JP2002271846A - Adaptive array base station and mobile communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adaptive array base station and a mobile communication terminal, by which speech quality can be maintained and a calculation converging time required for extracting a user can be reduced. SOLUTION: Since a UW(Unique Word) 1 is an encoded original UW in use conventionally, in order to make UWs respectively having UW 1, UW 2 orthogonal to each other, it is required to zero the inner product shown in Equation (3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an SDMA (Space Div.)
ision Multiple Access (hereinafter, referred to as “spatial multiplex” in the text) and relates to a communication system of an adaptive array base station (hereinafter abbreviated as “base station”). T same as user
It relates to a method of allocating to a CH (information channel or communication channel) physical slot.

[0002]

2. Description of the Related Art Channels provided in a radio section basically include a call channel (TCH) for transferring user information,
And a control channel (CCH) for transferring a control signal. UW (sync word) provided for both channels is a signal for frame synchronization of each channel.
A different pattern is defined to distinguish between CCH and CCH.

[0003]

However, when providing SDMA services to a plurality of users at the same frequency in the same slot, if one UW is shared and used, the plurality of users are identified algorithmically. Sometimes it is difficult to do. In such a case, the user extraction becomes incomplete, causing problems such as deterioration of the call quality and user swapping. An object of the present invention is to solve the problems of the related art and to provide an adaptive array base station and a mobile communication terminal capable of maintaining the communication quality. Another object of the present invention is to provide an adaptive array base station and a mobile communication terminal capable of shortening the calculation convergence time required for user extraction.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first invention of the present application is directed to adaptive beamforming for communicating with a maximum transmission power to a mobile communication terminal to be transmitted, By selectively using adaptive null steering that does not affect mobile communication terminals, the adaptive array base station that performs communication in the SDMA scheme in which the same physical slot is shared by a plurality of calls is used. Means for allocating an original UW pattern to one mobile communication terminal, means for calculating an optimum UW pattern to be allocated to mobile communication terminals other than the first mobile communication terminal based on reception alignment from each mobile communication terminal, Means for notifying the first mobile communication terminal of the UW pattern, and notifying the mobile communication terminal of the optimum UW pattern Characterized by comprising a that means.

When the reception alignment from the first mobile communication terminal and the reception alignment from a mobile communication terminal other than the first mobile communication terminal are the same, the adaptive array base station can transmit the original UW pattern and the optimum UW pattern. It is preferable to calculate the optimal UW pattern so that the inner product of the UW pattern becomes zero. The adaptive array base station,
For the reception alignment from the first mobile communication terminal,
If the reception alignment from a mobile communication terminal other than the first mobile communication terminal is + X symbol, the original UW
Data obtained by combining information obtained by encoding a signal provided before a synchronization word having a pattern by X symbols and information obtained by omitting the last X symbol of the original UW pattern, and the inner product of the optimum UW pattern become zero. It is preferable to calculate the optimal UW pattern.

[0006] The adaptive array base station, when the reception alignment from a mobile communication terminal other than the first mobile communication terminal is + X symbol with respect to the reception alignment from the first mobile communication terminal, sets the optimal UW pattern. Data obtained by combining information obtained by omitting the leading X symbol and information obtained by encoding a signal provided after the synchronization word having the optimum UW pattern by X symbols, and the optimum in which the inner product of the original UW pattern becomes zero. Preferably, the UW pattern is calculated. The adaptive array base station has an original UW pattern when a reception alignment from a mobile communication terminal other than the first mobile communication terminal is a -X symbol with respect to a reception alignment from the first mobile communication terminal. Data obtained by encoding the signal provided after the synchronization word for X symbols and information obtained by omitting the leading X symbol of the original UW pattern, and the optimum UW in which the inner product of the optimum UW pattern becomes zero. It is preferable to calculate the pattern.

The adaptive array base station, when the reception alignment from a mobile communication terminal other than the first mobile communication terminal is -X symbol, with respect to the reception alignment from the first mobile communication terminal, Of the original UW pattern, and data obtained by combining information obtained by omitting the last X symbol of the above and information obtained by encoding a signal provided before the synchronization word having the optimum UW pattern by X symbols, and the original UW pattern become zero. It is preferable to calculate the optimum UW pattern. Further, the second invention of the present application is a mobile communication terminal, comprising means for communicating with an adaptive array base station using a synchronization word having an original UW pattern or an optimum UW pattern notified from the adaptive array base station. It is characterized by having done.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A channel provided in a radio section is basically a communication channel (TC) for transferring user information.
H) and a control channel (CCH) for transferring a control signal. At the time of transition from CCH to TCH, synchronization is established between the base station and the user using a synchronization burst, and thereafter, communication is performed on the TCH. In the case of the PHS, the format of the UW of this synchronous burst is different from that of the TCH, and 32 bits of the upstream and downstream UWs are prepared. Usually, as a procedure for starting communication in SDMA, one user uses this synchronization burst to synchronize with the base station on the same channel as an existing call. At this time, the UW of the TCH of the existing call is 16 bits,
Therefore, it is considered that the UW pattern rarely causes a problem in extracting each user on the base station side. However, when a user performing SDMA communication enters a phase of synchronization re-establishment using a synchronization burst with a base station due to interference, the 32-bit UW used in the synchronization burst is also changed to the 16-bit TCH. U
As with W, it is necessary to assign different UWs to the user.

In the present embodiment, SDMA is performed by a plurality of users.
Before performing communication at the base station,
based on the original U
A different UW is calculated for each user other than W. At this time,
The calculation is performed so that the upstream UWs from each user have high orthogonality to each other. The calculated UW is notified to each user via the Air Interface, and each user who has received the notification accesses the base station using the specified UW. That is, rather than holding several UW patterns in a table in advance on the user side and instructing which pattern to use on the base station side, reception alignment at each base station from each user is not required.
The optimum UW based on the ent is assigned to each user. By doing as described above, uplink UWs from each user can ensure high orthogonality with each other, and
This is extremely advantageous in terms of the MA algorithm. In a mimicking manner, it is possible to shorten the calculation convergence time of the received Weights for each user for extracting each user, and at the same time, prevent erroneous extraction.

Next, with reference to the accompanying drawings, an embodiment in which a method of allocating physical slots by an adaptive array base station according to the present invention is applied to a PHS base station which is an adaptive array base station for digital wireless communication. This will be described in detail. FIG. 1 is a functional block diagram of the adaptive array base station, FIG. 2 is a diagram illustrating a signal format of TCH, and FIG. 3 is a diagram illustrating reception alignment from two users.

Referring to FIG. 1, there is shown a functional block diagram showing an embodiment when an adaptive array base station according to the present invention is applied to a PHS base station which is an adaptive array base station for digital radio communication. . In FIG. 1, adaptive array base station 10 according to the present embodiment
Has four antennas ANT <b> 1 to ANT <b> 4, and these antennas ANT are connected to the transmission / reception switch 12. The transmission / reception switch 12 controls these antennas ANT1 to ANT4 in a time-division manner to perform switching control between transmission and reception. The transmission / reception switch 12 includes a reception module 14 and a transmission module 2.
2 are connected.

The receiving system module 14 includes the antennas AN
4 low-noise amplifiers (LNA) 1 for each T
6, a down converter (D / C) 18 and an A / D converter (A / D) 20. The receiving system module 14 is also connected to the modem unit 30, and the low noise amplifier 16, the down converter 18 and the A / D converter (A / D) 20 are transmitted from the transmission / reception changeover switch 12, which is a signal path, to the modem unit 30. They are connected in order.

Similarly, the transmission system module 22 includes four D / A converters (D / A / D converters) provided for each antenna ANT.
A) 24, an upper converter (U / C) 26, and multiplication circuits (MP) 28a and 28b. The transmission system module 22 is also connected to the modem unit 30, and the D / A
The converter 24, the upper converter 26, and the multiplying circuits 28a and 28b are connected in this order from the modem unit 30, which is a signal path, to the transmission / reception system switch 12. When spatial multiplexing is performed on two calls, a multiplying circuit 28a and a multiplying circuit 28b are used so that each call can be transmitted with a different weight.

The modem section 30 is composed of a plurality of CPUs, and performs modulation / demodulation of transmission / reception data and phase control by digital signal processing. Specifically, the following 5
Perform one control. 1. The digital signal converted in the final stage of the receiving module 14 is combined and demodulated so that, for example, D / U (Desire / Undesire: desired wave / interference wave) becomes maximum. 2. The phase of reception at the antenna ANT is calculated, and control is performed so that the phase at the antenna end becomes equivalent at the time of transmission. As a result, directivity can be provided for both transmission and reception in the direction of the PHS terminal that performs communication. 3. Suppression is achieved by creating a null point in the arrival direction of the interference wave and the delayed wave. 4. By controlling the phases of the signals supplied to the n antennas, it is possible to transmit the beam by giving a directivity in an arbitrary direction and narrowing the beam. 5. Interference in the downlink direction is reduced with respect to peripheral base stations and terminals other than the user terminals that are engaged in a call or exchange data (communication). The modem unit 30 is connected to the control unit 32.

The control unit 32 comprises a plurality of CPUs.
It controls the entire adaptive array base station 10. Specifically, the following six controls are performed. 1. It instructs the necessary parameters and timing to the modem unit 30, and processes the data received by the modem unit 30. Further, data to be radiated in the air is created and passed to the modem unit 30. Further, it instructs the control of the transmission output based on the weight calculated by the calibration. 2. A change rate of a Spatial Signature (reception response vector) from a user terminal (a PHS terminal of the user, hereinafter simply referred to as a user) is calculated. 3. Statistical processing of the uplink RSSI from the user is performed. 4. The physical slot allocation of the spatial multiplexing is performed by a logic such that the GOS of the spatially multiplexed call becomes as similar as possible to the GOS of the normal call which is not the spatial multiplexing. 5. When a call is established to a plurality of users by spatial multiplexing, each user is set so that the C / I (Carrier / Interference) for each user is equal to or more than a value necessary for maintaining the GOS of the user well. Calculate the weight to. 6. It is connected to the ISDN line and executes the processing of the interface with it.

The power supply unit 34 is a power supply unit that receives a power supply of 100 V and supplies power to the adaptive array base station 10. Note that a digital signal processing unit is formed by the modem unit 30 and the control unit 32. In the adaptive array base station 10, based on received information (amplitude and phase) received from N (N is a natural number of 2 or more) antennas,
Adaptive array transmission is performed for each antenna with predetermined weighting.

In the embodiment of the present invention, a case will be described as an example where SDMA is realized by two multiplexes in a PHS. FIG. 2 shows a signal format of the TCH for performing a call in the PHS. In the figure, R is a ramp time for transient response, SS is a start symbol, PR is a preamble,
CI represents a channel type, SA represents a SACCH, and CRC represents an error detection code. In FIG. 2, R to UW and CI are common to any user when communicating with the user, and the actual voice is on the part I. Here, the synchronization word UW is SD
Consider a case in which two users use different uplink patterns in MA. In the case of SDMA, only the upstream UW becomes a problem because it is controlled on the base station side. Assuming that the two users are a user A and a user B, the user U uses the same upward UW pattern as before. For user B, the optimum UW pattern (herein referred to as “optimal UW pattern”) is calculated by the following method.

1. Calculation of Optimal UW Pattern (1) When Reception Alignment from Two Users Is the Same FIG. 3A shows a state where reception data from two users is received with the same alignment with respect to the transmission timing of the base station. It was done. In the figure, it is assumed that the traveling direction of the received data is from right to left. In PHS, π / 4
Since the DQPSK modulation method is used, a 16-bit UW
Is considered with eight symbols of data. In the present embodiment, UW
8 symbols encoded with π / 4DQPSK (see FIG. 3)
“A1 to a8” and “b1 to b8”) are called “UW patterns” and are defined as follows.

[0019]

(Equation 1)

[0020]

(Equation 2)

The case where the UWs having these UW patterns are orthogonal to each other is the optimum case in terms of the SDMA algorithm. UW1 is the original U
W encoded (original UW pattern,
Since these are "a1 to a8" in FIG. 3, UW1 ("a1 to a8" in FIG. 3) and UW2 ("b1 to b8" in FIG. 3)
In order to make the UWs each having the following orthogonal, it is necessary to make the following inner product zero.

[0022]

(Equation 3)

Here, ai ^* × bi (i = 1,... 8) is
It means the inner product of the conjugate complex number of ai and bi. a1 to a
8 is an upstream original UW pattern “111000”
0101001001 "is encoded. Therefore, from the equation, it is possible to calculate an optimal UW pattern, UW2, in which the original UW pattern and the mutually encoded one are orthogonal. For example," 1101001001111010 "can be considered as UW2.

(2) Case where reception alignment from two users is different FIGS. 3 (b) and 3 (c) show a state in which reception data from two users is received with different alignment with respect to the transmission timing of the base station. Is shown in the figure. Actually, there are many cases where reception alignment from two users differs, such as "when the user transmits at a different offset with respect to the transmission timing of the base station", "when the amount of delay differs depending on the communication distance between the base station and the user". In such a case, it is meaningless to calculate the inner product of only the UW pattern of two users,
It is also necessary to consider PR and CI before and after UW. For example, as shown in FIG.
If t is +2 symbols to that of user A, PR
PR3, PR2, PR3
3. The two encoded CI symbols are CI1, CI
Assuming that 2, the following two types of inner product calculations can be considered.

[0025]

(Equation 4)

[0026]

(Equation 5)

On the other hand, as shown in FIG.
If the received alignment from is 2 symbols relative to that of user A, the PR encoded 3 symbols are
Assuming that two encoded symbols of R1, PR2, PR3, and CI are CI1 and CI2, the following two types of inner product calculations can be considered.

[0028]

(Equation 6)

[0029]

(Equation 7)

2. Procedure for assigning a UW As a procedure for assigning a different UW to a user, there are two procedures described below. (1) When Spatial Channel is Realized in the Same Slot by Activating TCH Switching for Two Existing TCH Calls The respective reception alignments of user A and user B are calculated from the reception information of the two respective calls. Which of the user A and the user B is to switch the TCH is determined by a predetermined algorithm, and the optimum UW pattern of the user who performs the TCH switching is calculated. A TCH switching instruction message is transmitted to the user to be switched TCH. In the message, "the same frequency designation as the other user" and "optimum UW pattern calculated by" are entered. After receiving the TCH switching instruction message, the user establishes synchronization using the synchronization burst on the specified channel, and then accesses the base station using the UW having the specified optimum UW pattern.

(2) In the case of realizing the call of the existing TCH and the Spatial Channel for the user B requesting the establishment on the control channel, the reception alignment from the user B on the control channel and the reception alignment from the user A on the existing TCH are performed. calculate. The optimum UW pattern of the user B is calculated from the two reception alignments. The TCH allocation message (link channel establishment allocation in PHS) is transmitted to the user B on the control channel. In the message, "the same channel (slot and frequency as the existing TCH) (slot and frequency)" and "optimum UW pattern" Is specified. After establishing synchronization using the synchronization burst on the channel specified by the user B, the user B accesses the base station using the specified optimum UW pattern. However, when the user B receives the TCH specified from the control channel
There is a possibility that the reception alignment of the base station may change when shifting to the channel of (1). In that case, the optimum UW pattern of the user B is calculated again from the reception alignment of the two users on the TCH, a TCH switching instruction in the same slot is transmitted to the user B, and the base station is accessed with the optimum UW pattern. .

3. When the alignment of reception from a certain user changes significantly after the establishment of the Spatial Channel. In general, it is difficult to realize the Spatial Channel when the mobility of the user is large. Don't try to establish a Channel. However, when the user moves at a slow speed (for example, walking), the reception alignment from the user may significantly change. In this case, the optimum UW pattern is calculated again as in (2) of 2 (procedure for assigning UW), a TCH switching instruction message in the same slot is transmitted to the user, and the base station is transmitted using the optimum UW pattern. Try to access the station.

[0033]

As described above, according to the adaptive array base station and the mobile communication terminal of the present invention, the communication quality can be maintained and the calculation convergence time required for user extraction can be shortened.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment when a method of allocating physical slots by an adaptive array base station according to the present invention is applied to a PHS base station.

FIG. 2 is a diagram showing a signal format of TCH.

FIG. 3 is a diagram illustrating reception alignment from two users.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 adaptive array base station 12 transmission / reception switch 14 reception module 22 transmission module 30 modem section 32 control section

Claims (7)

[Claims] 1. An adaptive beamforming system that communicates with a maximum transmission power to a mobile communication terminal to be transmitted, and an adaptive null steering that does not affect an interfering mobile communication terminal. Means for allocating an original UW pattern to a first mobile communication terminal in an adaptive array base station performing communication in the SDMA scheme in which the same physical slot is shared by a plurality of calls, Means for calculating an optimal UW pattern to be assigned to a mobile communication terminal other than the first mobile communication terminal based on the reception alignment of: a means for notifying the first mobile communication terminal of the original UW pattern; Means for notifying the UW pattern to the mobile communication terminal. Tibuarei base station. 2. The adaptive array base station according to claim 1, wherein a reception alignment from the first mobile communication terminal is the same as a reception alignment from a mobile communication terminal other than the first mobile communication terminal. An adaptive array base station, wherein the optimal UW pattern is calculated such that an inner product between the original UW pattern and the optimal UW pattern becomes zero. 3. The adaptive array base station according to claim 1, wherein a reception alignment from the first mobile communication terminal is performed by a mobile communication terminal other than the first mobile communication terminal. When the reception alignment is + X symbols, information obtained by encoding a signal provided before the synchronization word having the original UW pattern by X symbols and information obtained by omitting the last X symbol of the original UW pattern An adaptive array base station, which calculates the optimal UW pattern in which the inner product of the optimal UW pattern and the data obtained by combining the above are calculated to be zero. 4. The adaptive array base station according to claim 1, wherein mobile communication other than the first mobile communication terminal is performed with respect to reception alignment from the first mobile communication terminal. When the reception alignment from the terminal is + X symbol, information obtained by omitting the leading X symbol of the optimum UW pattern and information obtained by encoding a signal provided after the synchronization word having the optimum UW pattern by X symbols are provided. And calculating the optimum UW pattern that makes the inner product of the original UW pattern zero. 5. The adaptive array base station according to claim 1, wherein reception alignment from the first mobile communication terminal is performed by a mobile communication terminal other than the first mobile communication terminal. When the reception alignment is -X symbol, information obtained by encoding the signal provided after the synchronization word having the original UW pattern by X symbols and information obtained by omitting the leading X symbol of the original UW pattern An adaptive array base station, wherein the optimum UW pattern in which the inner product of the optimum UW pattern becomes zero and the data obtained by combining the above are calculated. 6. The adaptive array base station according to claim 1, wherein mobile communication other than the first mobile communication terminal is performed with respect to reception alignment from the first mobile communication terminal. When the reception alignment from the terminal is −X symbol, information obtained by omitting the last X symbol of the optimum UW pattern and information obtained by encoding a signal provided before the synchronization word having the optimum UW pattern by X symbols. And calculating the optimal UW pattern in which the inner product of the original UW pattern becomes zero. 7. The mobile communication terminal according to claim 1, wherein a synchronization word having the original UW pattern or the optimum UW pattern notified from the adaptive array base station is used. And a means for communicating with the adaptive array base station.