JP2000201371A - Radio communication system, radio base station, and array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the establishment of a communication channel by calculating the weighting coefficient of the array antenna in a short time. SOLUTION: In a step S3, a terminal station sends a registration request packet. A base station sends a reference signal for registration in a step S7 and the terminal station sends a reference signal for the registration in response to it (step S9). The base station calculates direction estimating algorithm by using the transmit signal of the terminal station in the step S9. When the direction estimating algorithm converges in a step S13, the terminal direction, weighting coefficient or the like are registered in a step S14. The registration information is used as initial values to shorten control over antenna characteristics for practical communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radio communication system, a radio base station used in the radio communication system, and an array antenna used for the radio base station.

[0002]

2. Description of the Related Art Currently, wireless local loops (WL)
The development of a technology for inexpensively configuring a direct communication path to a subscriber using a radio called L) has been started. Among them, a system form in which a plurality of terminal stations can be accommodated for one base station is called a point-to-multipoint (PTMP).

FIG. 7 is an explanatory diagram for explaining a PTMP type WLL.

Areas A1 and A2 indicated by oblique lines in FIG. 7 indicate service areas of base stations B1 and B2, respectively. In general, in PTMP, a base station needs to communicate with a plurality of terminal stations in different directions, so that a base station antenna needs
An antenna having a relatively large half-value angle such as 0 to 120 degrees is used.

[0005] Terminal stations T1 and T2 installed in areas A1 and A2 respectively communicate with base stations B1 and B2. In the terminal stations T1 and T2, an antenna having a small half-value angle of about 10 degrees and a large gain is generally used.

[0006] Therefore, in the PTMP, interference from another terminal station other than the desired terminal station occurs at the time of reception at the base station. FIG. 8 shows an arrival state of an interference wave when the base station uses a sector antenna having a half-value angle of 120 degrees.

In FIG. 8, the service area of each base station is indicated by a hexagon, and the base station is indicated by a circle at the center of each service area. The service range when each base station directs the sector antenna with a half-value angle of 120 degrees in the same direction is indicated by oblique lines. On the other hand, each terminal station is indicated by an arrow. As shown by the arrow in FIG. 8, a terminal station other than the terminal station T3 desired by the base station B3 becomes a source of interference waves.

In particular, since a control channel used to make a call to a base station performs communication using a random access method that cannot be scheduled by the base station, there is a possibility that many interference waves may occur. Is big. For this reason, there is a possibility that the call cannot be accepted by the control channel and the communication becomes impossible.

As described above, when a general ordinary sector antenna is used, a transmission signal from a terminal having a sharp directional antenna may be received by a distant base station. Therefore, even when so-called frequency repetition is performed in which the same frequency channel is not used in an adjacent area using a plurality of frequency channels, it is necessary to set the repetition distance at which the same frequency channel can be used to a sufficiently large interval.

More specifically, about 4 to 7 cells are defined as one unit, and the frequency channel is divided in this unit.
The frequency reuse is performed by performing frequency repetition for each unit.

FIG. 9 shows an arrival state of an interference wave in the case of four-cell frequency repetition. The thick frame in FIG. 9 indicates a unit of frequency repetition. Adopting such frequency repetition has the disadvantage that the capacity of the subscriber that can be accommodated in the system as a whole is reduced due to the limitation of the frequency channels that can be allocated to the system.

Therefore, as a method of increasing the capacity of the subscriber without using the frequency repetition or reducing the number of repetitions and simultaneously avoiding interference, a signal from another interfering station is processed by signal processing from the original received signal. The adoption of an interference canceller or the like for removing the antenna and the adoption of an adaptive array antenna that directs the null direction of the antenna to another interfering station in a base station are being studied.

Usually, in response to a communication request from a terminal station, the base station allocates a predetermined communication channel, and thereafter, the terminal station performs communication using the allocated communication channel. The base station uses the signal arriving from the terminal, activates the adaptive algorithm, and saves the desired signal from the terminal,
Each element of the array antenna is weighted to remove an interference signal. As a result, communication with reduced adverse effects due to interference waves is possible without reducing the capacity of the subscriber.

However, in the adaptive array antenna, the weighting calculation processing for removing the interference signal generally requires a long time for the calculation processing. For this reason, there is a problem that the time required until communication is actually possible is long.

[0015]

As described above, conventionally, P
When an adaptive array antenna is used to reduce interference from a terminal station in TMP, there is a problem that a long time is required for calculation processing and a long time is required until communication is actually enabled.

An object of the present invention is to provide a radio communication system, a radio base station, and an array antenna that can reduce the time required until communication becomes possible even when interference is reduced by using an adaptive array antenna. And

[0017]

According to a first aspect of the present invention, there is provided a radio communication system comprising: a terminal station owned by a subscriber for communication; a base station accommodating the terminal station; Registration means for communicating with a base station to register the terminal station with the base station, detection means for detecting at least information of the direction of the terminal station with respect to the base station at the time of registration in the registration means, Storage means for storing a detection result of the detection means, and an antenna for controlling at least one antenna characteristic of the terminal station and the base station with information stored in the storage means at the time of communication between the terminal station and the base station as an initial value A radio base station according to claim 2 of the present invention, wherein the radio base station detects at least information on the direction of the terminal station at the time of registration by communication of the terminal station. Storage means for storing a detection result of the detection means, and antenna characteristics for controlling antenna characteristics at the time of transmission and / or reception with respect to the terminal station using information stored in the storage means as an initial value when communicating with the terminal station Control means, the array antenna according to claim 3 of the present invention, a plurality of antenna elements, a direction detection circuit for detecting the direction of the terminal station at the time of registration by communication of the terminal station with the base station, and A storage device that stores a detection result of the direction detection circuit for each terminal station, and a weighting coefficient calculated using information recorded in the storage device as an initial value,
And a weighting coefficient calculation circuit for assigning a weight to transmission / reception signals received by the plurality of antenna elements.

[0018] In claim 1 of the present invention, the registration unit registers the terminal station with the base station. At the time of this registration, the detecting means detects at least information on the direction of the terminal station, and the storage means stores the detection result. The antenna characteristic control means controls the antenna characteristic in a short time with the information stored in the storage means at the time of actual communication as an initial value.

According to the second aspect of the present invention, upon registration through communication with the terminal station, the detecting means detects the direction of the terminal station. The storage unit stores the detection result. The antenna characteristic control means uses the information stored in the storage means as an initial value,
Control antenna characteristics in a short time.

According to a third aspect of the present invention, transmission and reception signals received by a plurality of antenna elements are weighted by a weighting coefficient calculation circuit. The weighting coefficient calculating circuit calculates the weighting coefficient in a short time by reading the information on the direction of the terminal station detected at the time of registration of the terminal station from the storage means and using the information as an initial value for calculating the weighting coefficient.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a radio base station according to the present invention. FIG. 1 shows the configuration of the receiving system.

In the present embodiment, the weighting of the array antenna is performed at the time of terminal station registration processing when the terminal station newly starts operation or resumes operation for the first time after the existing terminal station changes its position. The coefficient is calculated, and at the time of actual transmission, the calculated coefficient is used as an initial value to calculate the weighting coefficient, thereby shortening the calculation processing time,
This makes it possible to quickly establish a communication channel.

The antenna section 1 is composed of a plurality of array antennas. FIG. 1 shows an example using four array antennas. The high-frequency (RF) signal induced in each array antenna is passed through each filter of the band-pass filter unit 2 and each buffer of the buffer unit 3 to the multiplier unit 4.
Is supplied to each multiplier. The oscillator 5 outputs a local oscillation output, and the distributor (DIV) 6 outputs the local oscillation output to each multiplier with a corresponding phase. Each multiplier multiplies the output of each buffer by the output of DIV 6 and outputs an intermediate frequency (IF) signal to each filter of band-pass filter unit 7.

Each filter of the band-pass filter section 7 has I
The F signal is band-limited and output to the IF / BB circuit 10 via each buffer of the buffer unit 8. When the orthogonal beams are formed at the same time, the output of each buffer of the buffer unit 8 is output by another distributor (not shown) by each distributor of the distributor unit 9.
The data is supplied to the F / BB circuit.

The output of each buffer of the buffer section 8 is supplied to each phase shifter of the phase shifter section 11. Each phase shifter is supplied with a phase shift control signal from each DAC of the digital / analog converter (DAC) unit 12, and shifts the phase of the input IF signal to each filter of the band-pass filter unit 13. Supply. Each filter limits the band of the input IF signal, and sets each RSSI of the received signal strength measurement (RSSI) unit 14.
Output to I. Each RSSI measures the received signal strength of the input IF signal and outputs it to the phase shift / amplitude weight calculation unit 23 and outputs the IF signal to each gain unit of the gain unit 15.

Each gain unit receives an amplitude weight control signal from each filter of the low-pass filter (LPF) unit 16, adds an excitation weight to the input IF signal, and outputs the signal to the adder 17. The adder 17 adds the outputs of the respective gain devices and outputs the result to the receiving circuit 18.

The receiving circuit 18 processes a received signal to a predetermined signal, interprets the received signal, and outputs the received signal to a control circuit 20 for controlling an array antenna.

The control circuit 20 includes a reception signal shaping circuit 21,
Reference signal reproduction circuit 22, phase shift amount / amplitude weight calculation unit 2
3 and the CPU 24. The reception signal generation circuit 21 is controlled by the CPU 24 to shape the input reception signal and output it to the reference signal reproduction circuit 22 and the phase shift amount / amplitude weight calculation unit 23.

In general, in a wireless communication system or a broadcasting system, information is transmitted using information frames or slots.
A known signal is periodically transmitted as a reference signal for each frame or slot. The reference signal reproducing circuit 22 is controlled by the CPU 24 to reproduce the reference signal from the received signal and output it to the phase shift amount / amplitude weight calculation unit 23. The phase shift amount / amplitude weight calculator 23 receives the shaped received signal and the reference signal, and receives the information of the received signal strength corresponding to each array antenna, and the amplitude weight to be given to each antenna input. And the phase shift amount. The phase shift / amplitude weight calculator 23 calculates
The information on the amount of phase shift for each array antenna is output to a demultiplexer (DEMUX) 19, and the information on the amplitude weight is output to D
Output to EMUX25.

The DEMUXs 19 and 25 separate the input information for each antenna and output the information to the DACs of the DAC units 12 and 26, respectively. Each DAC of the DAC unit 12 converts phase shift information of each array antenna into a phase shift control signal and outputs the signal to each phase shifter. Further, each DAC of the DAC unit 26 converts the information of the amplitude weight of each array antenna into an amplitude weight control signal and outputs the signal to each gain device.

The CPU 24 controls a circuit section in the control circuit 20. In the present embodiment, the CPU 24 has a memory or the like (not shown), stores registration information of each terminal station, and stores information of a phase shift amount and an amplitude weight at the time of registration for each terminal. It has become. CPU
In actual communication, the phase shift / amplitude weight calculation is performed using the information of the phase shift / amplitude weight stored for each terminal as an initial value.

Next, the operation of the embodiment configured as described above will be described with reference to FIGS. FIG. 2 is a flowchart showing the flow of processing at the time of terminal registration,
FIG. 3 is a flowchart showing the flow of processing during a call. FIG. 4 is an explanatory diagram showing a frame configuration employed in the embodiment of FIG. FIG. 4A illustrates a downstream frame, and FIG. 4B illustrates an upstream frame. 2 and 3, BSE indicates a radio base station (base station) having the receiving system of FIG. 1, and CPE indicates a terminal station.

First, the flow of processing at the time of terminal registration will be described. The wireless base station constantly monitors the uplink transmission path. In step S1 of FIG. 2, the base station monitors the uplink transmission path and determines whether the transmission path is in use. The base station transmits this determination result to the downlink SI (Upst
Using the ream Status Indicator), each terminal is notified of the transmission line status of the uplink.

FIG. 4A shows a downstream frame.
Control packets are arranged at the head of the downstream frame, and thereafter,
A plurality of data packets are arranged and configured. The control packet has a header, control information such as SI, and FEC (error correction bits). Each data packet is configured by arranging a header, data, and FEC from the beginning.

The terminal station which requests transmission requests determines whether or not the uplink is "vacant" by referring to the received SI. If the terminal station determines that the uplink is not idle, it waits until the next SI transmission.

When the terminal station determines that the uplink line is "vacant", in step S3, an UPPH (Upstream Packet Header) for collision detection including the ID of the terminal station and a CRC (Cyclic Redundancy Code) for error detection. Is transmitted to the control packet for the registration request in the slot in the uplink control window.

FIG. 4B shows an upstream frame.
The upstream frame is composed of a control window and a payload window. Each window is composed of a plurality of slots. For example, slot 1 of the control window
G (guard bit), PR (preamble), UW (unique word for synchronization), UPPH, control information, and G. The payload window is composed of variable-length data packets, and one data packet is composed of an arbitrary number of slots. One data packet is G, O
H (overhead), one or more payloads and FE
It is composed of C and G.

Note that the terminal station performs transmission at the maximum transmission power of the terminal station, so that even at the time of a packet collision, the difference between the reception powers of signals from other terminals becomes large with respect to the capture ratio. Registration can be started more likely. In addition, the base station can calculate the loss due to the propagation path by measuring the received signal strength, and the base station transmits the necessary and sufficient transmissions from the terminal to the terminal station during actual communication after registration is completed. By indicating the power, there is an advantage that the interference power from the terminal can be reduced and the subscriber capacity of the entire system can be increased.

In step S4, the base station determines whether or not control packet collision has occurred on the transmission line. That is, the base station demodulates the received UPPH,
The presence or absence of an error is determined using C, and if there is an error, it is determined that a control packet collision has occurred on the transmission line. If it is determined that a control bucket collision has occurred on the transmission line, the base station notifies the packet collision using the SI of the downlink control packet in step S5.

The terminal station determines whether or not a packet collision has occurred by demodulating the control packet from the base station. When it is indicated that a packet collision has occurred, in step S6, the terminal station temporarily stops transmitting the packet, waits for a random time, and enters a back-off process of transmitting a registration request packet again. .

On the other hand, if the base station determines that there is no error in the control packet, in step S7, it uses the SI of the downlink control packet to send a reference signal for registration to the target terminal station. Send Further, the base station indicates a transmission channel used for registration. In addition,
The base station may also specify the length of the data slot used for transmission. For example, it is conceivable to shorten the time required for the direction estimation by increasing the length of the reference signal used for the direction estimation as long as the congestion of the communication line allows.

The base station transmits an echo back to confirm the ID of the terminal station as part of the payload of the downlink data packet (step S7). Upon receiving the instruction from the base station, the terminal station determines whether or not the ID echoed back from the base station matches its own ID. If the result of the determination is that the IDs do not match, the terminal station enters backoff (Backoff) processing. On the other hand, if the IDs match, the reference signal for registration is transmitted in the data packet in the slot in the uplink payload window according to the instruction (step S9). If the IDs do not match, the terminal station shifts the processing to step S6 and enters back-off processing.

In step S9, the base station starts to estimate the direction of the terminal station using the direction estimation algorithm. That is, the received signal from the receiving circuit 18 is supplied to the received signal shaping circuit 21 of the control circuit 20. The reception signal shaping circuit 21 shapes the reception signal and outputs it to the phase shift amount / amplitude weight calculation unit 23. Further, the reference signal reproducing circuit 22 reproduces the reference signal from the output of the received signal shaping circuit 21 and
Output to the amplitude weight calculator 23.

The phase shift / amplitude weight calculator 23 calculates the CP
Under the control of U24, a direction estimation algorithm is executed based on the input reception signal and reference signal and the measurement result of the reception signal strength of each array antenna.

The base station adds FE to the received packet.
If a transmission error that cannot be corrected only by error correction processing using C (error correction bit) is detected, an instruction is issued to the terminal station to start back-off processing using SI (step S11). The terminal station enters the back-off process in response to (step S6).

If the transmission and reception of the reference signal are performed without detecting an uncorrectable transmission error, the base station continues the terminal station direction estimation algorithm (step S1).
2). When the direction estimation algorithm converges in step S13, the base station instructs the terminal station to stop transmitting the reference signal for registration by using the SI of the downlink control packet in step S14. Further, based on the direction estimation result based on the calculation result, the base station stores the direction of the terminal station and the weighting coefficient of the array antenna based on the direction together with information for identifying the terminal station such as the ID of the terminal station in a memory or a storage (not shown). Record in the device etc. and complete the registration.

The transmission power of the terminal station necessary and sufficient for the next and subsequent communications is determined based on the received signal strength measurement by the base station, and the transmission power value is notified to the terminal station together with an instruction to stop transmission. It is also possible to prevent an unnecessary large level signal from being transmitted from the terminal station, thereby increasing the subscriber capacity of the system.

Next, with reference to FIG. 3, a description will be given of a procedure in the case where the terminal station performs a call by making a call. In FIG. 3, the same procedures as those in FIG.

At the time of actual communication between the terminal station and the base station, in step S20, the terminal station transmits a communication request packet instead of transmitting a registration request packet at the time of registration. If the base station receives the communication request packet without error in step S4, the base station reads out the information of the terminal station recorded in the storage device in the next step S21, and determines the direction of the terminal station as the communication partner. The weighting factor of each array antenna is loaded as an initial value so that the maximum directivity of the array antenna matches.

The phase shift amount / amplitude weight calculator 23 calculates the CP
Using the information loaded by U24, information on the amount of phase shift and amplitude weight set for each array antenna is output. The information on the amount of phase shift is separated for each antenna by the DEMUX 19 and supplied to each phase shifter of the phase shifter unit 11 as an analog phase shift control signal by each DAC of the DAC unit 12. The information of the amplitude weight is DEMUX2
5, each antenna is separated by the DAC unit 26, converted into an analog amplitude weight control signal by each DAC of the DAC unit 26, and passed through each filter of the LPF unit 16 to the gain unit 15
Is supplied to each of the gain devices.

Thus, the base station forms at least an antenna pattern used at the time of reception in a short time. In the present embodiment, only the antenna pattern used at the time of reception is set according to the direction of the terminal station, but the antenna pattern used at the time of transmission is set according to the direction of the terminal station. It is clear that this may be done. For example, FDD (Frequency Division Duplex)
When the system is adopted, information such as weighting factors recorded in the storage device may be loaded as an initial value also at the time of transmission, and an antenna pattern used at the time of transmission may be set.

In step S21, the base station performs
The permission to continue packet transmission is also transmitted. Also in this case, the base station may set an antenna pattern for transmission.

The terminal station determines whether or not the ID echoed back from the base station matches its own ID. If the terminal station determines that the ID matches, the terminal station transmits information to be transmitted in a slot in the payload window. It is transmitted as a data packet (step S22).

On the other hand, the base station uses the received signal of the information packet or a part (unique word) of the information packet to update the weighting coefficient of the array antenna as necessary, such as when an interference station is detected. Is started (step S22). As an algorithm for correcting and occasionally updating the weighting coefficient, LMS (Least Mean Squ
are), CMA (Constant Modulus Algorithm), CM
P (Constrained Minimization of Power) and the like can be considered. The phase shift amount / amplitude weight calculator 23 sequentially updates the information obtained by this algorithm (step S2).
3) Output to DEMUX 19, 25.

In this way, in the phase shifter section 11 and the gain section 15, an optimal phase shift amount and amplitude weight are given to the received signal of each array antenna, and an optimal directivity gain is obtained with a desired terminal station. Can be In addition to adjusting the directivity gain with the desired terminal station, it is possible to direct the directivity null toward another terminal station which is the direction of arrival of the interference wave.

The procedures shown in FIGS. 2 and 3 are for the case where the terminal station calls and performs communication. However, when the terminal station is called from the base station, the first transmission path state notification and the terminal station call are made. The transmission of the communication request packet from the base station and the processing at the time of error are unnecessary, and the same procedure is performed except that the base station side notifies the terminal station of the call instead of permitting the continuation of the packet transmission using the SI. PTM using array antenna
P-type wireless communication can be performed.

Further, in a communication channel used for detecting the direction of the terminal station, the terminal station uses one signal of a random sequence having extremely strong autocorrelation and small cross-correlation as a transmission signal, and uses the signal as a neighboring signal. By using different transmission signals in the wireless zone, it is conceivable to reduce the error in the direction estimation due to co-channel interference.

In this embodiment, the input power of the interference wave can be reduced by reducing the gain of the base station antenna in the direction of the interference wave, and the directivity of the base station antenna in the direction of a specific terminal can be reduced. By increasing the gain, the transmission power of the specific terminal can be reduced, so that the distance interval of frequency repetition can be reduced.

FIG. 5 is an explanatory diagram for explaining an interference wave in a normal subscriber radio system using a sector antenna having a 4-cell frequency repetition arrangement. In FIG. 5, a hexagon indicates a service area provided by one radio base station, and a circle at the center of the hexagon indicates a radio base station. Arrows indicate terminal stations. The thick line indicates the boundary of the unit of frequency repetition.

For the radio base station 123, the terminal station 12
Reference numerals 1 and 122 denote interference sources from other service areas.
Although the interference level of terminal station 122 is sufficiently low,
1 is substantially the same as the distance (3d) from the base station 123 to the farthest terminal station in the service area of the base station 123. Therefore, assuming a propagation situation similar to free space propagation, the terminal station 121, which is the interference source, has the same interference level as that of the terminal station 122 using the smart antenna in the present embodiment, so that the direction of the interference station is the same. What is necessary is just to reduce the gain.

The ratio of the distance from the base station 123 to the terminal stations 122 and 121 is 5: 3. Therefore, 20 log (5
/3)=4.44 dB if the antenna gain is reduced with respect to the gain of the sector antenna, and the gain in the direction of a desired terminal station can be made equal to that of the sector antenna.
It is possible in principle to eliminate frequency repetition (one-cell frequency repetition). In the base station 123 of FIG.
3 of all frequency channels that can be assigned to the system
Assuming that / 4 is unusable, eliminating all frequency repetitions allows base station 123
But it can be used. Therefore, in this case, it is necessary to take into account the positional relationship of the terminals, the frequency of traffic, the size of the wireless device in the base station, and the like, but the subscriber capacity of the system can be quadrupled at the maximum. it can.

As an algorithm for the base station to detect the direction of the terminal station during terminal registration, MUSIC (MUSIC (MUSIC)
ultiple Signal Classification) and ESPRIT (Estim
ation of Signal Parameters via Rotational Invarian
It is also conceivable to use an LCMV-based or DCMP-based algorithm, such as a super-resolution algorithm represented by ce Techniques).

In particular, by using an algorithm that can be used for both direction detection and optimization for suppressing an interference wave by changing a very small part of the algorithm, the scale of hardware can be reduced, and A unique effect that the configuration can be achieved at low cost is produced. The LCMV-based algorithm can satisfy this condition.

The LCMV algorithm receives only incoming waves from a specific direction without distortion and suppresses incoming waves from other directions. That is, it is characterized in that the desired wave and the interference wave are distinguished according to the direction of arrival, and there is a special effect that a training signal required in an LMS algorithm is unnecessary.

The direction can be estimated by using the LCMV algorithm as follows. That is, when a new terminal station starts operation or resumes operation for the first time after an existing terminal station changes its position, the terminal station transmits a registration request signal to the base station. The base station specifies a communication channel and transmission power for terminal registration to the terminal station. The terminal station transmits on the designated communication channel at the designated transmission power.

The base station sets the direction in which the incoming wave can be received without distortion, and receives the transmission signal of the terminal station using the LCMV system algorithm. When the set direction matches the terminal station direction, the terminal station transmission signal is not suppressed.
The output of the array antenna does not become smaller than the transmission power specified by the base station. On the other hand, when the set direction does not match the terminal station direction, the terminal station transmission signal is suppressed, so that the output of the array antenna becomes smaller than the transmission power specified by the base station. As a result, the terminal direction can be detected.
The base station stores this terminal station direction, and then uses it as the initial value of the weighting coefficient of the LCMV-based algorithm when starting a call.

As described above, in the present embodiment, the direction estimation algorithm is executed for each terminal station when the terminal station is registered, the estimation result is stored for each terminal station, and the estimation result stored during actual communication is stored. Is loaded as an initial value to set the antenna pattern. Accordingly, when the terminal station and the base station start a call, the directivity gain is increased in the direction of the desired terminal station, and the directivity gain is decreased in the direction of another terminal station that is an interference source. Can be remarkably reduced, and a communication channel can be quickly established.

When employing a communication system in which not only the direction but also the frequency and the time slot are available, it is necessary to select a frequency, a time slot and an antenna pattern which are the least likely to cause interference. Is also conceivable.

Further, in the above embodiment, the weighting factor of the array is given by controlling the amplitude and phase of the IF signal, but instead of controlling the IF signal, the amplitude and phase of the RF signal are controlled. Alternatively, a digital beam forming technique such as AD conversion of the received signal of each array and weighting by digital signal processing may be used. Further, a combination of these IF control, RF control, and digital beam forming may be used. The same effect can be obtained by performing the weighting by using.

FIG. 6 is a block diagram showing another embodiment of the present invention. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. This embodiment is an example in which weight control of an array antenna is performed also in a transmission system.

In this embodiment, a control circuit 30 for controlling a reception system and a transmission system is provided in place of the control circuit 20. The control circuit 30 is a phase shift / amplitude weight calculator 2
The difference from the control circuit 20 in FIG. The phase shift amount calculating section 33 receives signals from the received signal shaping circuit 21 and the reference signal reproducing circuit 22 and is controlled by the CPU 24 to set a phase shift for each antenna based on the received signal strength of each array antenna. And calculate the amount of phase shift by using DEMUX19 and DEMUX.
35.

The transmission IF signal generation circuit 37 of the transmission system generates a transmission IF signal and outputs it to the distributor 38. Distributor 38
Distributes the transmission IF signal to each array antenna and outputs it to each phase shifter of the phase shifter group 39. The DEMUX 35 separates the information of the phase shift amount from the phase shift amount calculation unit 23 for each antenna and outputs the information to each DAC of the DAC unit 36. Each DAC converts the information of the phase shift amount into a phase shift amount control signal, and provides the same to each phase shifter of the phase shifter group 39. Each phase shifter 39 shifts the phase of the transmission IF signal from the splitter 38 based on the phase shift amount control signal, and provides the same to each filter of the band-pass filter group 40.

Each of the filters of the band-pass filter group 40 limits the band of the input transmission IF signal, and
D) Output to each ADD of the unit 41. When forming a quadrature beam, transmission IFs from each IF / BB circuit
D, the ADD combines the input signals and outputs the combined signals to the buffers of the buffer unit 42.

The output of each buffer is provided to each multiplier of the multiplier section 43. The output of the oscillator 5 is separated into a receiving system and a transmitting system by a DIV 44, and a local oscillation output having a phase corresponding to each antenna of the transmitting system is given to each multiplier by a DIV 45. The output of each multiplier of the multiplier unit 43 is supplied to each buffer of the buffer group 47 via each filter of the band-pass filter group 46. The transmission IF signal is frequency-converted into an RF signal by each multiplier. R
The transmission signal converted into the F signal is supplied from each buffer to each array antenna of the antenna group 1 via each filter of the band-pass filter group 48 and each switch of the switch group 49.

In the embodiment thus configured, the information on the amount of phase shift from the phase shift amount calculating section 23 is supplied to the DMUX 19 of the receiving system and the DEMUX of the transmitting system.
35. As a result, not only the antenna directivity at the time of reception is optimized, but also the antenna directivity at the time of transmission is optimized.

Other functions and effects are the same as those of the embodiment shown in FIG.

The present invention is not limited to the above embodiments. For example, in the embodiment of FIG. 1, both the phase shift amount and the amplitude weight are controlled, but only the phase shift amount is controlled. It is apparent that both the phase shift amount and the amplitude weight may be controlled in the embodiment of FIG.

Also, as shown in FIGS. 1 and 6, the IF signal is branched by a directional coupler, a distributor, or the like, and a plurality of I / O signals are divided.
F / BB circuits 10 and 50 branch the IF signal, or IF signals created by a plurality of IF / BB circuits 50
By adding at 1, transmission and reception with a plurality of terminal stations in the same time zone using the same frequency channel may be considered.

Note that in order to prevent interference of co-frequency channel signals during transmission, a reference (H. Liu and G. Xu, "Mul
tiuser Blind Channel Estimation and Spatial Channe
l Pre-Equalization, "Proc. ICASSP '95, Detroit, M
I, May 1995), based on the channel response obtained from the uplink received signal and the estimation result of co-channel interference, the inter-symbol interference
It is conceivable to obtain the characteristics of a pre-equalization filter that can receive a signal from which co-channel interference has been removed, and to perform a convolution operation on the transmission signal in advance according to the obtained characteristics.

The information stored in the control circuit may be the estimation result of the azimuth obtained for each terminal station or the weighting coefficient of each array antenna obtained from the estimation result. When azimuth information is stored, an initial weighting value is calculated from the azimuth information stored when actual communication is started. In this case, the stored information can be used even when the weighting method is changed or when the number or characteristics of the element antennas constituting the array antenna are changed. On the other hand, when storing the information of the weighting coefficient, the stored information is used as it is when starting the actual communication. In this case, the amount of processing until the start of actual communication can be further reduced.

[0081]

As described above, according to the present invention, even when interference is reduced by using an adaptive array antenna, the time required until communication becomes possible can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a radio base station according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the wireless communication system according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the wireless communication system according to the present invention.

FIG. 4 is an explanatory diagram showing a frame configuration used for transmission and reception.

FIG. 5 is an explanatory diagram for describing the embodiment in FIG. 1;

FIG. 6 is a block diagram showing another embodiment of the present invention.

FIG. 7 is an explanatory diagram for explaining a conventional example.

FIG. 8 is an explanatory diagram for explaining a conventional example.

FIG. 9 is an explanatory diagram for explaining a conventional example.

[Explanation of symbols]

10 IF / BB circuit, 11 phase shifter group, 19, 25
DEMUX, 15 Gain group, 20 Control circuit, 23
Phase shift / amplitude weight calculator, 24 CPU

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Osamu Shibata 1st address, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in the Toshiba R & D Center (reference) 5J021 AA05 AA06 AA11 CA06 DB02 DB03 EA04 FA06 FA13 FA17 FA20 FA23 FA24 FA26 FA29 FA32 GA02 GA08 HA05 HA10 5K067 AA23 BB02 DD13 DD20 DD24 DD51 EE02 EE10 FF03 FF13 HH05 HH24 JJ53 JJ56 JJ66 KK02 KK03

Claims (10)

[Claims] 1. A terminal station owned by a subscriber for communication, a base station accommodating the terminal station, and communication between the terminal station and the base station to connect the terminal station to the base station. Registration means for registering in the registration means, detection means for detecting at least azimuth information of the terminal station with respect to the base station at the time of registration in the registration means, storage means for storing a detection result of the detection means, the terminal station and the A wireless communication system comprising: antenna characteristic control means for controlling antenna characteristics of at least one of the terminal station and the base station using information stored in the storage means as an initial value when communicating with a base station. 2. A detecting means for detecting information on at least the direction of the terminal station at the time of registration by communication of the terminal station; a storing means for storing a detection result of the detecting means; and a storing means for communicating with the terminal station. A base station for controlling antenna characteristics at the time of transmission and / or reception with respect to the terminal station using the information stored in the base station as an initial value. 3. A plurality of antenna elements, a direction detection circuit for detecting a direction of the terminal station at the time of registration by communication of the terminal station with a base station, and a storage device for storing a detection result of the direction detection circuit for each terminal station An array antenna, comprising: a weighting coefficient calculation circuit that assigns a weighting coefficient calculated using information recorded in the storage device as an initial value to transmission / reception signals received by the plurality of antenna elements. 4. The registration unit executes the registration when the terminal station newly starts operation or when the existing terminal station restarts operation after changing its position, The base station transmits a second control signal in response to a first control signal from the terminal station, whereby the base station specifies a communication channel in subsequent communication with the terminal station, and specifies the communication channel. During communication using the communication channel, the direction of the terminal station is detected and stored in the storage unit for each terminal station, and the antenna characteristic control unit obtains the maximum directivity for the terminal station performing communication. The wireless communication system according to claim 1, wherein characteristics are set. 5. The registration means, when the terminal station newly starts operation or when the existing terminal station restarts operation after changing its position, uses the maximum possible transmission power. The terminal station performs transmission, and the antenna characteristic control means changes a desired transmission power obtained from the reception power at the time of registration to a desired transmission power during a call between the terminal station and the base station. Wireless communication system. 6. The signal sequence used in communication using a communication channel designated by the detection means is set to a different transmission signal sequence in a wireless zone adjacent to the terminal station. A wireless communication system as described. 7. The method according to claim 6, wherein the detecting unit specifies a length of a signal transmitted by the terminal station by the second control signal or transmission from the base station to the terminal station in subsequent communication. The wireless communication system according to claim 4. 8. The antenna characteristic control means, when the terminal station and the base station start talking, increases the directivity gain in the direction of the terminal station and communicates with the current base station. 2. The wireless communication system according to claim 1, wherein the antenna characteristic is controlled so as to reduce the directional gain in the direction stored in the storage device when another terminal station is registered. 9. The first control from the terminal station when the terminal station newly starts operation or when the existing terminal station restarts operation after changing its position. By transmitting the second control signal to the signal, to specify a communication channel in the subsequent communication with the terminal station, to detect the orientation of the terminal station at the time of communication using the specified communication channel, The radio base station according to claim 2, wherein the storage unit stores the terminal characteristics for each terminal station, and wherein the antenna characteristic control unit sets an antenna characteristic with which the maximum directivity is obtained for the terminal station performing communication. . 10. The method according to claim 3, wherein the weighting coefficient calculation circuit uses an LCMV algorithm for both a direction detection for detecting the direction of the terminal station and an optimization for suppressing an interference wave. An array antenna as described.