JP2001339339A - Adaptive antenna system and adaptive antenna control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adaptive antenna system that can reduce the time required for path detection so as to relieve a load on the system. SOLUTION: Three antenna elements 101, 102, 103 are connected to a retrieval section 104 to detect timing of a path to be received. Finger sections 105, 106, 107 detect a reception signal of a path of each antenna element. A control circuit section 108 controls the operation of the retrieval section 104 and the finger sections 105, 106, 107. A decoding section 111 decodes a symbol. The arrival direction and an arrival delay time of the received signal are registered in advance and when a reception electric field strength of an incoming signal reaches a prescribed level or below, the control circuit section 108 compares the arrival direction and the arrival delay time of the received signal to be registered with those of the incoming signal and controls the succeeding operation on the basis of the result of comparison. Thus, data by a geographic characteristic or the like are registered, the time required for path detection is decreased and the load imposed on the system can be relieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an adaptive antenna system and an adaptive antenna control method.
The present invention relates to an adaptive antenna system and an adaptive antenna control method applied to a MA communication system.

[0002]

2. Description of the Related Art Conventionally, CDMA (code division) to which an adaptive antenna system and an adaptive antenna control method are applied.
multiple access) In a communication system, when the reception electric field level of a path of an uplink signal falls below a predetermined level, the signal of the path is not combined, but is decoded using the signal of another path with a higher reception electric field level.

[0003] The reason why the reception electric field level of the path decreases is as follows.
There are "distance", "obstacle becomes an obstacle", and the like. Usually, in these cases, communication is continued without being disconnected in order to perform handoff (handover) to another cell. The sound is also continued without being cut off.

[0004] However, for example, when a mobile station enters a tunnel, the received electric field level is extremely reduced, and the number of base stations that can receive uplink signals is extremely reduced. If any of the base stations cannot receive the uplink signal, a phenomenon occurs in which the sound is interrupted. Further, when the time exceeds a predetermined time, the communication is disconnected. Therefore, when a path is lost, it is necessary to detect a new path as soon as possible and to maintain or recover the reception quality.

[0005] Inventive example 1 of the prior application which is similar in technical field to the present invention
Japanese Patent Application Laid-Open No. 11-266180 discloses an "array antenna system for a wireless base station". Invention example 1 of the present application
Selects the despread signal of one or a plurality of beams having a large measured value from all the beams of all paths, and combines the selected despread signals to determine received data. Thereby, transmission quality and reception characteristics are improved.

[0006] Further, Japanese Patent Application Laid-Open No.
There is “Wireless Communication Device and Wireless Communication Method” in JP-A-289293. The prior invention example 2 detects the timing of the arriving wave, receives the adaptive array antenna at the timing of the arriving wave, calculates a new weighting factor from the weighting factor of the reception result, and calculates the desired signal from the weighting factor and the received signal. The level of the received power or the SIR (desired wave received power / interference power) is detected, a weight coefficient having a higher level is selected, and transmission is performed using the selected weight coefficient. Thus, transmission with more optimal directivity is performed.

[0007]

However, in any of the above prior arts, once a path is lost, it takes time to find a new path. The arrival delay time is searched in a wide range, and the direction of arrival must be searched by forming a 120-degree beam in the case of a 3-sector base station. In this case, the time required for the search becomes longer, and there is a problem that the S / N ratio becomes worse as the beam is wider.

However, if the cause of the loss of the path is known, it is possible to predict where the new path will appear. That is, when a mobile device enters a tunnel, a path appears at another location, that is, at the other exit of the tunnel, after a certain period of time. If it is possible to identify that the path has been lost beforehand, the path may be detected in a direction expected to appear after a certain period of time.

An object of the present invention is to provide an adaptive antenna system and an adaptive antenna control method that reduce the time required for path detection and reduce the load on the system.

[0010]

In order to achieve the above object, an adaptive antenna system according to the first aspect of the present invention includes a search unit for detecting a timing of a path to which at least two antenna elements are connected and to receive, A finger unit for detecting a reception signal of a path of each antenna element, a control circuit unit for controlling operations of a search unit and a finger unit, and a decoding unit for decoding a symbol; The time is registered in advance, and when the received electric field level of the uplink signal falls below a predetermined value, the control circuit unit compares the registered arrival direction and arrival delay time, and based on the result of this comparison, The operation is controlled.

If the result of the comparison does not fall within the predetermined range, the range of the first path detection after the reception electric field level of the upstream signal falls below the predetermined level is widened, and the upstream beam is detected. The formation range is a range that covers all the corresponding sectors, and if the result of the comparison is included in the predetermined range, the first path detection after the reception electric field level of the uplink signal falls below the predetermined level. May be a range registered in advance based on the geographical conditions of the corresponding sector.

Further, the apparatus further includes an adder for adding an output from the finger unit, an error signal calculation unit, and storage means for storing the registered data. It is preferable to have a function of forming an uplink beam by applying a weight to a signal from the base station.

According to a sixth aspect of the present invention, in the adaptive antenna control method, a search step for detecting timing of a path to which at least two antenna elements are connected and to be received, and detecting a received signal of a path of each antenna element. A finger step, a control step of controlling operations of the search step and the finger step, and a decoding step of decoding a symbol, in which an arrival direction and an arrival delay time of a reception signal are registered in advance, and a reception electric field of an uplink signal is When the level falls below a predetermined value, the control step compares the registered arrival direction and arrival delay time with each other, and controls the subsequent operation based on the result of the comparison.

When the result of the comparison is not included in the predetermined range, the range of the first path detection after the reception electric field level of the upstream signal falls below the predetermined level is widened, and the upstream beam is detected. The formation range is a range that covers all the corresponding sectors, and if the result of the comparison is included in the predetermined range, the first path detection after the reception electric field level of the uplink signal falls below the predetermined level. May be a range registered in advance based on the geographical conditions of the corresponding sector.

Further, the method further comprises an adding step of adding outputs from the finger step, an error signal calculating step, and a storing step of storing registered data. It is preferable to have a function of forming an uplink beam by weighting a signal from an antenna.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the adaptive antenna system and the adaptive antenna control method according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 4, there is shown an embodiment of an adaptive antenna system and an adaptive antenna control method according to the present invention.

FIG. 1 shows an embodiment of the present invention, in which a CD using an adaptive antenna system and an adaptive antenna control method is used.
In the MA communication system, a searcher unit 104 that detects timing of a path to be received, and a fi that detects a received signal of each path.
The control circuit unit 108 controls the nger units 105, 106, 107, the searcher unit 104 and the finger unit, and the decoding unit 111 decodes symbols.

Further, a searcher (search) unit 104 and
Antenna elements (receiving systems) 101, 102, 1 connected to finger units 105, 106, 107
03, an adder 110 that adds outputs from the finger units 105, 106, and 107, an error signal calculation unit 113,
It has a means 109 for storing registered data and an output terminal 112.

The searcher unit 104 and the finger unit 1 described above
05, 106 and 107 have a function of forming an uplink beam by weighting the signal from each antenna.

The CDMA communication system is a communication system that allocates an individual spreading code to each user, thereby enabling a plurality of users to communicate.

In the adaptive antenna system and the adaptive antenna control method, the directivity can be sharpened as the number of antenna elements increases, and more paths can be received as the number of fingers increases. ,
Reception characteristics can be improved. However, for the sake of simplicity, the embodiment will be described below with three antenna elements and three fingers.

This will be described in detail with reference to FIG. The searcher unit 104 and the finger units 105, 106, and 107 include three antenna elements (and receiving systems) 101, 10
2, 103. Further, the saercher unit 104 and the finger units 105, 106, and 107 include the control circuit unit 10
8 is connected. Three finger parts 105, 106, 10
7 is connected to the adder 110, and the adder 110
11 and an error signal calculation unit 113. The decoding unit 111 is connected to an output terminal 112 that outputs a decoded signal, and is also connected to an error signal calculation unit 113.
The error signal calculation unit 113 includes the finger units 105 and 106,
107. A means 109 for storing the registered data is connected to the control circuit unit 108.

FIG. 2 is a block diagram showing a more detailed configuration example of the searcher unit 104. The searcher unit 104 will be described with reference to FIG. Antenna element 1
01, 102, and 103 are connected to the delay unit 201.
The delay unit 201 includes multipliers 202 and 20 for each received signal.
3, 204. Each multiplier 202, 203, 2
04 is connected to the weight control unit 207. The output of each multiplier 202, 203, 204 is
Connected to. Adder 205 is connected to correlator 206. The input / output interface unit 208 includes the delay unit 201,
It is connected to weight control section 207 and correlator 206. Further, the input / output interface unit 208 is connected to the control circuit unit 108 in FIG.

The finger units 105, 106 and 107 will be described with reference to FIG. Antenna element 10
1, 102 and 103 are finger units 105, 106, 1
07 delay device 301. The delay unit 301 includes a despreader 302, 303, 3 for each received signal.
04 and the respective despreaders 302, 303,
304 is connected to the respective multipliers 305, 306, 307. The input terminals of the multipliers 305, 306, 307 are connected to the weight control unit 311. Multipliers 305, 3
Outputs 06 and 307 are connected to an adder 308.
The adder 308 is connected to the output 309 terminal and the energy calculator 310.

The input / output interface unit 312 is a delay unit 3
01, weight control section 311 and energy calculation section 310
Connected to. Also, the input / output interface unit 312
It is connected to the control circuit unit 108 in FIG. Output terminal 309
Are connected to the adder 110 of FIG. Weight control unit 31
1 is connected to the error signal calculation unit 113 of FIG.

(Example of Operation) Next, the overall operation of the present embodiment will be described in detail with reference to FIG. 1, FIG. 2 and FIG.

In FIG. 1, the antenna element 10
From the three received signals sent from 1, 102 and 103, se
An archer unit 104 obtains a delay profile. In the control circuit unit 108, d sent from the searcher unit 104
Reception timi with high average correlation value in elay profile
ng, find it as a path and fi as the delay value
The notification is made to the nger units 105, 106 and 107. At the same time, weight data is also notified. Finger units 105, 106, and 107 adaptively control the beam based on the notified delay value and weight data, and demodulate the path signal. finger part 1
The outputs of 05, 106 and 107 are combined by an adder 110 and further decoded by a decoding unit 111. When the beam is adaptively controlled, an error signal obtained by subtracting data before decoding from decoded data obtained by decoding in the decoding unit 111 is used.

Here, the searcher unit 104 will be described with reference to FIG. The three received signals transmitted from the antenna elements 101, 102, and 103 are weighted by multipliers 202, 203, and 204 after being given a predetermined delay by a delay unit 201. The delay is based on the delay value notified from the control circuit unit 108 in FIG. The weights are sent from the weight control unit 207 to the multipliers 202, 203, and 204 based on the weight data notified from the control circuit unit 108 in FIG. The outputs of the multipliers 202, 203, 204 are
At 05, a beam is formed. A delay added by the delay unit 201 and multipliers 202, 203,
The weight applied in 204 is sent from the control circuit unit 108 in FIG. The correlator 206 calculates a correlation value with a predetermined code (pilot signal) from the obtained path signal to obtain a delay profile. The delay profile is sent to the control circuit unit 108 in FIG. 1 together with the weight data. The input / output interface unit 208
The data between the delay unit 201, the weight controller 207 and the correlator 206 and the control circuit unit 108 in FIG. 1 are separated and multiplexed.

FIG. 3 shows finger units 105, 106 and 107.
3 is a block diagram showing a more detailed configuration example of FIG. The finger units 105, 106, and 107 will be described with reference to FIG. The three received signals transmitted from the antenna elements 101, 102, and 103 are despread by despreaders 302, 303, and 304 after being given a predetermined delay by a delay unit 301, and are multiplied by multipliers 305, 306, and 307. Is weighted. The delay is based on the delay value notified from the control circuit unit 108 in FIG. The weight minimizes the error signal strength obtained by subtracting the data before decoding from the decoded data obtained by decoding in the decoding unit 111, using the weight data notified from the control circuit unit 108 in FIG. 1 as an initial value. Is adaptively controlled by the weight control unit 311 so that
05, 306 and 307. Multipliers 305, 30
The outputs of 6, 307 are added in an adder 308, thereby forming a beam. The obtained path signal is output from the output terminal 309 and the energy calculation unit 31
At 0, the energy of the path signal is calculated.

Each of the finger units 105, 106, and 107 monitors the reception electric field level, arrival direction, and arrival delay time of the upstream signal, and when the reception electric field level of the upstream signal is higher than a predetermined level, combines (see FIG. 1). Are added by an adder 110 shown in FIG. However, when the reception electric field level of the uplink signal falls below a predetermined level, the signal of that path is decoded without using the signal of another path with a higher reception electric field level. When the reception electric field level of the path is lowered and the combining is stopped, that is, when the path is lost, the searcher unit operates to detect a new path.

The above is performed by the conventional method and is not the gist of the present invention. The gist of the present invention will be described below.

When the reception electric field level of the upstream signal decreases,
In the control circuit, the arrival direction and arrival delay time are compared with the arrival direction and arrival delay time registered in advance. If the result of this comparison is not included in the predetermined range, the control circuit unit delays the delay unit so that the range of the first path detection after the reception electric field level of the uplink signal falls below the predetermined level is widened. Notify. Also, the range of formation of the up beam is
The control circuit unit notifies the weight control unit that the beam covers a range that covers all the corresponding sectors, for example, a 120-degree beam in the case of a three-sector configuration.

When the reception electric field level of the upstream signal decreases,
In the control circuit, the arrival direction and arrival delay time are compared with the arrival direction and arrival delay time registered in advance. If the result of this comparison is included in the predetermined range, the range of the first path detection and the range of the formation of the upstream beam after the reception electric field level of the upstream signal falls below the predetermined level are changed to the corresponding sector. Based on the geographical conditions, the control circuit notifies the delay unit and the weight control unit of the range registered in advance.

The means for storing the registered data, which is connected to the control circuit unit, registers weight data and delay values based on the geographical position where the path is lost, and when a path corresponding to the weight data and the delay appears. Weight data and delay values based on the expected geographic location are also registered. These data are not necessarily one each.

For example, as shown in FIG. 4, when one entrance of the tunnel is "A", weights and delays for forming a beam directed in that direction are (W0A, W1A, W2A, D
A). "B" at the other entrance of the tunnel
Then, the weights and delays that form the beam directed in that direction are (W0B, W1B, W2B, DB). Assuming that the weight and delay for forming a beam when the reception electric field level of the uplink signal is reduced are (W, W1, W2, D), this and (W0A, W1A, W2A, DA) (W0B, W1B, W2B, DB), and if any of the two values match in consideration of the error, it is considered that the mobile device has entered the tunnel. After a few seconds, the mobile is expected to appear at the other entrance, with the other beamforming weights and delays as initial values.
Notify the searcher that detects the path.

According to the above embodiment, in the mobile communication system using the adaptive antenna system and the adaptive antenna control method, the reception electric field level, arrival direction and arrival delay time of the uplink signal are monitored, and the reception electric field level of the uplink signal is monitored. Is lower than a predetermined level, the arrival direction and arrival delay time are included in the range of the arrival direction and arrival delay time registered in advance in the corresponding sector. The range of the path detection and the range of the formation of the upstream beam after the moment of the lowering are set as ranges registered in advance based on the geographical conditions of the corresponding sector. This reduces the time required for path detection and reduces the load on the system.

The above embodiment is an example of a preferred embodiment of the present invention. However, it is not limited to this.
Various modifications can be made without departing from the spirit of the present invention.

[0038]

As is apparent from the above description, the adaptive antenna system and the adaptive antenna control method of the present invention detect the timing of a path to which at least two antenna elements are connected and to receive, and each of the antenna elements , And control and decode the symbols. Furthermore, the arrival direction of the received signal and the arrival delay time are registered in advance, and when the reception electric field level of the uplink signal falls below a predetermined value, the registered arrival direction and arrival delay time are compared with each other. The subsequent operation is controlled based on the result. Therefore, it is possible to flexibly cope with a change in the received electric field level due to a geographical condition or the like, speed up path detection, and improve system performance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an adaptive antenna system and an adaptive antenna control method of the present invention.

FIG. 2 is a diagram illustrating a searcher unit that is a component of an embodiment of the present invention.

FIG. 3 is a diagram illustrating a finger unit that is a component of the embodiment of the present invention.

FIG. 4 is a diagram showing a state of beam generation in the embodiment of the present invention.

[Explanation of symbols]

101, 102, 103 Antenna element (reception system) 104 searcher unit 105, 106, 107 finger unit 108 control circuit unit 109 means for storing registered data 110 adder 111 decoding unit 112 output terminal 113 error signal calculation unit 201 Delay unit 202, 203, 204 Multiplier 205 Adder 206 Correlator 207 Weight control unit 208 Input / output interface unit 301 Delay unit 302, 303, 304 Despreader 305, 306, 307 Multiplier 308 Adder 312 Input / output interface unit 311 Weight control unit

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5J021 AA02 AA03 AA04 AA05 CA06 DB02 DB03 EA04 FA05 FA14 FA15 FA16 FA20 FA21 FA29 FA30 FA32 GA02 HA05 HA07 5K022 EE02 EE31 5K059 CC03 CC04 DD31 5K067 AA02 AA03 BB02 CC10 CC02 CC10 KK03

Claims (10)

[Claims] A search unit configured to detect timing of a path to which at least two antenna elements are connected and to be received; a finger unit configured to detect a received signal of the path of each antenna element; a search unit and a finger unit And a decoding unit for decoding symbols.The direction of arrival of the received signal and the arrival delay time are registered in advance, and the received electric field level of the uplink signal falls below a predetermined value. The control circuit unit compares the registered arrival direction and arrival delay time with each other, and controls subsequent operations based on the result of the comparison. 2. When the result of the comparison is not included in a predetermined range, the range of the first path detection after the reception electric field level of the uplink signal falls below the predetermined level is widened,
2. The adaptive antenna system according to claim 1, wherein the range of the formation of the uplink beam is a range covering all of the corresponding sectors. 3. If the result of the comparison falls within a predetermined range, the range of the first path detection after the reception electric field level of the uplink signal falls below the predetermined level is determined by the geographical location of the corresponding sector. The adaptive antenna system according to claim 1, wherein the range is set in advance based on a condition. 4. An apparatus according to claim 1, further comprising an adder for adding an output from said finger unit, an error signal calculating unit, and a storage unit for storing said registered data. The adaptive antenna system according to any one of the above. 5. The adaptive antenna system according to claim 4, wherein the search unit and the finger unit have a function of forming the uplink beam by weighting a signal from each antenna. 6. A search step for detecting a timing of a path to which at least two antenna elements are connected and to be received, a finger step for detecting a reception signal of the path of each antenna element, a search step and a finger step And a decoding step of decoding symbols.The direction of arrival of the received signal, the arrival delay time are registered in advance, and the reception electric field level of the uplink signal has dropped below a predetermined value. An adaptive antenna control method, wherein the control step compares the registered arrival direction and arrival delay time with each other, and controls subsequent operations based on a result of the comparison. 7. When the result of the comparison is not included in the predetermined range, the range of the first path detection after the reception electric field level of the uplink signal falls below the predetermined level is widened,
7. The adaptive antenna control method according to claim 6, wherein a range for forming the uplink beam is a range covering all the corresponding sectors. 8. When the result of the comparison falls within a predetermined range, the range of the first path detection after the reception electric field level of the uplink signal falls below the predetermined level is determined by the geographical location of the corresponding sector. 7. The adaptive antenna control method according to claim 6, wherein the range is set in advance based on a condition. 9. The method according to claim 6, further comprising an adding step of adding outputs from the finger step, an error signal calculating step, and a storing step of storing the registered data. The adaptive antenna control method according to any one of the above. 10. The adaptive antenna control method according to claim 9, wherein the search step and the finger step have a function of forming the uplink beam by weighting a signal from each antenna.