JP2005006089A - Radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radio communication apparatus which gives a power ratio between a transmission signal and an interference signal in the direction of each mobile station which carries out space division multiplex communication in accordance with a modulation scheme used for the mobile station, and a radio communication method. <P>SOLUTION: At a step S01, the modulation schemes used for respective mobile stations are recorded, at a step S02, the total transmission power of the radio communication apparatus is distributed among paths corresponding to respective mobile stations in accordance with D/U ratios required to obtain desired communication qualities using respective modulation schemes, and at a step S03, power coefficients are determined according to the ratios of the distributed powers to evenly distributed power. By transmitting a transmission signal whose transmission power is adjusted using a weight vector adjusted for every path or a variable gain amplifier having a controlled gain for every path in accordance with the thus determined power coefficients, an intended power ratio is given between the desired signal and the interference signal in the direction toward each mobile station. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless communication apparatus that performs space division multiplex communication, and more particularly, to a technique for reducing power consumption of the wireless communication apparatus.
[0002]
[Prior art]
In recent years, with the rapid increase in users of mobile radio communication systems such as mobile phone systems, social demands for effective use of frequency resources are increasing. One technology that meets this demand is communication using the space division multiplexing method.
The space division multiplexing method uses a single carrier wave at the same time by using the directivity of the antenna device between a radio base station and each of a plurality of mobile stations located in different directions from the radio base station. Multiple communication.
[0003]
In this method, an adaptive array antenna apparatus capable of adaptively controlling directivity is used. An adaptive array antenna apparatus includes a plurality of antennas fixedly installed, and gives a large gain in a desired direction as a whole antenna apparatus by giving an appropriate amplitude ratio and phase difference between transmission and reception signals of individual antennas. A directional pattern is formed (also referred to as directing the beam) and having a small gain in an undesired direction (also referred to as pointing the null point). Since the operation principle and configuration of the directivity pattern adaptive control using the adaptive array antenna apparatus are described in detail in, for example, Non-Patent Document 1, description thereof is omitted here.
[0004]
A conventional radio base station uses an adaptive array antenna apparatus to form different directivity patterns for each of a plurality of mobile stations performing multiplex communication, and signals are transmitted to each mobile station using the formed directivity patterns. Send and receive. The configuration of this type of radio base station and the signal processing performed to form a directivity pattern there are disclosed in detail in Patent Document 1.
[0005]
According to the spatial division division scheme, the gain directed toward other mobile stations in the directivity pattern formed for a certain mobile station is not actually reduced to infinitesimal, so transmission to a certain mobile station The signal leaks to some extent even in the direction of other mobile stations. The leaked transmission signal becomes an interference signal for other mobile stations.
In general, with regard to communication quality, in order to suppress the bit error rate below an intended target value, a predetermined ratio (required D / U) determined according to a modulation method between the power of a desired signal and the power of an interference signal. It is well known that there must be a power ratio that is equal to or above that).
[0006]
For this reason, the conventional radio base station provides a transmission signal in each mobile station direction by giving a predetermined gain ratio between the directivity pattern for the mobile station and the directivity pattern for other mobile stations. The required D / U ratio is given between the power of the interference signal and the power of the interference signal.
FIG. 7 shows the transmission power (vertical axis) of the transmission signal addressed to each mobile station and the direction from the radio base station (horizontal axis) when the conventional radio base station performs multiplex communication with two mobile stations. It is a graph showing the typical example of a relationship. As shown in FIG. 7, the conventional radio base station gives a uniform power ratio satisfying the required D / U ratio between the power of the transmission signal and the power of the interference signal in each mobile station direction. .
[0007]
[Patent Document 1]
Japanese Patent No. 3113737
[0008]
[Non-Patent Document 1]
"Applied signal processing by array antenna", Nobuyoshi Kikuma, Science and Technology Publishing, First Edition, November 25, 1998, Chapter 3
[0009]
[Problems to be solved by the invention]
However, since the wireless base station of the prior art gives a uniform power ratio between the transmission signal and the interference signal in the direction of each mobile station, it is necessary to use different modulation schemes for each mobile station being multiplexed. Since a signal is transmitted with a transmission power larger than necessary to a mobile station using a modulation method with a small D / U ratio, there arises a problem that power saving of the radio base station is hindered.
[0010]
In view of the above problems, the present invention is a radio communication apparatus applicable to a radio base station that performs multiplex communication with a plurality of mobile stations by a space division multiplex method, toward each mobile station that is performing multiplex communication. An object of the present invention is to provide a radio communication apparatus that gives a power ratio according to a modulation scheme used for a mobile station between a transmission signal and an interference signal.
[0011]
[Means for Solving the Problems]
(1) In order to solve the above problem, the wireless communication apparatus of the present invention performs space division multiplex communication by combining and transmitting transmission signals directed to each of a plurality of mobile stations according to individual directivity patterns. A wireless communication apparatus, wherein modulation means for modulating each transmission signal using an individual modulation method and the maximum transmission power of each transmission signal are individually determined according to the modulation method used for modulation of the transmission signal Determining means for transmitting, and transmitting means for combining and transmitting each transmission signal according to an individual directivity pattern that generates each of the determined maximum transmission powers in a desired direction.
(2) In addition, for each transmission signal, the determination unit determines that a ratio between the maximum transmission power of the transmission signal and the leakage power at which another transmission signal leaks in the direction in which the maximum transmission power is generated is Depending on the modulation scheme used for modulation, each maximum transmission power may be determined to be equal to or greater than the ratio required to achieve a predetermined bit error rate.
(3) Moreover, the said determination means may determine each maximum transmission power to the magnitude | size which the sum total does not exceed the maximum power which can be transmitted from an own apparatus.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The radio communication apparatus according to the present embodiment uses a time division multiple access (TDMA) scheme and a space division multiple access (SDMA) scheme in combination with a plurality of mobile stations. Wireless base station. This radio base station is common to radio base stations that have been conventionally implemented, for example, radio base stations that comply with the PHS (Personal Handyphone System) standard, in that both time division multiple access and space division multiple access are used. Yes.
[0013]
However, this radio base station modulates each information signal addressed to each mobile station to be space-division-multiplexed using a specific modulation scheme, and has one frequency with a specific intensity corresponding to each modulation scheme. It has an unprecedented feature in that it is multiplexed on a carrier wave and transmitted.
Hereinafter, a configuration for realizing this feature and an effect brought about by the configuration will be described in detail with reference to the drawings. In addition, about the matter which is common in the past, it demonstrates briefly or abbreviate | omits description.
(1. Overall configuration)
FIG. 1 is a functional block diagram showing an overall configuration of the radio base station 100 according to the first embodiment. The radio base station 100 includes an adaptive array unit 10, a modem unit 40, a baseband unit 50, a control unit 60, and a storage unit 70.
[0014]
The signal processing functions in the adaptive array unit 10, the modulation / demodulation unit 40, and the baseband unit 50 are realized by a DSP (Digital Signal Processor) executing a program stored in a memory. The function of the control unit 60 is realized by a CPU (Central Processing Unit) executing a program stored in the memory.
[0015]
In accordance with link channel assignment request information transmitted from a mobile station through a control channel using a predetermined modulation scheme, the control unit 60 uses a link channel, a modulation scheme, and a link scheme used for main communication with the mobile station. The transmission power of the transmission signal addressed to the mobile station is determined. The predetermined modulation scheme may be, for example, a π / 4 QPSK (Quadrature Phase Shift Keying) modulation scheme. Then, the storage unit 70 stores the determined link channel, modulation scheme, and power coefficient indicating the transmission power adjustment amount in association with each other. This determination process will be described in detail later.
[0016]
Thereafter, each unit of the radio base station 100 performs main communication with the mobile station through the determined link channel.
The baseband unit 50 acquires transmission information signals representing voice or data from a plurality of communication devices (not shown) via a network such as a telephone exchange network. Then, the acquired transmission information signal is time division multiplexed into a time division multiplexed signal, and the time division signal is output to the modem unit 40. Further, the time division multiplexed signal input from the modem unit 40 is time-division-separated into received information signals to each of the plurality of communication devices, and is supplied via the network.
[0017]
Such time division multiplexing and time division separation processing can be performed according to, for example, the conventional PHS standard. In this case, the time division multiplexed signal is represented by a TDMA frame repeated at a period of 5 ms, and one TDMA frame is divided into eight equal parts into four transmission time slots and four reception time slots, and each of transmission and reception is 1 A set of two time slots constitutes a bidirectional link channel with one mobile station. That is, four link channels are accommodated in one time division multiplexed signal.
[0018]
When the radio base station 100 spatially multiplexes four such time division multiplexed signals, a maximum of 16 link channels are provided for each time slot and for each divided space (hereinafter referred to as a path). Formed by a carrier of frequency. In this case, the baseband unit 50 performs parallel processing on the four signals that are spatially multiplexed.
[0019]
The modem unit 40 modulates the four time-division multiplexed signals, which are given from the baseband unit 50 and are to be space-division multiplexed, into transmission signals, and outputs the transmission signals obtained by the modulation to the adaptive array unit 10. Further, the modem unit 40 is provided with four received signals obtained by space division separation from the adaptive array unit 10, demodulates each of them into a time division multiplexed signal, and demodulates each time division multiplexed signal obtained by the demodulation. Output to the baseband unit 50.
[0020]
The modem unit 40 modulates and demodulates each time slot period of each space-division multiplexed signal using a modulation scheme stored in the storage unit 70 in association with the path and time slot in which the signal is accommodated. . Note that all the modulation schemes processed by the modem unit 40 are assumed to be well known. For example, assuming that 16QAM (Quadrature Amplitude Modulation), π / 4 QPSK, and BPSK (BiPhase Shift Keying) are processed, a circuit for processing each is provided, and a necessary circuit is operated for each time slot.
[0021]
The adaptive array unit 10 forms individual directivity patterns for each path, and transmits and receives signals accommodated in the paths using the formed directivity patterns. The adaptive array unit 10 further compares the signal level in each time slot period of each transmission signal that is space-division-multiplexed with the power coefficient stored in the storage unit 70 in association with the path and time slot in which the transmission signal is accommodated. And adjust each transmission signal after the adjustment. The adaptive array unit 10 will be described in detail later.
(2. Power coefficient determination process)
FIG. 2 is a flowchart showing a power coefficient determination process executed by the control unit 60.
[0022]
This process is executed for the time slot in which the space division multiplexing member has changed, and determines the power coefficient of each mobile station after the change. Here, the fluctuation of the space division multiplexing member means that a new mobile station participates in the space division multiplexing and the mobile station leaves the space division multiplexing in the time slot.
This process refers to the required D / U ratio information held in the storage unit 70 and updates the power coefficient information.
[0023]
FIG. 3 shows a required D / U ratio table 200 which is a specific example of a table for holding required D / U ratio information. The required D / U ratio table 200 has a modulation method column 201 and a required D / U ratio column 202.
The modulation method column 201 holds the identification name of each modulation method that can be processed by the modem unit 40, and the required D / U ratio column 202 holds the required D / U ratio corresponding to the modulation method.
[0024]
Here, for the sake of convenience, the required D / U ratio is represented by a dB value where the maximum required D / U ratio is 0 dB. A specific mounting value of the maximum required D / U ratio is a design item determined in consideration of mounting factors such as a circuit configuration and accuracy characteristics of components to be used.
FIG. 4 shows a power coefficient table 300 which is a specific example of a table for holding power coefficient information. The power coefficient table 300 includes a time slot column 301, a path column 302, a modulation method column 303, a power distribution ratio column 304, and a power coefficient column 305.
[0025]
The time slot column 301 holds a slot number for identifying a time slot, the path column 302 holds a path number for identifying a path, and the modulation method column 303 is a modulation used in a link channel provided in the path of the time slot. The power distribution ratio column 304 holds the distribution ratio of all transmission powers that can be output by the radio base station 100 in the time slot to each path, and the power coefficient column 305 transmits the transmission power transmitted on the link channel. Hold the adjustment amount.
[0026]
Hereinafter, each step of the power coefficient determination process will be described in detail.
(Step S01: Modulation method recording)
In this step, the modulation scheme determined to be used for communication on the link channel is recorded in the modulation scheme column 303 corresponding to the link channel in the power coefficient table 300.
[0027]
The procedure for determining the modulation scheme can be easily realized by being incorporated in the link channel assignment procedure defined in the conventional PHS standard. As a specific example, the mobile station transmits the link channel assignment request information transmitted to the radio base station 100 in each field of the link channel assignment request information defined in the conventional PHS standard. It may be expressed in a format (not shown) to which a modulation method field indicating a method is added.
[0028]
In this case, the control unit 60 may return link channel allocation notification information to the mobile station only when the mobile station approves the modulation scheme indicated in the modulation scheme field. Then, the control unit 60 records the approved modulation scheme in the modulation scheme column 303 corresponding to the allocated link channel.
Also, in this step, when communication is completed, a symbol indicating that the link channel is not used is recorded in the modulation scheme column corresponding to the link channel with which the communication was performed.
(Step S02: Calculation of power distribution ratio)
In this step, a power distribution ratio indicating a distribution ratio of all transmission powers that can be output from the radio base station 100 to each path is calculated as follows.
[0029]
The power coefficient table 300 is searched for a path in which an effective modulation scheme is recorded for a time slot in which the space division multiplexing member has changed. When there is only one such path, that is, when communication in the time slot is performed without space division multiplexing, 1 indicating the total transmission power is set to the power distribution ratio column corresponding to that path. Record to 304.
[0030]
When there are two or more such paths, first, the required D / U ratio corresponding to the modulation scheme used for each path is searched from the required D / U ratio table 200, and the searched required D / U is searched. A half of the difference between the maximum value and the second largest value of the ratio is obtained as a correction value. Next, the maximum required D / U ratio is left as it is, and the obtained correction value is added to each of the other D / U ratios to obtain a corrected D / U ratio. Then, a power distribution ratio obtained by allocating the total transmission power 1 according to each correction D / U ratio is calculated.
[0031]
This step is applied to the specific example shown in FIG. 4 as follows.
When applied to time slot 1, one path using 16QAM and one path using BPSK are searched. The correction value is obtained from (0 − (− 6.02)) / 2 to 3.01, and the correction D / U ratio of each path is 0 dB and −3.01 dB. 0.667 and 0.333 obtained by distributing the total transmission power 1 to about 1: 0.5, which is the corrected D / U ratio, are recorded in the power distribution ratio column 304 of the corresponding path.
[0032]
When applied to time slot 2, one path using 16QAM, one path using π / 4QPSK, and two paths using BPSK are searched. The correction value is obtained from (0 − (− 3.01)) / 2 to 1.51, and the correction D / U ratio of each path is −4.51 dB, −1.50 dB, −4.51 dB in order of the path number. , 0 dB. 0.146, 0.293, 0.146, 0.414 obtained by allocating the total transmission power 1 to this corrected D / U ratio of about 0.354: 0.707: 0.354: 1, It is recorded in the power distribution ratio column 304 of the corresponding path.
(Step S03: Calculation of power coefficient)
In this step, a dB value with respect to 0.250 of the power distribution ratio allocated to each path is calculated and determined as the power coefficient of each path. Here, 0.250 is a power distribution ratio when the transmission power is distributed equally to each path.
[0033]
This step is applied to the specific example shown in FIG. 4 as follows.
When applied to time slot 1, the power distribution ratio of each path is 0.667 and 0.333 in order of path number, and the dB values of 4.26 and 1.25 for 0.250 are the corresponding paths. Is recorded in the power coefficient column 305.
When applied to time slot 2, the power distribution ratio of each path is 0.146, 0.293, 0.146, 0.414 in order of path number, and is the dB value for each 0.250 -2. .33, 0.69, -2.33, 2.91 are recorded in the power coefficient column 305 of the corresponding path.
[0034]
In this way, the power coefficient is determined for each link channel, that is, each time slot / path pair, and recorded in the power coefficient table 300.
(3. Details of adaptive array section 10)
FIG. 5 is a functional block diagram showing a detailed configuration of the adaptive array unit 10. The adaptive array unit 10 includes antennas 11 to 14, a radio unit 20, and a signal processing unit 30.
[0035]
The radio unit 20 includes a receiving unit 21 realized using a low noise amplifier, a transmitting unit 22 realized using a high power amplifier, and a transmission / reception changeover switch 23. The signal processing unit 30 includes directivity control units 31 to 34 realized by signal processing using a DSP, and an adder 360.
The directivity control units 31 to 34 form individual directivity patterns for each time slot and each path using, for example, the least square error method. The logical basis of the least square error method and the specific calculation method are well-known matters detailed in Non-Patent Document 1 cited in the section of the prior art. Here, the operation of the directivity control unit 31 will be briefly described by focusing on one reception time slot and one path.
[0036]
The reception signal adjustment unit 310 performs complex multiplication of a complex vector called a reception weight vector supplied from the reception weight calculation unit 320 and a reception signal for each antenna supplied from the reception unit 21, thereby multiplying the reception signal individually for each antenna. Are added and synthesized.
The reference signal generation unit 340 generates a reference signal representing a desired reception signal, and the reception weight calculation unit 320 includes the reference signal supplied from the reference signal generation unit 340 and the combined signal obtained from the reception signal adjustment unit 310. The reception weight vector is sequentially corrected so as to reduce the error of.
[0037]
By this operation, an optimum reception weight vector that minimizes the error can be obtained. In the synthesized signal obtained by applying the optimum reception weight vector, the desired signal component is maximized and the undesired signal component is minimized. That is, a reception directivity pattern having a large gain in the desired direction and a small gain in the undesired direction is formed.
[0038]
The transmission weight calculation unit 330 stores the optimal reception weight vector for each reception time slot. Then, in each transmission time slot, a transmission weight vector is calculated based on the optimum reception weight vector stored in the immediately preceding corresponding reception time slot.
The transmission signal adjustment unit 350 uses the transmission weight vector supplied from the transmission weight calculation unit 330 to give the transmission signal supplied from the modulation / demodulation unit 40 an individual antenna amplitude and phase change, and the resultant signal is assigned to the corresponding antenna. The transmission directivity pattern equal to the reception directivity pattern is formed by transmitting from.
(4. Adjustment of transmission power)
Next, a configuration for adjusting the transmission power of the transmission signal in each time slot period will be described.
[0039]
The transmission weight calculation unit 330 acquires the power coefficient applied to each transmission time slot of the path processed by itself from the corresponding power coefficient column 305 of the power coefficient table 300.
Then, a transmission weight vector is calculated by multiplying the corresponding optimum reception weight vector by the acquired power coefficient for each transmission time slot, and the calculated transmission weight vector is supplied to the transmission signal adjustment unit 350.
[0040]
The transmission signal adjustment unit 350 uses the transmission weight vector obtained by the scalar multiplication operation to form a directivity pattern having a gain ratio equivalent to that when the optimum reception weight vector is used, and the amplitude of the transmission signal Adjust.
The directivity control units 32 to 34 also perform the same operation in parallel on the paths processed by each.
[0041]
Since the weight vector scalar multiplication operation is an amplitude adjustment operation of the transmission signal, the actual power is given as a power factor of 10 (power coefficient / 20) with respect to the power coefficient displayed in dB. Note that
(5. Specific example)
FIG. 6 is a graph showing an example of the relationship between the transmission power and the direction from the radio base station, which is obtained by the above-described configuration, and is based on the value of time slot 1 in the power coefficient table 300 of FIG. An example is drawn.
[0042]
Here, the solid line represents the transmission power of the transmission signal A addressed to the mobile station A accommodated in the path 1, and the broken line represents the transmission power of the transmission signal B addressed to the mobile station B accommodated in the path 2. d and u are the maximum power and the minimum power of each signal when the transmission power is equally distributed among the four signals. (Du) is a power ratio that is uniformly provided for each signal according to the direction separation performance of the adaptive array unit 10.
[0043]
The amplitudes of the transmission signals A and B are individually adjusted, the transmission power of the transmission signal A is increased by 4.26 dB compared to the case of the equal distribution, and the transmission power of the transmission signal B is increased by 1.25 dB compared to the case of the equal distribution.
As is apparent from the figure, the ratio of the desired signal and the interference signal in the direction of the mobile station A is (d−u + 3.01), and the ratio of the desired signal and the interference signal in the direction of the mobile station B is ( d-u-3.01).
[0044]
In this case, the required D / U ratio of 16QAM is RDU _16QAM And the adaptive array unit 10 is at least RDU _16QAM If the mobile station A has a direction separation performance sufficient to bring a power ratio of −3.01 (in the embodiment, this value is exemplified as a required D / U ratio of π / 4QPSK) to each signal, The ratio of the desired signal to the interference signal in each direction of mobile station B is RDU _16QAM , (RDU _16QAM −6.02), the 16QAM signal and the BPSK signal can be appropriately space-division multiplexed.
[0045]
Further, the adaptive array unit 10 is connected to the RDU. _16QAM Since the transmission power of the transmission signal B can be further reduced by −3.01 dB from FIG. 6, the transmission power can be further reduced to contribute to the power saving of the radio base station.
(Other variations)
Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. The following cases are also included in the present invention.
(1) The present invention may be a computer program for realizing the method described in the embodiment using a computer system, or may be a digital signal representing the program.
[0046]
Further, the present invention may be a computer-readable recording medium in which the program or the digital signal is recorded, for example, a flexible disk, a hard disk, a CD, an MO, a DVD, a BD, a semiconductor memory, or the like.
The present invention may be the computer program or the digital signal transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, or the like.
[0047]
The present invention is also a computer system including a microprocessor and a memory, wherein the memory stores the program, and the microprocessor operates according to the program stored in the memory, so that the method is performed. May be realized.
Further, the program or the digital signal may be recorded on the recording medium and transferred, or transferred via the network or the like, and executed in another independent computer system.
(2) When the radio base station and the mobile station can switch the modulation scheme to be used while continuing communication, the modulation scheme is switched as the case where the space division multiplexing member described in the embodiment fluctuates. Cases may be included.
(3) In the power distribution ratio calculation process in step S02, when there are a plurality of transmission signals giving the maximum required D / U ratio, the above-described correction value is not added. The addition of the correction value is performed when the ratio of the desired signal to the interference signal is reduced by reducing the transmission power of the second transmission signal when there is only one transmission signal giving the maximum required D / U ratio. This is because it is intended to expand.
(4) As another method for adjusting the power of the transmission signal, a variable gain amplifier that generates a gain according to the power coefficient may be used. In this case, for example, such a variable gain amplifier is provided in front of the transmission signal adjustment unit 350 in the directivity control unit 31 to adjust the level of the transmission signal acquired from the modulation / demodulation unit 40, and then delivered to the transmission signal adjustment unit 350. Can be considered. In addition, such a variable gain amplifier can be inserted at a suitable place between the modem unit 40 and the adder 360 for adding and synthesizing transmission signals for each path.
[0048]
【The invention's effect】
(1) A wireless communication device of the present invention is a wireless communication device that performs space division multiplex communication by combining and transmitting transmission signals directed to a plurality of mobile stations according to individual directivity patterns, Modulation means for modulating each transmission signal using an individual modulation method, determination means for individually determining the maximum transmission power of each transmission signal according to the modulation method used for modulation of the transmission signal, and each transmission Transmitting means for combining and transmitting a signal according to an individual directivity pattern that generates each of the determined maximum transmission powers in a desired direction.
[0049]
According to this configuration, each of the transmission signals to be space-division multiplexed can be transmitted with the minimum necessary transmission power corresponding to the modulation scheme, which can contribute to power saving of the radio base station.
(2) In addition, for each transmission signal, the determination unit determines that a ratio between the maximum transmission power of the transmission signal and the leakage power at which another transmission signal leaks in the direction in which the maximum transmission power is generated is Depending on the modulation scheme used for modulation, each maximum transmission power may be determined to be equal to or greater than the ratio required to achieve a predetermined bit error rate.
[0050]
According to this configuration, the necessary minimum transmission power described above is determined according to the bit error rate according to the modulation scheme, so that appropriate communication quality can be ensured in addition to the power saving of the radio base station. It becomes.
(3) Moreover, the said determination means may determine each maximum transmission power to the magnitude | size which the sum total does not exceed the maximum power which can be transmitted from an own apparatus.
[0051]
According to this configuration, in addition to the above-described effects, optimal power distribution can be performed for each transmission signal with the maximum transmittable power as an upper limit.
(4) A wireless communication method of the present invention is a communication method for performing space division multiplex communication by combining transmission signals directed to a plurality of mobile stations in accordance with individual directivity patterns and transmitting the signals. A modulation step for modulating the transmission signal using an individual modulation method, a determination step for individually determining the maximum transmission power of each transmission signal according to the modulation method used for modulation of the transmission signal, and each transmission signal Transmitting in combination with each determined maximum transmission power in accordance with an individual directivity pattern that produces the desired direction.
[0052]
According to this configuration, the same effect as in (1) can be obtained.
(5) The program of the present invention controls a wireless communication apparatus that performs space division multiplex communication by combining and transmitting transmission signals directed to each of a plurality of mobile stations according to individual directivity patterns. A computer-executable program for modulating each transmission signal using an individual modulation scheme and the maximum transmission power of each transmission signal according to the modulation scheme used to modulate the transmission signal And a transmission step of combining and transmitting each transmission signal in accordance with an individual directivity pattern that generates each of the determined maximum transmission powers in a desired direction.
[0053]
According to this configuration, the same effect as in (1) can be obtained.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing an overall configuration of a radio base station.
FIG. 2 is a flowchart showing a power coefficient determination process.
FIG. 3 is a content example of a required D / U ratio table.
FIG. 4 is a content example of a power coefficient table.
FIG. 5 is a functional block diagram showing a detailed configuration of an adaptive array unit.
FIG. 6 is a graph showing a relationship between transmission power and direction of a transmission signal transmitted by a radio base station.
FIG. 7 is a graph showing a relationship between transmission power and direction of a transmission signal transmitted by a conventional radio base station.
[Explanation of symbols]
10 Adaptive array section
11-14 Antenna
20 Radio section
21 Receiver
22 Transmitter
23 Transmission / reception selector switch
30 Signal processor
31-34 Directivity control unit
40 modem
50 Baseband part
60 Control unit
70 storage unit
100 radio base station
200 Required D / U ratio table
300 Power coefficient table
310 Received signal adjustment unit
320 Receive weight calculator
330 Transmission weight calculator
340 Reference signal generator
350 Transmission signal adjustment unit
360 adder

Claims (5)

A wireless communication device that performs space division multiplex communication by combining and transmitting transmission signals directed to each of a plurality of mobile stations according to individual directivity patterns,
Modulation means for modulating each transmission signal using an individual modulation method;
Determining means for individually determining the maximum transmission power of each transmission signal according to the modulation scheme used for modulation of the transmission signal;
A radio communication apparatus comprising: a transmission unit configured to synthesize and transmit each transmission signal according to an individual directivity pattern that generates each of the determined maximum transmission powers in a desired direction. For each transmission signal, the determining means determines the ratio of the maximum transmission power of the transmission signal and the leakage power at which another transmission signal leaks in the direction in which the maximum transmission power is generated. The wireless communication apparatus according to claim 1, wherein each maximum transmission power is determined to be equal to or greater than a ratio required to achieve a predetermined bit error rate according to a method. The wireless communication apparatus according to claim 1, wherein the determining means determines the maximum transmission power so that a sum thereof does not exceed a maximum power that can be transmitted from the own apparatus. A communication method for performing space division multiplex communication by combining and transmitting transmission signals directed to each of a plurality of mobile stations according to individual directivity patterns,
A modulation step for modulating each transmission signal using a separate modulation scheme;
A determination step of individually determining the maximum transmission power of each transmission signal according to the modulation scheme used for modulation of the transmission signal;
And a transmission step of transmitting each transmission signal by combining and transmitting each of the determined maximum transmission powers according to an individual directivity pattern that generates each of the determined maximum transmission powers in a desired direction. A computer-executable program for controlling a wireless communication apparatus that performs space division multiplex communication by combining and transmitting transmission signals directed to each of a plurality of mobile stations according to individual directivity patterns,
A modulation step for modulating each transmission signal using a separate modulation scheme;
A determination step of individually determining the maximum transmission power of each transmission signal according to the modulation scheme used for modulation of the transmission signal;
A program that causes a computer to execute a transmission step of combining and transmitting each transmission signal according to an individual directivity pattern that generates each of the determined maximum transmission powers in a desired direction.

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