JP4107494B2 - Wireless communication system - Google Patents

Wireless communication system Download PDF

Info

Publication number
JP4107494B2
JP4107494B2 JP2003136258A JP2003136258A JP4107494B2 JP 4107494 B2 JP4107494 B2 JP 4107494B2 JP 2003136258 A JP2003136258 A JP 2003136258A JP 2003136258 A JP2003136258 A JP 2003136258A JP 4107494 B2 JP4107494 B2 JP 4107494B2
Authority
JP
Japan
Prior art keywords
beam
signal power
base station
radio base
terminal station
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
JP2003136258A
Other languages
Japanese (ja)
Other versions
JP2004297750A (en
Inventor
嘉孝 原
一成 紀平
高志 関口
Original Assignee
三菱電機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to PCT/JP2002/009704 priority Critical patent/WO2004028037A1/en
Priority to JP2004537525 priority
Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to JP2003136258A priority patent/JP4107494B2/en
Publication of JP2004297750A publication Critical patent/JP2004297750A/en
Application granted granted Critical
Publication of JP4107494B2 publication Critical patent/JP4107494B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to radio communication between a radio base station and a terminal station used for mobile communication and the like, and in particular, reduces interference and achieves good information transmission efficiency while following fluctuations in propagation path characteristics. It is related with the radio | wireless communications system which can do.
[0002]
[Prior art]
In recent years, wireless communication systems centering on mobile phones have been recognized for their convenience and are spreading at a remarkable pace. On the other hand, with the increase in users, problems such as tight usage frequency and deterioration of communication quality have arisen. In particular, the occurrence of multipath fading due to reflection and scattering from surrounding structures is a problem specific to wireless communication and is a major factor in communication quality degradation. Conventionally, as a countermeasure for this, radio base stations have adopted a method of sequentially selecting the antenna with the best reception state by adopting a sector configuration in which a plurality of directional antennas having different directivities are arranged. .
[0003]
In a conventional FDD (Frequency Division Duplex) wireless communication system with different frequencies on the uplink and downlink, information on the propagation path characteristics of the downlink is measured at the terminal station, and the transmission beam is controlled at the radio base station. There is a feedback-type control method in which information necessary for transmission is extracted and the information is inserted into an uplink transmission signal to be notified to a radio base station.
[0004]
For example, in a conventional antenna selection type control method, pilot symbols of each beam (assuming N beams) are inserted into each slot in a downlink information symbol sequence and transmitted. Then, the N pilot symbol sequences transmitted from each beam are detected on the terminal station side, each received power is measured, and the beam number with the largest received power is reported on the uplink, so that the next slot The radio base station transmits information symbols using the selected beam (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-252614
[0006]
[Problems to be solved by the invention]
However, in the conventional antenna selection type control method, as the number of beams increases, the ratio of pilot symbols to information symbols in the entire slot increases, and as a result, the information transmission efficiency in the downlink deteriorates.
[0007]
An object of the present invention is to provide a wireless communication system that solves the above-described problems and can realize improvement in communication quality while maintaining information transmission efficiency while being robust to environmental changes.
[0008]
[Means for Solving the Problems]
  In view of the above object, the present invention provides a radio communication system comprising a radio base station that forms a plurality of beams having different directivity directions and a plurality of terminal stations that communicate with the radio base station. Means for estimating a ratio of desired signal power to interference signal power of a downlink transmitted from a plurality of beams of the radio base station, and beam selection for selecting an optimum beam from the desired signal power to interference signal power ratio Means for notifying the selected beam number using an uplink from the terminal station to the radio base station, wherein the radio base station has the beam number reported from the terminal station. For example, transmission control means for transmitting an information signal to the terminal station using a beam corresponding to the beam numberThe transmission control means of the radio base station includes a known signal that is different for each of a plurality of beams formed by the radio base station in a common channel in an information signal transmitted from the radio base station to the terminal station through an individual channel. Orthogonal signals are allocated, multiplexed and added, and the desired signal power to interference signal power ratio estimation means of the terminal station detects the known orthogonal signal of the common channel, and the desired signal power to interference signal power ratio EstimateThe wireless communication system is characterized by the above.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
First of all, this type of wireless communication system will be explained a little more. As described above, in recent years, wireless communication systems centered on mobile phones such as PDC (Personal Digital Cellular) and PHS (Personal Handy-phone System) have become more convenient. Is recognized and is spreading at a remarkable rate. On the other hand, with the increase in users, problems such as tight usage frequency and deterioration of communication quality have arisen. In particular, the occurrence of multipath fading due to reflection and scattering from surrounding structures is a problem specific to wireless communication and is a major factor in communication quality degradation. As a countermeasure, a radio base station has adopted a sector configuration in which a plurality of directional antennas having different directivities are arranged to sequentially select an antenna having the best reception state.
[0010]
In addition, as a technique for further enhancement of functionality, a plurality of beams that are spatially orthogonal to each other are arranged according to the positions of a plurality of terminal stations that are unevenly distributed in the service area and the arrival directions of signals transmitted from the terminal stations. Forming and allocating for reception of signals from each terminal station.
[0011]
Specifically, there is an adaptive array antenna that actively removes a signal from a terminal station (interference station) that causes interference in an arbitrary direction, which is different from a terminal station that desires communication. An adaptive array antenna is a signal processing system that suppresses an interference signal at the output by adjusting and synthesizing the amplitude and phase of the received signals using a plurality of antenna elements. That is, in an environment where there is an interference signal that affects communication quality, the beam is directed in the direction of arrival of the desired signal, and a directivity null is formed in the direction of arrival of the interference signal. . Adjusting the amplitude and phase of the received signal is equivalent to complex weighting of the output signal from each antenna element.
[0012]
For downlink (base station transmission, terminal station reception), in the case of TDD (Time Division Duplex) method (method that uses the same frequency by time division in transmission and reception), the transmission / reception channel characteristics are short In the case of a sector configuration, the antenna selected in the uplink (base station reception, terminal station transmission) is also used in the downlink, and when an adaptive array antenna is used, Sub-optimal control can be performed by directing a directivity null in the direction of the station.
[0013]
On the other hand, in the case of the FDD (Frequency Division Duplex) method with different frequencies for the uplink and downlink, the transmission / reception propagation path characteristics are different, and the above method for determining the downlink transmission method from the uplink reception signal has good characteristics. May not be obtained.
[0014]
Therefore, information on downlink channel characteristics is measured at the terminal station, and information necessary for controlling the transmission beam at the radio base station is extracted. Then, there is a feedback control method in which the information is inserted into the uplink transmission signal to notify the radio base station. In this case, it is possible to control the beam used for transmission on the radio base station side so that the reception state of the terminal station is always good regardless of the difference in transmission and reception frequencies, and an improvement in communication quality can be expected.
[0015]
For example, in the existing antenna selection type control method, as described above, pilot symbols of each beam (assuming N beams in the figure) are inserted into each slot and transmitted in the downlink information symbol sequence. By detecting the N pilot symbol sequences transmitted from each beam on the terminal station side, measuring each received power, and reporting the beam number with the largest received power on the uplink, in the next slot The radio base station transmits information symbols using the selected beam.
[0016]
In addition, when an adaptive array antenna is applied, as information to be broadcast in the uplink, when estimating a transmission path transmission coefficient for each antenna element of a radio base station and a transmission weight at a terminal station, This is a weighting factor for the antenna element.
[0017]
In this way, parameters related to propagation path characteristics are estimated at the terminal station and reported to the radio base station using the uplink, so that fluctuations in propagation path characteristics can be achieved even in systems with different uplink and downlink frequencies. Followed beam control becomes possible.
[0018]
However, in the beam selection type control method, as the number of beams increases, the ratio of pilot symbols to information symbols in the entire slot increases, and as a result, there is a problem that information transmission efficiency in the downlink is deteriorated.
[0019]
On the other hand, when an adaptive array antenna is used, the propagation path transmission coefficient or weighting coefficient broadcast from the terminal station is a complex number composed of amplitude and phase information, and each coefficient corresponding to the number of antenna elements needs to be fed back on the uplink. Therefore, the amount of information increases. For example, when the number of bits per weight coefficient is k and the number of beams is n, the amount of information to be fed back is k * n bits. For example, it is necessary to insert this control signal into an uplink information symbol for each slot, and the ratio of control symbols to be inserted with respect to the uplink information symbol increases, so that the uplink information transmission efficiency can be significantly reduced. There is sex.
[0020]
In addition, the technology for forming nulls in the direction of the interfering station is an extremely effective method in ideal operation. However, when actual operation is considered, the effects of processing delay in the terminal station and control delay due to feedback, etc. There is a possibility that the interference suppression effect cannot be sufficiently obtained with respect to the processing complexity.
[0021]
Therefore, the present invention provides a wireless communication system that can improve communication quality while maintaining information transmission efficiency while being able to cope with environmental fluctuations.
[0022]
Embodiment 1 FIG.
A radio communication system, a radio base station, and a terminal station according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are block diagrams showing examples of configurations of a radio base station and a terminal station of a radio communication system according to an embodiment of the present invention. FIG. 3 is a diagram showing transmission slots in the radio base station of the present invention. It is a figure which shows an example of a signal format.
[0023]
1 includes a plurality of antenna elements (# 1 to #N) 101 to 103 having directivities in different directions, duplexers 104 to 106, transmitters (Tx) 107 to 109, and receivers ( Rx) 110 to 112, a reception beam control circuit 113, a demodulator 114, a beam number detector 115, a modulator 116, a pilot symbol generator 117, and a beam switching circuit 118.
[0024]
2 includes an antenna element 141, a duplexer 142, a receiver (Rx) 143, a transmitter (Tx) 144, each beam SIR estimating unit 145, a beam selection circuit 146, and a modulator 147. Is done.
[0025]
An operation of the radio communication system according to the embodiment of the present invention will be described. In the terminal station shown in FIG. 2, the signal received by the antenna 141 is input to the receiver (Rx) 143 via the duplexer 142. The receiver 143 converts an RF (Radio Frequency) band received signal into a baseband digital signal. Each beam SIR estimation section 145 detects pilot symbols (known signals) of each beam multiplexed and inserted at the head of each slot as shown in FIG. Estimate signal-to-interference ratio (SIR).
[0026]
An example of a specific configuration of each beam SIR estimation unit 145 is a configuration as shown in FIG. 4, and includes a pilot symbol generator 151, correlators (1 to N) 152 to 154, timing detectors (1 to N) 155 to 157 and SIR calculators (1 to N) 158 to 160.
[0027]
The pilot symbol generator 151 generates pilot symbols for the same beams as those inserted in the transmission slot in the radio base station. Correlators 152 to 154 perform correlation calculation between these pilot symbols and the output signal from receiver 143 to extract a desired signal component. After that, the timing detectors 155 to 157 detect the timing of the sample with the best timing with the pilot symbol included in the received signal, that is, the sample with the most improved SIR, and then use the detected timing sample. The SIR calculators 158 to 160 derive the SIR of each beam. The SIR values of these beams are input to the beam selection circuit 146 at the subsequent stage.
[0028]
In the calculations in the SIR calculators 158 to 160, it is possible to estimate an accurate value by performing an averaging process using a plurality of samples.
[0029]
The beam selection circuit 146 selects the beam having the highest SIR. This is broadcast to the radio base station on the uplink, and the procedure is to insert the information of the selected beam number into the information symbol to be transmitted, perform modulation processing by the modulator 147, and then transmit to the transmitter (Tx ) 144 is converted to an RF band signal and radiated from the antenna 141 via the duplexer 142.
[0030]
Thus, since the information fed back from the terminal station only needs to have the beam number, the transmission efficiency of the uplink is hardly affected. For example, when 8 beams are used, the control information may be 3 bits. In addition, since the beam number is reported, the terminal station does not need to consider any shape of beam used in the radio base station, and the system expandability is excellent. Note that signal components including various information data such as voice transmitted from the radio base station are detected by a demodulator or the like. However, in the configuration example of FIG. This part is omitted for the sake of clarity.
[0031]
On the other hand, the radio base station in FIG. 1 receives the modulated signal transmitted from the terminal station by N antenna elements 101 to 103 having directivities in different directions, and receives them via the duplexers 104 to 106. The devices (Rx) 110 to 112 detect the signals and convert the RF band signals into baseband digital signals.
[0032]
The antenna element groups 101 to 103 have different directivities, and are set according to the communication range of the radio base station. For example, when covering the entire circumference of 360 degrees with eight antenna elements, the beam width of each antenna element may be about 45 degrees and arranged evenly.
[0033]
In the reception beam control circuit 113, the amplitude and phase of the reception signal of each antenna element are adjusted and combined to obtain an output signal. At this time, various existing algorithms are used in the control means of the reception beam control circuit 113. For example, diversity control methods such as selective combining and maximum ratio combining, and various control algorithms for adaptive array antennas that form nulls for interference signals are used. Can be mentioned.
[0034]
The output signal after the array synthesis is demodulated by the demodulator 114, and the beam number detector 115 detects the information of the selected beam number included in the received data. In order to simplify the description and make the features of the present invention easier to understand, in FIG. 1, the process of determining information symbols from the received data obtained from the demodulator 114 is omitted.
[0035]
The transmission operation will be described. The pilot symbol of the length specified by the pilot symbol generator 117 is generated by the number of beams to be formed, the information symbol subjected to modulation processing by the modulator 116, and the beam number detected by the beam number detector 115 The information is input to the beam switching circuit 118 together with the information.
[0036]
The beam switching circuit 118 creates a transmission slot having a format as shown in FIG. That is, an information symbol is added behind the pilot symbol of the beam corresponding to the beam number detected by the beam number detector 115 (FIG. 3 shows an example when Beam2 is selected). For other beams, nothing is added or null symbols such as all zero values are inserted. By multiplexing the transmission slots (N in this case) of these beams at the same time, it is possible to reduce the ratio of pilot symbols in the slots and prevent a decrease in transmission efficiency.
[0037]
In the embodiment of the present invention, since the pilot symbols of each beam are multiplexed and transmitted at the same time, the correlation characteristics of each pilot symbol should be as small as possible considering the accuracy of SIR estimation in the terminal station. Preferably, each pilot symbol is set to be orthogonal.
[0038]
For example, in a CDMA (Code Division Multiple Access) communication system, it is possible to perform communication in the same time by identifying a user by a spreading code. By assigning spreading codes that are orthogonal to each of the pilot symbols and performing spreading processing, the present invention can be applied to the CDMA scheme, and an efficient transmission scheme can be realized.
[0039]
Of course, if an orthogonal relationship is given between the pilot symbols, the spreading codes can be made the same between the beams, and in this case, the codes can be used effectively.
[0040]
Thereafter, the signal is converted into an RF band signal by the transmitters (Tx) 107 to 109 and radiated by the antenna elements 101 to 103 via the duplexers 104 to 106.
[0041]
In this manner, a plurality of beams are formed in the radio base station, signals orthogonal to each other are multiplexed and transmitted, and the terminal station selects and broadcasts the beam having the best reception state, thereby enabling the uplink and downlink to be transmitted. Even in wireless communication systems that use different frequencies on the line, it is possible to maintain information transmission efficiency and follow fluctuations in propagation path characteristics.
[0042]
In addition, as shown in FIG. 5, in the radio base station, a plurality of array antennas 10a, 10b... Each including antenna elements 101 to 103 are installed, and each of them is set to an interval at which the propagation path characteristics become uncorrelated with each other. It is also possible to obtain a diversity effect by performing the above control in the array antenna. Then, array antennas 10a, 10b, which form beams having a plurality of different directivity directions, may select and transmit the beams used for transmission, or may be transmitted as a whole (of all the beams). One optimum beam (highest SIR) may be selected and transmitted. 1 may be provided individually for each array antenna, or may be provided by switching one set in common.
[0043]
Embodiment 2. FIG.
Next, a radio base station according to another embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration of a radio base station according to another embodiment of the present invention. The radio base station of FIG. 6 forms each beam by digital signal processing, and includes a plurality of non-directional antenna elements (# 1 to #N) 121 to 123, duplexers 124 to 126, a transmitter ( (Tx) 127 to 129, receiver (Rx) 130 to 132, receive beam control circuit 133, demodulator 134, beam number detector 135, modulator 136, pilot symbol generator 137, and beam switching It comprises a circuit 138 and a beam forming circuit 139 for forming a plurality of beams by digital signal processing.
[0044]
A specific operation will be described. Since the antenna elements (# 1 to #N) 121 to 123 and the beam forming circuit 139 are basically the same as the corresponding parts shown in FIG.
[0045]
Arbitrary N antenna elements 121 to 123 are each formed of a so-called omnidirectional antenna element having no directivity in a specific direction.
[0046]
Subsequent operations are the same as those of the radio base station of FIG. 1, but after the beam switching circuit 138 creates a transmission slot for each beam, the beam forming circuit 139 performs a plurality of directivity directions by digital signal processing. Are transmitted by antenna elements 121-123.
[0047]
FIG. 7 shows an example of a specific configuration of the beam forming circuit 139. In FIG. 7, the beam forming circuit is composed of distributors (1 to L) 171 to 173, weight coefficient adders 174 for giving weight coefficients, and combiners (1 to N) 175 to 177. FIG. 7 shows an example in which the number of beams to be formed is L, but the number of beams L need not be the same as the number N of antenna elements. The transmission slots of each beam generated by the beam switching circuit 138 in FIG. 6 are N-divided by distributors 171 to 173.
[0048]
Each distributed slot is a complex weighting factor wi j(i = 1, ..., N; j = 1, ..., L) After the amplitude and phase components are adjusted by 174, they are synthesized by synthesizers (1 to N) 175 to 177 and multiplexed. The
[0049]
I.e. w1 j~ WN jCorresponds to the weighting factor of the array antenna for the beam j, and by preparing L sets of such weighting factors, beam forming at the digital stage is performed.
[0050]
These processes can be realized not only by hardware as shown in FIG. 7 but also by software. Therefore, it becomes easy to use orthogonal multi-beams by DFT (Discrete Fourier Transform) or FFT (Fast Fourier Transform).
[0051]
In this way, by forming each beam by digital signal processing, that is, setting the beam shape, it becomes possible to freely reshape the beam according to the installation environment of the radio base station and according to the environmental variation.
[0052]
Embodiment 3 FIG.
Next, a radio base station according to another embodiment of the present invention will be described. FIG. 8 is a configuration block diagram of a radio base station according to this embodiment, and FIG. 9 is a diagram illustrating an example of a signal format of a transmission slot in the radio base station according to this embodiment.
[0053]
In FIG. 8, since the receiving unit is the same as that in the first or second embodiment, the description thereof is omitted. The third radio base station according to this embodiment transmits a known signal for identifying each beam as a common pilot of a common channel, and includes a plurality of antenna elements 301 to 303, duplexers 304 to 306, transmission Units (Tx) 307 to 309, a beam forming circuit 310 for forming a plurality of beams, a pilot symbol generator 311, a beam switching circuit 312, and a modulator 313. FIG. 8 shows a configuration that accommodates M terminal stations, and is provided with a beam switching circuit and a modulator corresponding to an individual channel with each terminal station.
[0054]
In the above embodiment, a known signal for identifying a beam, that is, a pilot symbol is added to the head of an information symbol transmitted to a terminal station, that is, a dedicated channel with each terminal station. In the embodiment, the efficiency is further improved by adopting a configuration in which these pilot symbols are commonly used by one base station using a common pilot of a common channel.
[0055]
Specifically, as shown in FIG. 8, in the individual channel of each terminal, a signal obtained by modulating information to be transmitted by a modulator 313 is input to a beam switching circuit 312 together with a selected beam number detected from an uplink received signal. The beam used for transmitting information symbols is sequentially switched. This processing is performed for each channel corresponding to each terminal, and after the transmission signals for all the terminals are multiplexed, pilot symbols (known signals) generated by the pilot symbol generator 311 are further multiplexed as common pilots for the common channel. The Subsequent processing is the same as in the above embodiment.
[0056]
By using the common pilot of the common channel in this way, the transmission slot configuration as shown in FIG. 9 is obtained, and the influence on the throughput of the dedicated channel of the terminal station in the downlink can be further reduced. The common pilot in the common channel is also standardized as CPICH (Common Pilot Channel) in 3GPP (3rd Generation Partnership Project). Can be assigned CPICH. Therefore, the present embodiment can be easily applied to the CDMA communication system.
[0057]
Although FIG. 9 shows a configuration in which the number of pilot symbols is small with respect to information symbols of dedicated channels, it is of course possible to improve the accuracy of beam selection by increasing the number of pilot symbols. In particular, in the CDMA communication system, the same effect can be expected by increasing the spreading factor of the common pilot channel.
[0058]
Embodiment 4 FIG.
An example of the configuration of each beam SIR estimation unit (see 145 in FIG. 2) of the terminal station according to the present invention in the CDMA communication system is shown in FIG. Each beam SIR estimator 145a in FIG. 10 includes a spread code generator 181, MF (Matched Filter) (1 to N) 182 to 184, path timing detectors (1 to N) 185 to 187, , RAKE (1 to N) combiners 188 to 190 and SIR calculators (1 to N) 191 to 193.
[0059]
The spread code generator 181, the MF (Matched Filter) 182 to 184, the path timing detectors 185 to 187, and the SIR calculators 191 to 193 are the pilot symbol generator 151 and the correlator shown in FIG. Operations similar to 152 to 154, timing detectors 155 to 157, and SIR calculation units 158 to 160 are executed.
[0060]
In the CDMA communication system, a wideband signal is spread and transmitted with a spread code having a data rate higher than that of an information symbol. On the receiver side, the original information symbol is reproduced by performing correlation detection (referred to as despreading processing) using the same spreading code as that used on the transmitting side. At this time, the smaller the cross-correlation characteristic of the spreading code assigned to each user, the greater the interference suppression effect in the despreading process.
[0061]
In the radio communication system according to the embodiment of the present invention, this characteristic is used for beam selection processing in the terminal station. This will be specifically described below.
[0062]
As described in the first embodiment, when a terminal station receives a transmission slot in which pilot symbols are spread using spreading codes orthogonal to each beam, the spreading code generator 181 shown in FIG. The same spreading code as that used in the above is generated and input to the MFs 182 to 184. After performing correlation detection processing (despreading processing) between the received signal and the spreading code in MF182 to 184, each path timing detector 185 to 187 uses each path of the desired signal that has arrived through various propagation paths. Detect delay timing. RAKE combiners 188 to 190 perform RAKE combining that combines the maximum ratio of each path component based on each path timing, and SIR calculators 191 to 193 estimate the SIR value of each beam using the combined output. To do.
[0063]
By assigning orthogonal spreading codes to each beam in this way, a high interference suppression effect can be obtained at the time of correlation detection, and more accurate and most efficient by estimating the SIR of each beam using the signal after RAKE combining A good beam can be selected.
[0064]
Embodiment 5 FIG.
FIG. 11 shows an example of the configuration of each beam SIR estimation section of a terminal station in another embodiment of the present invention in the CDMA communication system. Each beam SIR estimator 145b in FIG. 11 includes a spread code generator 201, MF (Matched Filter) (1 to N) 202 to 204, maximum path timing detectors (1 to N) 205 to 207, , SIR computing units (1-N) 208-210.
[0065]
Spreading code generator 201, MF202 to 204, and SIR calculators 208 to 210 have the same operations as spreading code generator 181, MF182 to 184, and SIR calculators 191 to 193 in the fourth embodiment. Is omitted.
[0066]
Maximum path timing detectors 205 to 207 detect the timing of the path having the highest reception level among the paths of the desired signal that have arrived through various propagation paths. Thereafter, based on the detected sample timing of the maximum path, the SIR calculators 208 to 210 estimate the SIR value of each beam.
[0067]
By adopting a configuration that detects only the path of the maximum reception level in this way, the timing detector can be simplified and the number of RAKE combiners can be reduced, so that the device configuration of the terminal station can be simplified.
[0068]
Embodiment 6 FIG.
FIG. 12 shows a configuration example of each beam SIR estimator of the terminal station in another embodiment of the present invention in the CDMA communication system. It comprises a spread code generator 331, MFs (Matched Filters) 332 to 334, path timing detectors 335 to 337, RAKE combiners 338 to 340, and SIR calculators 341 to 343. Since the operation other than the spread code generator 331 is the same as that of the fourth embodiment, the description thereof is omitted. Of course, a configuration using only the path of the maximum reception level as shown in FIG. 11 described in the fifth embodiment is also possible.
[0069]
In Embodiments 4 and 5, since orthogonal spreading codes are assigned to each beam, excellent separation characteristics can be obtained. However, the number of orthogonal codes is limited, and in order to accommodate more terminals, it is not efficient to assign a code for each beam of each terminal. Therefore, in the present embodiment, as shown in FIG. 12, the spread code generator 331 generates only one spread code and uses it in common between the beams. Of course, in this case, as described in the first embodiment, it is necessary that the radio base station side performs the spreading process on the pilot symbols (known signals) of the respective beams using the same spreading code.
[0070]
Therefore, RAKE combining and SIR estimation of each beam in the present embodiment are performed using only pilot symbols that are orthogonal to each other.
[0071]
In addition, this configuration can realize a terminal station corresponding to a radio base station using a common pilot of a common channel shown in the third embodiment, and one base station can provide one common pilot channel for beam identification. Two spreading codes need only be prepared, and the orthogonal codes can be used effectively.
[0072]
Embodiment 7 FIG.
In the above embodiment, the terminal station selects the beam with the best SIR. However, depending on the propagation path characteristics, a multipath arrives from a distant angle, and so on. There may be more than one. A beam selection method in such a case will be described.
[0073]
In the terminal station, a target SIR is set in advance as a threshold value. The SIR of each beam is estimated using pilot symbols in the transmission slot from the radio base station, and a plurality of beams having a value larger than the previous target SIR are selected. Each of the selected beam numbers is notified to the radio base station via an uplink, and the radio base station transmits information symbols using the plurality of beams.
[0074]
FIG. 13 shows a transmission slot configuration in the radio base station in the present embodiment. Multiplexing for simultaneously transmitting the transmission slots of these N beams is performed. FIG. 13 shows an example in which, among N beams, J beams are selected at the terminal station, an information symbol is added to each transmission slot of the selected beam and multiplexed. Thus, it is possible to efficiently use a beam having a good propagation path characteristic.
[0075]
Further, even in a radio base station configuration using a common pilot channel as in Embodiment 3, transmission using a plurality of beams is naturally possible.
[0076]
Embodiment 8 FIG.
A transmission beam forming method in the radio base station according to the present embodiment will be described. FIG. 14 shows an example in which beams are formed at equal intervals in a horizontal plane. The selected beam 221 is a beam selected by the terminal station, and is used to transmit information symbols in the next slot in the radio base station. Adjacent beams 222 and 223 are adjacent to them.
[0077]
In a system that feeds back some control information from the terminal station to the radio base station, the information transmission efficiency of the uplink is affected by the amount of information. Therefore, it is desirable that the control information is as small as possible. This embodiment shows a method for realizing it.
[0078]
A specific operation will be described. Assume that pilot symbols are transmitted using all beams in the initial state of communication, and beam number information selected by the terminal station is broadcast to the radio base station via the uplink. As described in the previous embodiment, the radio base station detects the selected beam number and creates a transmission slot. At this time, a transmission slot is not created using all the beams, but a slot is created using only the selected beam 221 and adjacent beams 222 and 223 adjacent thereto. Then, the beam to be sequentially selected is updated.
In this way, the processing amount in the radio base station can be reduced, and the number of control information symbols to be inserted into the uplink and the beam selection processing in the terminal station can be reduced.
[0079]
Although FIG. 14 shows an example in the horizontal plane, when a beam is also formed in the vertical plane, it is possible to cope with the beam configuration of each radio base station by using adjacent beams around the selection beam 221.
[0080]
In addition, by periodically determining the selected beam using all the beams, it becomes possible to follow the change in the propagation path characteristics with higher accuracy.
[0081]
Embodiment 9 FIG.
Another transmission beam forming method in the radio base station according to the present embodiment will be described. FIG. 15 shows an example in which beams are formed at equal intervals in a horizontal plane. The selected beam group 225 is a set of beams selected by the terminal station in the initial state.
[0082]
In the initial state of communication, the radio base station transmits pilot symbols for all beams as described in the first embodiment. The terminal station estimates the SIR of each beam, and designates the selected beam group 255 from a good angle range of the SIR. At this time, the number of beams included in the selected beam group 255 is designated in advance.
[0083]
Examples of the beam group range setting include a method of sliding one beam at a time and a method of setting continuously.
[0084]
The radio base station that has been notified of the information of the selected beam group by the uplink transmits the pilot symbol using the beam in the selected beam group 225, and sequentially updates the beam selection process.
[0085]
Further, by periodically resetting the beam group to be used as described above, it becomes possible to follow changes in propagation path characteristics.
[0086]
Embodiment 10 FIG.
Another transmission beam forming method in the radio base station according to the present embodiment will be described. FIG. 16 shows an example in which beams are formed at equal intervals in a horizontal plane. In FIG. 16, a is an initial state, and b is a beam group at the start of communication. The selected beam group 230 is a set of beams selected by the terminal station in the initial state. The method of setting the selected beam group 230 is the same as that described in the ninth embodiment.
[0087]
The radio base station closely reshapes the beam using the maximum degree of freedom allowed in the angle range of the selected beam group 230 broadcast from the terminal station. Information symbols are transmitted after communication is started using the reshaped beam group 231.
[0088]
Thus, by densely arranging the beams in an angle range with a good SIR, it is possible to accurately follow the fluctuation of the propagation path characteristics.
[0089]
Further, by periodically resetting the beam group to be used as described above, it becomes possible to follow changes in propagation path characteristics.
[0090]
【The invention's effect】
As described above, according to the present invention, in a radio communication system including a radio base station that forms a plurality of beams having different directivity directions and a plurality of terminal stations that communicate with the radio base station, each of the terminal stations Means for estimating a ratio of desired signal power to interference signal power of a downlink transmitted from a plurality of beams of the radio base station, and beam selection for selecting an optimum beam from the desired signal power to interference signal power ratio Means for notifying the selected beam number using an uplink from the terminal station to the radio base station, wherein the radio base station has the beam number reported from the terminal station. For example, since the wireless communication system includes a transmission control means for transmitting an information signal to the terminal station using a beam corresponding to the beam number, it is possible to cope with environmental fluctuations. While retaining information transmission efficiency, provide improved communication quality can be provided a wireless communication system.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a radio base station of a radio communication system according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a terminal station of the wireless communication system according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of a signal format of a transmission slot in a radio base station according to an embodiment of the present invention.
4 is a diagram illustrating an example of a specific configuration of each beam SIR estimation unit in FIG. 2;
FIG. 5 is a block diagram showing a configuration of a radio base station of a radio communication system according to the present invention provided with a plurality of array antennas.
FIG. 6 is a block diagram showing a configuration of a radio base station of a radio communication system according to another embodiment of the present invention.
7 is a diagram showing an example of a specific configuration of the beam forming circuit in FIG. 6;
FIG. 8 is a configuration block diagram of a radio base station according to another embodiment of the present invention.
9 is a diagram illustrating an example of a signal format of a transmission slot in the radio base station of FIG.
FIG. 10 is a diagram illustrating an example of a specific configuration of each beam SIR estimation unit of a terminal station in the CDMA communication system of the present invention.
FIG. 11 is a diagram showing another example of a specific configuration of each beam SIR estimation unit of the terminal station in the CDMA communication system of the present invention.
FIG. 12 is a diagram showing another example of a specific configuration of each beam SIR estimation unit of the terminal station in the CDMA communication system of the present invention.
FIG. 13 is a diagram illustrating an example of a signal format of a transmission slot in a radio base station according to another embodiment of the present invention.
FIG. 14 is a diagram for explaining a transmission beam forming method in a radio base station according to another embodiment of the present invention;
FIG. 15 is a diagram for explaining a method of forming a transmission beam in a radio base station according to still another embodiment of the present invention.
FIG. 16 is a diagram for explaining a transmission beam forming method in a radio base station according to still another embodiment of the present invention.
[Explanation of symbols]
10a, 10b array antenna, 101-103, 141 antenna element, 104-106, 142 duplexer, 107-109, 144 transmitter (Tx), 110-112, 143 receiver (Rx), 113 receive beam control circuit, 114 Demodulator, 115 Beam number detector, 116 Modulator, 117 Pilot symbol generator, 118 Beam switching circuit, 145 Each beam SIR estimator, 146 Beam selection circuit, 147 Modulator, 151 Pilot symbol generator, 152-154 Correlation (1-N), 155-157 Timing detector (1-N), 158-160 SIR calculator (1-N).

Claims (9)

  1. In a radio communication system comprising a radio base station that forms a beam having a plurality of different directivity directions and a plurality of terminal stations that communicate with the radio base station,
    Each terminal station
    Means for estimating a ratio of desired signal power to interference signal power in a downlink transmitted from a plurality of beams of the radio base station, respectively;
    Beam selecting means for selecting an optimum beam from the desired signal power to interference signal power ratio;
    Means for notifying the selected beam number using an uplink from the terminal station to the radio base station;
    With
    The radio base station is
    Transmission control means for transmitting an information signal to the terminal station using the beam corresponding to the beam number if there is the beam number broadcast from the terminal station ;
    The radio base station transmission control means adds a known orthogonal signal different for each of a plurality of beams formed by the radio base station in the common channel to the information signal transmitted from the radio base station to the terminal station through an individual channel. Assign, multiplex and add these,
    A wireless communication system , wherein the desired signal power to interference signal power ratio estimation means of the terminal station detects the known orthogonal signal of the common channel and estimates a desired signal power to interference signal power ratio .
  2. The wireless communication system performs CDMA communication system communication, sets known orthogonal signal groups as mutually orthogonal data sequences, spreads them with a common spreading code, and uses them as common pilot signals of a common channel. The radio communication system according to claim 1, wherein the radio communication system is multiplexed with a transmission signal of a channel.
  3. A radio base station that forms a beam having a plurality of different directivity directions, and a plurality of terminal stations that communicate with the radio base station,
      Each terminal station
      Means for estimating a ratio of desired signal power to interference signal power of a downlink transmitted from a plurality of beams of the radio base station,
      Beam selecting means for selecting an optimum beam from the desired signal power to interference signal power ratio;
      Means for notifying the selected beam number using an uplink from the terminal station to the radio base station;
      With
      The radio base station is
      Transmission control means for transmitting an information signal to the terminal station using a beam corresponding to the beam number if there is the beam number broadcast from the terminal station;
      The transmission control means of the radio base station multiplexes and adds different known signals for each of a plurality of beams formed by the radio base station to the information signal transmitted from the radio base station to the terminal station,
      A desired signal power to interference signal power ratio estimating means of the terminal station detects the known signal and estimates a desired signal power to interference signal power ratio;
      A wireless communication system,
      The wireless communication system performs CDMA communication system communication,
      The transmission control means of the radio base station performs spreading processing of the known signal with orthogonal codes, and adds the spread known signals for each beam multiplexed to the information signal transmitted to the terminal station And
      A desired signal power to interference signal power ratio estimation means of the terminal station detects the spread known signal, estimates a desired signal power to interference signal power ratio,
      The known signal is made into a bit string or a symbol string orthogonal to each other, subjected to spreading processing by a common spreading code, and then multiplexed as a common pilot of a common channel on a transmission signal of an individual channel with each terminal station Communications system.
  4. Desired signal power to interference signal power ratio estimation means of the terminal station, a beam selector After determining the beam number using all the beams in the initial state of communication start, the beam corresponding to the beam number and the beam adjacent thereto are transmitted in the stage, the reporting unit, and the transmission control unit of the radio base station. The wireless communication system according to any one of claims 1 to 3, wherein the desired signal power to interference signal power ratio in a downlink is estimated and a beam to be sequentially selected is updated.
  5. In the terminal station desired signal power to interference signal power ratio estimation means, beam selection means, notification means, and transmission control means of the radio base station, in the initial state of communication start, the terminal station uses all the beams to download Estimating the desired signal power-to-interference signal power ratio of the line, reporting information on the angle range with good reception using the uplink to the radio base station, and then the selected range in the radio base station 4. The desired signal power-to-interference signal power ratio in the downlink is estimated using a plurality of beams formed on the base station, and the beam to be sequentially selected is updated. 5. The wireless communication system according to 1.
  6. In a radio communication system comprising a radio base station that forms a beam having a plurality of different directivity directions and a plurality of terminal stations that communicate with the radio base station,
      Each terminal station
      Means for estimating a ratio of desired signal power to interference signal power of a downlink transmitted from a plurality of beams of the radio base station,
      Beam selecting means for selecting an optimum beam from the desired signal power to interference signal power ratio;
      Means for notifying the selected beam number using an uplink from the terminal station to the radio base station;
      With
      The radio base station is
      If there is the beam number broadcast from the terminal station, transmission control means for transmitting an information signal to the terminal station using a beam corresponding to the beam number;
      With
      In the initial state of communication start, the beam number is determined using all the beams in the desired signal power to interference signal power ratio estimation means, beam selection means, notification means, and transmission control means of the radio base station in the terminal station Then, using the beam corresponding to the beam number and the beam adjacent thereto, the desired signal power to interference signal power ratio in the downlink is estimated, and the beam to be sequentially selected is updated. system.
  7. In a radio communication system comprising a radio base station that forms a beam having a plurality of different directivity directions and a plurality of terminal stations that communicate with the radio base station,
      Each terminal station
      Means for estimating a ratio of desired signal power to interference signal power of a downlink transmitted from a plurality of beams of the radio base station,
      Beam selecting means for selecting an optimum beam from the desired signal power to interference signal power ratio;
      Means for notifying the selected beam number using an uplink from the terminal station to the radio base station;
      With
      The radio base station is
      If there is the beam number broadcast from the terminal station, transmission control means for transmitting an information signal to the terminal station using a beam corresponding to the beam number;
      With
      In the terminal station desired signal power to interference signal power ratio estimation means, beam selection means, notification means, and transmission control means of the radio base station, in the initial state of communication start, the terminal station uses all the beams to download Estimating the desired signal power-to-interference signal power ratio of the line, reporting information on the angle range with good reception using the uplink to the radio base station, and then the selected range in the radio base station A wireless communication system, wherein a plurality of beams formed on the base station are used to estimate a desired signal power-to-interference signal power ratio in a downlink, and a sequentially selected beam is updated.
  8. The wireless communication according to claim 5 or 7, wherein the desired signal power to interference signal power ratio of the downlink is periodically estimated using all beams, and information on an angle range with a good reception state is updated. system.
  9. 8. The wireless communication according to claim 5, wherein a plurality of beams are re-formed within the range by utilizing an allowable degree of freedom to the maximum based on an angle range notified from the terminal station. system.
JP2003136258A 2002-09-20 2003-05-14 Wireless communication system Active JP4107494B2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
PCT/JP2002/009704 WO2004028037A1 (en) 2002-09-20 2002-09-20 Radio communication system
JP2004537525 2002-09-20
JP2003136258A JP4107494B2 (en) 2002-09-20 2003-05-14 Wireless communication system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2003136258A JP4107494B2 (en) 2002-09-20 2003-05-14 Wireless communication system

Publications (2)

Publication Number Publication Date
JP2004297750A JP2004297750A (en) 2004-10-21
JP4107494B2 true JP4107494B2 (en) 2008-06-25

Family

ID=33432206

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2003136258A Active JP4107494B2 (en) 2002-09-20 2003-05-14 Wireless communication system

Country Status (1)

Country Link
JP (1) JP4107494B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105324945A (en) * 2013-06-19 2016-02-10 高通股份有限公司 Devices and methods for detecting and handling deconstructive impacts of default weight factors for closed-loop transmission diversity communications

Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005071865A1 (en) * 2004-01-21 2005-08-04 Nec Corporation Transmission directivity antenna control system, base station, and transmission directivity antenna control method for use in them
JP4648015B2 (en) * 2005-01-28 2011-03-09 株式会社エヌ・ティ・ティ・ドコモ Transmitting apparatus and transmitting method
US20060203794A1 (en) * 2005-03-10 2006-09-14 Qualcomm Incorporated Systems and methods for beamforming in multi-input multi-output communication systems
JP4610388B2 (en) * 2005-03-24 2011-01-12 三洋電機株式会社 Wireless device
EP1895796B1 (en) 2005-06-17 2014-06-04 Fujitsu Ltd. Wireless access method, wireless base station device, and wireless terminal device
WO2007052602A1 (en) * 2005-10-31 2007-05-10 Sharp Kabushiki Kaisha Radio transmitter and radio transmission method
WO2007105999A1 (en) 2006-03-13 2007-09-20 Telefonaktiebolaget Lm Ericsson (Publ) Advanced handover for adaptive antennas
US8036669B2 (en) * 2006-04-20 2011-10-11 Qualcomm Incorporated Orthogonal resource reuse with SDMA beams
US20100015927A1 (en) * 2006-10-24 2010-01-21 Panasonic Corporation Radio communication device and radio communication method
EP2107699A4 (en) 2007-01-23 2013-12-04 Nec Corp Radio control method
AT504984T (en) * 2007-02-07 2011-04-15 Sony Deutschland Gmbh Method for sending a signal in a wireless communication system and communication system
WO2009087808A1 (en) * 2008-01-07 2009-07-16 Mitsubishi Electric Corporation Analog beam forming communication system
US8626080B2 (en) * 2008-03-11 2014-01-07 Intel Corporation Bidirectional iterative beam forming
KR101609492B1 (en) 2008-05-09 2016-04-05 애플 인크. System and method for supporting antenna beamforming in a cellular network
JP5172609B2 (en) * 2008-10-31 2013-03-27 株式会社東芝 Wireless communication apparatus, wireless terminal, and wireless communication method
JP5294170B2 (en) * 2009-01-21 2013-09-18 独立行政法人情報通信研究機構 Wireless communication device, wireless communication method, program, and information recording medium
JP5237450B2 (en) * 2009-06-16 2013-07-17 株式会社東芝 Communication device
JP5278279B2 (en) * 2009-10-16 2013-09-04 富士通株式会社 Wireless communication system
US9401753B2 (en) 2009-12-23 2016-07-26 Intel Corporation Native medium access control support for beamforming
US8306483B2 (en) * 2009-12-24 2012-11-06 Intel Corporation Method and system for improving wireless link robustness using spatial diversity
JP5556764B2 (en) * 2011-08-03 2014-07-23 日本電気株式会社 Mobile communication system, mobile body, and beam direction control method
KR101828836B1 (en) * 2011-08-23 2018-02-13 삼성전자주식회사 Apparatus and method for scheduling using beam scanning in beamformed wireless communication system
JP5443630B2 (en) * 2013-03-27 2014-03-19 株式会社東芝 Communication device
CN106412942A (en) * 2015-07-31 2017-02-15 株式会社Ntt都科摩 Sending method of beamformed reference signals, beam selection method, base station, and user equipment
JP2017152830A (en) * 2016-02-23 2017-08-31 Kddi株式会社 Wireless communication system, transmitting device, receiving device, and communication method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105324945A (en) * 2013-06-19 2016-02-10 高通股份有限公司 Devices and methods for detecting and handling deconstructive impacts of default weight factors for closed-loop transmission diversity communications

Also Published As

Publication number Publication date
JP2004297750A (en) 2004-10-21

Similar Documents

Publication Publication Date Title
US20200146013A1 (en) Transmission apparatus and transmission method using a plurality of divided frequency bands in a communication band
Jeong et al. Random access in millimeter-wave beamforming cellular networks: issues and approaches
EP2939479B1 (en) Uplink power control method and apparatus in a beam-forming based wireless communication system
EP2882110B1 (en) Communication method and device using beamforming in wireless communication system
US9160430B2 (en) Millimeter-wave transceiver with coarse and fine beamforming with interference suppression and method
JP2016506112A (en) Method and apparatus for operation of beam gain compensation by changing transmit and receive beam patterns in a beamforming based wireless communication system
US9042842B2 (en) System and apparatus for interference suppression using macrodiversity in mobile wireless networks
ES2292223T3 (en) Wire-free communication systems with multiple access by space division.
KR101058968B1 (en) Mobile Supported Downlink Beamforming Using Antenna Weighted Feedback
JP4546436B2 (en) Distributed base station, communication system, and signal transmission method for the base station and system
US7602837B2 (en) Beamforming for non-collaborative, space division multiple access systems
US7031368B1 (en) Adaptive transmitter/receiver
JP4230535B2 (en) Spectral efficient mass wireless communication system
DE10032426B4 (en) Beamforming method
DE602004012136T2 (en) Method and device for a multi-ray antenna system
US5982327A (en) Adaptive array method, device, base station and subscriber unit
US7706323B2 (en) Wireless communications in a multi-sector network
US7376428B2 (en) Positioning method and radio system
JP4536733B2 (en) Wireless communication system
EP1650883B1 (en) Method for transmission scheme selection based on the number of antennas and the data rate
JP3888189B2 (en) Adaptive antenna base station equipment
KR100955446B1 (en) Adaptive sectorization in cellular systems
EP1601119B1 (en) Radio base station apparatus and radio communication method
JP4121560B2 (en) Directional wireless communication method and apparatus
EP1998484B1 (en) Base station and its mimo-ofdm communication method

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20060118

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20071130

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20071204

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20080201

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20080226

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20080327

R150 Certificate of patent or registration of utility model

Ref document number: 4107494

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110411

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120411

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120411

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130411

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130411

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140411

Year of fee payment: 6

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250