JPH11331042A - Cdma cellular radio base station equipment, mobile station equipment, transmission method and reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the interference among other stations caused by the effect of a pilot channel onto a communication channel in a base station and to attain synchronous detection in mobile station in the case of sending the communication channel while performing the directivity control of a transmission antenna. SOLUTION: A base station multiplexes a signal interpolated with a pilot symbol on data through a communication channel 106 in addition to a pilot channel 101 and transmits the multiplexed data. Since the pilot channel 101 does not require transmission of a synchronous detection reference signal at a high transmission power to obtain high reliability, the signal is sent with lower power than that of the communication channel by using a weight 105 so as to reduce interference among other stations. Furthermore, a mobile station side attains accurate synchronous detection from the pilot symbol inserted in the communication channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA cellular radio base station apparatus used for digital cellular mobile communication and the like.

[0002]

2. Description of the Related Art In digital cellular mobile communications,
The multiple access method is a line connection method when a plurality of stations simultaneously communicate in the same band. CDMA
(Code Division Multiple Access) is a technology of performing multiple access by spread spectrum communication in which the spectrum of an information signal is spread and transmitted over a band sufficiently larger than the original information bandwidth. And may be referred to as spread spectrum multiple access (SSMA).
The direct spreading method is a method of directly multiplying an information signal by a spreading sequence code in spreading.

[0003] Among the detection systems in digital communication,
The synchronous detection method has better static characteristics than the delay detection method, and is the method that requires the lowest Eb / IO to obtain a certain average bit error rate (BER). As a method of compensating for the distortion of the transmission signal due to fading, an interpolation-type synchronous detection method has been proposed (Seiichi Sanjo, "Fading distortion compensation method of 16 QAM for land mobile communications," IEICE Trans.
B-II Vol.J72-B-II No.1 pp.7-15,1989). In this method, as shown in FIG. 7, a pilot symbol 701 is inserted into an information symbol to be transmitted for each period T, and a channel transfer function, that is, a state of a line is estimated to perform detection. Further, a scheme in which the above scheme is applied to direct spread CDMA has been proposed (Higashi, Taiguchi, Ohno, "DS / C
Characteristics of Interpolated Synchronous Detection RAKE in DMA "IEICE RCS
94-98, 1994). On the other hand, there is a pilot channel as a method for enabling synchronous detection in direct sequence CDMA. In this method, as shown in FIG. 8, one pilot channel 801 is always used as a detection reference signal independently of a channel for transmitting information data.

Conventional CDM using pilot channel
FIG. 4 shows the configuration of the A-method cellular radio base station apparatus. In downlink, transmission data of each mobile station of m-1 station (1 <m) (2)
(M) are spread by different spreading codes (2) to (m), multiplied by weights, and then multiplexed. A channel for transmitting transmission data such as information data and control data of each mobile station is hereinafter referred to as a “communication channel”. The weights are used for downlink transmission power control, and weight transmission power between communication channels. On the other hand, in pilot channel 401, transmission data (1) 402 is spread in spreading circuit 404 by spreading code (1) 403, multiplied by weight W (1) 405, and then transmitted from communication channels 406 to 411 and multiplexing circuit 412. , And up-converted by the wireless transmission unit 413,
It is transmitted from the antenna 414. At this time, send data
(1) Since there is no need to transmit information in 402, unmodulated data (all 0s or 1s) may be used.

FIG. 5 shows a configuration of a conventional CDMA cellular radio mobile station using a pilot channel. FIG.
In, the signal received from the antenna 501 is down-converted in the radio receiving section 502. And
The pilot channel 503 detects the phase information 512 from the output of the correlation circuit 505 by the phase estimation circuit 511 and transmits the phase information 512 to the detection circuit 516 of the communication channel 513. In the communication channel 513, the spreading code i (i =
The signals despread in 2 to m) are synchronously detected by a detection circuit 516 based on the phase information 512, determined by a binary determination circuit 517, and output as received data 518.

On the other hand, there is a method of using the pilot channel as information other than synchronous detection. In FIG.
From the correlator output of the pilot channel 503, the power detection circuit 506 calculates the reception power for each sampling (phase), and the chip synchronization circuit 507 integrates (filters) it with a certain time constant to obtain a chip synchronization signal. 508 is output. Using the chip synchronization signal 508, the correlation circuit 5 of the communication channel 513 is used.
The phase of the despreading with the spreading code (i) 514 at 15 is determined. Further, in a system in which another cell uses the same spreading code (1) 504 and transmits a pilot channel with a shifted phase, the output of the power detection circuit 506 indicates
The other cell monitor circuit 509 can obtain other cell signal level information 510. At this time, the transmission power of the pilot channel necessary to obtain the chip synchronization signal 508 and the other cell signal level information 510 is determined by integrating the output of the power detection circuit 506 with the chip synchronization circuit 507 and the other cell monitor circuit 509. It may be lower than the required power.

As a countermeasure for suppressing interference between other stations, there is a method in which a base station controls the directivity of a transmission antenna for each communication channel and transmits the signal (Japanese Patent Laid-Open No. 7-76049). FIG. 6 shows a state when directivity control is performed. The base station 601 has three mobile stations 602, 603, 6
04, the communication channel is transmitted in three directions A, B, and C with directivity controlled. On the other hand, the pilot channel to be transmitted as the reference signal for synchronous detection needs to be omnidirectionally transmitted because it is used in common for each communication channel. At this time, the path on which the pilot channel signal has propagated is different from the path on which the communication channel signal has propagated. That is, in FIG. 6, paths 605 and 606 show that the pilot channel transmitted omnidirectionally propagates on a different path from the communication channel signal, and that the communication channel transmitted directionally A Is a path that does not pass. Therefore, the phase information of the pilot channel signal is different from the phase information of the communication channel signal.

[0008]

In the above-described conventional multiplex transmission of pilot channels, in order to increase the reliability of the pilot channel and improve the synchronous detection performance, it is necessary to perform the following operations on other communication channels that cause interference. It is necessary to transmit with relatively strong power. That is, in FIG. 4, the weight W (1) 405 is a large value (W1> M) for the communication channel.
ax W2 ... Wm). However, when W (1) is increased, the reliability as a reference signal for synchronous detection increases, but the interference (interference between other stations) applied to the communication channel signal increases. There was a problem.

In the case where the base station transmits the signal while controlling the directivity of the transmitting antenna for each communication channel, the phase information obtained from the pilot channel is different from the detection phase of the communication channel. There is a problem that it is impossible to perform synchronous detection of a communication channel using information.

The present invention solves such a conventional problem. In a base station, a pilot channel reduces interference between other stations given to a communication channel and performs directivity control of a transmission antenna. Excellent C that enables synchronous detection in mobile stations when transmitting communication channels
An object of the present invention is to provide a DMA cellular radio transmission apparatus.

[0011]

According to the present invention, in order to achieve the above object, a base station side outputs a pilot channel, a communication channel in which pilot symbols are inserted, a pilot channel, and a pilot channel. Means for multiplexing and transmitting communication channels on the same frequency,
A configuration is characterized in that the pilot channel is transmitted with lower power than the communication channel. With this configuration, in the base station, interference between other stations given by the pilot channel to the communication channel can be reduced, and synchronous detection can be performed in the mobile station even when transmitting by performing transmission antenna directivity control of the communication channel. Can be.

[0012]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a base station outputs a pilot channel,
Means for outputting a communication channel in which pilot symbols are interpolated, and means for multiplexing and transmitting the pilot channel and the communication channel on the same frequency, wherein the pilot channel is transmitted at a lower power than the communication channel. In addition to the pilot channel, by periodically inserting a pilot symbol for the purpose of interpolation type synchronous detection in each communication channel,
The pilot channel does not need to be transmitted with higher power than the communication channel in order to obtain high reliability as a reference signal for synchronous detection, and it is possible to reduce interference between other stations given to the communication channel and to improve the communication channel quality. Can be improved. Further, even when transmitting a communication channel by performing transmission antenna control, on the mobile station side,
Synchronous detection can be performed by using pilot symbols inserted in the communication channel.

[0013] According to a second aspect of the present invention, there is provided a cellular radio base station apparatus using a direct spread CDMA system,
Means for outputting a pilot channel, means for outputting a communication channel in which pilot symbols are interpolated, means for multiplexing and transmitting the pilot channel and the communication channel on the same frequency, and transmitting the communication channel with directivity. Even when the base station performs transmission while controlling transmission directivity for each communication channel, accurate synchronous detection can be performed from pilot symbols inserted in the communication channel.

According to a third aspect of the present invention, there is provided a CDMA cellular radio mobile station apparatus for receiving a signal transmitted from the base station apparatus according to the first or second aspect. Synchronous detection can be performed by using the inserted pilot symbols, and a high-quality signal can be received.

Further, the invention according to claim 4 is a cellular radio mobile station apparatus using a direct spread CDMA system,
A means for performing chip synchronization using a pilot channel signal transmitted from a radio base station apparatus, and a means for performing synchronous detection using a pilot symbol interpolated in a communication channel. By detecting the chip synchronization signal from the pilot channel transmitted with lower power than the communication channel, it is possible to determine the phase of the despreading code in the communication channel,
Even when the base station performs transmission while controlling the transmission antenna directivity for each communication channel, accurate synchronous detection can be performed from pilot symbols inserted into the communication channel.

According to a fifth aspect of the present invention, there is provided a cellular radio mobile station apparatus using a direct spread CDMA system,
It comprises means for performing cell monitoring using a pilot channel signal transmitted from a radio base station apparatus, and means for performing synchronous detection using pilot symbols interpolated in a communication channel. Even in the case of a system that uses a spreading code and transmits a pilot channel with a phase shift, it is possible to accurately perform synchronous detection in its own cell by obtaining signal information of another cell.

In the inventions described in claims 6, 7, 8, and 9, the main parts of the configuration are the same as those in claims 1, 2, 4, and 5, and the operation and effect are also the same.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 shows a configuration of a CDMA cellular radio base station apparatus according to a first embodiment of the present invention. In FIG. 1, 101 is a pilot channel, 102 is transmission data (1), 103 is a spread signal (1),
104 is a spreading circuit, 105 is a weight W (1), 106 is a communication channel (1), 107 is transmission data (2), 108 is a pilot symbol (known symbol), 109 is a switch, 110 is a spreading code (2), 111 is a diffusion circuit, 112
Is the weight W (2), 113 is the communication channel (m-1),
114 is a multiplexing circuit, 115 is a wireless transmission unit, and 116 is an antenna.

Next, the operation of this embodiment will be described. In pilot channel 101, transmission data
(1) 102 is a spreading code by a spreading code (1) 103
And multiplied by the weight W (1) 105 and output. At this time, the transmission data (1) 102 does not need to transmit information, and may be unmodulated data (all 0 or 1 data). In FIG. 1, (m-
1) It is assumed that there is a channel, and the communication channel 106 is
While transmitting the transmission data (2) 107, the pilot symbol 108 is switched and output by the switch 109 every certain period T, and is spread by the spreading code (2) 110.
And multiplied by the weight W (2) 112 and output. The same operation is performed on the other communication channels up to the communication channel (m-1). The output of each channel is multiplexed by the multiplexing circuit 114, up-converted by the radio transmission unit 115, and transmitted from the antenna 116.

As described above, according to the first embodiment,
By periodically inserting pilot symbols (known symbols) for interpolation synchronous detection into each communication channel in addition to the pilot channel, the pilot channel can obtain high reliability as a reference signal for synchronous detection. Therefore, it is not necessary to transmit with higher power than the communication channel, so that it is possible to reduce interference between other stations given to the communication channel. Further, even when transmitting a communication channel by performing transmission antenna control, the mobile station can perform synchronous detection using pilot symbols inserted into the communication channel, so that wireless transmission with excellent static characteristics can be performed. It can be carried out.

(Embodiment 2) The configuration of a CDMA cellular radio base station apparatus according to a second embodiment of the present invention is the same as that of the first embodiment. In FIG. 1, weights W (2) to W (m) in communication channels are used for transmission power control, and weight transmission power between communication channels. On the other hand, in the present embodiment, the weight W (1) 105 of the pilot channel is set to a value lower than the weight of another communication channel, for example, the weight W (2).
From the minimum value of W (m) to Min W2 ... Wm, W1 <Min W
2 ... · Transmit with weighting of Wm.

FIG. 2 shows a channel format in the present embodiment. In each communication channel, a pilot symbol 201 is inserted every period T in addition to transmission data. In FIG. 2, the height dimension of each channel represents transmission power. In this embodiment, while the weights W (2) to W (m) of the communication channels are all equal, the pilot channel 203 transmits with lower power than the communication channel.

FIG. 2 shows a state in which a signal in which a pilot channel and a communication channel are multiplexed is continuously transmitted. However, burst transmission or intermittent transmission in which transmission is turned on / off temporally, or the same radio transmission is used. TDD (Time Divisio), which is a system that performs communication by dividing the frequency into transmission / reception time
n Duplex) system, the above channels can be multiplexed similarly.

As described above, according to the second embodiment,
The pilot channel does not need to obtain high reliability as a reference signal for synchronous detection, and can be transmitted with lower power than the communication channel, so that the amount of interference between other stations due to the pilot channel can be further reduced, Communication channel quality can be improved.

(Embodiment 3) FIG. 3 shows the configuration of a CDMA cellular radio mobile station apparatus according to a third embodiment of the present invention. 3, reference numeral 301 denotes an antenna, 302 denotes a radio reception unit, 303 denotes a pilot channel, 304 denotes a spread code (1), 305 denotes a correlation circuit, and 306 denotes a correlation circuit.
Is a power detection circuit, 307 is a chip synchronization circuit, 308 is a chip synchronization signal, 309 is another cell monitor circuit information, 310 is other cell signal level information, 311 is a communication channel, 312 is a spreading code (i), 313 is a correlation circuit, 314 Is the detection circuit,
315 is a binary decision circuit, and 316 is received data.

Next, the operation of this embodiment will be described. The signal received by antenna 301 is down-converted by radio receiving section 302. Then, in the pilot channel 303, the signal is despread by the correlation circuit 305 by the spreading code (1) 304, the power detection circuit 306 calculates the reception power for each sampling (phase), and the chip synchronization circuit 307 calculates the reception power with a certain time constant. The chip synchronization signal 308 is output by integrating (filtering). Using the chip synchronization signal 308, the phase of the despreading with the spreading code (i) 312 in the correlation circuit 313 of the communication channel 311 is determined. In the case of a system in which another cell uses the same spreading code (1) 304 and transmits a pilot channel with a phase shift, the other cell monitoring circuit 3
09, the other cell signal level information 31 is measured by measuring the reception levels of pilot channels having different phases.
0 can be obtained.

In the communication channel 311, the signal despread by the spreading code (i) 312 by the correlation circuit 313 is synchronously detected by the detection circuit 314 using the interpolated pilot symbols, and the binary judgment circuit 315 And demodulate, and output received data 316.

The chip synchronizing signal 308 is
It is not necessary to use a pilot channel signal,
By configuring the correlator of the communication channel with a digital matched filter and a plurality of sliding correlators, chip synchronization information can be obtained using the correlator output. Further, it is not always necessary to perform power detection to obtain the chip synchronization signal 308. Further, when other cells use the same spreading code (1) 304 and do not adopt a system for transmitting a pilot channel with a phase shift,
A configuration for obtaining the other cell signal level information 310 is unnecessary.

As described above, according to the third embodiment,
Since the mobile station is provided with a means 307 for obtaining chip synchronization from the pilot channel, a means 309 for obtaining signal information of another cell, and a means 314 for performing synchronous detection from the communication channel, the power from the base station is lower than that of the communication channel. By detecting the chip synchronization signal and other cell signal information from the pilot channel transmitted in the above, the phase of the despreading code in the communication channel can be obtained. Even when transmission is performed while controlling the characteristics, accurate synchronous detection can be performed from pilot symbols inserted in the communication channel.

[0030]

As described above, the present invention provides a direct diffusion CD
In a cellular radio base station apparatus using the MA system, a base station outputs a pilot channel, a means for outputting a communication channel in which pilot symbols are interpolated,
Means for multiplexing and transmitting a pilot channel and a communication channel on the same frequency, and transmitting the pilot channel at a lower power than the communication channel, whereby the pilot channel is used as a reference signal for synchronous detection. It is not necessary to obtain high reliability, and by transmitting with lower power than the communication channel, it is possible to reduce the amount of interference between other stations due to the pilot channel.
Further, in the case where the base station performs transmission while controlling the transmission antenna directivity for each communication channel, synchronous detection is performed from pilot symbols inserted in the communication channel, so that accurate synchronous detection can be performed. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a CDMA cellular radio base station apparatus according to Embodiments 1 and 2 of the present invention.

FIG. 2 is a channel format diagram showing an example of pilot channel multiplexing and pilot symbol interpolation in Embodiments 1 and 2 of the present invention.

FIG. 3 is a block diagram showing a configuration of a CDMA cellular radio mobile station apparatus according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram showing a configuration of a base station of a conventional CDMA cellular radio transmission apparatus.

FIG. 5 is a block diagram showing a configuration of a mobile station of a conventional CDMA cellular radio transmission apparatus.

FIG. 6 is a schematic diagram illustrating an example of a propagation path in transmission antenna directivity control and omnidirectional transmission;

FIG. 7 is a channel format diagram showing an example of conventional pilot symbol interpolation.

FIG. 8 is a channel format diagram showing an example of conventional pilot channel multiplexing.

[Explanation of symbols]

 Reference Signs List 101 pilot channel 102 transmission data (1) 103 spreading code (1) 104 spreading circuit 105 weight W (1) 106 communication channel 107 transmission data (2) 108 pilot symbol 109 switch 110 spreading code (2) 111 spreading circuit 112 weight W (2) 113 communication channel 114 multiplexing circuit 115 radio transmission section 116 antenna 201 pilot symbol 301 antenna 302 radio reception section 303 pilot channel 304 spreading code (1) 305 correlation circuit 306 power detection circuit 307 chip synchronization circuit 308 chip synchronization signal 309 and others Cell monitor circuit 310 Other cell signal level information 311 Communication channel 312 Spreading code (i) 313 Correlation circuit 314 Detection circuit 315 Binary decision circuit 316 Received data 401 Pilot channel 402 Transmission data (1) 403 Spreading code (1) 404 Spreading circuit 405 Weight W (1) 406 Communication channel 407 Transmission data (2) 408 Spreading code (2) 409 Spreading circuit 410 Weight W (2) 411 Communication channel 412 Multiplexing circuit 413 Radio transmitting section 414 Antenna 501 Antenna 502 Radio receiving section 503 Pilot channel 504 Spreading code (1) 505 Correlation circuit 506 Power detection circuit 507 Chip synchronization circuit 508 Chip synchronization signal 509 Other cell monitor circuit 510 Other cell signal level information 511 Phase estimation circuit 512 Phase information 513 Communication channel 514 Spreading code (i) 515 Correlation circuit 516 Detection circuit 517 Binary judgment circuit 518 Received data 601 Base station 602 Mobile station (1) 603 Mobile station (2) 604 Mobile station (3) 605 path 606 path 701 Pilot symbol 01 pilot channel

Claims (9)

[Claims] 1. A cellular radio base station apparatus using a direct spread CDMA system, comprising: means for outputting a pilot channel; means for outputting a communication channel in which pilot symbols are interpolated; and setting the pilot channel and the communication channel to the same frequency. Means for multiplexing and transmitting, the CDMA cellular radio base station apparatus transmitting the pilot channel at a lower power than the communication channel. 2. A cellular radio base station apparatus using a direct spread CDMA system, comprising: means for outputting a pilot channel; means for outputting a communication channel in which pilot symbols are interpolated; and setting the pilot channel and the communication channel to the same frequency. Means for multiplexing and transmitting, and transmitting the communication channel with directivity. 3. A CDMA cellular radio mobile station apparatus for receiving a signal transmitted from the radio base station apparatus according to claim 1. 4. A cellular radio mobile station apparatus using a direct spread CDMA system, means for achieving chip synchronization using a pilot channel signal transmitted from a radio base station apparatus, and a pilot symbol interpolated in a communication channel. Means for performing synchronous detection using the CDMA cellular radio mobile station apparatus. 5. A cellular radio mobile station apparatus using a direct spread CDMA system, comprising: means for performing cell monitoring using a pilot channel signal transmitted from a radio base station apparatus; and using a pilot symbol interpolated in a communication channel. CDMA cellular radio mobile station device comprising: 6. A transmission method using a direct spread CDMA system, wherein a radio base station apparatus outputs a pilot channel, a communication channel in which pilot symbols are interpolated, and a step of transmitting the pilot channel and the communication channel. Transmitting the pilot channel at a lower power than the communication channel. 7. A transmission method using a direct spread CDMA system, wherein the radio base station apparatus outputs a pilot channel, outputs a communication channel in which pilot symbols are interpolated, and outputs the pilot channel and the communication channel. Multiplexing and transmitting the same frequency, and transmitting the communication channel with directivity. 8. A receiving method using a direct spread CDMA system, wherein a radio mobile station apparatus performs chip synchronization using a pilot channel signal transmitted from a radio base station apparatus, and the radio channel is interpolated into a communication channel. Performing synchronous detection using pilot symbols. 9. A receiving method using a direct sequence CDMA system, wherein a radio mobile station apparatus performs cell monitoring using a pilot channel signal transmitted from a radio base station apparatus, and a pilot channel inserted into a communication channel. Performing a synchronous detection using a symbol.