JP2012175640A - Wireless base station device, wireless unit control device, and wireless communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a communication quality of a terminal in the vicinity of a cell edge with efficiency.SOLUTION: A wireless base station device according to an embodiment has: a reception power measurement section 104 measuring a reception power of a signal from a wireless terminal for each antenna; a throughput measurement section 106 measuring signal qualities in macro diversity communication and in single antenna communication; an antenna information production section 108 producing information representing a combination of antennas to be used in the macro diversity communication based on information representing an adjacent relation of the wireless units and antenna arrangement information; and an antenna selection section 110 selecting an antenna combination to be used in wireless communication based on the measurement result of the reception power, the measurement result of the signal qualities, and the information representing the combination of antennas. The antenna selection section 110, while making a signal processing section 103 perform the macro diversity communication or the single antenna communication, makes the signal processing section 103 try the other communication periodically, and switches over to the other communication based on the measurement result of the signal qualities.

Description

  Embodiments described herein relate generally to a radio base station apparatus, a radio unit control apparatus, and a radio communication method that perform radio communication with a radio terminal.

  2. Description of the Related Art In recent years, mobile radio communication systems have been advanced and speeded up, and studies have been conducted on the realization of radio communication having a theoretical speed exceeding 100 Mbps in communication systems such as WiMAX, LTE, and XGP systems. As a technology for realizing high-speed wireless communication, there is a MIMO (Multiple Input Multiple Output) technology in which a base station has a plurality of antennas and performs communication multiplexing with a terminal by performing spatial multiplexing. Application to the next generation mobile radio communication system is being studied.

  However, MIMO is expected to improve the speed at the center of the cell, but communication degradation near the cell edge has been a problem. Therefore, studies on macro diversity that improves the reception power of terminals using antennas of different base stations are being promoted, and are regarded as important techniques for improving the gain of terminals existing in the vicinity of the cell edge. In macro diversity, in order to improve the gain of a terminal through communication using a plurality of base stations, antenna control and a communication method across base stations are essential.

JP 2008-86032 A JP 2001-16633 A

  An object of the present embodiment is to provide a radio base station apparatus, a radio unit control apparatus, and a radio communication method that can efficiently improve the communication quality of terminals near the cell edge.

  The radio base station apparatus according to the present embodiment includes a plurality of antennas, a plurality of radio units that perform radio communication with the radio terminals using the antennas, and a macro diversity by the plurality of radio units between the radio terminals. Signal processing means for selectively performing communication and single antenna communication by a single radio unit, received power measuring means for measuring the received power of an uplink signal from the radio terminal for each antenna, and the macro diversity Used for the macro diversity communication based on the signal quality measuring means for measuring the signal quality in each of the communication and the single antenna communication, the information indicating the adjacency relationship of the radio unit, and the antenna arrangement information of the radio unit Creating means for creating information representing a combination of antennas to perform, measurement results of the received power, measurement results of the signal quality And a selection means for selecting an antenna combination to be used for the wireless communication based on the information representing the combination of the antennas, and the selection means provides the signal processing means with the macro diversity communication or the single antenna communication. The other communication is periodically tried during the operation, and the communication is switched to the other communication based on the measurement result of the signal quality by the signal quality measuring means.

  The radio | wireless part control apparatus which concerns on this embodiment is a radio | wireless part control apparatus provided with several antennas, and controls several radio | wireless parts which carry out radio | wireless communication between radio terminals with the said antenna, Comprising: Between the said radio | wireless terminals And signal processing means for selectively performing macro diversity communication by a plurality of the radio units and single antenna communication by a single radio unit, and measuring received power of an uplink signal from the radio terminal for each antenna Received power measurement means, signal quality measurement means for measuring signal quality in each of the macro diversity communication and the single antenna communication, information indicating the adjacency relationship of the radio unit, and antenna arrangement information of the radio unit And generating means for generating information representing a combination of antennas used for the macro diversity communication, and measuring the received power. A selection means for selecting an antenna combination to be used for the wireless communication based on a result, a measurement result of the signal quality, and information indicating the combination of the antennas, and the selection means includes the signal processing means in the signal processing means; While carrying out macro diversity communication or the single antenna communication, the other communication is periodically tried, and the communication is switched to the other communication based on the measurement result of the signal quality by the signal quality measuring means. .

  The wireless communication method according to the present embodiment is a method used in a wireless unit control apparatus that includes a plurality of antennas and controls a plurality of wireless units that perform wireless communication with a wireless terminal using the antennas. And selectively performing macro diversity communication by a plurality of the radio units and single antenna communication by a single radio unit, and measuring received power of an uplink signal from the radio terminal for each antenna And measuring the signal quality in each of the macro diversity communication and the single antenna communication, the information indicating the adjacency relationship of the radio unit, and the antenna arrangement information of the radio unit, Creating information representing the combination of antennas used for diversity communication, the measurement result of the received power, the signal quality Selecting a combination of antennas to be used for the wireless communication based on a result of the determination and information indicating the combination of the antennas, and performing the macro diversity communication or the single antenna communication in the selection During this period, the other communication is periodically tried, and the other communication is switched based on the measurement result of the signal quality.

The whole block diagram of a radio | wireless communications system provided with the radio base station apparatus which concerns on this embodiment. The block diagram which shows the structure of the wireless base station apparatus of FIG. The figure which shows the creation process of antenna combination information. The figure which shows a received power measurement process. The figure which shows a macro diversity availability determination process. The figure which shows a macro diversity use antenna selection process. The figure which shows a macro diversity communication start sequence. The figure which shows a macro diversity communication start sequence. The flowchart which shows the implementation determination process of macro diversity.

  The radio base station apparatus, radio unit control apparatus, and radio communication method according to the present embodiment will be described below with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a radio system including a radio base station apparatus according to the present embodiment. In the present embodiment, the radio unit and the control unit of the conventional base station are separated, and macro diversity is realized by a base station form in which the control units are aggregated.

  In FIG. 1, an IP network / public communication network NW is connected to the gateway device GW, and a plurality of radio base station devices BS1 and BS2 are connected to the gateway device GW. The radio base station apparatus BS1 includes a plurality of radio units R11 to R1n that perform radio transmission and reception, and a radio unit control device G1 that performs signal processing and signal distribution related to radio. Wireless terminal devices MS11 to MS1m such as wireless terminals or PCs (personal computers) equipped with wireless communication data cards perform voice or data communication with the wireless units R11 to R1n. Each of the radio units R11 to R1n includes a plurality of antennas, and can adjust the transmission power of the plurality of antennas to give directivity to the downlink signal. Similarly to the radio base station device BS1, the radio base station device BS2 includes a radio unit control device G2 and a plurality of radio units R21 to R2n that perform radio communication with the radio terminal device.

  FIG. 2 is a block diagram illustrating an example of a configuration of the radio base station apparatus. Below, radio base station apparatus BS1 is demonstrated as a representative.

  In FIG. 2, a gateway device GW is connected to an IP network / public communication network NW and a wireless unit control device G1, and the wireless unit control device G1 and a plurality of wireless units R11 and R12 are connected by a wired transmission line such as an optical fiber, for example. Connected. The wireless unit R11 is provided with a plurality of antennas AN11 to AN1n for wireless communication with the wireless terminal devices MS11 and MS12. Similarly, the wireless unit R12 is also provided with a plurality of antennas AN21 to AN2n for wireless communication.

  The wireless terminal devices MS11 and MS12 and the wireless units R11 and R12 are provided with a wireless communication unit 101, and the wireless terminal devices MS11 and MS12 perform wireless communication with one or more wireless units by the wireless communication unit 101. The wireless unit control device G1 includes a signal distribution unit 102 that distributes data received from the gateway device GW to the wireless units R11 and R12 that perform wireless communication with the wireless terminal devices MS11 and MS12, and a signal that controls wireless communication. A processing unit 103 is provided.

  The signal processing unit 103 has a role of controlling the signal processing of the radio units R11 and R12. Here, a plurality of signal processing units 1031 and 1032 are provided according to the number of radio units R11 and R12. However, the present invention is not limited to this, and one signal processing unit 103 can control a plurality of radio units, and the number of radio units and the number of signal processing units are allowed to be different values.

  The radio unit controller G1 transmits uplink data from the radio terminal devices MS11 and MS12 received via the radio units R11 and R12 to the IP network / public communication network NW via the gateway device GW. Also, downlink data received from the IP network / public communication network NW via the gateway device GW is distributed to an appropriate radio unit by the signal distribution unit 102, and the radio terminal devices MS11, MS12 are transmitted via the radio units R11, R12. Send to.

  Further, the radio unit controller G1 includes a received power measurement unit 104, a received power aggregate information storage unit 105, a throughput measurement unit 106, an adjacent radio unit information storage unit 107, an antenna information creation unit 108, an antenna combination information storage unit 109, and An antenna selection unit 110 is provided. The received power measuring unit 104 measures the received power of the uplink signals from the radio terminal apparatuses MS11 and MS12 for each antenna of each radio unit, and stores received power aggregate information obtained by aggregating the measured values of received power. Store in the unit 105.

  The throughput measuring unit 106 measures the throughput from the communication state of the radio units R1 and R2. For example, the throughput is a value obtained by measuring the total number of communication data and the number of normal communication data and dividing the number of normal communication data by the total number of communication data. The adjacent radio unit information storage unit 107 stores information (adjacent radio unit information) indicating a combination of geographically adjacent radio units. The determination of whether or not geographically adjacent to each other is based on the distance between the wireless units and the transmission radio wave range of each radio unit, for example, determining that the radio units with overlapping transmission radio wave ranges are adjacent. The antenna information creation unit 108 is configured to determine whether the adjacent wireless unit information is stored based on the adjacent wireless unit information stored in the adjacent wireless unit information storage unit 107, the antenna arrangement information of each wireless unit, the received power of the wireless units R1 and R2, and the throughput. Antenna combination information representing the combination of antennas is created for each and stored in the antenna combination information storage unit 109. Based on the received power aggregation information, adjacent radio unit information, and antenna combination information, the antenna selection unit 110 selects the radio terminal device MS11, from the antennas AN11 to AN1n of the radio unit R11 and the antennas AN21 to AN2n of the radio unit R12. A combination of antennas used for wireless communication between the MSs 12 is selected.

The operation of the wireless unit control apparatus G1 configured as described above will be described below.
(Creation of antenna combination information)
FIG. 3 shows an example of antenna combination information creation processing.

  In FIG. 3, for the radio unit R11, the antenna arrangement information of the antennas AN11 to AN14 when the base station is installed is given as initial information. The same applies to the radio units R12 and R13. The antenna information creation unit 108 of the radio unit controller G1 determines an antenna combination for the radio unit combination information based on the adjacent radio unit information stored in the adjacent radio unit information storage unit 107. The number of radio unit combinations that determine the combination of antennas depends on the upper limit number M of antennas that can be macrodiversified, and determines the antenna combination for combinations that are less than or equal to the upper limit number of antennas. For example, when the antenna upper limit number M = 2, the antenna combination pattern is determined in consideration of the combination of two radio units. When the antenna upper limit number M = 3, the antenna combination pattern is determined in consideration of the combination of three radio units. The antenna combination information storage unit 109 has a combination reception power and throughput area, but is empty when determining the antenna combination.

(Macro diversity control)
In macro diversity communication between the wireless terminal device and the wireless unit, the received power of the uplink signal from the wireless terminal device is measured by the received power measuring unit 104, and if there is past throughput information (past performance), the past If there is no past throughput information (past performance) based on the throughput information, the macro diversity is determined based on the received power measurement result. If it is determined that macro diversity is possible, the macro diversity This is achieved by determining the antenna combination to be used and performing transmission control. Details will be described later.

(Received power measurement)
FIG. 4 shows an example of reception power measurement of an uplink signal of a wireless terminal device.

  In FIG. 4, a plurality of radio units R11 to R14 are connected to the radio unit controller G1. The reception power measurement unit 104 of the radio unit control apparatus G1 measures the reception power of the uplink signal A12 transmitted from the radio terminal apparatus MS11 in each radio unit R11 to R14, and receives the reception power information IN11 to 14 from the radio unit control apparatus. Notify G1 antenna selector 110. Since each of the radio units R11 to R14 has a plurality of antennas AN11 to AN14, AN21 to 24, AN31 to 34, and AN41 to 44, the received power is measured for each radio communication antenna of each radio unit. In this figure, an example with four antennas is shown, but the number of antennas depends on the wireless communication system.

(Judgment of macro diversity availability)
FIG. 5 shows an example of the content stored in the received power aggregation information storage unit 105 of the radio unit control apparatus and the macro diversity availability determination (when there is no throughput information (past performance)).

  When the received power information of each of the radio units R11 to R14 is notified from the received power measuring unit 104 in the radio unit controller G1, the antenna selecting unit 110 aggregates the received power information IN11 to IN14 and stores the received power aggregated information storage. Stored in the unit 105. Further, when storing as received power aggregated information, information indicating a corresponding radio unit and information indicating an antenna are stored for each received power information, and sorting is performed according to the magnitude of received power.

  Reception power threshold information R is set in advance in the antenna selection unit 110 of the radio unit controller G1, and whether macro diversity is possible using the reception power aggregation information and the reception power threshold information R aggregated in the reception power aggregation information storage unit 105 Judging.

  5 and 6 show an example of macro diversity availability determination when the received power threshold information R = 50 dB.

  In FIG. 5, the antenna selection unit 110 of the radio unit controller G1 refers to the received power aggregation information in the received power aggregation information storage unit 105, and the received power from the radio terminal device MS11 is larger than the received power threshold information R. Are determined as macro diversity candidate antennas. In the case where there are a plurality of antennas determined as macro diversity candidate antennas, macro diversity availability determination as shown in FIG. 6 is further performed.

  When either the throughput for each candidate antenna (past performance) or the throughput for each combination of antennas in the antenna combination information storage unit 109 (past performance) does not exist, macro diversity is performed. When all of them exist, the received power of each candidate antenna is compared with the combined received power of the antenna combination information storage unit 109, and the received power of each antenna is larger than the combined received power, and the received power of each antenna. When the throughput of the antenna combination information storage unit 109 is large compared to any of the throughputs for the above, macro diversity is performed. Other than that, communication by a single antenna is performed by an antenna having the highest throughput of candidate antennas. If the macro diversity candidate antenna is a single antenna, it is determined that macro diversity is not possible and communication is performed using a single antenna.

(Antenna combination information creation sequence)
FIG. 7 shows an example of a macro diversity communication start sequence.

  When the target terminal (wireless terminal apparatus MS11) is determined, the reception power measurement unit 104 notifies the antenna selection unit 110 of reception power (S702) when the reception power measurement timing (S701) is generated. The antenna selection unit 110 instructs the antenna information creation unit 108 to store received power (S703), refers to received power and throughput (if there is a past record) (S706), and performs macro diversity availability determination (S705). .

  Here, it is determined that macro diversity communication is possible, and macro diversity communication (S707) is performed. An instruction to perform macro diversity communication (S708) is given to the radio units R11 to 1n. The antenna selection unit 110 performs reception power reference (S709) from the reception power measurement unit 104, and instructs the throughput measurement unit 106 to perform measurement with macro diversity (S710). The throughput measurement unit 106 notifies the antenna information creation unit 108 of the throughput measurement result and the reception power, and instructs the combination reception power / throughput area of the antenna combination information storage unit 109 to store the reception power and throughput (S711). Thereafter, the operation is performed for 5 minutes with macro diversity (S712).

  Thereafter, the single antenna communication trial (S713) is entered, and the antenna selection unit 110 instructs the radio units R11 to 1n to perform the single antenna communication trial (S714). The antenna selection unit 110 performs reception power reference (S715) from the reception power measurement unit 104, and instructs the throughput measurement unit 106 to perform measurement using a single antenna (S716). The throughput measurement unit 106 notifies the antenna information creation unit 108 of the throughput measurement result and the reception power, and instructs the combination reception power of the antenna combination information storage unit 109, the reception power in the throughput area, and the throughput storage (S717). . The antenna selection unit 110 determines whether or not the macro diversity throughput is more effective from the throughput of the single antenna (S718). If it is determined that there is no effect, the macro selection communication (S719) is performed, and the macro diversity communication (S707) is performed. ) Performs the same operation. Thereafter, the single antenna communication trial (S720) performs the same operation as the single antenna communication trial (S713). Thereafter, the macro diversity communication and the single antenna communication trial are repeated. Although not shown in FIG. 7, when it is determined that single antenna communication is more effective, single antenna communication (S807) and macro diversity communication trial (S813) in FIG. 8 are repeated. It will be.

  FIG. 8 shows another example of the macro diversity communication start sequence. Note that operations from S801 to S806 in FIG. 8 are the same as those from S701 to S706 in FIG. The difference from the sequence of FIG. 7 is a case where it is determined that single antenna communication is performed in the macro diversity availability determination (S805), and macro diversity communication trial (S813) is performed while performing single antenna communication (S807). And determining whether to change to macro diversity communication by periodically determining the effect of macro diversity (S818).

(Evaluation of macro diversity implementation)
FIG. 9 is a flowchart showing macro diversity implementation determination processing.

  When the target terminal is determined (S901), the antenna selection unit 110 determines whether there is a throughput (past performance) (S902). If there is no throughput (past performance) (S902: NO), it is determined whether macro diversity is possible based on the received power and the combined received power (S907). If macro diversity is possible (S907: YES), the process proceeds to S904. If macro diversity is not possible (S907: NO), the process proceeds to S908.

  When there is a throughput (past performance) (S902: YES), it is determined whether macro diversity is possible (S903) based on the throughput (past performance). If macro diversity is possible (S903: YES), macro diversity communication is performed and throughput is measured (S904). Five minutes later, a single antenna communication is tried and the throughput is measured (S905). It is determined whether the single antenna communication is more effective (S906). If it is determined that the effect is not effective (S906: NO) Continues the macro diversity communication, and after 5 minutes, tries the single antenna communication again, and performs the throughput measurement (S905). When it is determined that there is an effect (S906: YES), communication with a single antenna is performed and throughput measurement is performed (S908). After 5 minutes, macro diversity is tried and throughput is measured (S909), and it is determined whether there is an effect (S910).

  In the above-described embodiment, as an index for determining whether macro diversity is performed or not, other indexes that mean communication efficiency such as an error bit rate and a frequency modulation rate can be used in addition to the throughput. For example, as the signal quality, the error bit rate is measured, and the value obtained by (1-error bit rate) or the modulation rate of the reception frequency with respect to the reference frequency is measured and obtained by (1-maximum modulation rate of the reception frequency). Can be used.

  As described above, according to this embodiment, in order to decide whether to implement or not to perform based on the results of the macro diversity effect, and to determine the effect by periodically performing both macro diversity and single-antenna communication. Therefore, it is possible to determine the exact effect according to the situation and to implement macro diversity. In addition, even if the received power is the same, even if there is a difference between when the macro diversity effect can be expected and when it cannot be expected depending on the arrangement of the radio unit and the terminal, the effect is judged in real time. Implementation / non-implementation of macro diversity can be expected.

  Therefore, according to the present embodiment, it is possible to efficiently improve the communication quality of the terminals near the cell edge by efficiently selecting the macro diversity communication in the mobile communication system.

  Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  BS1, BS2 ... wireless base station device, G1, G2 ... wireless unit control device, R11-R1n, R21-R2n ... wireless unit, MS11-MS1m, MS21-MS2m ... wireless terminal device, GW ... gateway device, NW ... IP network / Public communication network, AN11 to 1n, AN21 to AN2n ... Radio communication antennas 101,201 ... Wireless communication unit, 102 ... Signal distribution unit, 103 ... Signal processing unit, 104 ... Reception power measurement unit, 105 ... Reception power aggregation Information storage unit 106 ... Throughput measurement unit 107 ... Adjacent radio unit information storage unit 108 ... Antenna information creation unit 109 ... Antenna combination information storage unit 110 ... Antenna selection unit

Claims (6)

A plurality of radio units including a plurality of antennas, and a plurality of radio units that perform radio communication with radio terminals by the antennas;
Signal processing means for selectively performing macro diversity communication by a plurality of the radio units and single antenna communication by a single radio unit with the radio terminal;
Received power measuring means for measuring the received power of the uplink signal from the wireless terminal for each antenna;
Signal quality measuring means for measuring signal quality in each of the macro diversity communication and the single antenna communication;
Creation means for creating information representing a combination of antennas used for the macro diversity communication based on information representing the adjacent relationship of the wireless unit and antenna arrangement information of the wireless unit;
Selection means for selecting an antenna combination to be used for the wireless communication based on the measurement result of the received power, the measurement result of the signal quality, and information representing the combination of the antennas;
The selecting means causes the signal processing means to periodically try the other communication while the macro diversity communication or the single antenna communication is being performed, and uses the signal quality measurement means as a result of the signal quality measurement. And switching to the other communication based on the radio base station apparatus.   The signal quality measuring means measures the total number of communication data and the number of normal communication data in the wireless communication, and sets a value obtained by dividing the number of normal communication data by the total number of communication data as the signal quality. The radio base station apparatus according to claim 1, wherein:   2. The radio base station apparatus according to claim 1, wherein the signal quality measurement unit measures an error bit rate in the radio communication and uses the value obtained by (1−error bit rate) as the signal quality.   The signal quality measuring unit measures a modulation rate of a reception frequency with respect to a reference frequency in the wireless communication, and uses the value obtained by (1-maximum modulation rate of the reception frequency) as the signal quality. The radio base station apparatus according to 1. A wireless unit control apparatus that includes a plurality of antennas and controls a plurality of wireless units that perform wireless communication with a wireless terminal using the antennas,
Signal processing means for selectively performing macro diversity communication by a plurality of the radio units and single antenna communication by a single radio unit with the radio terminal;
Received power measuring means for measuring the received power of the uplink signal from the wireless terminal for each antenna;
Signal quality measuring means for measuring signal quality in each of the macro diversity communication and the single antenna communication;
Creation means for creating information representing a combination of antennas used for the macro diversity communication based on information representing the adjacent relationship of the wireless unit and antenna arrangement information of the wireless unit;
Selection means for selecting an antenna combination to be used for the wireless communication based on the measurement result of the received power, the measurement result of the signal quality, and information representing the combination of the antennas;
The selecting means causes the signal processing means to periodically try the other communication while the macro diversity communication or the single antenna communication is being performed, and uses the signal quality measurement means as a result of the signal quality measurement. A radio unit control device that switches to the other communication based on the above. A method comprising: a plurality of antennas, and a radio unit control apparatus that controls a plurality of radio units that perform radio communication with a radio terminal using the antennas,
Selectively performing macro diversity communication by a plurality of the radio units and single antenna communication by a single radio unit with the radio terminal;
Measuring the received power of the uplink signal from the wireless terminal for each antenna;
Measuring signal quality in each of the macro diversity communication and the single antenna communication;
Creating information representing a combination of antennas used for the macro diversity communication based on information representing the adjacency relationship of the wireless unit and antenna arrangement information of the wireless unit;
Selecting an antenna combination to be used for the wireless communication based on the measurement result of the received power, the measurement result of the signal quality, and information representing the combination of the antennas,
In the selection, the other communication is periodically tried while the macro diversity communication or the single antenna communication is performed, and the communication is switched to the other communication based on the measurement result of the signal quality. A wireless communication method.

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