JP2007027908A - Adaptive array antenna receiver and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adaptive array antenna receiver and a control method thereof whereby a signal processing amount of the receiver can be reduced. <P>SOLUTION: A SIR (Signal to Interference power Ratio) measurement section 160 measures the SIR of a desired wave and informs a reception processing section 131 about the result. The reception processing section 131 respectively applies synchronization acquisition and inverse spread processing to input signals with a low SIR from all antenna elements and transmits the resulting signal to a beam forming section 132. On the other hand, when the SIR is high, the reception processing section 131 applies the synchronization acquisition and inverse spread processing to only the signal received from one antenna element and directly gives the result to a demodulation section 133. In the case of the high SIR, it is possible to reduce the processing amount in the reception processing section 131. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an adaptive array antenna receiving apparatus and a control method thereof, and more particularly to an adaptive array antenna receiving apparatus of a base station in a mobile communication system using a direct spread CDMA (Code Division Multiple Access) system and a control method thereof.

  A diversity antenna is currently used in a receiver of a mobile communication system using a DS (Direct Spread) -CDMA system. In this diversity antenna, in order to reduce the correlation between antenna elements, the distance between the elements is large. Because the correlation is small, even if the reception level of one antenna element decreases due to fading, the other element can often receive at a high level, and the probability of quality degradation is higher than when receiving a fading wave with one antenna. Can be reduced. However, the reception method using the diversity antenna is directly affected by the presence of interference waves.

  On the other hand, there is a reception technique using an array antenna as a technique for reducing quality degradation due to interference waves. In this array antenna, a plurality of antenna elements are arranged at narrow intervals, and the antenna directivity pattern (beam) can be equivalently formed by multiplying the signal received by each antenna element by the amplitude weight and the phase weight. it can.

  By dividing the area with a plurality of beams, it is possible to suppress the influence from an interference wave having a different arrival direction from the desired wave. However, since the array antenna has a narrow element interval, the correlation between the antenna elements is extremely large. For this reason, a decrease in the reception level due to fading affects all elements constituting the array antenna, and the deterioration cannot be compensated. If the element spacing is increased, an ideal beam cannot be formed, and the original purpose of interference wave suppression cannot be achieved.

  FIG. 4 is a configuration example of an example of a conventional adaptive array antenna receiving apparatus. Although the processing configuration for one user is shown in the figure, the receiving apparatus usually has a plurality of such configurations.

  Referring to the figure, an example of a conventional receiving apparatus includes an array antenna 110 including a plurality of antenna elements, a radio unit 120, receivers 130 for the number of paths, a path combining unit 140, and a diversity combining unit 150. And a SIR (Signal to Interference power Ratio) determination unit 160. Two systems are provided from the array antenna 110 to the path synthesis unit 140.

  The receiver 130 includes a reception processing unit 131, a beam forming unit 132, a demodulation unit 133, and an adaptive control unit 134.

  The conventional adaptive array antenna receiving apparatus can weight all input signals from a plurality of antenna elements and equivalently form directivity (beam) as shown in FIG. FIG. 5 is a diagram illustrating an example of directivity of a conventional adaptive array antenna. In the figure, the horizontal axis indicates the beam direction (degrees), and the vertical axis indicates the gain (dB).

  According to this receiving apparatus, it is possible to improve the reception quality by estimating the direction of arrival of the signal from the terminal and directing this directivity toward the direction of arrival of the signal from the terminal. However, these weighting and direction-of-arrival estimation require a large amount of processing at the base station, and as a result, the number of users to be processed in the base station becomes tight.

  On the other hand, FIG. 6 is a configuration example of a receiving apparatus using a diversity antenna that is generally widely used. FIG. 6 shows the processing configuration for one user as in FIG. 4, and the receiving apparatus has a plurality of this configuration. In FIG. 6, the same components as those in FIG.

  Referring to FIG. 6, an example of a conventional receiving apparatus includes an array antenna 110 including one antenna element, a radio unit 120, receivers 130 corresponding to the number of paths, a path combining unit 140, and a diversity combining unit 150. And a SIR (Signal to Interference power Ratio) determination unit 160. Two systems are provided from the array antenna 110 to the path synthesis unit 140.

  The receiver 130 includes a reception processing unit 131 and a demodulation unit 133.

  According to this receiving apparatus, since the diversity antenna base station does not perform weighting or direction-of-arrival estimation with respect to the input signal unlike the adaptive array antenna base station, the apparatus scale can be relatively reduced. As compared with the base station of the array antenna, the reception quality and the resistance against interference waves are inferior.

  On the other hand, as a method that compensates for the disadvantages of diversity antennas and array antennas and takes advantage of each, it has multiple array antennas composed of multiple antenna elements, and the distance between the array antennas where the correlation can be ignored (For example, refer patent document 1).

  This has a plurality of array antennas composed of a plurality of antenna elements, and the array antennas are composed of adaptive array antennas having a distance where the correlation can be ignored, and have a diversity effect such as fading compensation. The interference wave from the same direction is removed, the gain due to the main beam tracking is increased, and the array antenna has one or a plurality of calibration signal coupling units and a multi-beam combining circuit, and individual differences in the calibration signal are detected. It eliminates and performs highly reliable calibration.

  Further, on the premise of diversity control by a two-antenna element configuration, each antenna element has an upper and lower two-stage configuration of a main antenna and an adaptive processing antenna, an output of the main antenna of one antenna element of the antenna part, Combine the output of the antenna for adaptive processing of the other antenna element, combine the output of the main antenna of the other antenna element and the output of the adaptive processing antenna of one antenna element, and adjust the amplitude and phase for removing the interference signal respectively. A base station antenna apparatus including an adaptive control unit is provided (see, for example, Patent Document 2).

  In addition, a base station antenna is disclosed that uses two elements at both ends constituting an array antenna as a diversity antenna and another element as an adaptive antenna (see, for example, Patent Document 3). Further, this document also discloses a technique for adjusting the number of branches for the diversity antenna and the adaptive antenna according to the propagation state.

Special Table WO00 / 03456 (Summary, Fig. 1) JP 2001-257634 A (Claim 1, paragraphs 0012, 0019, FIG. 1, FIG. 3) JP 2004-36381 A (paragraphs 0018, 0036, FIG. 1, FIG. 6)

  However, the array antenna receiving device disclosed in Patent Document 1 requires such processing as input signal processing from a plurality of antenna elements, multiplication of weights for forming a directivity pattern, estimation of arrival directions of desired waves and interference waves, and the like. The amount of calculation to be taken is very large compared to the diversity antenna receiver, and it was difficult to put it to practical use.

  In addition, the base station antenna device disclosed in Patent Document 2 has a configuration in which the antenna has a two-element configuration and combines the output of the main antenna of one antenna element and the output of the adaptive processing antenna of the other antenna element. The configuration is completely different from the present invention, and the effects obtained from the configuration are also completely different from the present invention.

  In addition, the base station antenna disclosed in Patent Document 3 uses a part (plurality) of a plurality of elements constituting an array antenna as a diversity antenna and other elements as adaptive antennas. The configuration is completely different from the present invention, and the effects obtained from the configuration are also completely different from the present invention.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an adaptive array antenna receiving apparatus capable of reducing the processing amount in the receiving apparatus and a control method therefor.

  In order to solve the above-mentioned problems, an adaptive array antenna receiving apparatus according to the present invention is an adaptive array antenna receiving apparatus for a base station in a mobile communication system, and includes two adaptive array antenna receiving means and each adaptive array antenna. A diversity combining means for combining the outputs of the receiving means; and a reception quality measuring means for measuring the reception quality based on the output of the diversity combining means, wherein the adaptive array antenna receiving means is based on the measurement result of the reception quality measuring means. It is characterized in that whether to process input signals from all antenna elements or to process input signals from only one antenna element is selected.

  According to the present invention, there is provided a control method for an adaptive array antenna receiving apparatus of a base station in a mobile communication system, wherein the adaptive array antenna receiving apparatus has two systems of adaptive array antenna receiving means. And diversity combining means for combining the outputs of the respective adaptive array antenna receiving means, and reception quality measuring means for measuring reception quality based on the output of the diversity combining means, wherein the adaptive array antenna receiving means is configured to receive the reception quality. The method includes a step of selecting whether to process input signals from all antenna elements or to process input signals from only one antenna element based on the measurement result of the measuring means.

  Since the present invention includes a configuration for selecting whether to process input signals from all antenna elements or to process input signals from only one antenna element, it is possible to reduce the amount of processing in the receiving apparatus. Become.

  That is, if the adaptive array antenna receiver according to the present invention is used, the adaptive array antenna receiver according to the conventional adaptive array antenna receiver can appropriately switch between the adaptive array antenna processing and the diversity antenna processing according to the propagation environment of the desired wave from the terminal. The amount of processing required can be reduced, and the device scale can be made smaller than that of a conventional adaptive array antenna receiver. On the other hand, if the apparatus scale is the same as the conventional one, the number of users that can be processed by the conventional adaptive array antenna receiving apparatus can be increased.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of an example of an adaptive array antenna receiving apparatus according to the present invention. This figure shows an example of the processing configuration for one user as in FIGS. It is assumed that an actual receiving apparatus has a plurality of configurations shown in FIG.

  Referring to FIG. 1, an adaptive array antenna receiving apparatus according to the present invention is, as an example, an adaptive array antenna receiving apparatus for a base station in a mobile communication system using a direct spreading CDMA system, and includes a plurality of antenna elements. Array antenna 110, radio section 120 that converts an RF signal into a digital baseband signal, a receiver 130 that demodulates an uplink signal (transmission signal from a terminal to a base station) of each path, and a demodulation result of each path Includes a path combining unit 140 that performs RAKE combining, a diversity combining unit 150 that performs diversity combining, and an SIR measuring unit 160 that measures reception quality.

  Two systems are provided from the array antenna 110 to the path synthesis unit 140.

  In addition, the receiver 130 equivalently forms directivity (beam) by multiplying the uplink processing by a complex weight (phase weight, amplitude weight) with a reception processing unit 131 that performs synchronization acquisition and despreading processing. Using an adaptive algorithm such as MMSE (Minimum-Mean-Squared-Error) based on the result output from the demodulator 133, the demodulator 133 demodulating the output signal from the upstream beamformer And an adaptive control unit 134 for calculating weights.

  Compared to the configuration diagram of the conventional adaptive array antenna receiver shown in FIG. 4, the signal path 201 for directly reporting the result from the reception processing unit 131 to the demodulation unit 133 and the SIR measurement unit 160 to the reception processing unit 131. The signal path 202 is added. The same applies to the other diversity branch.

  The SIR measurement unit 160 measures the SIR of the desired wave (the signal intensity of the desired wave with respect to the interference wave), and notifies the reception processing unit 131 of the result. In the reception processing unit 131, for those having a low SIR, the input signals from all the antenna elements are synchronously captured and despread, and then the result is transmitted to the beam forming unit, which is the same as that of the conventional adaptive array antenna reception device of FIG. Process.

  On the other hand, when the SIR is high, only the signal input from one antenna element is received by the reception processing unit 131 so as to perform the same processing as the receiving apparatus of the base station using the conventional diversity antenna shown in FIG. It is assumed that the result is directly passed to the demodulator 133 after the synchronization supplement and despreading. In this case, since the amount of processing in the reception processing unit 131 is reduced and the beam forming unit 132 and the adaptive control unit 134 are not used, it is possible to reduce the necessary processing.

  Note that the present invention is not limited to the number of antenna elements, the number of receivers 130 (the number of multipaths used for RAKE combining), and how to divide processing blocks in the receiver.

  If the adaptive array antenna receiving apparatus according to the present invention is used, it is necessary for the conventional adaptive array antenna receiving apparatus by appropriately switching the processing of the adaptive array antenna and the processing of the diversity antenna according to the propagation environment of the desired wave from the terminal. Thus, the processing amount can be reduced, and the scale of the apparatus can be reduced as compared with the conventional adaptive array antenna receiving apparatus. Further, if the apparatus scale is the same, the number of users that can be processed by the conventional adaptive array antenna receiving apparatus can be increased.

  The operation of the adaptive array antenna receiving apparatus shown in FIG. 1 will be described. Since the two diversity branches have the same operation, only one of them will be described. The RF signal received by the array antenna 110 is subjected to amplification processing and frequency conversion processing by the radio unit 120 for each antenna element, and then subjected to quadrature detection to the baseband signal of the I / Q channel, and an A / D converter (not shown) Is converted into a digital signal.

  The reception processing unit 131 performs synchronization supplementation and despreading on the baseband signal output from the radio unit 120. However, according to the result from the SIR measurement unit 160, it is possible to switch between processing of all antenna elements and processing of only one antenna element. Also, the output destination of the result can be switched between the beam forming unit 132 and the demodulating unit 133 according to the result from the SIR measurement unit 160.

  The beam forming unit 132 performs weighting (weight multiplication) on the despread signal output from the reception processing unit 131, and equivalently forms directivity (beam) by performing addition synthesis. The beam forming unit 132 outputs the signal after the addition and synthesis to the demodulating unit 133, and the demodulating unit 133 demodulates the signal from the beam forming unit 132 or the reception processing unit 131 and then passes it to the path synthesizing unit 140. .

  The path combining unit 140 combines the demodulated results for the number of multipaths, and then outputs the result to the diversity combining unit 150. The diversity combining unit 150 combines the results of both diversity branches. The SIR measurement unit calculates reception quality from the output result from the diversity combining unit 150 and notifies the reception processing unit 131 of the result.

  Next, the operation of the present invention will be described with reference to the flowcharts of FIGS. FIG. 2 is a flowchart showing an example of a control method of the adaptive array antenna receiving apparatus according to the present invention. This flowchart mainly shows the operation in the receiver 130.

  Now, it is assumed that the reception quality is notified from the SIR measurement unit 160 to the reception processing unit 131. The reception processing unit 131 compares the notified reception quality with the threshold value X (step 210 in FIG. 2). If the reception quality is smaller than the threshold value X (“Yes” in step 210), the reception processing unit 131 performs synchronization supplementation and despreading of all antenna elements (step 221). The result of despreading the antenna element is output to the beam forming unit 132 (step 222).

  The adaptive control unit 134 performs adaptive control using the previous demodulation result and calculates the beam weight (step 223). The beam forming unit 132 multiplies the beam weight notified from the adaptive control unit 134 and adds and synthesizes the beam equivalently (step 224). The output result of the beam forming unit 132 is output to the demodulation unit 133 (step 225).

  On the other hand, if it is determined in step 210 that the reception quality is greater than the threshold value X (if “No” in step 210), the reception processing unit 131 performs synchronization supplementation and despreading for only one antenna element ( Step 231). The reception processing unit 131 outputs the result of despreading to the demodulation unit 133 (step 232).

  When the processing in the frame indicated by 220 in FIG. 2 (steps 221 to 225) is performed, the apparatus functions as an adaptive array antenna receiving device, and the processing in the frame indicated by 230 (steps 231 and 232) is performed. If done, the device will act as a diversity antenna receiver. In either case, the subsequent processing is the same, and the result is output from the demodulator 133 to the path combiner 140 (step 240).

  FIG. 7 is a schematic diagram showing an example of the beam direction of an antenna of a conventional receiving apparatus. In an adaptive array antenna base station using a conventional receiving apparatus, a beam is formed for all users as shown in FIG. For example, the conventional adaptive array antenna base station 301 can process only a maximum of three terminals 310 to 312 in one base station due to a processing amount problem, and more terminals (for example, the terminal 313) communicate with the base station 301. I can't.

  FIG. 3 is a schematic diagram showing an example of the beam direction of the antenna of the receiving apparatus of the present invention. In such a case, if the receiving apparatus of the present invention is used, since a beam is not formed as shown in the figure for a terminal having a good reception environment (for example, the terminal 313), the processing amount can be reduced. If the device scale is also considered, it is possible to increase the number of terminals that can be processed (communicable).

  In this embodiment, the processing at the adaptive array antenna and the processing at the diversity antenna are switched based on the SIR of the desired wave calculated by the SIR measurement unit 160. However, BLER (Block Error Rate) indicating reception quality, etc. Other parameters can also be applied.

  Also, in this embodiment, an example of a receiving apparatus configuration in an adaptive array antenna base station having a plurality of array antennas and also having a diversity effect has been described. However, an adaptive array antenna having only one array antenna and having no diversity effect has been described. It can also be applied to base stations.

It is a block diagram of an example of the adaptive array antenna receiver which concerns on this invention. It is a flowchart which shows an example of the control method of the adaptive array antenna receiver which concerns on this invention. It is a schematic diagram which shows an example of the beam direction of the antenna of the receiver of this invention. It is an example of a structure of an example of the conventional adaptive array antenna receiver. It is a figure which shows an example of the directivity of the conventional adaptive array antenna. It is an example of 1 structure of the receiver using the diversity antenna generally used widely. It is a schematic diagram which shows an example of the beam direction of the antenna of the conventional receiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Array antenna 120 Radio | wireless part 130 Receiver 131 Reception processing part 132 Beam formation part 133 Demodulation part 134 Adaptive control part 140 Path combining part 150 Diversity combining part 160 SIR measurement part

Claims (16)

An adaptive array antenna receiver for a base station in a mobile communication system,
Two types of adaptive array antenna receiving means, diversity combining means for combining the outputs of each adaptive array antenna receiving means, and reception quality measuring means for measuring reception quality based on the output of the diversity combining means,
The adaptive array antenna receiving means selects whether to process input signals from all antenna elements or to process input signals from only one antenna element based on the measurement result of the reception quality measuring means. An adaptive array antenna receiver. The adaptive array antenna receiving means performs processing of input signals from all antenna elements when the reception quality measuring means determines that the reception quality is lower than the threshold value, and when the reception quality is determined to be higher than the threshold value. The adaptive array antenna receiving apparatus according to claim 1, wherein an input signal from only one antenna element is processed. The adaptive array antenna receiving means includes an array antenna composed of a plurality of antenna elements, a radio unit that converts a signal received via the array antenna into a digital baseband signal, and a receiver that demodulates an uplink signal of each path; A path synthesis unit that synthesizes the demodulation results of each path,
The adaptive array antenna receiving apparatus according to claim 1, wherein the receiver selects processing of the input signal. The receiver includes a reception processing unit that performs synchronization acquisition and despreading processing, a beam forming unit that equivalently forms directivity by multiplying an uplink signal by a complex weight, and an output from the beam forming unit A demodulator that demodulates the signal, and an adaptive controller that calculates a weight using an adaptive algorithm based on the result output from the demodulator,
The adaptive array antenna receiving apparatus according to claim 3, wherein the reception processing unit selects processing of the input signal. When the reception quality measurement means determines that the reception quality is lower than the threshold, the reception processing unit performs synchronization supplementation and despreading of all antenna elements and performs despreading results of all antenna elements And processing in the beam forming unit, demodulating unit and adaptive control unit,
The reception quality measuring means, when it is determined that the reception quality is greater than a threshold value, performs synchronization supplementation and despreading of only one antenna element, and outputs the result of despreading to the demodulator. 5. The adaptive array antenna receiver according to 4. 6. The adaptive array antenna receiving apparatus according to claim 1, wherein the reception quality measured by the reception quality measuring means is SIR (Signal to Interference power Ratio). 6. The adaptive array antenna receiving apparatus according to claim 1, wherein the reception quality measured by the reception quality measuring means is BLER (Block Error Rate). An adaptive array antenna receiver for a base station in a mobile communication system,
One adaptive array antenna receiving means, and reception quality measuring means for measuring the reception quality based on the output of the adaptive array antenna receiving means,
The adaptive array antenna receiving means selects whether to process input signals from all antenna elements or to process input signals from only one antenna element based on the measurement result of the reception quality measuring means. An adaptive array antenna receiver. A control method for an adaptive array antenna receiver of a base station in a mobile communication system, comprising:
The adaptive array antenna receiving apparatus includes two types of adaptive array antenna receiving means, diversity combining means for combining the outputs of each adaptive array antenna receiving means, and reception quality measurement for measuring reception quality based on the output of the diversity combining means. Means,
The adaptive array antenna receiving means includes a step of selecting whether to process input signals from all antenna elements or to process input signals from only one antenna element based on the measurement result of the reception quality measuring means. A control method for an adaptive array antenna receiving apparatus. The adaptive array antenna receiving means performs processing of input signals from all antenna elements when the reception quality measuring means determines that the reception quality is lower than the threshold value, and when the reception quality is determined to be higher than the threshold value. 10. The method of controlling an adaptive array antenna receiving apparatus according to claim 9, wherein an input signal from only one antenna element is processed. The adaptive array antenna receiving means includes an array antenna composed of a plurality of antenna elements, a radio unit that converts a signal received via the array antenna into a digital baseband signal, and a receiver that demodulates an uplink signal of each path; A path synthesis unit that synthesizes the demodulation results of each path,
The method of controlling an adaptive array antenna receiving apparatus according to claim 9 or 10, wherein the receiver selects processing of the input signal. The receiver includes a reception processing unit that performs synchronization acquisition and despreading processing, a beam forming unit that equivalently forms directivity by multiplying an uplink signal by a complex weight, and an output from the beam forming unit A demodulator that demodulates the signal, and an adaptive controller that calculates a weight using an adaptive algorithm based on the result output from the demodulator,
12. The adaptive array antenna receiving apparatus control method according to claim 11, wherein the reception processing unit selects processing of the input signal. When the reception quality measurement means determines that the reception quality is lower than the threshold, the reception processing unit performs synchronization supplementation and despreading of all antenna elements and performs despreading results of all antenna elements And processing in the beam forming unit, demodulating unit and adaptive control unit,
The reception quality measuring means, when it is determined that the reception quality is greater than a threshold value, performs synchronization supplementation and despreading of only one antenna element, and outputs the result of despreading to the demodulator. 12. A control method for an adaptive array antenna receiver according to 12. 14. The method of controlling an adaptive array antenna receiving apparatus according to claim 9, wherein the reception quality measured by the reception quality measuring means is SIR (Signal to Interference power Ratio). 14. The method of controlling an adaptive array antenna receiving apparatus according to claim 9, wherein the reception quality measured by the reception quality measuring means is BLER (Block Error Rate). A control method for an adaptive array antenna receiver of a base station in a mobile communication system, comprising:
One adaptive array antenna receiving means, and reception quality measuring means for measuring the reception quality based on the output of the adaptive array antenna receiving means,
The adaptive array antenna receiving means includes a step of selecting whether to process input signals from all antenna elements or to process input signals from only one antenna element based on the measurement result of the reception quality measuring means. A control method for an adaptive array antenna receiving apparatus.

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