JP2006013786A - Adaptive antenna array receiver and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adaptive antenna array receiver suitable for packet transmission capable of preventing detection accuracy of a path reception timing and an arrival direction from being considerably deteriorated. <P>SOLUTION: The adaptive antenna array receiver is provided with an array antenna comprising a plurality of antenna elements and receives a transmission signal by a plurality of the antenna elements. The adaptive antenna array receiver is characterized by to including: a two-dimensional power profile generating means that uses a control signal received by a plurality of the antenna elements to produce a two-dimensional power profile including dimensions of the time and the angle of an arrival path; a path detection/arrival direction estimate means that uses the two-dimensional power profile to detect the reception timing of a path and the arrival direction of the path; and an antenna weight generating means for generating an antenna weight with respect to a detection signal from a plurality of the antenna elements on the basis of the result of the path arrival direction estimation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an adaptive antenna array receiving apparatus and method, and more particularly to an adaptive antenna array receiving apparatus and method for generating antenna weights based on arrival direction estimation results.

  An adaptive antenna array is known as an antenna that directs a main beam in the direction of arrival of a desired signal and forms a directional zero point in the direction of arrival of an interference signal. A conventional example of a receiving apparatus using such an adaptive antenna array is shown in FIG. As shown in FIG. 21, the conventional adaptive antenna array receiving apparatus includes N antenna elements 101-1 to 101-N, N correlation detection units 102-1 to 102-N, and N antenna elements. Complex profile generation units 103-1 to 103 -N, adder 104, combined delay profile generation unit 105, path detection unit 106, DOA (Direction of arrival) estimation unit 107, and antenna weight generation unit , N multipliers 109-1 to 109 -N, an adder 110, and a demodulator 111.

  Pilot symbols in pilot signals received by antennas 101-1 to 101-N are input to correlation detection sections 102-1 to 102-N, and complex correlations using pilot symbols are detected by the respective antennas. And the detected complex correlation value is taken into the complex profile production | generation parts 103-1 to 103-N, and a complex delay profile is produced | generated. The complex delay profiles generated by the complex profile generation units 103-1 to 103 -N are added by the adder 104, then input to the combined delay profile generation unit 105, and the combined delay profile synthesized by the unit 105. Is generated. The path detection unit 106 detects the reception timing for each path using the combined delay profile, and outputs the detection result to the DOA estimation unit 107 and the demodulation unit 111.

  The DOA estimation unit 107 estimates the DOA of the signal arriving through each path based on the complex delay profiles generated by the complex profile generation units 103-1 to 103 -N and the detected reception timing. Based on the DOA estimation result estimated by the DOA estimation unit 107, the antenna weight generation unit 108 generates an antenna weight (reception antenna weight) so that directivity is formed in the estimated direction. The antenna weight generated based on the DOA estimation result is multiplied by each of the path signals received by the antennas 101-1 to 1-1-N by the multipliers 109-1 to 109-N, and then added. The multiplier 110 combines the signals after multiplication. The signal synthesized in this way is demodulated by the demodulator 111, whereby demodulated data, that is, reproduced data output is obtained.

As a method for obtaining the weight of the adaptive antenna array, Patent Document 1 discloses a method for detecting the direction of a peak appearing in a delay profile and obtaining the weight in consideration of the direction.
JP2003-110476

  In the conventional adaptive antenna array receiving apparatus described above, sector antennas directed in the sector are used for the antennas 101-1 to 101 -N. That is, in the conventional method, a combined delay profile is generated by combining signals received by sector beams of each antenna having a wide beam width, so that the detection accuracy of the path reception timing and the arrival direction is significantly deteriorated. was there.

  On the other hand, in the fourth generation mobile communication system, which is the next generation of the third generation mobile communication system (IMT-2000) that is currently in practical use, WWW browsing, downloading of large-capacity data, etc. from the circuit switching type centered on voice communication, etc. It is thought that this will shift to a packet switching type centered on packet communications. In this case, if the transmission rate of the uplink / downlink communication channel is, for example, when downloading large-capacity data, the data transmission rate of the downlink communication channel is Very large compared to the uplink. Furthermore, it is assumed that only the downlink is transmitted and the uplink communication channel is not transmitted. As described above, in the packet switching type system in the fourth generation mobile communication system, it is preferable that the transmission is performed in the packet signal format even in the wireless section in accordance with the IP of the core network. However, in this case, the received signal from the mobile station user in the base station is bursty, and the antenna weight generation using the MMSE (Minimum Mean Square Error) algorithm generally applied to the adaptive array antenna is sufficiently converged. As a result, there is a problem that an error in generating the antenna weight increases.

  In addition, the above-described adaptive array antenna directs the main beam (point at which the antenna gain is maximized) in the direction of arrival of the user's signal to be received, and has a beam null or a low antenna gain in the direction of arrival of the other user's signal. Although it is a technique for improving transmission characteristics by transmitting and receiving with an antenna pattern, conventionally, uplink reception is performed using a reception antenna weight generated using an adaptive algorithm such as MMSE in the uplink, and this reception antenna weight is received. Based on the above, transmit antenna weights in downlink transmission are generated. In this case, as in the example of the large-capacity data download described above, when the downlink is transmitted but the uplink is not transmitted at the same time, the receiving antenna weight is not obtained. It is also impossible to generate downlink transmission antenna weights.

Also, the uplink receiving antenna weights only realize interference suppression of the user's communication channel that is causing interference in the uplink, and the arrival direction differs in the downlink due to asymmetry of the uplink and downlink. When transmitting to other users with high power, interference suppression in downlink transmission cannot be performed sufficiently.

  Furthermore, in the uplink of broadband wireless access in the fourth generation mobile communication system, there are control channels such as a high-power shared channel for transmitting high-rate traffic, an individual / shared channel for transmitting low-rate traffic, and a reservation packet. It is considered to be mixed. For example, as shown in FIG. 22, mobile station 600 and mobile station 610 may communicate with base station 500 at a low rate, and mobile station 620 may communicate with the base station at a high rate. In such a case, when an adaptive array reception of a low-rate dedicated / control channel is performed, there is a problem that a high-power shared channel becomes interference and the detection accuracy of a desired wave at a low-rate deteriorates.

  The present invention has been made in view of the above problems, and the problem is that the detection accuracy of the path reception timing and the arrival direction can be prevented from being significantly deteriorated and is suitable for packet transmission. An adaptive antenna array receiver is provided.

  In order to solve the above-mentioned problems, the present invention comprises an array antenna comprising a plurality of antenna elements as described in claim 1 and receiving a transmission signal by the plurality of antenna elements. Two-dimensional power profile generation means for generating a two-dimensional power profile having dimensions of time and angle of arrival path using control signals received by a plurality of antenna elements, and path reception using the two-dimensional power profile Path detection / arrival direction estimation means for estimating timing detection and path arrival direction; and antenna weight generation means for generating antenna weights for received signals from the plurality of antenna elements based on the arrival direction estimation result of the path. It is characterized by providing.

  According to claim 2 of the present invention, in the adaptive antenna array receiver, the antenna weight generation means considers received power obtained from the two-dimensional power profile when generating the antenna weight. It is characterized by.

  According to claim 3 of the present invention, in the adaptive antenna array receiving apparatus, the two-dimensional power profile generation means inputs an uplink pilot channel as the control signal and is inserted into the pilot channel. A complex correlation processing means for outputting a complex correlation value of a pilot symbol at each antenna using symbols and a complex correlation value obtained by the complex correlation processing means are added in-phase to generate a complex delay profile at each antenna. Complex delay profile generation means, directional beam reception combining means for scanning a directional beam within a predetermined angle range, multiplying the complex delay profile at each timing by an antenna weight forming the directional beam, and combining the complex delay profile; Timing method using the synthesized signal It is characterized by and a received power calculation means for calculating a reception power of.

  According to claim 4 of the present invention, in the adaptive antenna array receiving apparatus, the received power calculation means calculates the received power using a beam former method or a Capon method.

  According to claim 5 of the present invention, in the adaptive antenna array receiving apparatus, the path detection / arrival direction estimating means uses the two-dimensional power profile generated by the two-dimensional power profile generating means, and uses a peak. Path independent reception timing detection means for detecting a predetermined number of paths having power and detecting the reception timing of the path in each detected path; path independent arrival direction estimation means for estimating the arrival direction in the detected path; It is characterized by having.

  According to claim 6 of the present invention, in the adaptive antenna array receiver, the path-independent reception timing detection means detects a predetermined number of paths in descending order of power among paths having peak power. It is a feature.

  According to claim 7 of the present invention, in the adaptive antenna array receiver, the path detection / arrival direction estimation means uses the two-dimensional power profile generated by the two-dimensional power profile generation means to A predetermined number of paths each having a peak power is detected, the power sum of the paths for each detected angle is calculated as a combined power, and one angle at which the calculated combined power is maximum is estimated as an arrival direction common to the paths It is characterized by comprising path common arrival direction estimation means and path common reception timing detection means for detecting the reception timing of each path in the estimated path common arrival direction.

  According to claim 8 of the present invention, in the adaptive antenna array receiver, the common path arrival direction estimating means detects a predetermined number of paths in descending order of power among paths having peak power. It is a feature.

  According to claim 9 of the present invention, in the adaptive antenna array receiving apparatus, the antenna weight generation means is an antenna that forms a main beam in the arrival direction of each path estimated by the path independent arrival direction estimation means. Path independent antenna weight generation means for generating weights, and path common antenna weight generation means for generating antenna weights for forming a main beam in the common arrival direction estimated by the path common arrival direction estimation means. It is characterized by.

According to claim 10 of the present invention, in the adaptive antenna array receiving apparatus, the path independent antenna weight generation means is independent arrival of each path of the own user and other users estimated by the path independent arrival direction estimation means. Based on the direction estimation result and the received power of the own user and other users obtained from the two-dimensional power profile generation means, an antenna weight is generated that forms a main beam in the direction of the own user and forms a null beam in the direction of the other user. A path-independent null control means, and the path-common antenna weight generation means generates a direction-of-arrival estimation result common to each path of the own user and other users estimated by the path-common arrival direction estimation means, and the two-dimensional power profile generation. Based on the received power of the own user and other users obtained from the means. Forming a over arm, it is characterized in that it comprises a path common null control means for generating antenna weights for forming a null beam in the other user directions.
According to claim 11 of the present invention, in the adaptive antenna array receiver, path detection is performed using power values at all timings of all angles of the two-dimensional power profile generated by the two-dimensional power profile generating means. It is further characterized by further comprising an all-angle common path detection threshold value setting means for setting a threshold value for.

  According to claim 12 of the present invention, in the adaptive antenna array receiver, path detection is performed using power values at all timings of each angle of the two-dimensional power profile generated by the two-dimensional power profile generating means. Further, it is characterized by further comprising a path detection threshold value setting means for setting a threshold value for each angle.

  According to the present invention, the pilot channel is used to generate the two-dimensional power profile by synthesizing the signals received by the directional beam, so that the detection accuracy of the path reception timing and the arrival direction of the incoming wave is improved. be able to.

  The essence of the present invention is to generate a two-dimensional power profile using a pilot channel in a packet frame in the uplink, perform path reception timing and DOA estimation based on the generated two-dimensional power profile, and based on the DOA estimation result. The reception weight of the array antenna is generated.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an adaptive antenna array receiving apparatus according to an embodiment of the present invention. In FIG. 1, the same components as those in FIG. 21 are denoted by the same reference numerals, and the description thereof will be omitted. The adaptive antenna array receiver 1 of this embodiment is different from the conventional adaptive antenna array receiver shown in FIG.
Beam sweep control unit 201, antenna weight generation unit 202, multipliers 203-1 to 203-N, adder 204, two-dimensional power profile generation unit 205, memory 206, path detection / DOA estimation unit 207 Is newly provided.

  Hereinafter, in this embodiment, a case where the adaptive antenna array receiving apparatus 1 according to the present invention is applied to a base station (receiving station) of a mobile communication system will be described as an example.

  In the figure, the correlation detectors 102-1 to 102-N use a pilot channel (control signal) code-multiplexed to an uplink data packet channel transmitted from a mobile station (transmitting station) to delay time. A complex correlation by one pilot symbol in each antenna 101-1 to 101-N is detected by shifting in the direction of the axis τ. The complex profile generators 103-1 to 103-N take in the complex correlation values detected as described above, and perform in-phase addition of the complex correlations of all pilot symbols of the pilot channels in one packet, so that each antenna Generate a complex delay profile.

  The beam sweep control unit 201 has a control function for inserting and sweeping the antenna beam at predetermined intervals in all directions. The antenna weight generation unit 202 receives an angle instruction from the beam sweep control unit 201. Therefore, an antenna weight (= receiving antenna weight) for generating directivity in the angular direction is generated.

  When the antenna weight for generating directivity in a certain angle direction is generated in accordance with the insertion / extraction operation of the beam sweep control unit 201, the complex delay profile in each antenna and the generated antenna weight are determined at all timings. Multiplying by the multipliers 203-1 to 203-N and combining by the adder 204, the received power (power profile) in the timing direction is calculated. Then, by performing this processing in all angular directions, the two-dimensional power profile generation unit 205 performs a power profile (two-dimensional power profile) having two dimensions of timing (timing) and angle (angle) as shown in FIG. ) Is generated.

  As a method for calculating the received power (power profile) in the timing direction described above, a beam former method or a Capon method can be used. The beamformer method is a method in which the main beam of the antenna is swept in all directions to search for a direction in which the output power of the antenna increases, and the received power P (τ, θ) by the beamformer method is expressed by the following equation (1) Is calculated according to

The Capon method is a method of directing the main beam in a certain direction and at the same time minimizing the contribution to the output from the other direction. The received power P (τ, θ) by the Capon method is expressed by the following equation (2). ).

In the above formulas (1) and (2),
a (θ): Steering vector (column vector having row components with N antennas)
R _xx : Autocorrelation vector (N × N matrix) of the received signal of the array antenna
R _xx (τ) _{m, n} = h _{m, τ} h _{n, τ} ^*
h _{n, τ} : pilot complex correlation value at τ timing of n antenna The two-dimensional power profile generated in the two-dimensional power profile generation unit 205 is stored in the memory 206 and then path detection / DOA estimation at a predetermined timing Is output to the unit 207. The path detection / DOA estimation unit 207 detects the reception timing of each path and performs DOA estimation based on the obtained two-dimensional power profile. The detection of the path reception timing and the DOA estimation method performed by the path detection / DOA estimation unit 207 will be described later.

  The antenna weight generation unit 108 generates an antenna weight for each path using the obtained DOA estimation result. The generated antenna weights are multiplied by the received signals from the antennas 101-1 to 101-N by the multipliers 109-1 to 109-N, and the multiplied signals are combined by the adder 110. Demodulation section 111 receives the Rake combining reception path timing detected by path detection / DOA estimation section 207 and the signal combined by adder 110, demodulates the data at the reception timing for each path, and reproduces the data. Is output.

  Next, detection of the path reception timing and DOA estimation method performed by the path detection / DOA estimation unit 207 will be described. The detection of the path reception timing and the DOA estimation method performed by the path detection / DOA estimation unit 207 include two methods: (1) a reception timing / path independent DOA estimation method and (2) a reception timing / path common DOA estimation method. There is. First, the reception timing / path independent DOA estimation method (1) will be described.

  FIG. 3 is a flowchart showing a processing procedure in the path detection / DOA estimation unit 207 when the reception timing / path independent DOA estimation method is applied.

  In this method, first, a maximum L path is detected in descending order of power using a two-dimensional power profile (step S1). For example, as shown in FIG. 4, the path (b), the path (a), and the path (c) are detected in descending order of power.

Next, the timing τ and DOA (θ) in each path detected in this way are simultaneously detected (step S2). For example, in the example of FIG. 4, the timing τ ₂ and DOA (θ ₂ ) for the path (b), the timing τ ₁ and DOA (θ ₁ ) for the path (a), the timing τ ₃ and DOA (for the path (c) θ ₃ ) is detected simultaneously.

  That is, according to the reception timing / path independent DOA estimation method according to the present embodiment, the reception timing of each path is detected by the reception signal at the time of directivity reception in which the main beam is directed to the DOA of each path. Compared with the conventional method in which the DOA is detected after detecting the reception timing of the path, the reception timing of each path can be detected with higher accuracy.

  Next, the reception timing / path common DOA estimation method (2) will be described.

  FIG. 5 is a flowchart showing a processing procedure in the path detection / DOA estimation unit 207 when the reception timing / path common DOA estimation method is applied.

In this method, first, a maximum L path is detected in descending order of power for each angle using a two-dimensional power profile (step S11). Then, the power sum of all the detected paths is calculated (step S12), and the maximum L path timing τ and the DOA θ _{common common} to the paths are detected in descending order of the power at the maximum angle θ _common (step S12). S13). For example, in the example shown in FIG. 6, the timing tau ₃ at the timing tau _{2, P 3} at the timing tau _{1, P 2} at the peak power _{P 1} at the maximum angle theta _{common in} is detected.

  The antenna weight generation unit 108 uses the DOA estimation result detected by the path independent method (method (1) above) shown in FIG. 3 or the path common method (method (2) above) shown in FIG. An antenna weight that directs the main beam toward the user is generated. For example, as shown in FIG. 7, the base station 500 to which the adaptive antenna array receiving apparatus according to the present embodiment is applied directs the main beam to the DOA of each path (common path) of the own user (mobile station 600). Generate antenna weights.

  FIG. 8 is a block diagram illustrating a configuration of the adaptive antenna array receiver 2 when the main beam direction is controlled based on the DOA estimation result. The adaptive antenna array receiving apparatus 2 according to the present embodiment has the same basic configuration as the adaptive antenna array receiving apparatus 1 shown in FIG. 1, and includes two-dimensional power profile generation units 211-1 to 211 -M and a DOA estimation unit 212-1. To 212-M, antenna weight generation units 213-1 to 213-M, and the like are provided for the number of users M.

  In the present embodiment, the two-dimensional power profile generation units 211-1 to 211-M and DOA estimation units 212-1 to 212-M for each user (user 1 to user M) use the path independent method or the common path method for DOA. Is estimated. Each antenna weight generation unit 213-1 to 213-M generates an antenna weight using only the estimated DOA so that the main beam is directed to each user.

  In the above embodiment, the case where only the control for directing the main beam toward each user is illustrated, but the present invention is not limited to such a mode. For example, when there are other users in addition to the own user, as shown in FIG. 9, the base station 500 to which the adaptive antenna array receiver according to this embodiment is applied is estimated by a path independent method or a path common method. It is also possible to generate the antenna weight so that the main beam is directed to the DOA of the own user (mobile station 600) and the beam null is directed to the DOA of another user (mobile station 610).

FIG. 10 is a block diagram showing a configuration of adaptive antenna array receiver 3 when the main beam direction and the null direction are controlled based on the DOA estimation result. The adaptive antenna array receiving apparatus 3 in the present embodiment has the same basic configuration as the adaptive antenna array receiving apparatus 2 shown in FIG. 8, and generates antenna weights with respect to the adaptive antenna array receiving apparatus 2 in the embodiment shown in FIG. The operation is different. Therefore, here, differences from the adaptive antenna array receiving apparatus 2 of the embodiment shown in FIG. 8 will be described.
The antenna weight generation units 223-1 to 223 -M in the present embodiment generate antenna weights using the DOA estimation result of the own user estimated by the path independent method or the path common method and the DOA estimation result of other users. Specific examples will be described below.

In this figure, in this embodiment, the DOA estimation units 222-1 to 222-M for each user (user 1 to user M) are estimated by the DOA of the own user estimated by the path independent method or the path common method, respectively. Are output to each antenna weight generation section 223-1 to 223 -M.

  On the other hand, the received power calculated by the two-dimensional power profile generation units 221-1 to 221-M for each user is output to the antenna weight generation units 233-1 to 223-M for each user. Here, paying attention to a certain antenna weight generation unit 223-1, the antenna weight generation unit 223-1 determines the DOA estimation result of the own user output from the DOA estimation unit 222-1 for the user 1, and the user M's DOA estimation result. The DOA estimation result of another user output from the DOA estimation unit 222-M, the received power of the own user output from the two-dimensional power profile generation unit 221-1 for the user 1, and the two-dimensional power profile for the user M Using the received power of the other user output from the generation unit 221 -M, an antenna weight that directs the main beam in the direction of the own user and the beam null in the direction of the other user is generated. Thereby, other user interference can be suppressed effectively.

  In this embodiment, when performing the control which directs the beam null toward the other user direction, a case where the DOA estimation result of the other user as well as the other user and the received power of the other user are used is illustrated as a preferable aspect. . The reason will be described below.

  In an adaptive antenna array, considering an ideal situation where an unwanted wave of another user that causes interference comes from one direction, if a DOA estimation result in the other user direction is obtained, the beam null is directed toward the arrival direction of the unwanted wave. be able to. However, other users who cause interference, that is, the number of arrivals of unnecessary waves are plural, and communication quality cannot be improved unless they are removed. In general, the number of independent nulls that can be generated by the adaptive antenna array is (N-1) where N is the number of antenna elements. As a result, (N-1) number of unnecessary waves can be removed. Null control exceeding the degree of freedom (N-1 number) of the array antenna is not possible.

  Therefore, in the present embodiment, in consideration of the case where the number of other users causing interference is large, in addition to the DOA of other users, the direction of other users having strong interference based on interference power from other users, that is, received power information. The control which directs null to is performed. As a result, the null can be effectively directed to the direction of the user having strong interference within the limit of the degree of freedom of the array antenna, and the transmission capacity can be increased. When the number of other users that cause interference is small, null control can be performed without using information on received power.

  As described above, in the present embodiment, the method of estimating the DOA independently of the path (see FIG. 3) and the method of estimating the DOA common to the paths (see FIG. 5) have been described. The path-independent weight generation method that estimates DOA in a path-independent manner and generates an antenna weight based on the estimation result obtains the antenna weight with a small received signal power for each path. Compared to a path common weight generation method that generates antenna weights based on DOA estimation, an antenna weight generation error is slightly increased, but the antenna gain is not reduced even if the angular spread between paths is increased. Here, the angular spread refers to the standard deviation of the arrival angle when the distribution of the arrival angles of the signal is assumed to be a normal distribution, and is generally large depending on the installation location of the array antenna and the surrounding building height. Will be decided.

  On the other hand, in the common path weight generation method, when the angular spread between the paths is small, the antenna weight is generated using a large received power obtained by combining all the paths. . However, when the angular spread between paths becomes large, a large antenna gain cannot be obtained for all paths. Therefore, the adaptive antenna array receiving apparatus according to the present embodiment performs control to selectively use the path independent weight generation method and the path common weight generation method according to the angular spread between paths. Hereinafter, specific examples will be described.

  FIG. 11 is a block diagram showing a configuration of adaptive antenna array receiving apparatus 4 that performs switching control between a path independent weight generation method and a path common weight generation method. In this figure, the adaptive antenna array receiver 4 includes a DOA estimation unit 311, a DOA estimation result memory 312, an angular spread detection unit 313 between paths, an angular spread threshold determination unit 314, a weight generation unit 315 for each path, A common weight generation unit 316, an antenna weight generation switching control unit 317, a switch 318, multipliers 321-1 to 321-N for each path, an adder 322 for each path, and a demodulation unit 323 are configured.

  The operation of the adaptive antenna array receiving apparatus 4 configured as described above will be described with reference to the flowchart shown in FIG.

  In the figure, a DOA estimation unit 311 performs DOA estimation of each path based on a two-dimensional power profile obtained from a two-dimensional power profile generation unit (not shown here) (step S21), and the result is DOA estimation. The result is stored in the result memory 312 and output to the angular spread detection unit 313 between passes.

  The angular spread detection unit 313 between the paths detects the angular spread between the paths based on the DOA estimation result in accordance with Method 1 or Method 2 shown below (Step S22).

(Angle spread detection method 1)
The arrival direction estimated value (DOA estimation result) and received power of each path are
θ ₁ , θ ₂ , θ ₃ ,. . . , Θ _L ,
P ₁ , P ₂ , P ₃ ,. . . , P _L ,
, The angular spread σ is calculated by the following equation using θ _l and P _l .

here,

(Angle spread detection method 2)
Angle spread [degree] = Maximum angle difference between maximum K paths in descending order of received power satisfying XdB from the path with the maximum received power FIG. 13 shows the concept of angle spread detection in Method 2. In this example, XdB = 5, K = 3, and the path 1, path 2, and path 3 are detected in descending order of received power, and the angular spread between paths 1 to 3 is detected ( Angular spread detection value = θ ₂ −θ ₁ ).

  Returning to FIG. 12, the angle spread threshold value determination unit 314 compares and determines the angle spread detected as described above and the threshold value (step S <b> 23), and outputs the determination result to the antenna weight generation switching control unit 317. . When the antenna weight generation switching control unit 317 obtains a result that the angular spread is larger than the threshold value in the determination (step S23), the antenna weight generation switching control unit 317 controls the switch 318 to connect to the contact on the path weight generation unit 315 side. Thereafter, the antenna weight generated by the path weight generation unit 315 is output to the multiplication units 321-1 to 321-N via the antenna weight generation switching control unit 317.

  On the other hand, if it is determined in the above determination (step S23) that the angular spread is smaller than the threshold value, the antenna weight generation switching control unit 317 controls the switch 318 to connect the contact point to the path common weight generation unit 316 side. Connecting. Thereafter, the antenna weight generated by the path common weight generation unit 316 is output to the multiplication units 321-1 to 321-N via the antenna weight generation switching control unit 317.

  Thus, in the present embodiment, whether to generate a weight for each path or to generate a common weight for each path according to the angular spread is used. For example, in a complicated propagation path environment such as an antenna having a low height (eg, an underground shopping center) and a reflection of an object, a large angular spread of an incoming wave is detected. In this case, the antenna weight generation switching control unit 317 performs a path A weight generation method in each weight generation unit 315 is selected, and an antenna weight is generated for each path.

  On the other hand, in a propagation path environment where the antenna height is high (eg, the roof of a building) and the influence of blocking of the propagation path is relatively small, the angular spread of the incoming wave is detected to be small. The weight generation switching control unit 317 selects a weight generation method in the path common weight generation unit 316, and an antenna weight is generated in common for the paths. As a result, the antenna weight generation method can be selectively used according to the installation status of the antenna height, and a more flexible system can be constructed.

  As described above, according to the present embodiment, since the antenna weight is generated for each packet based on the DOA estimation result, as compared with the case where the MMSE algorithm is applied to the packet switching type system. Antenna weight generation errors can be improved.

  In the above embodiment, the DOA of the received signal is estimated using the pilot symbol in the pilot channel, and the antenna weight is generated based on the estimation result. However, the present invention is limited to such an aspect. It is not something. For example, in a packet-switched system, a random reservation method is used to send a short reservation packet (a packet for notifying a different service quality requirement condition such as delay and data size) before a transmitting terminal (mobile station) transmits packet data. In such a case, it is possible to perform control in which DOA estimation is performed in advance using the reservation packet and null is directed to the subsequent packet data channel using the estimation result.

  FIG. 14 is a diagram illustrating an operation concept when DOA is estimated using a reservation packet and null control is performed on a subsequent packet data channel.

  FIG. 6A shows a state in which a reservation packet is sent from the mobile station 610, which is another user, when the base station 500 and the mobile station 600 to which the adaptive antenna array receiving apparatus according to this embodiment is communicating. Show. In such a case, the base station 500 to which the adaptive antenna array receiver in the present embodiment is applied performs DOA estimation using a known pattern included in the reserved packet transmitted from the mobile station 610, and based on the estimation result An antenna weight that directs null toward the mobile station 610 is generated in advance. Thereafter, DOA estimation is performed using a pilot channel multiplexed in the packet data channel of mobile station 610 transmitted subsequently, and an antenna weight that directs null toward mobile station 610 is generated based on the estimation result. .

  As described above, in this embodiment, DOA estimation of the received signal from the mobile station 610 is performed using the reservation packet before the packet data is transmitted, and an antenna weight that directs null toward the mobile station 610 is generated in advance. Therefore, when generating an antenna weight that directs a null to the subsequent packet data channel, it can be swept in all angular directions and the angle around the direction of arrival obtained in advance without performing directional reception. The DOA for the packet data channel can be detected by sweeping the range and receiving directivity. As a result, it is possible to reduce the amount of calculation processing for generating the antenna weight.

  FIG. 15 is a block diagram showing a specific configuration example when the adaptive antenna array receiving apparatus according to the present invention is applied to a base station. This configuration is configured such that reception is performed using antenna weighting factors corresponding to the number of multipaths in reception in a multipath environment.

  The base station in this embodiment includes two-dimensional power profile generation units 405-1 to 405-M, path detection / DOA estimation units 406-1 to 406-M, and antenna weight generation units 407-1 to 407-M. Minutes (user 1 to user M). Since these operate in the same manner, the operation in the user 1 will be described below as a representative.

  In the figure, signals received by the antennas 401-1 to 401 -N pass through LNAs 402-1 to 402 -N and RF circuits 403-1 to 403 -N, and A / D converters 404-1 to 404 -N. N is converted to a digital baseband signal. The converted digital baseband signal is input to a two-dimensional power profile generation unit 405-1, and a two-dimensional power profile is generated using a pilot channel multiplexed with a data channel. Thereafter, the reception timing / DOA estimation unit 406-1 estimates the DOA of the received signal and the reception timing of the path. The antenna weight generation unit 407-1 generates an antenna weight for each path based on the DOA and the estimation result of the path reception timing.

  The signals received by the antenna elements 401-1 to 401 -N are multiplied by the antenna weight generated by the antenna weight generation unit 407-1 by the multipliers 408-1 to 408 -N and added by the adder 409. After that, despreading is performed at the reception timing for each path in the despreader 410-1. The signal for each path despread in this way is subjected to channel estimation by the channel estimation unit 411, then subjected to Rake synthesis by the Rake synthesis unit 412, and demodulated by the demodulation unit 416, whereby transmission data is reproduced. .

  Next, path detection based on a two-dimensional power profile when there is a high-power interference wave as described above will be described with reference to FIG.

  As shown in the figure, when there is a high-power interference wave that transmits high-rate traffic, the influence of cross-correlation due to pilot symbols remains, so that power remains in the interference wave direction. In such a case, when detecting a desired wave path, the probability of erroneously detecting a high-power interference wave increases. Therefore, the reception timing / DOA estimation unit 406 in the present embodiment sets a path detection threshold for all angles or for each angle using a two-dimensional power profile. A specific example will be described below with reference to FIGS. FIG. 17 is a flowchart illustrating a processing procedure in the reception timing / DOA estimation unit 406 in the case where a path detection threshold is set for all angles. FIG. 18 is a two-dimensional power profile for explaining the concept of setting the path detection threshold for all angles in common.

  In FIG. 17, the reception timing / DOA estimation unit 406 obtains a two-dimensional power profile from the two-dimensional power profile generation unit 405 in the method of setting the path detection threshold for all angles in common (step S31). Then, the noise power common to all angles is calculated by averaging the power values excluding L × 4 timing in descending order from the power values of all angles and all timings of the two-dimensional power profile (step S32). A value offset by Δ to the noise power value common to all angles is calculated as a path detection threshold value common to all angles (step S33). In step S34, the power value exceeding the path detection threshold value common to all angles is calculated. The maximum L paths are detected in descending order of the ratio of the path detection threshold to the path detection threshold. In step S 35, the reception timing and DOA are detected for the detected L path, and the result is output to the antenna weight generation unit 407.

  Next, a case where a path detection threshold is set for each angle using a two-dimensional power profile will be described. FIG. 19 is a flowchart illustrating a processing procedure in the reception timing / DOA estimation unit 406 when setting a path detection threshold value for each angle. FIG. 20 is a two-dimensional power profile for explaining the concept of setting a path detection threshold value for each angle.

  In FIG. 19, in the method of setting the path detection threshold for each angle, the reception timing / DOA estimation unit 406 obtains the two-dimensional power profile from the two-dimensional power profile generation unit 405 (step S41). Noise power for each angle is calculated by averaging power values obtained by removing L × 4 timing in descending order from the power values of all timings for each angle of the two-dimensional power profile (step S42). A value offset by Δ to the noise power value for each angle is calculated as a path detection threshold value for each path (step S43), and for each angle, a ratio between the power and the path detection threshold value for each angle is obtained, The maximum L paths are detected in descending order of this ratio at all angles (exceeding the path detection threshold) (step S44). In step S <b> 45, the reception timing and arrival direction are detected for the detected L path, and the result is output to the antenna weight generation unit 407.

  As described above, in the method of setting a threshold value for path detection for all angles in common, noise for setting a path detection threshold value using power values at all timings of all angles of a two-dimensional power profile. Since the power is calculated in common for all angles, the noise power averaging effect is large. However, if there is a high-power interference wave, the detection of the desired wave path due to false detection that detects the interference wave as the reception timing and the increase of the path detection threshold common to all angles due to the interference wave. Detection miss increases.

  On the other hand, in the method of setting a threshold for path detection for each angle, the noise power for setting the path detection threshold is set to the angle using the power values at all timings of each angle of the two-dimensional power profile. Since the noise power averaging effect is reduced every time, even when there is a high-power interference wave, the path detection threshold is set for each angle. Because the power is high, the path detection threshold value is high and the path detection threshold value in the desired wave direction is set small, so that the desired wave bus can be detected with high accuracy without being affected by the interference wave.

  That is, there is a trade-off relationship between a method for setting a threshold for detecting a path for all angles and a method for setting a detection threshold for a path for each angle. Therefore, which one of these is adopted is a trade-off between the merits of both, but in the absence of high-power interference waves, the noise power averaging effect is large and the characteristics are improved for all angles. Select the method for setting the threshold for path detection, and if there is a high-power interference wave, detect the desired wave path with high accuracy without being affected by the high-power interference wave. It is preferable to select a method for setting a detection threshold value for the path for each angle at which the image can be detected. Thereby, even when a high-power shared channel causes interference, path detection can be performed with high accuracy, and reception timing and arrival direction can be detected with high accuracy. As a result, an increase in uplink cell coverage and an increase in link capacity can be realized.

  In conclusion, the present invention can provide an adaptive antenna array receiving apparatus suitable for a packet switching type system in which traffic having different transmission rates is mixed.

  Note that it is also possible to generate a transmission antenna weight on the transmission side using the uplink DOA estimation result already described above. For example, when uplink transmission of each user is performed, DOA estimation is performed and the value is stored, and when performing downlink transmission of a certain user, the stored DOA estimation result of the user is stored. The transmission antenna weight is generated based on the above. At this time, as a transmission antenna weight generation method, for example, the following method can be considered.

  (A) A transmission antenna weight for directing the main beam in the arrival direction of the path with the maximum received power is generated.

(B) A transmission antenna weight for directing the main beam in the arrival direction of all paths is generated.
(C) A transmission antenna weight for directing the main beam in the average arrival direction of all paths is generated.

  By generating transmit antenna weights as described above, adaptive array transmission can be performed even when the uplink and downlink are asymmetrical, and downlink cell coverage and link capacity can be increased. it can.

  In each of the above-described embodiments, the case where the adaptive antenna array receiving apparatus of the present invention is applied to the base station of the mobile communication system has been described. However, the present invention is not limited to the base station, but is adaptive using a plurality of antennas. Needless to say, the present invention is also applicable to mobile stations that perform array processing.

It is a block diagram which shows the structure of the adaptive antenna array receiver which concerns on one Embodiment of this invention. It is a figure which shows the example of a production | generation of a two-dimensional electric power profile. It is a flowchart which shows a path | pass reception timing detection and a path independent DOA estimation procedure. It is a two-dimensional power profile for explaining path detection and DOA estimation by path reception timing detection / path independent DOA estimation method. It is a flowchart which shows a path | pass reception timing detection and path common DOA estimation procedure. It is a two-dimensional power profile for explaining path detection and DOA estimation by path reception timing detection / path common DOA estimation method. It is a figure which shows an example of the beam control (the 1) in the base station to which the adaptive antenna array receiver in this embodiment is applied. It is a block diagram which shows the structure of the adaptive antenna array receiver shown in FIG. It is a figure which shows an example of the beam control (the 2) in the base station to which the adaptive antenna array receiver in this embodiment is applied. FIG. 10 is a block diagram illustrating a configuration of the adaptive antenna array receiver illustrated in FIG. 9. It is a block diagram which shows the structure of the adaptive antenna array receiver which performs control which switches the production | generation method of an antenna weight. It is a flowchart which shows the control procedure which switches the production | generation method of an antenna weight according to an angle spread. It is a figure which shows the detection concept of an angular spread. It is a figure which shows the operation | movement concept in the case of performing null control based on a reservation packet. It is a block diagram which shows the specific structural example at the time of applying the adaptive antenna array receiver in this invention to a base station. It is a figure for demonstrating the path | pass detection method by a two-dimensional power profile in case a high-power interference wave exists. It is a flowchart which shows the process sequence in the reception timing / DOA estimation part in the case of setting a path | pass detection threshold value common to all angles. It is a two-dimensional power profile for demonstrating the concept which sets a path | pass detection threshold value in common with all angles. It is a flowchart which shows the process sequence in the reception timing / DOA estimation part in the case of setting a path | pass detection threshold value for every angle. It is a two-dimensional power profile for demonstrating the concept which sets a path | pass detection threshold value for every angle. It is a block diagram which shows the structure of the conventional adaptive antenna array receiver. It is a figure which shows the channel state of the uplink in broadband wireless access.

Explanation of symbols

1-4 Adaptive antenna array receivers 101 to 101-N, 401-1 to 401-N Antenna elements 102-1 to 102-N Correlation detectors 103-1 to 103-N Complex profile generators 104, 110, 204, 322, 409, 415 Adder 105 Synthesis delay profile generation unit 106 Path detection unit 107 DOA (Direction of arrival) estimation unit 108, 202, 213-1 to 213-M, 223-1 to 223-M, 407 -1 to 407-M antenna weight generation units 109-1 to 109-N, 203-1 to 203-N, 321-1 to 321-N, 408-1 to 408-N, 413, 414 multipliers 111 and 111 -1 to 111-M, 323, 416 Demodulator 201 Beam sweep controller 205, 211-1 to 211-M, 221-1 221-M, 405-1 to 405-M Two-dimensional power profile generation unit 206 Memory 207, 212-1 to 212-M, 222-1 to 222-M, 406-1 to 406-M Path detection / DOA estimation unit 311 DOA estimation unit 312 DOA estimation result memory 313 Angle spread detection unit between paths 314 Angle spread threshold determination unit 315 Weight generation unit for each path 316 Path common weight generation unit 317 Antenna weight generation switching control unit 318 Switch 402-1 402-N LNA
403-1 to 403 -N RF circuit 404-1 to 404 -N A / D converters 410-1 to 410 -M Despreader 411 Channel estimation unit 412 Rake combining unit 500 Base station 600 to 620 Mobile station

Claims (13)

In an adaptive antenna array receiving apparatus comprising an array antenna composed of a plurality of antenna elements and receiving a transmission signal by the plurality of antenna elements,
Two-dimensional power profile generation means for generating a two-dimensional power profile having dimensions of time and angle of arrival path using control signals received by the plurality of antenna elements;
Path detection / arrival direction estimation means for detecting path reception timing and estimating the arrival direction of the path using the two-dimensional power profile;
Antenna weight generating means for generating antenna weights for received signals from the plurality of antenna elements based on the arrival direction estimation result of the path;
An adaptive antenna array receiving apparatus comprising: The adaptive antenna array receiver according to claim 1,
The adaptive antenna array receiver according to claim 1, wherein the antenna weight generation means considers received power obtained from the two-dimensional power profile when generating the antenna weight. The adaptive antenna array receiver according to claim 1 or 2,
The two-dimensional power profile generation means inputs an uplink pilot channel as the control signal,
Complex correlation processing means for outputting a complex correlation value of pilot symbols in each antenna using pilot symbols inserted into the pilot channel;
Complex delay profile generation means for generating a complex delay profile at each antenna by adding in-phase the complex correlation values obtained by the complex correlation processing means;
Directional beam reception combining means for scanning a directional beam within a predetermined angle range, multiplying the complex delay profile at each timing by an antenna weight for forming the directional beam, and combining the complex delay profile;
Received power calculation means for calculating received power in the timing direction using the combined signal synthesized;
An adaptive antenna array receiver comprising: The adaptive antenna array receiver according to claim 3,
The adaptive antenna array receiving apparatus, wherein the received power calculating means calculates the received power using a beam former method or a Capon method. The adaptive antenna array receiver according to any one of claims 1 to 4,
The path detection / arrival direction estimation means detects a predetermined number of paths having peak power using the two-dimensional power profile generated by the two-dimensional power profile generation means, and the path reception timing in each detected path Path independent reception timing detection means for detecting
Path-independent arrival direction estimation means for estimating an arrival direction in the detected path;
An adaptive antenna array receiver comprising: The adaptive antenna array receiver according to claim 5,
The adaptive antenna array receiving apparatus according to claim 1, wherein the path independent reception timing detecting means detects a predetermined number of paths in descending order of power among paths having peak power. The adaptive antenna array receiver according to any one of claims 1 to 4,
The path detection / arrival direction estimation means detects a predetermined number of paths having peak power for each angle using the two-dimensional power profile generated by the two-dimensional power profile generation means, and detects a path for each detected angle. A common path arrival direction estimating means for estimating one angle at which the calculated combined power is maximized as a common arrival direction of paths,
Path common reception timing detection means for detecting the reception timing of each path in the estimated common path arrival direction;
An adaptive antenna array receiver comprising: The adaptive antenna array receiver according to claim 7,
The path common arrival direction estimating means detects a predetermined number of paths in descending order of power among paths having peak power. The adaptive antenna array receiver according to any one of claims 5 to 8,
The antenna weight generation means includes path independent antenna weight generation means for generating an antenna weight for forming a main beam in the arrival direction of each path estimated by the path independent arrival direction estimation means,
Path common antenna weight generating means for generating an antenna weight for forming a main beam in the common direction of arrival estimated by the path common arrival direction estimating means;
An adaptive antenna array receiver comprising: The adaptive antenna array receiver according to claim 8,
The path-independent antenna weight generation means includes a path-independent arrival direction estimation result of the own user and other users estimated by the path-independent arrival direction estimation means, and the own user and other users obtained from the two-dimensional power profile generation means. Path independent null control means for generating an antenna weight for forming a main beam in the direction of the own user and a null beam in the direction of the other user based on the received power of
The path common antenna weight generation means includes arrival direction estimation results common to each path of the own user and other users estimated by the path common arrival direction estimation means, and the own user and other users obtained from the two-dimensional power profile generation means. An adaptive antenna array receiver comprising path common null control means for generating an antenna weight for forming a main beam in the direction of the own user and a null beam in the direction of the other user based on the received power of the receiver. In the adaptive antenna array receiver according to claim 1 or 10,
All-angle common path detection threshold value setting means for setting a threshold value for path detection using power values at all timings of all angles of the two-dimensional power profile generated by the two-dimensional power profile generation means. An adaptive antenna array receiving apparatus, further comprising: In the adaptive antenna array receiver according to claim 1 or 10,
A per-angle path detection threshold value setting means for setting a threshold value for path detection using power values at all timings of each angle of the two-dimensional power profile generated by the two-dimensional power profile generation means; An adaptive antenna array receiving apparatus comprising: A receiving method in an adaptive antenna array receiving apparatus that includes an array antenna including a plurality of antenna elements and receives transmission signals by the plurality of antenna elements,
Generating a two-dimensional power profile having dimensions of time and angle of arrival path using control signals received by the plurality of antenna elements;
Using the generated two-dimensional power profile, detecting a reception timing of a path and estimating an arrival direction of the path;
Generating antenna weights for received signals from the plurality of antenna elements based on the estimated direction-of-arrival direction estimation results;
A receiving method in an adaptive antenna array receiving apparatus.