JP2006054674A - Base station device and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the optimal signal transmission following the propagating circumstances of each terminal equipment in a sector without increasing the number of beams in the sector. <P>SOLUTION: A base station device 100 is provided with a radio parameter information referring part 112, a radio parameter correcting part 114, a user assigning part 115 and a transmission signal generating part 116. The radio parameter information referring part 112 extracts radio parameter information from a reception signal demodulated by a reception signal demodulating part 110. At the time of executing radio parameter correction, the radio parameter correcting part 114 corrects a radio parameter by using the difference of SNR or delay spread to be outputted by a reception signal comparing part 111 in response to the radio parameter information to be outptuted by the radio parameter information referring part 112. A user assigning part 115 assigns a transmission source to a user with the most satisfactory radio parameter corrected by the radio parameter correcting part 114. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  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 adaptation (adaptive modulation) in a common packet channel.

  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).

  The base station apparatus 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. 6, the conventional base station apparatus 60 divides the sector into four beams using an adaptive array antenna, and transmits pilot signals specific to each beam using different spreading codes.

  In FIG. 6, 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 transmits it to the base station device 60. Instruct.

  The base station device 60 determines the assigned beam and the assigned terminal by the scheduler using the transmission rate instructed from each of the terminal devices A, B, C, D, E, F, G, and H, and directs it to the corresponding terminal device. Conduct directional transmission with an adaptive array antenna.

As a result, the transmission rate is optimized by adaptive modulation, and at the same time, the influence of interference can be limited to a specific region by the effect of space division by directional transmission, and high frequency utilization efficiency can be utilized.
Published paper; 2003 IEICE Communication Society B-5-4, Sep. 2003

  In this type of base station apparatus, it is necessary to transmit a pilot signal corresponding to each beam. On the other hand, the terminal device needs to demodulate a pilot signal corresponding to each beam and perform quality measurement.

  By the way, in the base station apparatus 60 which intends to cover the inside of the sector with four beams as shown in FIG. 6, a terminal apparatus (terminal apparatus shown in FIG. 6) which cannot receive the benefits of beam transmission depending on the position of the user. There is a problem that I) comes out. 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 perform directional transmission to all terminal apparatuses in the sector.

  However, when 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, so that the number of beams per beam increases as the number of beams increases. The transmission power of the pilot signal must be reduced.

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

  Further, 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, so that the beam As the number increases, demodulation processing increases.

  The present invention has been made in view of the above point, and a base station apparatus capable of realizing optimal signal transmission according to the propagation status of each terminal apparatus in the sector without increasing the number of beams in the sector. And providing a communication method.

  In order to solve such a problem, 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, An omnidirectional synthesis means for synthesizing one received signal, an individual directivity synthesis means for synthesizing a second received signal received with the individual directivity, the omnidirectional synthesis means and the individual directivity synthesis means. From the first received signal, a despreading unit that despreads each of the combined received signals, a received signal comparing unit that compares the first received signal and the second received signal that have been despread, Wireless parameter information reference means for extracting wireless parameter information; wireless parameter correction means for adjusting an output of the wireless parameter information reference means based on a difference in comparison result in the received signal comparison means; and User allocating means for allocating transmission resources to a user whose radio parameter after correction by the parameter correcting means is the best, and transmitting means for directionally transmitting a signal to the user allocated by the user allocating means Take the configuration.

  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. Optimal signal transmission along the line can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a base station apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, base station apparatus 100 according to the present embodiment includes antennas 101 and 102, reception RF units 103 and 104, omnidirectional combining units 105 and 106, individual directivity combining units 107 and 118, and inversely. Spreading units 108 and 109, received signal demodulating unit 110, received signal comparing unit 111, radio parameter information referring unit 112, radio parameter correction standard instructing unit 113, radio parameter correcting unit 114, user allocating unit 115, transmission signal generating unit 116, A modulation / coding unit 117 and transmission RF units 119 and 120 are provided.

  In FIG. 1, each antenna 101 and 102 receives a signal transmitted from the terminal device 200 and transmits a signal toward the terminal device 200.

  Reception RF sections 103 and 104 perform band limitation and amplification on the reception signals captured by antennas 101 and 102.

  The omnidirectional synthesis units 105 and 106 and the individual directivity synthesis unit 107 synthesize the reception signals band-limited and amplified by the reception RF units 103 and 104.

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

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

  The reception signal comparison unit 111 includes a reception signal synthesized by the omnidirectional synthesis unit 105 and despread by the despreading unit 108, and a reception signal synthesized by the individual directivity synthesis unit 107 and despread by the despreading unit 109. Are compared with each other, and the original value and the difference between the two are output to the wireless parameter correction reference instructing unit 113 and the wireless parameter correcting unit 114.

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

  The radio parameter correction reference instructing unit 113 indicates that “perform radio parameter correction” if the difference between the SNR or the delay spread input from the received signal comparison unit 111 exceeds a predetermined threshold. The unit 114 is instructed. If the difference does not exceed the threshold value, the wireless parameter correction unit 114 is instructed to “do not perform wireless parameter correction”.

  When the wireless parameter correction reference instructing unit 113 issues an instruction to “perform wireless parameter correction”, the wireless parameter correction unit 114 applies the wireless parameter information output from the wireless parameter information reference unit 112 to the wireless parameter information. The radio parameter is corrected using the difference in SNR or delay spread output from the received signal comparator 111.

  Specifically, for example, when the individual directivity is better than the omni directivity by 5 dB in SNR, the shift is performed so as to realize a transmission rate higher by 5 dB than the radio parameter output by the radio parameter information reference unit 112. Set radio parameters. Here, as in the reference table shown in FIG. 5, radio parameters 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 are shown. Set. FIG. 5 is a diagram illustrating a reference table used when setting radio parameters in the base station apparatus.

  Note that, as another example, the radio parameter correction unit 114 can reduce the delay spread to a ratio equal to or less than a certain value in a ratio, and if the delay spread is shorter than a predetermined value, the output of the radio parameter information reference unit 112 Control for assigning a modulation multi-level number higher than the radio parameter to be performed may be performed.

  The user allocation unit 115 allocates transmission resources to a user whose radio parameter corrected by the radio parameter correction unit 114 is the best.

  The transmission signal generation unit 116 generates a transmission signal to be transmitted to the user assigned by the user assignment unit 115.

  Modulation / encoding section 117 modulates and encodes the transmission signal generated by transmission signal generation section 116 using the corrected radio parameter calculated by radio parameter correction section 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.

  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 transmit the transmission signal to the terminal device 200 of the assigned user through the antennas 101 and 102. .

  In this base station apparatus 100, the received signals are synthesized by each of the omnidirectional synthesis units 105 and 106 and the individual directivity synthesis unit 107, and the result is compared by the received signal comparison unit 111. Then, the wireless parameter correction unit 114 calculates a correction value from the comparison result, passes the result together with the wireless parameter information output from the wireless parameter information reference unit 112 to the user allocation unit 115, and the user allocation unit 115 allocates the result. Determine the user.

  Subsequently, the transmission signal of the allocated user is modulated and encoded using the corrected radio parameter, output to the transmission RF units 119 and 120, and the transmission RF units 119 and 120 perform predetermined processing such as up-conversion. Then, this transmission signal is transmitted from the antennas 101 and 102.

  FIG. 2 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. 2, 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. 2, the antenna 201 receives a signal transmitted from the base station apparatus 100 and transmits a signal toward the base station apparatus 100.

  The reception RF unit 202 performs band limitation and amplification on the reception signal captured by the antenna 201.

  The received signal demodulator 203 refers to control information such as radio parameters notified separately by the control information reference unit 204, and performs despreading and demodulation processing on the received signal sent from the received RF unit 202.

  The reference signal observation unit 205 observes the propagation state of the reference signal among the signals demodulated by the reception signal demodulation unit 203 and instructs the radio parameter generation unit 206 of the observation result.

  Radio parameter generation unit 206 generates radio parameters such as a modulation scheme and a coding 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 section 208 performs predetermined processing such as turbo decoding on the communication channel signal among the signals demodulated by reception signal demodulation section 203.

  In this terminal device 200, the received signal demodulation unit 203 performs despreading and demodulation processing with reference to control information such as radio parameters notified separately. Among the demodulated signals, the reference signal is used for observing the propagation state by the reference signal observation unit 205, the result is instructed to the radio parameter generation unit 206, and predetermined processing is performed by the transmission RF unit 207. 201 to transmit. Of the demodulated signals, communication channel signals are subjected to predetermined processing such as turbo decoding in the communication channel decoding unit 208, and decoding is completed.

  Next, the flow of processing between the base station apparatus and the terminal apparatus according to the present embodiment will be described. FIG. 3 is a schematic diagram showing a flow of processing between the base station apparatus and the terminal apparatus according to the present embodiment. 2 is shown as terminal devices A, B, C,... Located in the sector of base station device 100.

  In FIG. 3, base station apparatus 100 transmits a common pilot signal to the entire sector as shown in FIG. 4 (step ST301). FIG. 4 is a schematic diagram showing beams in the radio communication system according to the present embodiment. Many user terminal devices A, B, C,... Generate radio parameters such as a modulation scheme and a coding rate based on the reception quality of the common pilot channel transmitted to the entire sector (step ST302). The generated radio parameters are notified (reported) to the base station apparatus 100 (step ST303).

  When the base station apparatus 100 receives radio parameter information notified from each terminal apparatus A, B, C,..., The base station apparatus 100 generates the directivity generated individually for each user based on the adaptive algorithm, the arrival direction estimation result, and the like. Both reception and omnidirectionality are received, and both reception results are compared (step ST304).

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

  Next, after completing the radio parameter notification and the above adjustment (radio parameter correction) for all reported users, base station apparatus 100 determines an assigned user (step ST305).

  Also, the base station apparatus 100 encodes and modulates transmission data (common packet channel) for the allocated user according to the radio parameters determined in the above procedure, and uses a control signal used for notification of user allocation and radio parameter correction values. In addition, it is transmitted as a transmission signal (step ST306).

  On the other hand, when the terminal apparatus A detects a transmission signal from the base station apparatus 100 as a signal addressed to itself, the terminal apparatus A assumes a radio parameter that takes the correction value into account for the radio parameter reported to the base station apparatus 100, and receives the received signal. The demodulating and decoding processes are executed.

  Next, terminal apparatus A sends back a reply (demodulation result report) to base station apparatus 100 as an ACK / NACK signal as to whether or not a packet has been extracted as a result of demodulating the received signal (step ST307).

  As described above, in the communication method between the base station apparatus and the terminal apparatus according to the present embodiment, terminal apparatus 200 only observes the reception quality of the common pilot signal, and base station apparatus 100 uses the individual directivity. The obtained effect can be reflected in the setting of the radio parameter, and the optimum signal transmission according to the propagation status of each user can be realized.

  As a reference for calculating the difference between the individual directivity and the non-directivity described above, several desired signal power or delay spread can be assumed.

  Here, if the desired signal power is used as a reference when calculating the difference between individual directivity and non-directivity, an improvement in signal power obtained by transmitting individual directivity to the corresponding user is 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.

  Further, in the communication method using the base station apparatus according to the present embodiment, it is possible to cope with the above-mentioned problem by forming individual directivity as in terminal B in FIG. All users will benefit from beam transmission.

  Also, when calculating the difference between individual directivity and omni directivity, using delay spread as a reference, estimate the reduction effect of own cell interference obtained by transmitting individual directivity to the corresponding user. And optimal radio parameters can be determined. Also in this case, as a result, effective signal transmission and interference with adjacent cells can be reduced.

  Since the base station apparatus according to the present invention can realize optimal signal transmission according to the propagation status of each user, it is useful as a base station apparatus that implements link adaptation (adaptive modulation) in a common packet channel.

The block diagram which shows the structure of the base station apparatus which concerns on one embodiment of this invention The block diagram which shows the structure of the terminal device used with the base station apparatus which concerns on one embodiment of this invention The schematic diagram which shows the flow of a process with the base station apparatus and terminal device which concern on one embodiment of this invention Schematic which shows the beam in the base station apparatus which concerns on one embodiment of this invention The figure which shows the reference table at the time of setting a radio | wireless parameter with the base station apparatus which concerns on one embodiment of this invention Schematic showing a beam in a conventional base station apparatus

Explanation of symbols

100 base station apparatus 101, 102, 201 antenna 103, 104, 202 reception RF unit 105, 106 omnidirectional synthesis unit 107, 118 individual directivity synthesis unit 108, 109 despreading unit 110, 203 reception signal demodulation unit 111 reception signal Comparison unit 112 Radio parameter information reference unit 113 Radio parameter correction standard instruction unit 114 Radio parameter correction unit 115 User allocation unit 116 Transmission signal generation unit 117 Modulation / coding unit 119, 120, 207 Transmission RF unit 200 Terminal device 204 Reference control information Unit 205 reference signal observation unit 206 wireless parameter generation unit 208 communication channel decoding unit

Claims (8)

A plurality of receiving means for receiving a signal transmitted from the terminal device with both omnidirectionality and individual directivity;
Omnidirectional synthesis means for synthesizing the first received signal received with the omnidirectionality;
Individual directivity synthesis means for synthesizing the second received signal received with the individual directivity;
Despreading means for despreading each received signal synthesized by the omnidirectional synthesis means and the individual directivity synthesis means;
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 between comparison results in the reception signal comparison unit;
User allocating means for allocating transmission resources to a user with 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. When the difference of the comparison result in the received signal comparison means exceeds a predetermined threshold, the radio parameter correction is instructed. When the difference is not exceeded, the radio parameter correction is not performed. Wireless parameter correction reference instruction means for instructing
2. The base station apparatus according to claim 1, wherein the radio parameter information reference means adjusts the output of the radio parameter information reference means when the radio parameter correction reference instruction means gives an instruction to carry out correction of the radio parameters.   The base station apparatus according to claim 1 or 2, wherein the terminal apparatus is notified of the adjustment result of the radio parameter by the radio parameter correction means by a control signal.   The base station apparatus according to any one of claims 1 to 3, wherein a difference in desired signal power is used as a reference when adjusting the radio parameter.   The base station apparatus according to any one of claims 1 to 3, wherein a difference in delay spread is used as a reference when adjusting the radio parameter.   The base station apparatus according to any one of claims 1 to 5, wherein the user allocating unit determines an allocated user by reflecting an adjustment result of the radio parameter in the radio parameter correcting unit. A terminal device that receives a transmission signal from the base station device according to any one of claims 1 to 5,
Receiving means for receiving a channel assigned by the criterion;
A reference signal observation means for observing the propagation state of the reference signal of the received signals;
Radio parameter generation means for generating radio parameters based on the reception quality of the common pilot channel transmitted to the entire sector based on the observation result of the reference signal observation means;
And a transmission unit configured to transmit a transmission signal output from the wireless parameter generation unit. 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 omnidirectionality;
An individual directivity synthesis step of synthesizing the second received signal received with the individual directivity;
A despreading step for despreading each received signal synthesized in the omnidirectional synthesis step and the individual directivity synthesis step;
A received signal comparison step of comparing the first received signal and the second received signal that have been despread;
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 whose radio parameter after the correction in the radio parameter correction step is the best;
A transmission method comprising: a directional transmission of a signal to a user assigned in the user assignment step.

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