JPH098716A - Communication equipment for mobile object - Google Patents

Abstract

PURPOSE: To provide the base station transmission diversity and transmission power control of intermittent communication concerning the radio communication system of a CDMA/TDD system. CONSTITUTION: At a base station, correlation levels inversely spreading signals, which are received by plural antennas 101 and 201, for each channel by inverse spread circuits 104 and 204 are compared between the antennas for each channel by comparator circuits 106 and 206 and based on the result, selection circuits 110 and 210 select which channel is to perform transmission for each channel at the time of transmission. Each mobile station is provided with a means for transmitting the fixed pattern of a transmissive frame just before the frame to be first received after a transmission/reception stop zone in the case of intermittent communication and based on the reception power of this fixed pattern, the base station selects any antenna for mobile station transmission power control and transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication device which adopts a code division multiple access and a transmission / reception same band system (CDMA / TDD system) in a digital automobile telephone, a mobile telephone and the like.

[0002]

2. Description of the Related Art The multiple access system is a line connection system in which a plurality of stations simultaneously communicate in the same band. CDMA (Code Division Multiple Access) is code division multiple access, and multiple access is performed by spread spectrum communication in which the spectrum of an information signal is spread and transmitted in a band sufficiently wider than the original information bandwidth. It is a technology. The direct spreading method is a method of directly multiplying an information signal by a spreading sequence code in spreading. CDM
In the A method, the bit rate per channel (the amount of information that can be transmitted in a fixed time) is uniquely determined by the number of spreading code sequences and the transmission rate of the spread spectrum transmission signal. When the bit rate of the information to be transmitted is lower than the bit rate that can be transmitted by CDMA, the transmission / reception is operated only during the time for transmitting the required amount of information, and the transmission / reception is stopped at other times (hereinafter By performing intermittent communication), it is possible to eliminate interference with other channels (inter-station interference) during the suspension period and to effectively use the frequency.

[0003] TDD (Time Division Duplex) is a transmission / reception same-band system and is also called a ping-pong system.
This is a method of performing communication by time division of the same radio frequency into transmission / reception, and one transmission / reception is called one frame. In the case of the TDD method, since the same band method is used for transmission and reception, the frequency correlation between fading fluctuations of the transmitted wave and the received wave is 1, and if the switching time between the two is sufficiently short, mutual fading fluctuations are propagated. Since the road condition has a high time correlation, the mobile station controls the transmission power using the reception level from the base station (open loop power control), or the base station uses the reception wave level from the mobile station. By determining the mobile station transmission power control information, and adding the above information to the transmission information from the base station to the mobile station and transmitting (closed loop power control), the reception level at the base station can be suppressed within a certain range. it can. In addition, when the base station has multiple antennas, by applying the transmit diversity that selects the optimal transmit antenna from the reception level at each antenna, the space diversity is not required in the mobile station, and the mobile station can be downsized. Is possible.

FIG. 9 shows an example of transmission / reception timing of the CDMA / TDD system viewed from the two mobile stations PS1 and PS2. In FIG. 9, mobile stations PS1 and PS2 are transmitting information amount which is 1/2 of the transmission amount that can be transmitted. Intermittent communication is performed in frame units.

[0005]

However, in the above-mentioned conventional mobile communication apparatus using the CDMA / TDD system,
Antenna selection for mobile station transmission power control and base station transmission diversity is determined from the reception result in the immediately preceding frame, but when intermittent communication is performed when the amount of transmission bits per channel is small, continuous transmission between multiple frames is performed. Since transmission / reception is continuously performed for multiple frames after transmission / reception in between, the interval between reception and transmission becomes long before and after the stop section, during which the propagation path state changes, and accurate movement is made at the time transmission / reception starts. There is a problem that the station transmission power control and the transmission antenna selection control cannot be performed.

The present invention solves such a conventional problem and is intended for mobile station transmission power control and base station transmission diversity by open loop control or closed loop control in intermittent communication by the CDMA / TDD system. An object of the present invention is to provide an excellent mobile communication device that enables antenna selection.

[0007]

In order to achieve the above object, the present invention uses a CDMA / TDD system which employs a direct spreading system, after a base station and a mobile station continuously transmit and receive for a plurality of frames. In a mobile communication device that performs communication by continuously stopping transmission / reception for a plurality of frames, a base station has a plurality of antennas, a wireless transmission / reception unit provided for each antenna, and a reception signal for each channel for each antenna. Despreading means, means for comparing the correlation level obtained by despreading between the antennas for each channel, and based on the comparison result, the transmission signal spread at the time of transmission from each antenna for each channel And means for selecting whether to transmit.

According to the present invention, the mobile station further comprises means for transmitting a fixed pattern before starting transmission / reception, and the base station selects a transmitting antenna according to the reception result of the fixed pattern.

The present invention also comprises means for allowing the mobile station to perform transmission power control according to the reception level of the signal transmitted from the antenna selected by the base station.

The present invention also employs a CDM that employs a direct diffusion method.
In a mobile communication device that uses the A / TDD method to perform communication by continuously transmitting and receiving for a plurality of frames after a base station and a mobile station transmit and receive for a plurality of frames continuously, The mobile station is provided with means for calculating the transmission power control information of the mobile station based on the reception power for each and / or the desired wave power to interference power ratio, and means for transmitting the transmission power control information to each mobile station. It is provided with means for controlling the transmission power by the power control information.

The present invention also comprises means for the mobile station to transmit a fixed pattern with a predetermined power before starting transmission / reception, and the base station calculates transmission power control information based on the reception result of the fixed pattern, Each mobile station controls the transmission power according to the transmission power control information.

[0012]

Therefore, according to the present invention, the base station compares the reception correlation levels obtained by despreading the signals received by the plurality of antennas for each channel between the antennas, and based on the comparison result. Choose the best antenna to transmit to,
It is possible to realize transmission diversity at the base station,
In the mobile station, space diversity is unnecessary, and the device can be downsized.

Further, the mobile station transmits a fixed pattern before starting transmission / reception, so that the base station selects a transmission antenna based on the reception result of the fixed pattern. By performing the transmission power control according to the reception level of the signal of, the optimum open loop power control can be performed from the transmission start point.

Further, the base station calculates the transmission power control information of the mobile station based on the comparison result of the reception correlation levels and transmits it to each mobile station, and each mobile station transmits based on the transmission power information. By performing power control, optimum closed-loop power control can be performed.

Furthermore, the mobile station transmits a fixed pattern before starting transmission / reception, so that the base station calculates transmission power control information based on the reception result of the fixed pattern and transmits it to each mobile station. Then, each mobile station performs transmission power control based on the transmission power information, so that optimum closed-loop power control can be performed from the transmission start point.

[0016]

【Example】

(Embodiment 1) FIG. 1 shows a configuration of a base station for two mobile stations PS1 and PS2 of a mobile communication device according to a first embodiment of the present invention, in the case of having two antennas A and B. Is an example of. In FIG. 1, 101 is an antenna A, 201 is an antenna B, 102 is a transmission / reception switch for the antenna A 101, and 202 is an antenna B201.
And a transmission / reception changeover switch for use with the antenna A10
1 is a wireless receiving unit, and 203 is a wireless receiving unit for the antenna B201. 104 and 105 are antennas A1
Despreading circuit for 01, 204 and 205 for antenna B
Despreading circuit for 201, which is distributed to the PS1 circuit 100 and the PS2 circuit 200,
The received data is despread using a spreading code. 106, 2
Reference numeral 06 denotes the despreading circuits 104, 105 and 204, 205.
The correlation level (received signal power level) obtained by despreading in the antenna A101 and the antenna B20.
It is a comparison circuit for comparing between 1. 107 and 207 are synthesis circuits for synthesizing the despread reception signals in the despreading circuits 104 and 105 or 204 and 205, and 108 and 20.
Reference numeral 8 is a decoding circuit for decoding the combined reception signal. 1
Reference numerals 09 and 209 denote spreading circuits that spread the transmission data by spreading codes, 110 and 210 denote transmission antenna selection circuits that select from which antenna the spread transmission signals are to be transmitted, and 111 and 211 denote the transmission antenna selection signals. is there. Reference numeral 112 is an adder circuit for adding the spread transmission signal for the antenna A 101, 212 is an adding circuit for adding the spread transmission signal for the antenna B 201, 113
Is a wireless transmission unit for the antenna A 101, 213 is a wireless transmission unit for the antenna B 201, and 300 is a transmission / reception switching timing signal for operating the transmission / reception changeover switches 102 and 202.

Next, the operation of the above embodiment will be described. The reception signals received by the antennas A101 and B201 are first demodulated by the radio reception units 103 and 203 via the transmission / reception change-over switches 102 and 202, down-converted and detected, and then the despreading circuits 104, 10 are received.
Correlation detection is performed at 5 and 204 and 205. The correlation detection results independently obtained from the two antennas A101 and B201 are the comparison circuits 106 and 206 in the PS1 circuit 100 and the PS2 circuit 200, respectively.
Then, the frame average power of the correlation level (received signal power level) is calculated.
Then, the transmission path state (transmission path transfer function) of the antenna B201 is obtained, which antenna of A101 or B201 is used to transmit at the next transmission timing, and the transmission antenna selection signals 111 and 211 are output. Comparison circuit 10
The received signals that have passed through 6 and 206 are combined circuits 107 and 2
The data is combined in 07 and decoded by the decoding circuits 108 and 208 to obtain received data.

On the other hand, the transmission data is spread by the spreading circuits 109 and 209 by the assigned spreading code, and then added through the transmission antenna selection circuits 110 and 210 switched by the transmission antenna selection signals 111 and 211. All the transmission signals selecting the same antenna in the circuit 112 or 212 are added, up-converted in the wireless transmission unit 113 or 213, and transmitted / received by the transmission / reception switching timing signal 300.
01 or antenna B201. In this base station configuration example, two mobile stations (PS1, PS2)
The circuit configuration for PS1 circuit 100 is PS
The dual circuit 200 has the same configuration, but the spreading code and the despreading code are different. Further, it is possible to transmit / receive more mobile stations. In this case, as many PS1 circuits 100 and adder circuits 1 as the number of mobile stations that can be connected are connected.
The number of addable times of 12 and 212 is added.

FIG. 2 shows an example of transmission / reception timing of the CDMA / TDD system as seen from the mobile station. In FIG. 2, mobile stations PS1 and PS2 are transmitting an amount of information that is half the amount of transmission that can be transmitted, and are performing intermittent communication in 4-frame units with a time shift. In the direct sequence CDMA communication, it is necessary to reduce interference between other stations in order to improve communication quality or increase capacity (number of accommodated channels, number of multiplexed channels). When performing intermittent communication, each mobile station is divided into multiple blocks of several frames (grouping)
Then, the number of simultaneous multiplexes can be reduced by communicating with the base station. In FIG. 2, eight frames are divided into two blocks BL1 and BL2 in units of four frames, and one block BL1 communicates with PS1 and the other block BL2 communicates with PS2.

The base station according to the present embodiment shown in FIG. 1 is set to 1 after the start of intermittent transmission / reception received by the antennas A101 and B201.
The antenna used for transmission of the second frame is selected by comparing the reception correlation level at each antenna of the frame.
Subsequent selection of transmission antennas for 3 frames and 4 frames is similarly performed.

As described above, according to this embodiment, in the intermittent communication, the two antennas 101 and 201 of the base station receive in the second and subsequent frames from the start of the intermittent communication, and the comparison circuits 106 and 206 obtain the values. It is possible to apply the transmission diversity for selecting the optimum transmission antenna from the received correlation level, the spatial diversity is not required in the mobile station, and the size of the mobile station can be reduced. It is also possible to perform transmission diversity from the first frame by reversing the transmission / reception timing.

(Embodiment 2) Next, a second embodiment of the present invention will be described. The configuration of the base station in the second embodiment is the same as that in the first embodiment shown in FIG. FIG. 3 shows the configuration of the mobile station in this embodiment. In FIG. 3, 301 is an antenna for receiving a signal from a base station and transmitting the signal to the base station, 302 is a transmission / reception selector switch for switching between transmission and reception according to a transmission / reception switching timing signal, and 303 is a demodulation of the signal received from the base station. Radio receiving section for detecting, 304 is despreading circuit for detecting correlation of received signal, 305 is decoding circuit for decoding received signal to obtain received data, 306 is received power level detection for detecting received power level of received signal Circuit. Reference numeral 307 is a coding circuit for coding transmission data, 308 is a transmission power level control circuit for deciding the transmission power level based on the reception power level detected by the reception power level detection circuit 306, 309.
Is a spreading circuit that spreads the transmitted data by adding a spreading code, 3
Reference numeral 10 is a guide pattern generation circuit for generating the same guide pattern as the fixed pattern of the transmission frame at the same timing.
Reference numeral 11 is an adder circuit that adds a spread signal and a guide pattern signal to create a transmission signal, and 312 is a wireless transmission unit that modulates the transmission signal into a wireless signal and outputs the wireless signal from the antenna 301. It should be noted that the transmission power level control circuit 308 uses the SIR in addition to the reception power level to determine the transmission power.
The (desired wave power to interference power ratio) can also be used. It is also possible to determine these in combination.

FIG. 4 shows an example of the frame structure in this embodiment. In FIG. 4, one frame is a reception section 401.
And a transmission section 402. Each transmission / reception section includes a guard time 403 for avoiding duplication of transmission and reception due to a delay on the transmission path, a fixed pattern 404 for frame synchronization and mobile station identification, and an information signal 405. Composed of and.

FIG. 5 shows an example of transmission / reception timing of the CDMA / TDD system as seen from the mobile station. In FIG. 5, the mobile stations PS1 and PS2 are transmitting an amount of information that is half the amount of transmission that can be transmitted, and are performing intermittent communication in units of two frames with a time shift. That is, four frames are divided into two blocks BL1 and BL2 in units of two frames, and one block BL1 communicates with PS1 and the other block BL2 communicates with PS2. The mobile stations PS1 and PS2 transmit the guide pattern (fixed pattern) 406 from the guide pattern generation circuit 310 in FIG. 3 at the end of each transmission / reception stop section, that is, in the transmission section of the frame immediately before the transmission / reception start section. The base station uses the guide pattern 4 received by the antennas 101 and 201.
By comparing the reception correlation level of 06 in the comparison circuits 106 and 206, the antenna used for transmission at the start of intermittent transmission is selected. Then, the mobile station detects the reception level of the signal transmitted from the selected antenna by the reception power level detection circuit 306, and determines the transmission power by the transmission power level control circuit 308 according to the detected reception level.
As a result, it is possible to realize the transmission power control by the appropriate transmission open loop control from the start of transmission.

As described above, according to the present embodiment, the mobile station receives the guide pattern (fixed pattern) before starting transmission / reception.
Since the base station selects a transmission antenna based on the reception result of this fixed pattern, it is possible to select the optimum transmission antenna from the reception correlation level at each antenna at the base station from the frame of intermittent communication start in intermittent communication. It is possible to apply the transmission diversity for selecting, and it is possible to reduce the size of the mobile station by eliminating the need for space diversity in the mobile station.

(Embodiment 3) Next, a third embodiment of the present invention will be described. FIG. 6 shows the configuration of the base station according to the present embodiment, and has a configuration in which the reception power calculation circuits 114 and 214 and the transmission power control circuits 115 and 215 are added to the base station according to the first embodiment shown in FIG. The configuration is the same as that of FIG. 1 except for these two circuits. As shown in FIG. 7, the mobile station has a configuration in which a guide pattern generation circuit 310 is removed from the configuration shown in FIG. 3 and a transmission power control information detection circuit 313 is provided instead of the reception power level detection circuit 306. Other than these, the configuration is the same as that of FIG.

FIG. 8 shows an example of the frame structure of transmission information viewed from the base station of this embodiment. In FIG.
One frame consists of a transmission section 501 and a reception section 502, and each transmission / reception section has a guard time 503 for avoiding duplication of transmission and reception due to a delay on the transmission path, and a fixed pattern for frame synchronization and mobile station identification. 504,
The mobile station transmission power control information 506 is added before the information signal 505 in the transmission section 501.

Next, the operation of this embodiment will be described.
In the base station, the reception power calculation circuits 114 and 214 calculate the reception power from the current mobile station from the reception signals selected by the comparison circuits 106 and 206, and the output power or the output power change amount at the time of the next mobile station transmission. Power control circuit 11
5, 215, and the mobile station transmission power control information 506 is transmitted to the mobile station in addition to part of the transmission data from the base station to the mobile station. In the mobile station, the transmission power control information detection circuit 313 detects the mobile station transmission power control information 506, and the transmission power level control circuit 308 controls the transmission power. At the base station, the mobile station transmission power control information 5
As an input for calculating 06, SIR (desired wave power to interference power ratio) can be used in addition to the above reception power. It is also possible to calculate by combining these.

Also in this embodiment, as shown in FIG.
PS1 and PS2 transmit information amount which is ½ of the transmittable transmission amount, and are intermittently communicated in units of 4 frames at different times. After starting the received intermittent transmission / reception, the base station calculates the mobile station power control information 506 at the time of transmission of the second frame by each reception power of the first frame and transmits it to the mobile station. The mobile station receives the mobile station power control information 506.
Is used to determine the transmission power of the second frame. Thereafter, the mobile station transmission powers of 3 frames and 4 frames are similarly controlled.

As described above, according to this embodiment, the optimum closed loop power control is performed by performing mobile station transmission power control by the reception power at the base station in the second and subsequent frames from the start of intermittent communication in intermittent communication. Can be done.

(Embodiment 4) The structure of the base station and the frame structure in this embodiment are the same as those in the above-mentioned third embodiment, and the structure of the mobile station is as shown in FIG. 3 in the structure of FIG. A guide pattern generation circuit 310 is added.

Therefore, the operation of this embodiment is the same as that of the second
And the third embodiment are combined. As shown in FIG. 5, PS1 and PS2 are transmitting an information amount that is 1/2 of the transmittable transmission amount, and are intermittently communicated in units of two frames at different times. PS1 and PS2 transmit the guide pattern (fixed pattern) 406 in the transmission section of the frame immediately before the end of the transmission / reception stop section. The base station uses the reception power of the received guide pattern to make the third
The mobile station transmission power control information is calculated as in the embodiment of the present invention, the power control information is transmitted to the mobile station from the transmission at the start of intermittent transmission, and the mobile station controls the transmission power based on the received power control information. By performing the above, optimum closed loop power control can be performed from the transmission start point.

[0033]

As is apparent from the above embodiment, the present invention compares the reception correlation level obtained by despreading the signals received by a plurality of antennas by the base station between the antennas for each channel. , The optimum antenna for transmission is selected based on the comparison result, so that it is possible to realize the transmission diversity in the base station, the mobile station does not need the space diversity, and the device can be downsized. it can.

Further, the mobile station transmits a fixed pattern before starting transmission / reception, so that the base station selects a transmitting antenna based on the reception result of the fixed pattern, and the mobile station sends the fixed pattern from the base station. By performing the transmission power control according to the reception level of the signal of, the optimum open loop power control can be performed from the transmission start point.

Further, the base station calculates the transmission power control information of the mobile station based on the comparison result of the reception correlation levels and transmits it to each mobile station, and each mobile station transmits based on the transmission power information. By performing power control, optimum closed-loop power control can be performed.

Furthermore, the mobile station transmits a fixed pattern before starting transmission / reception, so that the base station calculates transmission power control information based on the reception result of the fixed pattern and transmits it to each mobile station. Then, each mobile station performs transmission power control based on the transmission power information, so that optimum closed-loop power control can be performed from the transmission start point.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a base station according to first and second embodiments of the present invention.

FIG. 2 is a schematic diagram showing a timing example of intermittent transmission / reception in the first and third embodiments of the present invention.

FIG. 3 is a block diagram showing a configuration of a mobile station according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing an example of a frame structure according to second and fourth embodiments of the present invention.

FIG. 5 is a schematic diagram showing an example of intermittent transmission / reception timing in the second and fourth embodiments of the present invention.

FIG. 6 is a block diagram showing the configuration of a base station according to the third and fourth embodiments of the present invention.

FIG. 7 is a block diagram showing a configuration of a mobile station according to a third embodiment of the present invention.

FIG. 8 is a schematic diagram showing an example of a frame structure according to third and fourth embodiments of the present invention.

FIG. 9 is a schematic diagram showing an example of a conventional intermittent transmission / reception timing.

[Explanation of symbols]

 101, 201 Base station antenna A 102, 202 Transmission / reception changeover switch 103, 203 Radio receiving section 104, 105, 204, 205 Despreading circuit 106, 206 Comparison circuit 107, 207 Combining circuit 108, 208 Decoding circuit 109, 209 Spreading circuit 110 , 210 transmission antenna selection circuit 111, 211 transmission antenna selection signal 112, 212 addition circuit 113, 213 wireless transmission section 114, 214 reception power calculation circuit 115, 215 transmission power control circuit 300 transmission / reception switching timing signal 301 antenna 302 transmission / reception changeover switch 303 Radio reception unit 304 Despreading circuit 305 Decoding circuit 306 Reception power level detection circuit 307 Encoding circuit 308 Transmission power level control circuit 309 Spreading circuit 310 Guide pattern generation circuit 311 Addition circuit 3 12 wireless transmission unit 313 transmission power control information detection circuit

Claims (6)

[Claims] 1. A mobile unit that uses a CDMA / TDD system that employs a direct spreading system, in which a base station and a mobile station perform continuous transmission / reception for a plurality of frames and then stop transmission / reception for a plurality of frames continuously to perform communication. In a communication device, a base station has a plurality of antennas, a radio transmission / reception means provided for each of the antennas, a means for despreading a reception signal at each antenna for each channel, and a correlation obtained by the despreading. Moving means provided with means for comparing the level of each channel between antennas, and means for selecting from which antenna to transmit the transmission signal spread at the time of transmission for each channel based on the comparison result Body communication device. 2. The mobile station comprises means for transmitting a fixed pattern before starting transmission / reception, and the base station selects a transmission antenna according to the reception result of the fixed pattern.
The mobile communication device according to claim 1. 3. A mobile station according to claim 2, wherein the mobile station comprises means for performing transmission power control according to a reception level of a signal transmitted from an antenna selected by the base station or a desired wave power to interference power ratio. Body communication device. 4. A mobile unit that performs communication by continuously transmitting and receiving for a plurality of frames by a base station and a mobile station using the CDMA / TDD system that adopts a direct spread system, and then transmitting and receiving for a plurality of frames. In the communication device, the base station, means for calculating the transmission power control information of the mobile station by the reception power or desired wave power to interference power ratio for each channel, and means for transmitting the transmission power control information to each mobile station A mobile communication device, comprising: a mobile station including means for controlling transmission power according to the received transmission power control information. 5. The mobile communication device according to claim 4, wherein the base station calculates the transmission power control information of the mobile station based on the comparison result of the comparison means in the mobile communication device according to claim 1. 6. The mobile station comprises means for transmitting a fixed pattern with a predetermined power before starting transmission / reception,
The mobile communication device according to claim 4, wherein the base station calculates transmission power control information based on the reception result of the fixed pattern, and each mobile station controls the transmission power based on the transmission power control information.