WO2006016563A1 - Base station apparatus and communication method - Google Patents

Abstract

A base station apparatus capable of providing optimum signal transmissions in accordance with the propagation statuses of terminal apparatuses in a sector without increasing the number of beams in the sector. In this base station apparatus (100), a wireless parameter information referring part (112) extracts wireless parameter information from a received signal as demodulated by a received signal demodulating part (110). A wireless parameter correcting part (114), when executing a wireless parameter correction, uses the difference of delay spread or SNR, outputted by a received signal comparing part (111), to correct the wireless parameters with the respect to the wireless parameter information outputted by the wireless parameter information referring part (112). A user assigning part (115) assigns a transmission resource to a user having the best wireless parameter of those as corrected by the wireless parameter correcting part (114).

Description

 Specification

 Base station apparatus and communication method

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a base station apparatus and a communication method, and more particularly to a base station apparatus and a communication method that are useful when performing link stabilization (adaptive modulation) in a common packet channel.

 Background art

 Conventionally, as a published paper on this type of base station apparatus, there has been known one related to the development of a space-time packet scheduler (throughput improvement effect by beam forming) (for example, see Non-Patent Document 1).

[0003] The base station device described in Non-Patent Document 1 assumes a configuration including an adaptive array antenna in a transmission system using link adaptation (adaptive modulation) on a downlink common channel.

 As shown in FIG. 1, in the conventional base station apparatus 60, the sector is divided into four beams using an adaptive array antenna, and the pilot signals specific to each beam are spread differently from each other. Transmit using a code.

In FIG. 1, each terminal device A, B, C, D, E, F, G, and H estimates the available downlink transmission rate based on the reception quality of each pilot signal, and Direct to device 60.

[0006] The base station apparatus 60 uses the transmission rates indicated by the terminal apparatuses A, B, C, D, E, F, G, and H to determine the allocated beam and the allocated terminal by the scheduler, and Directive transmission using adaptive array antennas is performed toward the terminal equipment.

[0007] With this, it is possible to optimize the transmission rate by adaptive modulation, and simultaneously limit the influence of interference to a specific region by the effect of spatial division by directional transmission, making it possible to utilize high frequency utilization efficiency become.

 Non-Patent Document 1: Published Paper; 2003 IEICE Communication Society B— 5-4, Sep. 2003

Disclosure of the invention Problems to be solved by the invention

 [0008] In this type of base station apparatus, it is necessary to transmit a no-lot signal corresponding to each beam. On the other hand, the terminal device needs to demodulate the pilot signal corresponding to each beam and measure the quality.

 Incidentally, as shown in FIG. 1, in the base station device 60 that attempts to cover the inside of the sector with four beams, a terminal device that cannot receive the benefits of beam transmission depending on the position of the user (FIG. 1). There is a problem that the terminal device I) shown below appears. In order to solve such a problem, it is necessary to increase the number of beams so as to cover a wide area in the sector and to transmit directional transmissions to all terminal apparatuses in the sector.

 [0010] However, if the number of beams in the sector is increased, the base station device 60 needs to allocate the limited total transmission power to the pilot signals for each beam. Therefore, the pilot signal transmission power per beam must be reduced accordingly.

 For this reason, in such a base station apparatus 60, the influence of noise increases with a decrease in transmission power due to an increase in the number of beams, so that the terminal apparatuses A, B, C, D, E, F, It is expected that the measurement accuracy in G and H will deteriorate and the accuracy of measurement accuracy will be lost.

 [0012] Also, the terminal devices A, B, C, D, E, F, G, and H used in such a base station device 60 demodulate all pilot signals transmitted from the base station device 60. Therefore, demodulation processing increases as the number of beams increases.

 An object of the present invention is to provide a base station apparatus and a communication method capable of realizing optimal signal transmission according to the propagation status of each terminal apparatus in a sector without increasing the number of beams in the sector. It is to be.

 Means for solving the problem

[0014] The base station apparatus of the present invention includes a plurality of receiving means for receiving a signal transmitted from a terminal apparatus with both omnidirectionality and individual directivity, and a first received signal received with the omnidirectionality. Synthesized by the omnidirectional synthesis means, the individual directional synthesis means for synthesizing the second received signal received with the individual directivity, the omnidirectional synthesis means and the individual directivity synthesis means. Despreading means for despreading each received signal, received signal comparing means for comparing the first received signal and the second received signal that have been despread, Wireless parameter information reference means for extracting wireless parameter information from one received signal, wireless parameter correction means for adjusting the output of the wireless parameter information reference means on the basis of the difference of the comparison result in the received signal comparison means, User allocating means for allocating transmission resources to a user having the best radio parameter after correction by the radio parameter correcting means, and transmitting means for directionally transmitting a signal to the user allocated by the user allocating means. The structure to comprise is taken.

 The invention's effect

 According to the present invention, the terminal device can reflect only the reception quality of the common pilot signal, and the effect obtained by the individual directivity in the base station device can be reflected in the radio parameter setting. It is possible to realize optimal signal transmission according to the user's propagation situation.

FIG. 1 is a schematic diagram showing a beam in a conventional base station apparatus.

 FIG. 2 is a block diagram showing a configuration of a base station apparatus according to an embodiment of the present invention.

 FIG. 3 is a block diagram showing a configuration of a terminal apparatus used in the base station apparatus according to one embodiment of the present invention.

 FIG. 4 is a schematic diagram showing a processing flow between a base station apparatus and a terminal apparatus according to an embodiment of the present invention.

 FIG. 5 is a schematic diagram showing a beam in a base station apparatus according to an embodiment of the present invention.

 FIG. 6 is a diagram showing a reference table when radio parameters are set in the base station apparatus according to one embodiment of the present invention.

 BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing the configuration of the base station apparatus according to one embodiment of the present invention.

As shown in FIG. 2, base station apparatus 100 according to the present embodiment includes antennas 101 and 102, reception RF sections 103 and 104, omnidirectional combining sections 105 and 106, and individual directivity combining sections 107, 118, despreading sections 108 and 109, received signal demodulating section 110, received signal comparing section 111, radio parameter information referring section 112, radio parameter correction reference indicating section 113, radio parameter correcting section 114 A user allocation unit 115, a transmission signal generation unit 116, a modulation / coding unit 117, and transmission RF units 119 and 120.

 In FIG. 2, each of the antennas 101 and 102 receives a signal transmitted from the terminal device 200 and transmits a signal toward the terminal device 200.

[0020] Reception RF sections 103 and 104 perform band limitation and amplification on reception signals captured by antennas 101 and 102, respectively.

 The omnidirectional synthesis units 105 and 106 and the individual directivity synthesis unit 107 are received RF units 103 and 10.

4 synthesizes the band-limited and amplified received signal.

[0022] Despreading sections 108 and 109 despread the reception signals combined by omnidirectional combining sections 105 and 106 and individual directivity combining section 107, respectively.

Received signal demodulation section 110 performs demodulation processing on the received signal despread by despreading section 108.

 [0024] Received signal comparing section 111 is synthesized by omnidirectional synthesis section 105 and despread by despreading section 108, and is synthesized by individual directivity synthesis section 107 and despread by despreading section 109. The SNR with the received signal is compared with the delay spread, and the original value and the difference between the two are output to the radio parameter correction reference instructing unit 113 and the radio parameter correcting unit 114.

 Radio parameter information reference section 112 extracts radio parameter information from the received signal demodulated by received signal demodulation section 110 and outputs the radio parameter information to radio parameter correction section 114.

 [0026] Radio parameter correction reference instructing section 113 determines that "perform radio parameter correction" if the SNR or delay spread differential power input from received signal comparison section 111 exceeds a predetermined threshold. The parameter correction unit 114 is instructed. If the difference exceeds the threshold value, the wireless parameter correction unit 114 is instructed to “do not perform wireless parameter correction”.

 Radio parameter correction unit 114 outputs radio parameter information reference unit 112 when radio parameter correction reference instruction unit 113 issues an instruction to “perform radio parameter correction”. For the radio parameter information, the radio parameter is corrected using the difference in SNR or delay spread output from the received signal comparator 111.

[0028] Specifically, for example, when individual directivity is better by 5 dB in SNR than omnidirectionality Next, a radio parameter shifted so as to realize a transmission rate higher by 5 dB than the radio parameter output from the radio parameter information reference unit 112 is set. Here, as in the reference table shown in FIG. 6, a wireless node shifted so as to realize a transmission rate higher by a predetermined amount using desired wave power as a reference for calculating the difference between individual directivity and non-directivity. Set the meter. FIG. 6 is a diagram showing a reference table when radio parameters are set in the base station apparatus.

 [0029] Note that, as another example, the radio parameter correction unit 114 can reduce the radio parameter information when the delay spread can be reduced to a ratio equal to or smaller than a predetermined value and is shorter than a predetermined value. It may be possible to implement control for assigning a modulation multi-level number higher than the radio parameter output from the reference unit 112.

 [0030] User allocating section 115 allocates a transmission resource to a user whose radio parameter corrected by radio parameter correcting section 114 is the best.

 [0031] Transmission signal generating section 116 generates a transmission signal to be transmitted to the user assigned by user assigning section 115.

The modulation / coding unit 117 modulates and encodes the transmission signal generated by the transmission signal generation unit 116 using the corrected radio parameter calculated by the radio parameter correction unit 114.

 The individual directivity synthesis unit 118 synthesizes the signals modulated and encoded by the modulation / coding unit 117 so as to have individual directivities for the users assigned by the user assignment unit 115.

 [0034] The transmission RF units 119 and 120 perform band limitation and amplification on the transmission signal synthesized by the individual directivity synthesis unit 118, and the antennas 101 and 101 are directed toward the terminal device 200 of the user to which the transmission signal is assigned. Send in 102.

In this base station apparatus 100, received signals are synthesized by omnidirectional synthesis sections 105 and 106 and individual directivity synthesis section 107, and the result is compared by received signal comparison section 111. Then, the wireless parameter correction unit 114 calculates a correction value for the comparison result power, and the result is transferred to the user allocation unit 115 together with the wireless parameter information output from the wireless parameter information reference unit 112. Determine the assigned user. [0036] Subsequently, the transmission signal of the allocated user is modulated and encoded using the corrected radio parameter, and is output to the transmission RF sections 119 and 120. The transmission RF sections 119 and 120 perform upconversion or the like. After performing predetermined processing, this transmission signal is transmitted from each of the antennas 101 and 102.

 [0037] FIG. 3 is a block diagram showing a configuration of a terminal apparatus used in the base station apparatus according to the present embodiment. As shown in FIG. 3, the terminal device 200 includes an antenna 201, a reception RF unit 202, a reception signal demodulation unit 203, a control information reference unit 204, a reference signal observation unit 205, a radio parameter generation unit 206, a transmission RF unit 207, a communication A channel decoding unit 208 is provided.

 In FIG. 3, antenna 201 receives a signal sent to base station apparatus 100 and transmits a signal to base station apparatus 100.

 [0039] Reception RF section 202 performs band limitation and amplification on the received signal captured by antenna 201.

[0040] Received signal demodulation section 203 refers to control information such as radio parameters notified separately by control information reference section 204, and performs despreading and demodulation on the received signal sent from received RF section 202. Apply processing.

 [0041] Reference signal observation section 205 observes the propagation state of the reference signal among the signals demodulated by reception signal demodulation section 203, and instructs observation result to radio parameter generation section 206.

 [0042] Radio parameter generation section 206 generates radio parameters such as a modulation scheme and a code rate based on the reception quality of the common pilot channel transmitted to the entire sector.

 Transmission RF section 207 performs band limitation and amplification on the transmission signal given from radio parameter generation section 206, and transmits this transmission signal to base station apparatus 100 through antenna 201.

 Communication channel decoding unit 208 performs predetermined processing such as turbo decoding on the communication channel signal among the signals demodulated by reception signal demodulation unit 203.

In terminal apparatus 200, received signal demodulation section 203 performs despreading and demodulation processing with reference to control information such as radio parameters notified separately. Of the demodulated signals, the reference signal is used for observation of the propagation status by the reference signal observation unit 205, and the result Is transmitted to the antenna 201 after instructing the wireless parameter generation unit 206 to perform predetermined processing in the transmission RF unit 207. Of the demodulated signals, communication channel signals are subjected to predetermined processing such as turbo decoding in the communication channel decoding unit 208, and then decoding is completed.

 [0046] Next, a processing flow between the base station apparatus and the terminal apparatus according to the present embodiment will be described. FIG. 4 is a schematic diagram showing a processing flow between the base station apparatus and the terminal apparatus according to the present embodiment. Here, terminal device 200 shown in FIG. 3 is shown as terminal devices A, B, C,... Located in the sector of base station device 100.

 In FIG. 4, base station apparatus 100 transmits a common pilot signal to the entire sector as shown in FIG. 5 (step ST301). FIG. 5 is a schematic diagram showing beams in the radio communication system according to the present embodiment. Terminal devices A, B, C, ... of many users generate radio parameters such as modulation scheme and coding rate based on the reception quality of the common pilot channel transmitted to the entire sector (step ST302). ), And notifies (reports) the generated radio parameter to base station apparatus 100 (step ST303).

 [0048] When the base station apparatus 100 receives the radio parameter information notified from each terminal apparatus A, B, C, ..., each user individually, based on the adaptive algorithm, arrival direction estimation result, etc. Reception is performed with both the generated directivity and non-directivity, and the reception results of both are compared (step ST304).

 [0049] Next, base station apparatus 100 adjusts the radio parameter reported for the corresponding user power using a difference such as desired signal power and delay spread in the reception result. Specifically, for example, if the desired signal power due to individual directivity is improved by 5 dB due to omnidirectionality as in terminal device A shown in FIG. 6, the radio parameters reported from this terminal device A are The radio parameter shifted so as to realize the transmission rate is set higher by a predetermined value.

 [0050] Next, the base station apparatus 100 determines allotted users after completing the radio parameter notification and the above adjustment (radio parameter correction) for all reported users! ST305).

[0051] Also, base station apparatus 100 transmits transmission data (common packet channel) to the allocated users. Are encoded and modulated in accordance with the radio parameters determined in the above procedure, and transmitted as a transmission signal together with a control signal used for notification of user assignment and radio parameter correction values (step ST306).

[0052] On the other hand, when the terminal device A detects a transmission signal from the base station device 100 as a signal addressed to itself, the terminal device A assumes a radio parameter considering the correction value in the radio parameter reported to the base station device 100. The received signal is demodulated and decoded.

[0053] Next, terminal device A replies (reports the demodulation result) to base station device 100 as an ACKZNACK signal as to whether or not the packet has been extracted as a result of demodulating the received signal (step ST307).

 [0054] As described above, the communication method between the base station apparatus and the terminal apparatus according to the present embodiment! Therefore, the terminal device 200 can reflect only the reception quality of the common pilot signal, and can reflect the effect obtained by the individual directivity in the base station device 100 in the setting of the radio parameter. Optimal signal transmission along the line can be realized.

 [0055] Note that as a reference for calculating the difference between the individual directivity and the non-directivity described above, several powers such as desired signal power or delay spread can be assumed.

 [0056] Here, if the desired signal power is used as a reference when calculating the difference between individual directivity and omni directivity, the signal power obtained by performing individual directivity transmission to the corresponding user is improved. A good amount can be estimated and optimal radio parameters can be determined. In this case, as a result, effective signal transmission and interference with adjacent cells can be reduced.

 [0057] Further, in the communication method using the base station apparatus according to the present embodiment, the individual directivity is formed as shown in terminal B in FIG. This will allow all users in the sector to benefit from beam transmission.

[0058] In addition, when delay spread is used as a reference when calculating the difference between individual directivity and omni directivity, reduction of own cell interference obtained by transmitting individual directivity to the corresponding user is reduced. The effect can be estimated and optimal radio parameters can be determined. Even in this case, as a result, effective signal transmission and interference to adjacent cells can be reduced. [0059] This specification is based on Japanese Patent Application No. 2004-234822 filed on Aug. 11, 2004. All this content is included here.

 Industrial applicability

[0060] Since the present invention can realize optimal signal transmission according to the propagation status of each user, it is used for a base station apparatus that performs link adaptation (adaptive modulation) in a common packet channel. Is preferred.

Claims

The scope of the claims  [1] A plurality of receiving means for receiving a signal transmitted from a terminal device with both omnidirectionality and individual directivity;  Non-directional synthesis means for synthesizing the first reception signal received with the non-directionality, Individual directivity synthesis means for synthesizing the second received signal received with the individual directivity, and Non-directional synthesis means And despreading means for despreading each received signal synthesized by the individual directivity synthesis means,  A received signal comparing means for comparing the first received signal and the second received signal that have been despread;  Radio parameter information reference means for extracting radio parameter information from the first received signal;  A radio parameter correction unit that adjusts an output of the radio parameter information reference unit based on a difference in comparison result in the received signal comparison unit;  User allocating means for allocating transmission resources to a user having the best wireless parameter after correction by the wireless parameter correcting means;  A base station apparatus comprising: transmission means for directionally transmitting a signal to a user assigned by the user assignment means. [2] When the difference of the comparison result in the received signal comparison means exceeds a predetermined threshold value! /, The radio parameter correction is instructed, and if the difference exceeds the threshold value, There is a wireless parameter correction standard instruction means for instructing that the wireless meter is not corrected.  2. The base station apparatus according to claim 1, wherein the radio parameter information reference unit adjusts an output of the radio parameter information reference unit when the radio parameter correction reference instructing unit gives an instruction to perform correction of the radio parameter. 3. The base station apparatus according to claim 1, wherein the terminal apparatus is notified of the adjustment result of the radio parameter by the radio parameter correction means by a control signal. 4. The base station apparatus according to claim 1, wherein a difference in desired signal power is used as a reference when adjusting the radio parameter. 5. The base station apparatus according to claim 1, wherein a difference in delay spread is used as a reference when adjusting the radio parameter.  6. The base station apparatus according to claim 1, wherein the user allocating unit determines an allocated user reflecting the adjustment result of the radio parameter by the radio parameter correcting unit. [7] A terminal device that receives a transmission signal from the base station device according to claim 1, and a receiving unit that receives a channel assigned by the reference,  Based on the reception quality of the reference signal observing means for observing the propagation state of the reference signal among the received signals, and the reception quality of the common pilot channel transmitted to the entire sector based on the observation result of the reference signal observing means, the radio parameter is set. A terminal device comprising: radio parameter generation means for generating; and transmission means for transmitting a transmission signal output from the radio parameter generation means.  [8] A plurality of reception steps for receiving a signal transmitted from the terminal device with both omnidirectionality and individual directivity;  An omnidirectional synthesis step of synthesizing the first received signal received with the omnidirectional; an individual directivity synthesis step of synthesizing the second received signal received with the individual directivity; and the omnidirectional synthesis step; A despreading step of despreading each received signal synthesized in the individual directivity synthesis step;  A received signal comparing step of comparing the first received signal and the second received signal that have been despread;  A radio parameter information reference step for extracting radio parameter information from the first received signal;  A radio parameter correction step for adjusting an output in the radio parameter information reference step based on a difference in comparison result in the received signal comparison step;  A user allocation step of allocating transmission resources to a user with the best radio parameter after correction in the radio parameter correction step; A signal is transmitted in a directional manner to the user assigned in the user assignment step. And a transmission step.