JP2003051775A - W-cdma/tdd base station and array antenna directivity control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a W-CDMA/TDD base station provided with a function of reducing the effect of an arriving strong interference wave. SOLUTION: An array algorithm control section 105 receives the outputs of a plurality of inverse spread sections 103, carries out a prescribed algorithm, and outputs a weight control signal to direct a null of an adaptive array antenna 102 to an array synthesis section 104 in the direction of an FDD terminal 703. The array synthesis section 104 receives the outputs of a plurality of the inverse spread sections 103, applies weighting to the outputs amplifier circuit according to the weight control signal from the array algorithm control section 105 and gives a desired signal from the TDD terminal 702 to a channel estimate/pass synthesis section 713.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a W-CDMA / TDD base station and an array antenna directivity control method for transmitting / receiving to / from a mobile terminal by a TDD method.

[0002]

2. Description of the Related Art Next-generation mobile communication IMT-2000 (Inter
national Mobile Telecommunication-2000) is ITU
(International Telecommunication Union) is a standardized third generation mobile communication system. In the third generation mobile communication system, Code Division Multiple Access (CDMA) is adopted as a radio access method. In Japan, DS-CDMA (Direct Sequen
ce-CDMA) based W-CDMA (Wideband CDMA)
Has been decided to be adopted.

In the TDD system of this W-CDMA mobile communication system, transmission / reception between the base station and the mobile terminal is performed.
This is performed by a TDD (Time Division Duplex) method in which the uplink and downlink signals are transmitted in the same frequency band in a time division manner.
In the TDD method, strong detection performance improving technology such as Joint Detection exists, so it is desirable to operate in a region where the time spread of multipath is small in order to take advantage of its characteristics. Because of this, it is expected that the cell will be operated with a relatively small cell radius of about 100 m. Hereinafter, a base station based on the TDD scheme will be referred to as a TDD base station, and a mobile terminal based on the TDD scheme will be referred to as a TDD terminal.

In the CDMA mobile communication system, it is desired to communicate with the minimum transmission power that satisfies the required quality. Since the cell radius is small in the TDD system, T
The amount of attenuation between the DD terminal and the TDD base station is small, and communication is performed with power corresponding to that (for example, 4 dBm).

On the other hand, in the IMT-2000, as a transmission / reception method between a base station and a mobile terminal, an FDD (Frequency Division Duplex) that uses different frequencies for the uplink and the downlink is used.
The plex method is also defined as a standard. In the FDD system, a macro cell having a cell radius of several kilometers can be formed. In the FDD system operated in this macro cell,
The FDD terminal will transmit with power according to the distance attenuation of several km (for example, 24 dBm). Hereinafter, a mobile terminal using the FDD method will be referred to as an FDD terminal.

FIG. 7 shows a conventional W-CDMA / TD.
The structure of a D base station is shown. As shown in this figure, the conventional T
The DD base station 701 includes an antenna 711 and a despreading unit 71.
2. Channel estimation / path combining unit 713 and demodulation processing unit 7
14 are provided. The despreading unit 712 extracts a desired signal from the code-multiplexed signal using a predetermined spreading code.
The channel estimation / path combination unit 713 performs channel estimation from the despread signal and combines each path in the estimated channel. The demodulation processing unit 714 demodulates the signal from the channel estimation / path combining unit 713 and outputs a reception baseband signal.

[0007]

However, as described above, in the IMT-2000, since the TDD system and the FDD system are defined as standard, it is possible that both coexist in adjacent frequencies. The following problems occur in the environment.

The line set up by the FDD terminal is mainly always connected, which causes interference in any time slot as seen from the TDD base station. As shown in FIG. 7, consider a case where an FDD terminal 703 accommodated in a peripheral macro cell approaches a TDD base station 701 communicating with a surrounding TDD terminal 702.

In such a case, the radio wave transmitted from the FDD terminal 703 is received by the TDD base station 701 as an interference wave.
The receive filter of the TDD base station 701 is designed to remove adjacent channel interference, so the FDD terminal 70
Although it can be reduced to some extent by the transmission filter of No. 3 and the reception filter of the TDD base station 701, the FDD terminal 7
Since the transmission power of 03 is large, the interference is not negligible.

The present invention has been made in view of the above problems, and provides a W-CDMA / TDD base station and an array antenna directivity control method having a function of reducing the influence of an incoming strong interference wave. It is an object.

[0011]

The W-CDMA / of the present invention
The TDD base station receives a weight control signal by controlling a plurality of antennas, a plurality of despreading means provided for each of the plurality of antennas, and controls the weighting of the directivity combination of the plurality of antennas. Weight combining means for extracting a desired signal from the output of the despreading means, and the weight for receiving the outputs of the plurality of despreading means and directing nulls in the directivity of the plurality of antennas to the arrival direction of the strong interference wave. And an array algorithm control means for generating a control signal.

According to this structure, since the adaptive array antenna is introduced to form the null-oriented weight for the FDD terminal whose transmission power is larger than that of the TDD terminal, the weights are continuous in time. It becomes possible to cancel the incoming interference signal, and the TDD terminal can receive the interference from the FDD terminal in a small state.

Also, in the W-CDMA / TDD base station of the present invention, in the above W-CDMA / TDD base station, the array algorithm control means performs least squares on a signal on which despreading is performed and user identification is performed. The weight control signal is generated by applying a method / algorithm.

According to this structure, the weight control signal is generated by the least square method / algorithm. By generating this weight control signal when receiving all signals from the TDD terminals accommodated by the base station, all TDD terminals connected to the corresponding base station can receive with a small interference wave. Becomes

Also, in the W-CDMA / TDD base station of the present invention, in the W-CDMA / TDD base station, the array algorithm control means is an arbitrary one of the signals for which user identification is performed by despreading. The power inversion adaptive array algorithm is applied to the signal for the slots of the above to generate the weight control signal.

According to this configuration, the power inversion adaptive array algorithm is applied to the signal subjected to the despreading and the user identification to generate the weight control signal. By generating this weight control signal when receiving all signals from the TDD terminals accommodated by the base station, all TDD terminals connected to the corresponding base station
It is possible to receive in a state where the interference wave is small.

Further, in the W-CDMA / TDD base station of the present invention, in the W-CDMA / TDD base station, the array algorithm control means applies a power inversion adaptive array algorithm to a signal before user identification. To generate the weight control signal.

According to this configuration, the power inversion adaptive array algorithm is applied to the signal before user identification to generate the weight control signal. By generating this weight control signal when receiving all signals from the TDD terminals accommodated by the base station, all TDD terminals connected to the corresponding base station can receive with a small interference wave. Becomes

Also, in the W-CDMA / TDD base station of the present invention, in the W-CDMA / TDD base station, the array algorithm control means estimates the arrival direction of an interference wave using a signal before user identification. Then, the weight control signal for forming a null in the direction prepared in advance is generated.

According to this structure, the arrival direction of the interference wave is estimated by using the signal before the user identification, and the weight control signal which is prepared in advance and forms the null in that direction is generated. The T that the base station accommodates this weight control signal
By generating it when receiving all signals from the DD terminals, it becomes possible for all TDD terminals connected to the corresponding base station to receive in a state of small interference waves.

Further, in the W-CDMA / TDD base station of the present invention, in the W-CDMA / TDD base station, the array algorithm control means outputs a signal for which user identification is performed after despreading in an arbitrary slot. The weight control signal is generated by selecting the weight having the best reception SIR from a plurality of weights having nulls in an arbitrary direction.

According to this configuration, the signal having the best received SIR is selected from a plurality of weights having nulls in an arbitrary direction by using the signal on which the user identification is performed after despreading in an arbitrary slot. Since the weight control signal is generated, all TDD terminals connected to the corresponding base station are
It is possible to receive in a state where the interference wave is small.

Further, the W-CDMA / TDD base station of the present invention uses the array algorithm control means and the weight control signal generated by the array algorithm control means at the time of transmitting the transmission signal to directivity of a plurality of antennas. And a weight multiplication means for controlling.

According to this structure, the TDD to the FDD terminal is
Since the interference from the base station is reduced, it is possible to improve the SIR at the FDD terminal. By this means, it is possible to maintain high quality when the FDD terminal receives a signal from the FDD base station. Therefore, the error rate of the transmission power control command is reduced and the transmission power of the FDD terminal is maintained appropriately, so that the interference power received by the TDD base station from the FDD terminal is reduced.

According to the array antenna directivity control method of the present invention, the plurality of despreading means provided for each of the plurality of antennas forming the adaptive array antenna are received and the plurality of the plurality of antennas in the direction of arrival of a strong interference wave are received. A weight control signal for directing a null in the directivity of the antenna is generated, and the weighting of the directivity combination of the plurality of antennas is controlled based on the generated weight control signal.

According to this method, it is possible to form a null-oriented weight for an FDD terminal whose transmission power is higher than that of a TDD terminal. This makes it possible to remove interference signals that arrive consecutively in time, and
The DD terminal can receive the interference from the FDD terminal in a small state.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is that the line transmitted from an FDD terminal is mainly a constant transmission, and it is an adaptive characteristic in view of the fact that interference occurs in any time slot as seen from the TDD base station. The introduction of the array antenna is to remove interference signals that arrive continuously in time.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG.1 is a block diagram showing a configuration of a W-CDMA / TDD base station according to Embodiment 1 of the present invention. In this figure, the TDD base station 10
Reference numeral 1 denotes a plurality of antennas 102-1 to 102-N forming the adaptive array antenna 102, a plurality of despreading units 103 provided for each antenna, and an array combining unit (which receives outputs of the plurality of despreading units 103 ( A weight combining means) 104 and an array algorithm control section (array algorithm control means) 105, a channel estimation / path combining section 713, and a demodulation processing section 714.

The array algorithm control unit 105 receives the outputs of the plurality of despreading units 103, executes a predetermined algorithm, and directs the array combining unit 104 to direct the null of the adaptive array antenna 102 toward the FDD terminal 703. A wait control signal is output.

The array combining unit 104 includes a plurality of despreading units 1.
03 output, the array algorithm control unit 105
According to the weight control signal from
The desired signal from D terminal 702 is input to channel estimation / path combining section 713. Channel estimation / path combining unit 713
Performs channel estimation from the despread signal and combines each path in the estimated channel. Demodulation processing unit 714
Demodulates the signal from the channel estimation / path combination unit 713 and outputs a reception baseband signal.

Next, the TDD base station 1 having the above configuration
The operation of 01 will be described. In the first embodiment, TDD
When the user of the terminal 702 has been connected for a relatively long time, interference is removed when the signal (desired signal) from the user is taken out as follows.

In the array algorithm control unit 105, nulls may be directed in the interference wave direction when the desired signal after despreading by a plurality of despreading units 103 and user identification is taken out in the observed section. Possible algorithms (eg least squares method; MMSE (Minimum Mean Squa)
red Error)) is used to output a weight control signal for directing null to the FDD terminal 703 to the array combining unit 104. As a result, the adaptive array antenna 1 that directs the null in the direction of the incoming wave from the FDD terminal 703.
The weighting of 02 is performed, and the desired wave can be extracted.

The weight according to the MMSE algorithm is
It can be expressed as the following equation (1). In the equation (1), d (t) is the desired signal, X (t) is the input signal vector to the adaptive array antenna 102,
E [•] is a long-term average.

[0035]

[Equation 1]

The TDD base station 101 transmits this to the TDD terminal 7
By applying when receiving all signals from 02,
All TDD terminals 7 connected to the corresponding TDD base station 101
02 can be received with a small amount of interference from the FDD terminal 703.

As described above, according to the present embodiment, since the adaptive array antenna is introduced, it is possible to form a null-oriented weight for an FDD terminal having a higher transmission power than that of a TDD terminal. By this means, it is possible to remove interference signals that arrive consecutively in time, and the TDD terminal can receive interference from the FDD terminal in a small state.

(Embodiment 2) FIG.2 is a block diagram showing a configuration of a W-CDMA / TDD base station according to Embodiment 2 of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to. In the second embodiment, in the configuration shown in FIG. 2, array algorithm control section 202 provides an interference canceling weight control signal to array combining section 104 using an arbitrary signal in TDD base station reception. .

The signal to be used is the signal after despreading in any slot and user identification. Regardless of which timing the signal is handled, the FDD terminal 703 continuously transmits the interference signal to the TDD base station 201 as described above. Using this property, the array algorithm control unit 202 directs nulls to the FDD terminal 703 by using an algorithm that directs nulls to strong continuous interference (for example, PIAA (Power Inversion Adaptive Array)). The weight control signal is output to the array synthesis unit 104.

The weight according to the PIAA algorithm is
It can be expressed as the following equation (2). In the equation (2), X (t) is an input signal vector to the adaptive array antenna 102 arbitrarily extracted, E
[•] is an average for a long time.

[0041]

[Equation 2]

By applying the calculated weights when receiving all the signals from the TDD terminal 702, all the TDD terminals 702 connected to the corresponding TDD base station 201 cause interference from the FDD terminal 703. Can be received in a small state.

(Embodiment 3) FIG.3 is a block diagram showing a configuration of a W-CDMA / TDD base station according to Embodiment 3 of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to. In the third embodiment, in the configuration shown in FIG. 3, array algorithm control section 302 uses a signal before user identification in TDD base station reception to give a weight control signal for interference cancellation to array combining section 104. ing.

The signal used is a signal before despreading at an arbitrary timing. Regardless of which timing the signal is handled, as described above, the FDD terminal continuously operates the TD.
The interference signal is continuously transmitted to the D base station. Using this property, an FDD terminal 703 is used by using an algorithm (for example, PIAA) that directs null to strong interference that continuously exists.
A weight control signal for directing null to is output to the array combining unit 104. The weight by the PIAA algorithm can be expressed as the above equation (2).

Similar to the second embodiment, the calculated weights are used to apply when receiving all signals from the TDD terminal 702, so that all TDD terminals 702 connected to the corresponding TDD base station 301 are connected. However, it is possible to receive the signal from the FDD terminal 703 with a small interference.

(Embodiment 4) FIG.4 is a block diagram showing a configuration of a W-CDMA / TDD base station according to Embodiment 4 of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to.

In the fourth embodiment, in the configuration shown in FIG. 4, array algorithm control section 402 gives a weight control signal for interference cancellation to array combining section 104 using a signal before user identification in TDD base station reception. . The array algorithm control unit 402 includes an arrival direction estimation unit 403.
And a weight generation unit 404. Arrival direction estimating section 403 estimates the arrival directions of strong continuous interference waves, and weight generating section 404 causes FDD terminal 703.
A weight control signal for directing null to is output.

The signal used is a signal before despreading at an arbitrary timing. Regardless of which timing the signal is handled, the FDD terminal 703 continues to transmit the interference signal to the TDD base station 401 as described above.
Using this property, an algorithm (eg, Capon method) that estimates the direction of arrival of consecutive strong interference waves is used.
A weight control signal for directing null to the FDD terminal 703 is output to the array synthesis unit 104.

The direction of arrival estimation by the Capon method can be expressed by the following equation (3). In Expression (3), X (t) is an arbitrarily extracted input signal vector to the adaptive array antenna 102, and E [•] is a long-term average.

[0050]

[Equation 3]

By defining the correlation matrix R and the steering vector a as in the equation (3), θ that maximizes P (θ) is calculated. This θ is the estimated arrival direction. After the arrival direction θ is estimated, a weight having a null in the θ direction prepared in advance is used to apply when receiving all signals from the TDD terminal 702, so that the corresponding TDD base station 4
All TDD terminals 702 connected to 01 can receive the signal from the FDD terminal 703 with a small interference.

(Embodiment 5) FIG.5 is a block diagram showing a configuration of a W-CDMA / TDD base station according to Embodiment 5 of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to.

In the fifth embodiment, in the configuration shown in FIG. 5, array algorithm control section 502 gives a weight control signal for interference cancellation to array combining section 104 using an arbitrary signal in TDD base station reception. The array algorithm control unit 502 includes an SIR calculation unit 503 and a weight generation unit 504. SIR calculation unit 503
Is SIR (Signal to Interference Ra) of each user signal.
tio), and the weight generation unit 504 selects the weight that gives the maximum SIR when receiving the signal of the corresponding user.

The signal used is the signal after despreading in any slot and user identification. No matter which timing the signal is handled, as described above, the FDD
The terminal 703 continuously transmits the interference signal to the TDD base station 501.

The array algorithm control unit 502 prepares a plurality of weights having nulls in arbitrary directions in advance, and sets the maximum SI when receiving the signal of the corresponding user.
Use a weight that gives R. FDD with this weight
It is determined that the strong interference of the terminal 703 can be eliminated, and T
It is applied when receiving all signals from the DD terminal 702. As a result, all the TDD terminals 702 connected to the corresponding TDD base station 501 can receive the signal from the FDD terminal 703 with a small interference.

(Embodiment 6) FIG. 6 is a block diagram showing the configuration of a W-CDMA / TDD base station according to Embodiment 6 of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to.

In the sixth embodiment, in the configuration shown in FIG. 6, when the array algorithm control unit 602 transmits a signal to the accommodated TDD terminal 702, the direction from the TDD base station 601 to the FDD terminal 703. A weight control signal having null is given to the weight multiplication unit (weight multiplication means) 604. The weight multiplication unit 604 controls the directivity of the adaptive array antenna 102 using the weight control signal when transmitting the signal.

As a result, the TDD base station 601 sends the FD
Since interference with the D terminal 703 is reduced, it is possible to improve SIR in the FDD terminal 703. As a result, it is possible to maintain high quality when the FDD terminal 703 receives a signal from an FDD base station (not shown).
The error rate of the transmission power control command is reduced. As a result F
The transmission power of the DD terminal 703 becomes low, and the TDD base station 6
The interference power that 01 receives from the FDD terminal 703 is reduced. In the configuration of the transmission unit shown in FIG.
3 is a spreading unit, 605 is a distributor, and 606 is a transmission signal generator. The diffusion unit 603 is used for each of the antennas 102-1 to 10-10.
It is provided every 2-N.

[0059]

As described above, according to the present invention,
It is possible to provide a W-CDMA / TDD base station having a function capable of reducing the influence of an incoming strong interference wave.

[Brief description of drawings]

FIG. 1 is a W-CDMA / T according to a first embodiment of the present invention.
Block diagram showing the configuration of the DD base station

FIG. 2 is a W-CDMA / T according to a second embodiment of the present invention.
Block diagram showing the configuration of the DD base station

FIG. 3 is a W-CDMA / T according to a third embodiment of the present invention.
Block diagram showing the configuration of the DD base station

FIG. 4 is a W-CDMA / T according to a fourth embodiment of the present invention.
Block diagram showing the configuration of the DD base station

FIG. 5 is a W-CDMA / T according to a fifth embodiment of the present invention.
Block diagram showing the configuration of the DD base station

FIG. 6 is a W-CDMA / T according to a sixth embodiment of the present invention.
Block diagram showing the configuration of the DD base station

FIG. 7 is a block diagram showing a configuration of a conventional W-CDMA / TDD base station.

[Explanation of symbols]

101, 201, 301, 401, 501, 601 T
DD base station 102 Adaptive array antennas 102-1 to 102-N Antennas constituting an adaptive array antenna 103 Despreading unit 104 Array combining unit 105, 202, 302, 402, 502, 602 Array algorithm control unit 403 Arrival direction estimation 404 Weight generation section 503 SIR calculation section 504 Weight generation section 603 Spreading section 604 Weight multiplication section 605 Distributor 606 Transmission signal generator 702 TDD terminal 703 FDD terminal 713 Channel estimation / path combining section 714 Demodulation processing section

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5J021 AA05 AA11 DB01 EA04 FA13                       GA06 GA08 HA10 JA03                 5K022 EE01 EE32 EE35                 5K028 AA04 BB04 CC02 CC05 SS02                       SS12                 5K067 AA03 CC04 CC10 EE04 EE10                       HH21 KK02 KK03

Claims (8)

[Claims] 1. A plurality of antennas, a plurality of despreading means provided for each of the plurality of antennas, and a weight control signal to control the weighting of directivity combination of the plurality of antennas to control the plurality of the plurality of antennas. Weight combining means for extracting a desired signal from the output of the despreading means, and the weight for receiving the outputs of the plurality of despreading means and directing nulls in the directivity of the plurality of antennas to the arrival direction of the strong interference wave. Array algorithm control means for generating a control signal, and W-CDMA / T
DD base station. 2. The array algorithm control means generates the weight control signal by applying a least squares method / algorithm to a signal subjected to despreading and user identification. W-CDMA /
TDD base station. 3. The array algorithm control means applies the power inversion adaptive array algorithm to a signal for an arbitrary slot among the signals subjected to despreading and user identification to generate the weight control signal. The W-C according to claim 1, wherein
DMA / TDD base station. 4. The W-CDM according to claim 1, wherein the array algorithm control means applies a power inversion adaptive array algorithm to a signal before user identification to generate the weight control signal.
A / TDD base station. 5. The array algorithm control means performs arrival direction estimation of an interference wave using a signal before user identification, and uses a weight prepared in advance to form a null in the direction, and this weight is used. 3. The W- according to claim 1, wherein the weight control signal corresponding to
CDMA / TDD base station. 6. The array algorithm control means receives from a plurality of weights having nulls in arbitrary directions prepared in advance, using a signal on which user identification has been performed after despreading in arbitrary slots. 2. The W- according to claim 1, wherein the one that maximizes the SIR is selected and the weight control signal corresponding to this weight is generated.
CDMA / TDD base station. 7. The directivity of a plurality of antennas using the array algorithm control means according to claim 1 and a weight control signal generated by the array algorithm control means when transmitting a transmission signal. A weight multiplication means for controlling
DMA / TDD base station. 8. A null in the directivity of the plurality of antennas is directed to the arrival direction of a strong interference wave by receiving the output of a plurality of despreading means provided for each of the plurality of antennas constituting the adaptive array antenna. An array antenna directivity control method, comprising: generating a weight control signal for controlling the weighting; and controlling the weighting of directivity combination of the plurality of antennas based on the generated weight control signal.