present invention. FIG. 1 illustrates the present invention as code division multiple access (CDM).
A) An example applied to a mobile device of a digital car phone / mobile phone system (cellular system) using the system.

In the mobile device shown in FIG. 1, an antenna 101 transmits an upstream RF signal (radio signal) amplified by a transmission amplifier (not shown) in a transmission / reception amplification unit (AMP) 102, and also from a base station device. The spread wide band down RF signal is received and output to a low noise reception amplifier (not shown) in the transmission / reception amplification unit (AMP) 102.

The transmission / reception amplification unit (AMP) 102 is connected to the antenna 101, is equipped with a transmission amplifier for amplifying the upstream RF signal and a reception amplifier for amplifying the downstream RF signal, and multiplexes the upstream RF signal and the downstream RF signal. To separate. A radio section (TRX) 103 D / A converts the baseband spread transmission signal to convert it into an upstream RF signal by quadrature modulation, and quasi-coherently detects the reception signal from the reception amplifier,
/ D conversion is performed and the result is sent to the baseband signal processing unit (BB) 104.

Baseband signal processor (BB) 104
Is a process for the transmission signal, performs error correction coding of the transmission data, framing, data modulation and spread modulation, and outputs the baseband spread transmission signal to the radio unit 103,
Further, as processing for the reception signal output from the wireless unit 103, despreading of the reception signal, reception path timing detection, chip synchronization, finger / rake.
e) Perform baseband signal processing such as reception, error correction decoding, data demultiplexing, reception level measurement, and error rate measurement of received signal.

The control unit (MS-CONT) 105 controls the entire mobile unit. Terminal interface section (T
The ERM-INT) 106 has an adapter function for voice and various data, and also has an interface function with a handset, a terminal operation and an image / data terminal.

In particular, the baseband signal processing section 104 is equipped with the reception path timing control section shown in FIG. The reception path timing control unit, as shown in FIG. 2, measures the error rate of the received signal by the error rate measuring unit 201.
And a reception quality measuring unit 20 for measuring the reception quality of the received signal.
2 is compared with the error rate and a preset threshold value, and the reception quality is compared with a preset threshold value,
A comparison / selection unit 203 for selecting a cycle of detection and update of path timing to be received, and a preset threshold value and a cycle of detection and update cycle of path timing to be received as options Internal RAM 204,
The reception path timing detection unit 205 operates according to the cycle of detection and update of the selected reception path timing.

Next, the operation of the present embodiment shown in FIG. 1 and the reception path timing control section shown in FIG. 2 will be described using the selection control flowchart of the reception path timing detection and update cycle shown in FIG. First, the received signal rake-received by the baseband signal processing section 104 and error-corrected and decoded is taken into the error rate measuring section 201 of the receiving path timing control section in order to measure the error rate. The error rate measuring unit 201 cumulatively measures the number of errors in the received signal and measures the error rate A for the received signal (step 3 in FIG. 3).
01).

The received signal rake-received by the baseband signal processing section 104 is measured by the reception quality measuring section 202 of the reception path timing control section in order to measure the reception quality.
Be taken in. The reception quality measuring unit 202 measures the reception quality B of the rake received signal (step 3).
02). As a method of measuring the reception quality B, for example, there is a method of measuring the reception level of a known pilot signal included in the reception signal as the reception quality B.

Next, the comparison / selection unit 203 compares the error rate A measured by the error rate measurement unit 201 with the error rate threshold Th-R held in the internal RAM 204, and the reception quality measurement unit 202. Reception quality B and internal RA measured in
The reception quality threshold Th-Q held in M204 is compared (steps 303 to 305).

Then, the comparison and selection section 203 has the error rate A equal to or lower than the preset error rate threshold Th-R and the reception quality B equal to or higher than the preset reception quality threshold Th-Q. In this case, the maximum candidate value T1 is selected from the candidate values T1, T2, T3, T4 of the cycle set in advance in the internal RAM 204, and this candidate value T1 is used as the cycle for detecting and updating the reception path timing. Detector 2
It outputs to 05 (step 306).

Further, when the error rate A exceeds the error rate threshold Th-R and the reception quality B falls below the reception quality threshold Th-Q, the comparison and selection section 203 determines the cycle candidate value T.
The minimum candidate value T4 is selected from among 1, T2, T3 and T4, and this candidate value T4 is output to the reception path timing detection unit 205 as the cycle of detection and update of the reception path timing (step 307).

If the error rate A is equal to or lower than the error rate threshold Th-R and the reception quality B is lower than the reception quality threshold Th-Q, the comparison and selection section 203 determines the candidate values T1 of the cycle.
A candidate value T3 that is larger than the minimum value T4 and smaller than the maximum value T1 is selected from T2, T3, and T4, and this candidate value T3 is output to the reception path timing detection unit 205 as a cycle of detection and update of the reception path timing ( Step 30
8).

Further, when the error rate A exceeds the error rate threshold Th-R and the reception quality B is equal to or higher than the reception quality threshold Th-Q, the comparison / selection unit 203 further selects the cycle candidate values T1. A value T2 that is larger than T3 and smaller than the maximum value T1 is selected from T2, T3, and T4, and this candidate value T2 is output to the reception path timing detection unit 205 as a cycle for detecting and updating the reception path timing (step 309). .
As can be seen from the above description, the periods T1, T2, T
The relationship of 3, T4 is set as T1>T2>T3> T4.

Then, the reception path timing detection unit 205
Detects the reception path timing based on the reception signal despread in the baseband signal processing unit 104 for each cycle selected by the comparison and selection unit 203, and outputs the detected reception path timing information to the finger circuit. (Step 310). Various methods have been proposed as a method of detecting the reception path timing.
No. 251962.

FIG. 4 is a block diagram showing the configuration of the finger / rake receiving unit in the baseband signal processing unit 104. The reception signal output from the wireless unit 103 is input to each of the finger circuits 401-1 to 401-n. Each of the finger circuits 401-1 to 401-n performs despreading on the input signal using the same spreading code as that on the transmission side at the timing indicated by the reception path timing information output from the reception path timing detection unit 205. The rake combining unit 402 applies the multipath components despread by the finger circuits 401-1 to 401-n to the finger circuits 401-1.
˜401-n output times are added together and then added. In this way, the received signal after rake reception is obtained.

In the present embodiment, the reception environment when the detection and update cycle of the reception path timing is T1 is such that the error rate A is lower than the preset error rate threshold Th-R as described above. , And the reception quality B exceeds the preset reception quality threshold Th-Q,
The reception environment is judged to be in a good state. Therefore, since the change in the reception path timing is small, a stable reception state can be maintained even if the detection and update cycle of the reception path timing is set long.

As described above, the reception environment when the period of detection and update of the reception path timing is T4 is the error rate A.
Is above the error rate threshold Th-R and the reception quality B is below the reception quality threshold Th-Q, so it is judged that the state is extremely deteriorated. Therefore, it is necessary to quickly improve the reception situation by setting the cycle of detection and update of the reception path timing to the shortest and performing high-speed control.

As described above, the reception environment when the cycle of detecting and updating the reception path timing is T2 is the error rate A.
Is higher than the error rate threshold Th-R and the reception quality B is higher than the reception quality threshold Th-Q. Therefore, it is determined that the multipath fading environment is relatively slow. Therefore, it is possible to improve the reception environment by setting the cycle of detecting and updating the reception path timing slightly longer and shorter than the maximum cycle T1.

As described above, the reception environment when the cycle of detection and update of the reception path timing is T3 is the error rate A.
Is lower than the error rate threshold Th-R and the reception quality B is lower than the reception quality threshold Th-Q. Therefore, it is determined that the multipath fading environment is relatively fast. Therefore, the reception environment can be improved by setting the cycle of detecting and updating the reception path timing to be slightly shorter and longer than the minimum cycle T4.

The cycles T1, T2, T3, T4 and the threshold values Th-R, Th-Q are stored in the internal RAM 204 and can be rewritten arbitrarily by an operation from the terminal interface section 106. When measuring the error rate of the received signal, the measurement target is the pass / fail of a known information bit (for example, pilot signal or synchronization word) or an error detection code (for example, CRC code) inserted for each known information length. The result is okay. Further, when measuring the reception quality of the reception signal, the measurement target may be Ec / Io (reception power of desired wave to total reception power ratio) or SIR (reception power of desired wave to reception power of interference wave). This allows a flexible control configuration.

Further, although the present embodiment has been described by taking the mobile device of the CDMA system as an example, the present invention is not limited to this, and the present invention is also applied to the base station device of the CDMA system. Good.

[0032]

According to the present invention, the receiving means for receiving a radio signal as a received signal, the measuring means for measuring the error rate and the receiving quality of the received signal, and the measuring means for measuring the error rate and the receiving quality By providing a control means for controlling the cycle of detection and update of the path timing to be received,
It is possible to measure the error rate and the reception quality of the received signal and adaptively detect the reception path timing according to the reception environment and control the update cycle.Therefore, the reception state deteriorates due to the multipath fading environment and the reception error occurs. Even in a situation in which a problem occurs, it becomes possible to maintain a stable communication situation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mobile device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a reception path timing control unit mounted in a baseband signal processing unit of the mobile device of FIG.

FIG. 3 is a flow chart diagram for explaining the operation of the reception path timing control unit of FIG.

4 is a block diagram showing a configuration of a finger / rake receiving unit mounted in a baseband signal processing unit of the mobile device of FIG.

[Explanation of symbols]

101 ... Antenna, 102 ... Transmission / reception amplification section, 103 ... Radio section, 104 ... Baseband signal processing section, 105 ... Control section, 106 ... Terminal interface section, 201 ... Error rate measuring section, 202 ... Reception quality measuring section, 203 ... Comparison / selection unit, 204 ... Internal RAM, 205 ... Reception path timing detection unit.

Continued front page    F term (reference) 5K014 AA01 CA05 EA08 FA11 GA01                       GA02 HA10                 5K022 EE02 EE31 EE36

Claims (4)

[Claims] 1. A receiving apparatus of a code division multiple access (CDMA) system, receiving means for receiving a radio signal as a received signal, measuring means for measuring an error rate and a receiving quality of the received signal, and the measuring means. A receiving device, comprising: a control unit that controls a cycle of detecting and updating a path timing to be received according to an error rate and a reception quality. 2. The receiving device according to claim 1, wherein the control unit sets the error rate to be lower than a preset error rate threshold value, and the reception quality to be a preset reception quality threshold value. If it exceeds, the preset candidate value T
1, T2, T3, T4 (T1>T2>T3> T4) is selected as the maximum candidate value T1 as the cycle for detecting and updating the path timing, and the error rate exceeds the error rate threshold value. And, if the reception quality is lower than the reception quality threshold, the minimum candidate value T4 is selected as a cycle for detecting and updating the path timing, and the error rate is lower than the error rate threshold, and If the reception quality is lower than the reception quality threshold, a candidate value T3 that is larger than the minimum value T4 and smaller than the maximum value T1 is selected as a cycle for detecting and updating the path timing, and the error rate is set to the error rate threshold value. , And the reception quality exceeds the reception quality threshold value, the maximum value T is larger than T3.
A receiving apparatus, wherein a candidate value T2 smaller than 1 is selected as a cycle of detecting and updating the path timing. 3. A method of controlling a path timing to be received in a receiver of a code division multiple access (CDMA) system, a receiving procedure of receiving a radio signal as a received signal, and measuring an error rate and a received quality of the received signal. And a control procedure for controlling a cycle of detecting and updating a path timing to be received according to the measured error rate and reception quality. 4. The receiving path timing control method according to claim 3, wherein the control procedure is such that the error rate is below a preset error rate threshold and the reception quality is a preset reception quality. If the threshold value is exceeded, the preset candidate value T
1, T2, T3, T4 (T1>T2>T3> T4) is selected as the maximum candidate value T1 as the cycle for detecting and updating the path timing, and the error rate exceeds the error rate threshold value. And, if the reception quality is lower than the reception quality threshold, the minimum candidate value T4 is selected as a cycle for detecting and updating the path timing, and the error rate is lower than the error rate threshold, and If the reception quality is lower than the reception quality threshold, a candidate value T3 that is larger than the minimum value T4 and smaller than the maximum value T1 is selected as a cycle for detecting and updating the path timing, and the error rate is set to the error rate threshold value. , And the reception quality exceeds the reception quality threshold value, the maximum value T is larger than T3.
A reception path timing control method, wherein a candidate value T2 smaller than 1 is selected as a cycle for detecting and updating the path timing.