JP4395499B2 - Mobile station, base station, communication system and communication method - Google Patents

Description

  The present invention relates to a mobile station, a base station, a communication system in which a mobile station and a base station communicate with each other, and a communication method using the communication system.

  Conventionally, in W-CDMA (Wideband Code Division Multiple Access), a mobile station receives and transmits signals in a plurality of sectors or cells having the same frequency band in the downlink and uplink and different spreading codes. By performing a handover, continuous communication without instantaneous interruption is performed, and high-quality communication is performed. However, in soft handover in the downlink, interference is increased because a plurality of base stations transmit dedicated physical channels with the same information. Therefore, soft handover in the downlink has less site diversity effect obtained by performing soft handover than in the uplink. Therefore, only one base station (hereinafter referred to as “optimum base station”) having the highest received signal power to interference power ratio or the highest received signal power among base stations performing soft handover is allowed to transmit data. , An SSDT (Site Selection Diversity Transmission Power Control) method for switching the optimum base station at high speed has been proposed (SSDT-Site Selection Diversity Transmission Power Control for CDMA Forward Link (H. Furukawa, K. Hamabe, and A). Ushirokawa: IEEE Journal on selected areas in communications, vol.18, no.8, pp.1546-1554, August 2000).

  On the other hand, taking into account the rapid spread of the Internet in recent years, the diversification of information, the increase in capacity of information, the development of the next generation Internet, etc., the development of a wireless access system that realizes an information transmission rate exceeding 2 Mbps in a mobile communication system Is an urgent need. In particular, in downlink wireless links, it is considered that traffic requiring high speed and large capacity, such as downloading of moving images such as images, files, and videos from a database or website, will increase. Therefore, a high-speed packet transmission technique suitable for such high-speed and large-volume traffic is indispensable.

  Against this background, a method for realizing high-speed packet transmission with a maximum information transmission speed of 2.4 Mbps based on the IS-95 wireless interface has been proposed as "CDMA / HDR: A Bandwidth-Efficient High-Speed Wireless". Data Services for Nomadic Users (P. Bender, P. Black, M. Grob, R. Padovani, N. Shindhushyana, and A. Viterbi: IEEE Communication Magazine, Vol. 38, no. 7, pp. 70-77, July. 2000). Also in the 3rd Generation Partnership Project (3GPP), realization of high-speed packet transmission with a maximum information transmission rate of about 10 Mbps, which is an extension of the W-CDMA wireless interface, is being studied.

  For such high-speed packet transmission, “Symbol Rate and Modulation Level—Controlled Adaptive Modulation / TDMA / TDD system for High—Bit—Rate Wireless Data Transmission (T. Ue, S. Sampei, and N. Morinaga: IEEE Transaction. VT, pp. 1134-1147, Vol. 47, no. 4, Nov. 1988) etc., and other techniques such as adaptive modulation / demodulation and error correction based on adaptive radio link control (link adaptation) such as channel coding. Application is under consideration. Adaptive modulation / demodulation and error correction based on adaptive radio link control means that data modulation multi-value number, spreading factor (SF), multi-code is used according to the propagation environment of each user in order to efficiently perform high-speed data transmission. This is a method of switching the number of multiplexing and the coding rate of error correction. For example, with respect to data modulation, as the propagation environment becomes better, the QPSK (Quadrature Phase Shift Keying) modulation used in current W-CDMA is changed to a more efficient multilevel modulation, 8PSK modulation, 16QAM (Quadrature Amplitude Modulation). By switching to modulation or 64QAM modulation, the maximum throughput (transmission speed) of the communication system can be increased. For high-speed packet transmission, “Automatic-Repeat-Request Error Control Schemes (S. Lin, D. Costello, Jr., and M. Miller: IEEE Communication. Magazine. Vol. 12, no. 12, pp. 5). -17, Dec. 1984) "and the like are also being considered for application of techniques such as automatic repeat request (ARQ).

  In such a high-speed packet transmission, a high-speed packet channel used for transmitting packets at high speed is a shared channel used by a plurality of mobile stations, so the transmission power is a user used for voice transmission and the like. Each is very large compared to an individual physical channel. For this reason, the SSDT method in which only one optimum base station always transmits data is used to reduce interference with other cells and sectors as compared with soft handover in which a plurality of base stations simultaneously transmit data. It is a very effective technology. Therefore, in high-speed packet transmission, the throughput of communication performed by the mobile station at the end of the communication area such as a cell or sector is improved, or the communication area such as cell or sector that can achieve the target value of the communication throughput performed by the mobile station is expanded. In order to increase the so-called cell coverage, application of the SSDT method of switching the optimum base station at high speed is being studied.

  However, in high-speed packet transmission in which a plurality of mobile stations perform packet transmission using a high-speed packet channel that is a shared channel, each base station assigns high-speed packet channels to the plurality of mobile stations. Therefore, the mobile station to which the opportunity of receiving and transmitting data using the high-speed packet channel instantaneously, that is, the opportunity of communication is basically one user or a small number of users.

  Therefore, using the above-described SSDT method, based on the received signal power and the received signal power to interference power ratio, the optimum base station, that is, the optimum communication area such as a cell or sector covered by the base station is selected. However, it is not always possible for a mobile station to perform communication by having a base station allocate a high-speed packet channel to the base station in the communication area and receive an opportunity to receive or transmit a packet, that is, perform communication. . As a result, the throughput of communication performed by mobile stations existing at the edge of the communication area such as cells and sectors is reduced, and the expansion of communication areas such as cells and sectors that can achieve the target throughput of communication performed by the mobile stations So-called cell coverage cannot be expanded.

  In particular, when there is a large amount of traffic in a communication area such as a selected cell or sector, the opportunity of communication given to a mobile station that performs communication in that communication area is greatly limited. That is, the frequency at which the base station gives a communication opportunity (service) to the mobile station decreases, and the throughput of the mobile station that has not been given a communication opportunity decreases. Furthermore, when a plurality of base stations select communication areas for a plurality of mobile stations based on the received signal power at the mobile station, the received signal power to interference power ratio, etc., the control load at the base station becomes large. For this reason, the efficiency of the control performed for the base station to communicate with the mobile station also decreases. As a result, the throughput of communication performed by the mobile station at the end of the communication area decreases, and the cell coverage cannot be expanded.

  Therefore, the present invention increases the communication opportunity that the base station gives to the mobile station, increases the throughput of communication performed by the mobile station at the end of the communication area, and achieves the target value of the throughput of communication performed by the mobile station. The purpose is to expand the possible communication area.

  A mobile station according to the present invention is a mobile station that communicates with a base station, and includes a receiving unit that receives a signal transmitted from the base station, and a traffic amount in a plurality of communication areas in which the receiving unit can receive the signal. On the basis of the above, a selection means for selecting a communication area for communication from a plurality of communication areas and a notification means for notifying the base station of the communication area for communication selected by the selection means are provided.

  Here, the communication area refers to an area where the mobile station can receive a signal transmitted from the base station and can communicate with the base station, that is, a radio area covered by the base station.

  The unit of the communication area includes a cell that is a radio area covered by one base station, a sector obtained by further dividing the cell, and the like. The traffic amount in the communication area refers to the amount of communication being performed in the communication area.

  The amount of traffic is set, for example, between the number of mobile stations communicating with the base station in the communication area and the amount of data transmitted / received between the base station and the mobile station, that is, between the base station and the mobile station. Indicators such as the percentage of channels used to transmit and receive data, the total amount of data transmitted to mobile stations held by the base station, and the number of mobile stations that are the destinations of data held by the base station Can be used.

  According to such a mobile station according to the present invention, the mobile station can recognize a communication area in which the signal can be received by receiving the signal transmitted from the base station by the receiving means.

  Further, the selection means selects a communication area for performing communication from the communication areas based on the traffic volume in the plurality of communication areas. Therefore, the mobile station can select a communication area that is easily given a communication opportunity in consideration of the traffic volume in the communication area as a communication area for communication.

  Further, the notifying means notifies the base station of the communication area for performing the communication selected by the selecting means. Therefore, the base station can control communication with the mobile station using the notified communication area. That is, it is not necessary for the base station to perform control for selecting a communication area in which the mobile station performs communication for a plurality of mobile stations, and the control load in the base station can be distributed to the mobile stations.

  Therefore, it is possible to improve the efficiency of control that is performed for the base station to communicate with the mobile station.

  As a result, the communication opportunity that the base station gives to the mobile station can be increased, that is, the service throughput of the base station can be increased, and the mobile station has an opportunity to perform communication in the communication area. To increase. Also, the control efficiency of the base station is improved.

  Therefore, it is possible to increase the throughput of communication performed by the mobile station existing at the end of the communication area, and it is possible to expand the communication area that can achieve the target value of the throughput of communication performed by the mobile station, that is, so-called cell coverage.

  The receiving means receives a control signal including traffic in a plurality of communication areas transmitted from the base station using a control channel, and the selecting means is based on the traffic included in the control signal received by the receiving means. The communication area for communication can be selected.

  According to this, since the mobile station can use the traffic volume transmitted from the base station using the control channel and the mobile station does not need to obtain the traffic volume, the control load on the mobile station is slightly reduced. Can be dispersed.

  Therefore, while improving the control efficiency of the base station, it is possible to improve the control efficiency such as the selection of the communication area in the mobile station, which can contribute to an increase in the throughput of communication performed by the mobile station.

  Further, the mobile station includes an estimation unit that estimates a traffic amount in a plurality of communication areas based on reception power of a signal received by the reception unit, and the selection unit performs communication based on the traffic amount estimated by the estimation unit. You may make it select the communication area to perform.

  According to this, the estimation means estimates the traffic amount based on the received power of the signal transmitted from the base station, and the selection means determines the communication area for communication based on the traffic amount estimated by the estimation means. You can choose.

  Therefore, on the mobile station side, the traffic amount can be estimated and the communication area can be selected, and the control load on the base station can be further reduced.

  In addition, since the selection means does not need to separately use a control signal or the like for grasping the traffic volume in a plurality of communication areas and does not consume radio resources for control, radio resources can be used for data transmission. it can. As a result, the throughput of communication performed by the mobile station can be further increased.

  Furthermore, it is preferable that the selection means selects a communication area for performing communication based on the reception quality of the signal received by the reception means and the amount of traffic in a plurality of communication areas.

  According to this, the selection means can select a communication area for communication in consideration of not only the traffic amount in the communication area but also the reception quality. Therefore, the mobile station can perform communication in a communication area with good reception quality, and can improve the probability of successful data transmission / reception. Therefore, the throughput of communication performed by the mobile station can be further improved.

  Further, a base station according to the present invention is a base station that communicates with a mobile station, and a transmission unit that transmits a control signal including a traffic amount in a communication area to the mobile station using a control channel, and Control means for controlling the mobile station to perform communication in a communication area in which the mobile station performs communication selected from among a plurality of communication areas based on a traffic amount included in the transmitted control signal. And

  According to such a base station, since the transmission means transmits a control signal including the traffic amount in the communication area to the mobile station, the mobile station performs communication using the traffic amount included in the control signal. A region can be selected.

  Therefore, the mobile station can select a communication area that is easily given a communication opportunity in consideration of the traffic volume in the communication area as a communication area for communication.

  Further, since it is not necessary for the mobile station itself to determine the traffic volume, the control load on the mobile station can be distributed to the base stations only slightly.

  Further, since the control means controls the mobile station to perform communication in a communication area in which the mobile station performs communication selected based on the traffic volume, the base station performs communication with which the mobile station performs communication for a plurality of mobile stations. There is no need to perform control for selecting a region, and the control load in the base station can be distributed to the mobile stations.

  Therefore, it is possible to improve the efficiency of control that is performed for the base station to communicate with the mobile station.

  As a result, the communication opportunity that the base station gives to the mobile station can be increased, so-called service throughput of the base station can be increased, and the opportunity for the mobile station to perform communication in the communication area increases. Also, the control efficiency of the base station and mobile station is improved.

  Therefore, it is possible to increase the throughput of communication performed by the mobile station existing at the end of the communication area, and it is possible to expand the communication area that can achieve the target value of the throughput of communication performed by the mobile station, that is, so-called cell coverage.

  In addition, another mobile station according to the present invention is a mobile station that communicates with a base station, and includes a reception unit that receives a signal transmitted from the base station, and a reception quality of a signal received by the reception unit, A calculating means for calculating a ratio between an average value of the reception quality in the short period and an average value of the reception quality in the long period; an average value of the reception quality in the short period and an average value of the reception quality in the long period calculated by the calculating means; And a selection means for selecting a communication area for performing communication from a plurality of communication areas based on the ratio.

  Further, another base station according to the present invention is a base station that communicates with a mobile station, and the average reception quality in a short cycle is a reception quality of a signal received by the mobile station from a base station. Based on the ratio of the average value of the reception quality in the short period and the average value of the reception quality in the long period calculated by the calculation means for calculating the ratio of the value and the average value of the reception quality in the long period Selecting means for selecting a communication area in which the mobile station performs communication from among the communication areas.

  According to such a mobile station or base station, the calculation means uses the average value of the reception quality in the short cycle and the reception quality in the long cycle as the reception quality of the signal received by the mobile station from the signal transmitted from the base station. A ratio with the average value is calculated, and the selection means selects a communication area using the ratio. The base station selects which mobile station to transmit data to and from which mobile station to receive data, and allocates a channel to the selected mobile station. The base station selects a mobile station to which a channel is assigned on the basis of the ratio between the average value of received quality in a short period and the average value of received quality in a long period.

  For this reason, the selection means selects a communication area for communication using the same criteria as the channel assignment criteria, so that a communication area that is easy to be assigned a channel, that is, a communication area that is easily given an opportunity for communication. Can be selected as a communication area for communication.

  As a result, the communication opportunity that the base station gives to the mobile station can be increased, that is, the service throughput of the base station can be increased, and the mobile station has an opportunity to perform communication in the communication area. To increase.

  Therefore, it is possible to increase the throughput of communication performed by the mobile station existing at the end of the communication area, and it is possible to expand the communication area that can achieve the target value of the throughput of communication performed by the mobile station, that is, so-called cell coverage.

  When the mobile station calculates the ratio between the average value of the reception quality in the short cycle and the average value of the reception quality in the long cycle and selects the communication area for communication, the control load of the base station is distributed. In addition, since the control efficiency of the base station can be improved, the throughput of communication performed by the mobile station can be further increased.

  As described above, according to the present invention, the communication opportunity that the base station gives to the mobile station is increased, the throughput of communication performed by the mobile station at the end of the communication area is increased, and the communication performed by the mobile station is increased. The communication area in which the target value of throughput can be achieved can be expanded.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration of a communication system 1 according to the embodiment of the present invention. As shown in FIG. 1, the communication system 1 includes a plurality of base stations 2 a, 2 b, 2 c and a plurality of mobile stations 3. The base stations 2a to 2c and the mobile station 3 perform data transmission / reception and communication. The mobile station 3 includes base stations 2a to 2c in wireless areas such as cells and sectors covered by the base stations 2a to 2c, that is, in a communication area in which the mobile station 3 can receive signals transmitted from the base stations 2a to 2c. And send and receive data to communicate.

  FIG. 2 is a block diagram showing a configuration of base stations 2a to 2c according to the embodiment of the present invention. As illustrated in FIG. 2, the base stations 2 a to 2 c include an antenna 21, a radio unit 22, a baseband processing unit 23, a buffer 24, a network interface unit 25, and a control unit 26. The base station 2 communicates with the mobile station 3 by transmitting packets at high speed. The antenna 21 transmits the packet and control signal transmitted from the radio unit 22 to the mobile station 3, and transmits the packet and control signal received from the mobile station 3 to the radio unit 22. The radio unit 22 transmits the packet or control signal transmitted from the baseband processing unit 23 to the mobile station 3 via the antenna 21 or the packet or control signal transmitted from the mobile station 3 via the antenna 21. Or transmitted to the baseband processing unit 23.

  The radio unit 22 also functions as a transmission unit that transmits a control signal including the traffic volume in the communication area covered by the base stations 2a to 2c to the mobile station 3 using the control channel. Here, the radio unit 22 transmits control information to the mobile station 3 using a downlink control channel that transmits control signals including various control information from the base stations 2 a to 2 c to the mobile station 3. ing. The downlink control channel includes a downlink common control channel, a downlink shared control channel, a common pilot channel, and the like. In addition, the radio unit 22 transmits data to the mobile station 3 using a downlink high-speed packet channel that transmits packets including data from the base stations 2 a to 2 c to the mobile station 3.

  The downlink common control channel is a channel that transmits a control signal of common control information to each mobile station 3. Therefore, the downlink common control channel is the same for all mobile stations 3 and is effective for transmitting the traffic amount in the communication area that does not change for each mobile station 3. Therefore, it is preferable that the radio | wireless part 22 transmits the traffic amount in the communication area which each base station 2a-2c covers itself using a downlink common control channel.

  The downlink shared control channel is a channel that transmits a control signal shared and used by a plurality of mobile stations 3. Therefore, each mobile station 3 can acquire control information transmitted through the downlink shared control channel. Therefore, the downlink shared control channel is effective for transmitting the traffic amount in the communication area required by all the mobile stations 3. Therefore, the radio unit 22 preferably transmits the traffic amount in the communication area covered by each of the base stations 2a to 2c using the downlink shared control channel. The radio unit 22 transmits the traffic volume in the communication area to the mobile station 3 using a control channel such as a downlink common control channel or a downlink shared control channel according to the control of the control unit 26.

  The common pilot channel is a dedicated channel for transmitting a common pilot signal to each mobile station 3. The pilot signal is a known signal in the mobile station 3 necessary for the mobile station 3 to perform channel estimation. The high-speed packet channel is a downlink shared channel that is shared and used by the mobile stations 3 for transmitting packets including data from the base stations 2 a to 2 c to the mobile station 3. The radio unit 22 transmits a packet including data to the mobile station 3 using the high-speed packet channel according to the channel assignment of the control unit 26.

  Note that when the wireless unit 22 transmits a packet including data using a high-speed packet channel, there is a case where directional beam transmission is performed in which the packet is transmitted in a predetermined direction. In that case, two types of common pilot channels, a first common pilot channel and a second common pilot channel, are used as common pilot channels. The first common pilot channel is used to transmit a pilot signal, but is transmitted with an omnidirectional beam. The second common pilot channel is used to transmit a pilot signal, but is transmitted with a directional beam.

  The radio unit 22 also functions as a receiving unit that receives a control signal transmitted from the mobile station 3 via the uplink channel. The control signal transmitted from the mobile station 3 includes data indicating a communication area in which the mobile station 3 selected by the mobile station 3 performs communication. The data indicating the communication area includes identification data specific to the base stations 2a to 2c that can identify the base stations 2a to 2c, such as addresses and base station IDs of the base stations 2a to 2c covering the communication area, There are identification data unique to a cell or sector, which is a communication area that can identify the communication area, such as an ID and a sector ID.

  Here, the radio unit 22 performs control from the mobile station 3 using an uplink channel in the uplink direction in which a control signal including control information and a packet including data are transmitted from the mobile station 3 to the base stations 2a to 2c. Receive packets containing information and data. The uplink channel includes an individual channel for each mobile station 3 and a shared channel shared by a plurality of mobile stations 3. Further, the individual channels include an individual physical data channel and an individual physical control channel. The shared channel and the dedicated physical data channel are used for transmitting packets including control signals and data, and the dedicated physical control channel is used for transmitting control signals.

  The baseband processing unit 23 performs signal processing on the packet or control signal transmitted to the mobile station 3 and transmits the signal to the radio unit 22. For example, the baseband processing unit 23 performs signal processing such as error correction coding, data modulation, and spread modulation on a packet or control signal to be transmitted. The baseband processing unit 23 acquires a packet to be transmitted from the buffer 24. The baseband processing unit 23 receives a control signal to be transmitted from the control unit 26.

  The baseband processing unit 23 performs signal processing on the packet and control signal received by the wireless unit 22 from the mobile station 3. For example, the baseband processing unit 23 performs signal processing such as error correction decoding, data demodulation, and despreading on the received data packet and control signal. The baseband processing unit 23 stores the received packet in the buffer 24. In addition, the baseband processing unit 23 transmits the received control signal to the control unit 26.

  The buffer 24 holds packets transmitted to the mobile station 3 and packets transmitted from the mobile station 3. The network interface unit 25 acquires a packet transmitted from the mobile station 3 from the buffer 24 and transmits the packet via the network 4. Further, the network interface unit 25 stores, in the buffer 24, a packet to be transmitted to the mobile station 3 acquired via the network 4.

  The control unit 26 controls the wireless unit 22, the baseband processing unit 23, and the network interface unit 25. The control unit 26 controls the radio unit 22 to cause the radio unit 22 to transmit the traffic volume in the communication area using a control channel such as a downlink common control channel or a downlink shared control channel. Specifically, the control unit 26 generates a control signal including the traffic volume and transmits the control signal to the baseband processing unit 23. The radio unit 22 acquires the control signal generated by the control unit 26 via the baseband processing unit 23, and transmits the control signal using a control channel such as a downlink common control channel or a downlink shared control channel.

  As the traffic volume, the control unit 26, for example, the number of mobile stations 3 communicating with the base stations 2a to 2c in the communication area or the data volume transmitted and received between the base stations 2a to 2c and the mobile station 3 That is, the usage rate of the high-speed packet channel, the total number of packets transmitted to the mobile station 3 held in the buffer 24 by the base stations 2a to 2c, and the number of packets held in the buffer 24 by the base stations 2a to 2c A control signal including the number of mobile stations 3 serving as transmission destinations is generated.

  When the number of mobile stations 3 communicating with the base stations 2a to 2c in the communication area or the usage rate of the high-speed packet channel is used as the traffic volume, the number of mobile stations 3 communicating is determined by the radio unit 22 Is the number of mobile stations 3 connected, and the usage rate of the high-speed packet channel is known in the radio unit 22 because it is the usage rate of the high-speed packet channel transmitted by the radio unit 22. Therefore, the radio unit 22 transmits to the control unit 26 the number of mobile stations 3 to which the radio unit 22 is connected and the usage rate of the high-speed packet channel transmitted by the radio unit 22. Then, the control unit 26 generates a control signal including the number of mobile stations 3 transmitted from the radio unit 22 and the usage rate of the high-speed packet channel, and transmits the control signal to the baseband processing unit 23.

  Further, as the traffic volume, the total number of packets transmitted to the mobile station 3 held by the base stations 2a to 2c in the buffer 24, and the movement that becomes the transmission destination of the packets held by the base stations 2a to 2c in the buffer 24 When the number of stations 3 is used, the control unit 26 refers to the buffer 24 and acquires the total number of packets and the number of mobile stations 3 that are the transmission destinations of the packets. Then, the control unit 26 generates a control signal including the acquired total number of packets and the number of mobile stations 3 that are the transmission destinations of the packets, and transmits the control signal to the baseband processing unit 23.

  The control unit 26 also functions as a control unit that controls the mobile station 3 to transmit and receive data and perform communication in the communication area selected by the mobile station 3.

  The control unit 26 receives the control signal from the baseband processing unit 23, thereby acquiring the control signal received by the wireless unit 22 from the mobile station 3 via the baseband processing unit 23. The control unit 26 acquires, from the control signal, data indicating a communication area in which communication selected by the mobile station 3 included in the control signal is performed. When the data indicating the communication area indicates the communication area covered by the base stations 2a to 2c, that is, the data indicating the communication area covers the communication area. Baseband processing so that if the address of 2a to 2c, base station ID, cell ID or sector ID, the packet to mobile station 3 is transmitted to the mobile station 3 via the high-speed packet channel The unit 23 and the radio unit 22 are controlled.

  Specifically, the control unit 26 assigns a high-speed packet channel for transmission of packets to the mobile station 3. The control unit 26 transmits the assignment result of the high-speed packet channel to the radio unit 22, and instructs the radio unit 22 to transmit a packet according to the channel assignment. In addition, the control unit 26 instructs the baseband processing unit 23 to acquire the packet for the mobile station 3 from the buffer 24, perform signal processing, and transmit the packet to the radio unit 22. Thus, the baseband processing unit 23 processes the packet for the mobile station 3 and transmits the packet to the radio unit 21, and the radio unit 22 uses the high-speed packet channel according to the channel assignment instructed by the control unit 26. Send the packet to the mobile station. The control unit 26 also assigns an uplink channel for transmission of packets from the mobile station 3 to the base stations 2a to 2c.

  On the other hand, when the data indicating the communication area does not indicate the communication area covered by the base stations 2a to 2c, the control unit 26 determines not to transmit the packet to the mobile station 3, and No particular processing is performed on the band processing unit 23 and the radio unit 22.

  FIG. 3 is a block diagram showing a configuration of mobile station 3 according to the embodiment of the present invention.

As shown in FIG. 3, the mobile station 3 includes an antenna 31, a radio unit 32, a baseband processing unit 33, an input unit 34, an output unit 35, a card interface unit 36, a buffer 37, and a control unit. 38. The mobile station 3 communicates with the base stations 2a to 2c by transmitting and receiving packets.

  The antenna 31 transmits packets and control signals transmitted from the radio unit 32 to the base stations 2a to 2c, and transmits packets and control signals received from the base stations 2a to 2c to the radio unit 32. The radio unit 32 transmits the packet and control signal transmitted from the baseband processing unit 33 to the base stations 2a to 2c via the antenna 31.

  The radio unit 32 functions as a notification unit that notifies the base stations 2a to 2c of a communication area in which communication selected by the mobile station 3 is performed. Specifically, the radio unit 32 uses the uplink channel such as the above-described dedicated channel or shared channel to indicate data indicating a communication area in which communication is performed by the mobile station 3, for example, the addresses of the base stations 2a to 2c, A control signal including the base station ID, cell ID, sector ID, and the like is transmitted to the base stations 2a to 2c for notification. The radio unit 32 multiplexes a control signal including data indicating a communication area with a packet including other control signals and data, and transmits the multiplexed signal. As a control signal multiplexing method, time multiplexing, code multiplexing, or the like can be used. Under the control of the control unit 38, the radio unit 32 notifies a control signal including data indicating the selected communication area to the base stations 2a to 2c using the uplink channel. The radio unit 32 transmits a packet including data to the base stations 2a to 2c using a shared channel or a dedicated physical data channel.

  The radio unit 32 is a receiving unit that receives signals including packets and control signals transmitted from the base stations 2a to 2c via the antenna 31, and receives signals and control signals including the received packets. And transmitted to the baseband processing unit 33. The radio unit 22 receives a control signal including the traffic volume via the downlink common control channel and the downlink shared control channel. The radio unit 32 receives a pilot signal transmitted from the base stations 2a to 2c using the common pilot channel and a packet including data transmitted using the high-speed packet channel. Further, the radio unit 32 measures received power received through a channel such as a control channel or a high-speed packet channel transmitted from the base stations 2 a to 2 c and transmits the received power to the control unit 38.

  The baseband processing unit 33 acquires data to be transmitted to the base stations 2a to 2c from the input unit 34 and the card interface unit 36, and generates a packet including the data. In addition, the baseband processing unit 33 performs signal processing on the generated packet and control signal and transmits them to the radio unit 32. For example, the baseband processing unit 33 performs signal processing such as error correction coding, data modulation, and spread modulation on a packet or control signal to be transmitted. The baseband processing unit 33 stores the generated packet in the buffer 37 and acquires the packet from the buffer 37 when transmitting the packet. The baseband processing unit 33 receives a control signal to be transmitted from the control unit 38.

  The baseband processing unit 33 performs signal processing on the packets and control signals received by the radio unit 32 from the base stations 2a to 2c. For example, the baseband processing unit 33 performs signal processing such as error correction decoding, data demodulation, and despreading on the received data packet and control signal. The baseband processing unit 33 outputs data included in the received packet to the output unit 35. The baseband processing unit 33 transmits data included in the received packet to the card interface unit 36. Further, the baseband processing unit 33 transmits the received control signal to the control unit 38.

  The input unit 34 inputs data transmitted from the mobile station 3 to the baseband processing unit 33. The output unit 35 outputs data received by the mobile station from the baseband processing unit 33. The card interface unit 36 acquires data transmitted from the mobile station from an external device such as a personal computer via a dedicated data transmission card such as a PC card. The card interface unit 36 transmits the acquired data to the baseband processing unit 33. The card interface unit 36 transmits data received by the mobile station from the baseband processing unit 33. The card interface unit 36 transmits data received by the mobile station to an external device such as a personal computer via a data transmission dedicated card. The buffer 37 holds a packet to be transmitted to the base stations 2a to 2c.

  The control unit 38 controls the radio unit 32 and the baseband processing unit 33. The control unit 38 functions as a selection unit that selects a communication area in which the mobile station 3 performs communication. The control unit 38 can select a communication area for performing communication based on the traffic volume in the plurality of communication areas. For example, the control unit 38 selects a communication area with the smallest traffic volume as a communication area for communication.

  For example, the control unit 38 can grasp the traffic amount in each communication area by the following method. When the control unit 38 receives the control signal from the baseband processing unit 33, the radio unit 32 transmits the downlink common control channel and the downlink shared control channel from the base stations 2 a to 2 c via the baseband processing unit 33. The control signal received through the communication is acquired. The control unit 38 can grasp the traffic amount by acquiring the traffic amount in each communication area included in the control signal from the control signal. For example, the control unit 38 holds in the buffer 24 the number of mobile stations 3 communicating with the base stations 2a to 2c in each communication area, the usage rate of the high-speed packet channel, and the base stations 2a to 2c. The total number of packets to be transmitted to the mobile station 3, the number of mobile stations 3 that are the transmission destinations of the packets held in the buffer 24 by the base stations 2a to 2c, and the like are acquired as the traffic amount in the communication area.

  The control unit 38 also functions as an estimation unit that estimates the traffic amount in the communication area based on the received power at which the radio unit 32 receives the signals transmitted from the base stations 2a to 2c. FIG. 4 is a graph showing received power of a signal received by mobile station 3 according to the embodiment of the present invention. As described above, the base stations 2a to 2c transmit a high-speed packet channel for transmitting a packet including data and a plurality of control channels for transmitting a control signal including control information. Here, the base stations 2a and 2b will be described as an example. FIG. 4A shows the received power when the radio unit 32 receives the channel transmitted from the base station 2a, and FIG. 4B shows the reception when the radio unit 32 receives the channel transmitted from the base station 2b. Indicates power. In FIG. 4, the vertical axis represents the received power received by the mobile station 2, and the horizontal axis represents time.

  The radio units 22 of the base stations 2a and 2b transmit the high-speed packet channel with very large transmission power. The radio unit 22 transmits the control channel with a small transmission power. Therefore, when there is no packet to be transmitted at the base station 2a, 2b at a certain timing, that is, when the traffic volume in the communication area covered by the base station 2a, 2b is small, the radio unit 22 sends a high-speed packet channel. Is not sent. Therefore, since the radio unit 32 of the mobile station 3 receives only the control channel transmitted with a small transmission power, the reception power of the channel received by the mobile station 3 is only the reception power 10 received by the control channel, which is small. Become.

  On the other hand, when there is a packet to be transmitted at the base station 2a, 2b at a certain timing, that is, when the traffic volume in the communication area covered by the base station 2a, 2b is large, the radio unit 22 sends a high-speed packet channel. Is sent.

  Therefore, the radio unit 32 of the mobile station 3 receives the control channel transmitted with a small transmission power and the high-speed packet channel transmitted with a large transmission power, so that the reception power of the channel received by the mobile station 3 is controlled. The sum of the received power 10 received for the channel and the received power 9 received for the high-speed packet channel is very large.

  Therefore, the control unit 38 can acquire the received power received from the radio unit 32 and estimate the packet amount in the communication area using the received power. Specifically, when the received power is low, the control unit 38 estimates that the traffic volume in the communication area is small because the high-speed packet channel is not transmitted.

  On the other hand, when the received power is large, the control unit 38 estimates that the traffic volume in the communication area is large because the high-speed packet channel is transmitted.

  Alternatively, the control unit 38 calculates the ratio between the received power received from the common pilot channel included in the received power 10 received from the control channel and the received power received from other channels. The ratio between the large received power 9 that received the high-speed packet channel and the small received power that received the pilot channel should be large. Therefore, the control unit 38 includes a high-speed packet channel in the other channels other than the pilot channel when the ratio between the received power received by the common pilot channel and the received power received by other channels is small. Therefore, it can be estimated that the traffic volume in the communication area is small. On the other hand, when the ratio between the received power received by the common pilot channel and the received power received by other channels is large, the control unit 38 includes a high-speed packet channel in the other channels other than the pilot channel. Therefore, it can be estimated that the traffic volume in the communication area is large.

  In the case of FIG. 4, at timings 5 and 7, the received power at which the mobile station 3 receives the channel from the base station 2 a is the received power 10 at which the control channel is received and the received power 9 at which the high-speed packet channel is received. It becomes the sum and becomes very large. In addition, the ratio of the received power received by the common pilot channel included in the received power 10 received by the control channel and the received power received by other channels including the received power 9 received by the high-speed packet channel is also increased. Therefore, the control unit 38 can estimate that the traffic volume of the communication area covered by the base station 2a is large. On the other hand, at timings 5 and 7, the received power at which the mobile station 3 receives the channel from the base station 2b is only the received power 10 at which the control channel is received, and the power is reduced. Further, the ratio of the received power received by the common pilot channel included in the received power 10 received by the control channel and the received power received by other channels included in the received power 10 received by the control channel is also reduced. Therefore, the control unit 38 can estimate that the traffic volume of the communication area covered by the base station 2b is small. Therefore, at the timings 5 and 7, the control unit 38 can select the communication area of the base station 2b with the estimated small traffic volume as the communication area for communication.

  Similarly, at timings 6 and 8, on the contrary, the control unit 38 can estimate that the traffic volume of the communication area covered by the base station 2a is small, and the control unit 38 can estimate the base station 2a with a small estimated traffic volume. Can be selected as a communication area for performing communication.

  In addition to the traffic volume in the communication area, the control unit 38 can select the communication area in which communication is performed in consideration of the reception quality of the signal received by the wireless unit 32. For example, the control unit 38 obtains the reception quality of the common pilot channel received by the radio unit 32. Specifically, the control unit 38 acquires the received power received from the radio unit 32 from the common pilot channel, and based on the received power, the received signal power of the pilot signal, the received signal power of the pilot signal, and the interference Received quality such as a ratio of received signal power to interference wave power, which is a ratio with wave power, is obtained. The required reception quality may be an instantaneous received signal power or a received signal power to interference wave power ratio, or an average received signal power or a received signal power to interference wave power ratio.

  The control unit 38 holds a predetermined threshold value of the reception quality range from the best reception quality. The control unit 38 selects a communication area having a reception quality within a predetermined threshold value as a communication area candidate for communication from the communication area having the best received quality. The control unit 38 selects a communication area having the smallest traffic volume in the communication area as a communication area for communication from the selected communication area candidates.

  Or the control part 38 may hold | maintain the threshold value of the range of the traffic volume from the smallest traffic volume defined beforehand. In this case, the control unit 38 selects a communication area having a traffic volume within a predetermined threshold from communication areas having the smallest traffic volume as a candidate communication area for communication. The control unit 38 selects a communication area having the best reception quality in the communication area as a communication area for communication from the selected communication area candidates.

  As described above, when the radio unit 22 of the base stations 2a to 2c transmits a packet including data using the high-speed packet channel, the directional beam transmission is performed as a common pilot channel. Two types of common pilot channels are used, one common pilot channel and the second common pilot channel. The first common pilot channel is transmitted with an omnidirectional beam as described above. For this reason, the reception quality obtained using the first common pilot channel does not match the reception quality of the high-speed packet channel that performs directional beam transmission. Therefore, the reception quality obtained using the first common pilot channel is not preferable as the reception quality used for selecting a communication area in which communication is performed.

  On the other hand, the reception quality obtained using the second common pilot channel transmitted by the directional beam matches the reception quality of the high-speed packet channel that performs directional beam transmission. Therefore, it is preferable that the control unit 38 selects a communication area in which communication is performed using the reception quality obtained using the second common pilot channel. According to this, it is possible to select a communication region in which communication is performed based on reception quality in consideration that the high-speed packet channel is transmitted in a directional beam.

  As described above, the control unit 26 of the base stations 2a to 2c performs channel assignment for transmission of packets from the base stations 2a to 2c to the mobile station 3 and transmission of packets from the mobile station 3 to the base stations 2a to 2c. . As a channel allocation method, a channel allocation algorithm is selected in which the mobile station 3 having the largest ratio between the average value of the reception quality of the mobile station 3 in a short cycle and the average value of the reception quality of the mobile station 3 in a long cycle is selected. There is a method of performing channel assignment using This channel allocation method is called Proportional Fairness scheduling, “Data Throughput of CDMA—HDR a High Efficiency—High Data Rate Personal Communication Wireless System (A. Jalali, R. Padovani, R. Pankaj: Proc. Of IEEE VTC2000—Spring, pp. 1854-1858, May 2000).

  When the control unit 26 of the base stations 2a to 2c performs Proportional Fairness scheduling using the above-described channel allocation algorithm as a channel allocation method, the control unit 38 determines the reception quality in the short cycle of the signal received by the radio unit 32. A communication area in which communication is performed may be selected based on a ratio between the average value and the average value of reception quality in a long cycle. In this case, the control unit 38 also functions as a calculation unit that calculates the ratio between the average value of the reception quality in the short cycle and the average value of the reception quality in the long cycle as the reception quality of the signal received by the radio unit 32. .

  For example, as the reception quality of the common pilot channel received by the radio unit 32, the control unit 38 calculates a ratio between the average value of the reception quality in the short cycle and the average value of the reception quality in the long cycle. Specifically, the control unit 38 acquires the received power received from the radio unit 32 from the common pilot channel, and based on the received power, the received signal power of the pilot signal, the received signal power of the pilot signal, and the interference Received quality such as a ratio of received signal power to interference wave power, which is a ratio with wave power, is obtained. Based on the obtained reception quality, the control unit 38 calculates an average value of the reception quality in a short cycle (short cycle) and an average value of the reception quality in a long cycle (long cycle), and calculates a ratio between the two. . Then, the control unit 38 selects a communication area having the largest ratio between the calculated average value of the reception quality in the short cycle and the average value of the reception quality in the long cycle as the communication area for communication.

  As described above, when the radio unit 22 of the base stations 2a to 2c transmits a packet including data using a high-speed packet channel, the same as the high-speed packet channel is performed. Using the second common pilot channel transmitted by the directional beam that transmits the packet in the direction, the average value of the reception quality in the short period and the average value of the reception quality in the long period are calculated, and the ratio between the two is calculated. Try to calculate. According to this, it is possible to select a communication region in which communication is performed based on reception quality in consideration that the high-speed packet channel is transmitted in a directional beam.

  When the control unit 38 selects a communication area for communication based on the ratio between the average value of the reception quality in the short cycle of the signal received by the radio unit 32 and the average value of the reception quality in the long cycle. In addition, it is possible to select a communication area for communication in consideration of the traffic volume in the communication area. For example, the control unit 38 holds a threshold value in the range of the ratio value from the value having the largest value of the ratio between the average value of the reception quality in the short cycle of the signal and the average value of the reception quality in the long cycle. Keep it. The control unit 38 selects a communication area having a ratio value within a predetermined threshold value as a communication area candidate for communication from the communication areas having the largest obtained ratio value. The control unit 38 selects a communication area having the smallest traffic volume in the communication area as a communication area for communication from the selected communication area candidates.

  Or the control part 38 may hold | maintain the threshold value of the range of the traffic volume from the smallest traffic volume defined beforehand. In this case, the control unit 38 selects a communication area having a traffic volume within a predetermined threshold from communication areas having the smallest traffic volume as a candidate communication area for communication. The control unit 38 performs communication with a communication area in which the ratio of the average value of the reception quality in the short cycle of the signal and the average value of the reception quality in the long cycle is the largest among the selected communication area candidates. Select as.

  The control unit 38 generates a control signal including data indicating a communication area in which the selected communication is performed. The control unit 38 controls the radio unit 32 to cause the radio unit 32 to transmit a control signal including data indicating a communication area in which the selected communication is performed using an uplink channel such as a common channel or an individual channel. Specifically, the control unit 38 generates a control signal including data indicating the selected communication area and transmits the control signal to the baseband processing unit 33.

  The radio unit 32 obtains the control signal generated by the control unit 38 via the baseband processing unit 33, multiplexes the control signal in an uplink channel such as a common channel or an individual channel, and performs base stations 2a to 2c. To send to.

  Next, a communication method performed using such a communication system 1 will be described. Hereinafter, in FIG. 5 to FIG. 11, the base station 2 c is not shown, but the base station 2 c performs the same operation as the base stations 2 a and 2 b. 5 to 11, an example in which the unit of the communication area is a cell will be described. FIG. 5 shows a communication method when the mobile station 3 selects a communication area for communication based on the traffic volume in the communication area included in the control signal transmitted from the base stations 2a to 2c using the control channel. It is a flowchart which shows a procedure. First, the radio unit 22 of the base stations 2a to 2c transmits, to the mobile station 3, a control signal including the traffic volume of the cells covered by the base stations 2a to 2c using the downlink common control channel and the downlink shared control channel. (S101).

  The radio unit 32 of the mobile station 3 receives the control signal including the traffic amount transmitted from each of the base stations 2a to 2c using the downlink common control channel and the downlink shared control channel (S102). The control unit 38 of the mobile station 3 acquires the control signal received by the radio unit 32 via the baseband processing unit 33, and acquires the traffic amount in each cell from the control signal. And the control part 38 selects the cell with the smallest traffic amount as a cell which communicates. Here, since the unit of the communication area is a cell, the base stations 2a to 2c that cover the selected cell are selected (S103). The control unit 38 of the mobile station 3 generates a control signal including the identification data of the selected base stations 2a to 2c, and the radio unit 32 multiplexes the control signal in the uplink channel to each base station 2a to 2c. Transmit (S104).

  In each of the base stations 2a to 2c, the radio unit 22 receives the control signal including the identification data of the base stations 2a to 2c selected by the mobile station 3 transmitted from the mobile station 3 using the uplink channel, and performs baseband processing. The unit 23 performs data demodulation processing (S105). The control unit 26 of each of the base stations 2a to 2c determines whether or not the identification data of the base stations 2a to 2c included in the control signal indicates the base station itself (self base station). That is, it is determined whether the cell covered by the base stations 2a to 2c is indicated (S106).

  In step (S106), the control unit 26 of each of the base stations 2a to 2c determines to transmit a packet when the identification data of the base stations 2a to 2c included in the control signal indicates the own base station, The high-speed packet channel is assigned to the transmission of the packet to the mobile station 3, and the wireless unit 22 transmits the packet (S107). On the other hand, in step (S106), the control unit 26 of each of the base stations 2a to 2c must transmit a packet when the identification data of the base stations 2a to 2c included in the control signal does not indicate the own base station. Determine (S108). In this way, packets are transmitted only from the base stations 2a to 2c covering the cell selected from the mobile station 3.

  FIG. 6 shows a communication method in which the mobile station 3 estimates a traffic amount in the communication area based on the received power received from the signals transmitted from the base stations 2a to 2c and selects a communication area in which communication is performed. It is a flowchart which shows the procedure of. First, the radio unit 22 of the base stations 2a to 2c transmits a channel such as a downlink control channel or a high-speed packet channel to the mobile station 3 (S201).

  The radio unit 32 of the mobile station 3 measures received power received from the channels from the base stations 2 a to 2 c and transmits the received power to the control unit 38. Alternatively, the control unit 38 calculates the ratio between the received power received from the common pilot channel and the received power received from other channels from the received power transmitted from the radio unit 32 (S202). The control unit 38 estimates a cell having a small received power, a cell having a small ratio between the received power received by the common pilot channel and the received power received by other channels, and the traffic amount of the cell is small, Select as a cell to communicate. Here, since the unit of the communication area is a cell, the base stations 2a to 2c that cover the selected cell are selected (S203). Hereinafter, Step (S204) to Step (S208) are substantially the same as Step (S104) to Step (S108). Therefore, description is abbreviate | omitted here.

  FIG. 7 is a flowchart illustrating a procedure of a communication method when the mobile station 3 selects a communication area for communication based on the traffic amount and signal reception quality in the communication area. First, the radio unit 22 of the base stations 2a to 2c transmits, to the mobile station 3, a control signal including the traffic volume of the cells covered by the base stations 2a to 2c using the downlink common control channel and the downlink shared control channel. (S301). The radio unit 22 of the base stations 2a to 2c transmits a pilot signal to the mobile station 3 using the common pilot channel (S302).

  The radio unit 32 of the mobile station 3 receives the common pilot channel from each of the base stations 2a to 2c, measures the received power of the received common pilot channel, and transmits it to the control unit 38. The control unit 38 obtains reception quality such as the reception signal power of the pilot signal and the reception signal power to interference wave power ratio in the cells covered by the base stations 2a to 2c (S303). The control unit 38 communicates the base stations 2a to 2c that cover cells having reception quality within a predetermined threshold from the base stations 2a to 2c that cover the cell having the best received quality. It selects as a candidate of base station 2a-2c which covers the cell to perform (S304). The control unit 38 selects a cell having the smallest traffic amount included in the control signal transmitted in step (S301) from the selected candidates for the base stations 2a to 2c as a cell for communication. Here, since the unit of the communication area is a cell, the base stations 2a to 2c that cover the selected cell are selected (S305). Hereinafter, Step (S306) to Step (S310) are substantially the same as Step (S104) to Step (S108). Therefore, description is abbreviate | omitted here.

  FIG. 8 shows a communication method when the mobile station 3 selects a communication area for communication based on the traffic volume and signal reception quality in the communication area when the base stations 2a to 2c transmit using directional beams. It is a flowchart which shows the procedure of. First, the radio unit 22 of the base stations 2a to 2c transmits a control signal including the traffic volume of the cell to the mobile station 3 (S401). The radio unit 22 of the base stations 2a to 2c transmits a pilot signal to the mobile station 3 using the first common pilot channel and the second common pilot channel (S402).

  The radio unit 32 of the mobile station 3 receives the first common pilot channel and the second common pilot channel from the base stations 2a to 2c. The radio unit 32 measures the received power of the second common pilot channel transmitted by the directional beam and transmits it to the control unit 38. The control unit 38 obtains reception quality such as the reception signal power of the pilot signal transmitted through the second common pilot channel in the cell covered by each of the base stations 2a to 2c, and the reception signal power to interference power ratio (S403). . The control unit 38 includes base stations that cover cells having reception quality within a predetermined threshold from the base stations 2a to 2c that cover the cells having the best reception quality obtained using the second common pilot channel. The stations 2a to 2c are selected as candidates for the base stations 2a to 2c covering the cell to be communicated (S404). Hereinafter, step (S405) to step (410) are substantially the same as step (S305) to step (S310). Therefore, description is abbreviate | omitted here.

  FIG. 9 is a flowchart illustrating a communication method procedure when the base stations 2a to 2c perform Proportional Fairness scheduling using a predetermined channel allocation algorithm. First, the radio units of the base stations 2a to 2c transmit pilot signals to the mobile station 3 using the common pilot channel (S501). The radio unit 32 of the mobile station 3 receives the common pilot channel from each of the base stations 2a to 2c, measures the received power of the received common pilot channel, and transmits it to the control unit 38. The control unit 38 obtains reception quality such as the reception signal power of the pilot signal and the reception signal power to interference wave power ratio in the cells covered by the base stations 2a to 2c (S502).

  Based on the obtained reception quality, the control unit 38 obtains an average value of reception quality in a short cycle (short cycle) (S503), and obtains an average value of reception quality in a long cycle (long cycle) (S504). The control unit 38 calculates the ratio between the average value of the reception quality in the short cycle (short cycle) obtained in steps (S503) and (S504) and the average value of the reception quality in the long cycle (long cycle), and A cell having the largest ratio is selected as a communication area for communication. Here, since the unit of the communication area is a cell, the base stations 2a to 2c that cover the selected cell are selected (S505). Hereinafter, step (S506) to step (S510) are substantially the same as step (S104) to step (S108). Therefore, description is abbreviate | omitted here.

  FIG. 10 is a flowchart showing a procedure of a communication method when the base stations 2a to 2c perform high-speed packet channel directional beam transmission and perform Proportional Fairness scheduling using a predetermined channel allocation algorithm. First, the radio units of the base stations 2a to 2c transmit pilot signals to the mobile station 3 using the first common pilot channel and the second common pilot channel (S601). The radio unit 32 of the mobile station 3 receives the first common pilot channel and the second common pilot channel from the base stations 2a to 2c. The radio unit 32 measures the reception power of the second common pilot channel transmitted with a directional beam in the same manner as the high-speed packet channel, and transmits it to the control unit 38. The control unit 38 obtains reception quality such as reception signal power of a pilot signal transmitted through the second common pilot channel in a cell covered by each of the base stations 2a to 2c, and a ratio of reception signal power to interference power (S602). .

  The control unit 38 obtains an average value of reception quality in a short cycle (short cycle) based on the reception quality obtained using the second common pilot channel (S603), and averages the reception quality in a long cycle (long cycle). A value is obtained (S604). The control unit 38 calculates the average value of the reception quality in the short cycle (short cycle) of the second common pilot channel obtained in steps (S603) and (S604) and the average value of the reception quality in the long cycle (long cycle). A ratio is calculated, and a cell having the largest ratio is selected as a communication area for communication. Here, since the unit of the communication area is a cell, the base stations 2a to 2c that cover the selected cell are selected (S605). Hereinafter, step (S606) to step (S610) are substantially the same as step (S104) to step (S108). Therefore, description is abbreviate | omitted here.

  FIG. 11 shows that when the base stations 2a to 2c perform Proportional Fairness scheduling using a predetermined channel allocation algorithm, the mobile station 3 selects a communication area for communication in consideration of the traffic volume in the communication area. It is a flowchart which shows the procedure of the communication method in a case. First, the radio unit 22 of the base stations 2a to 2c transmits, to the mobile station 3, a control signal including the traffic volume of the cells covered by the base stations 2a to 2c using the downlink common control channel and the downlink shared control channel. (S701). The radio unit 22 of the base stations 2a to 2c transmits a pilot signal to the mobile station 3 using the common pilot channel (S702).

  The radio unit 32 of the mobile station 3 receives the control signal including the traffic volume, and the control unit 38 acquires the traffic volume in each cell from the control signal. Then, the control unit 38 selects the base stations 2a to 2c that cover cells having a traffic volume within a predetermined threshold from the cell having the smallest traffic volume, and the base stations 2a to 2c that cover cells that perform communication. It is selected as a candidate for 2c (S703). For the candidate base stations 2 a to 2 c selected by the control unit 38, the radio unit 32 measures the received power of the common pilot channel received from each of the base stations 2 a to 2 c and transmits it to the control unit 38. The control unit 38 obtains reception quality such as the reception signal power of the pilot signal and the reception signal power to interference power ratio in the cells covered by the candidate base stations 2a to 2c (S704).

  The control unit 38 obtains an average value of the reception quality in a short cycle (short cycle) based on the reception quality in the cells covered by the obtained candidate base stations 2a to 2c (S705), and a long cycle (long cycle). The average value of the reception quality is obtained (S706).

The control unit 38 determines the average value of the reception quality in the short cycle (short cycle) and the long cycle (long cycle) in the cells covered by the candidate base stations 2a to 2c obtained in steps (S705) and (S706). A ratio with the average value of the reception quality is calculated, and a cell having the largest ratio is selected as a communication area for communication. Here, since the unit of the communication area is a cell, the base stations 2a to 2c that cover the selected cell are selected (S707). Hereinafter, step (S708) to step (S712) are substantially the same as step (S104) to step (S108). Therefore, description is abbreviate | omitted here.

  According to the communication system 1, the base stations 2a to 2c, the mobile station 3, and the communication method according to the embodiment of the present invention, the radio unit 32 of the mobile station 3 transmits from the radio unit 22 of the base stations 2a to 2c. By receiving the received signal, the mobile station 3 can grasp the communication area in which the signal can be received. Further, the control unit 38 selects a communication area for communication from the communication areas based on the traffic volume in the plurality of communication areas. Therefore, the mobile station 3 can select a communication area in which communication opportunities are easily given in consideration of the traffic volume in the communication area as a communication area for communication. Further, the radio unit 32 multiplexes a control signal including a communication area for performing communication selected by the control unit 38 in the uplink channel and transmits the multiplexed signal to the base stations 2a to 2c for notification. Therefore, the control unit 26 of the base stations 2a to 2c can control communication with the mobile station 3 using the notified communication area. That is, it is not necessary for the base stations 2a to 2c to perform control for selecting a communication area in which the mobile station 3 communicates for a plurality of mobile stations 3, and the control load in the base stations 2a to 2c is distributed to the mobile stations 3. Can do.

  Therefore, it is possible to improve the efficiency of the control performed for the base stations 2a to 2c to communicate with the mobile station 3.

  As a result, it is possible to increase the communication opportunities that the base stations 2a to 2c give to the mobile station 3, that is, it is possible to increase the service throughput of the base stations 2a to 2c. Opportunities to communicate in the area increase. In addition, the control efficiency of the base stations 2a to 2c is improved. Therefore, the throughput of communication performed by the mobile station 3 existing at the end of the communication area can be increased, and the communication area that can achieve the target value of the communication throughput performed by the mobile station 3 can be expanded, that is, so-called cell coverage can be expanded. .

  The control unit 38 of the mobile station 3 selects a communication area with a small traffic volume as a communication area for communication, and the control unit 26 of the base stations 2a to 2c communicates with the mobile station 3 in the selected communication area. Control to do. Therefore, the traffic volume can be distributed to each communication area, and when the traffic volume is small in all the communication areas or when the traffic volume in each communication area is uneven, the base stations 2a to 2c move respectively. The opportunity of communication given to the station 3 can be increased, that is, the service throughput of the base stations 2a to 2c can be increased.

  The radio unit 32 receives control signals including traffic amounts in a plurality of communication areas transmitted from the base stations 2a to 2c using the downlink common control channel and the downlink shared control channel, and the control unit 26 controls the control signal. A communication area in which communication is performed can be selected based on the amount of traffic included in the signal. Therefore, the mobile station 3 can use the traffic volume transmitted from the base stations 2a to 2c, and it is not necessary for the mobile station 3 to obtain the traffic volume. Therefore, the control load on the mobile station 3 is slightly increased. 2c can be dispersed. Therefore, while improving the control efficiency of the base stations 2a to 2c, the control efficiency such as selection of a communication area in the mobile station 3 can also be improved, which can contribute to an increase in the throughput of communication performed by the mobile station 3. .

  The control unit 38 of the mobile station 3 estimates the traffic volume in a plurality of communication areas based on the received power of the signal received by the radio unit 32, and performs communication based on the estimated traffic volume. Can be selected. Therefore, on the mobile station 3 side, the traffic amount can be estimated and the communication area can be selected, and the control load on the base stations 2a to 2c can be further reduced. Further, the control unit 38 can grasp the traffic volume in a plurality of communication areas, and can select a communication area based on the traffic volume without separately using a control signal or the like for selecting the communication area. Furthermore, since radio resources are not consumed for the control signal, the radio resources can be used for data transmission. As a result, the throughput of communication performed by the mobile station 3 can be further increased.

  Furthermore, the control unit 38 can select a communication area for communication in consideration of not only the traffic amount in the communication area but also the reception quality. For example, the control unit 38 selects a communication area with a small amount of traffic from communication areas having a certain level of reception quality, or selects a communication area with good reception quality from a communication area with a certain amount of traffic. I can do it. Therefore, the mobile station 3 can select a communication area that has a small amount of traffic in the communication area and is easily given a communication opportunity and that has good reception quality. Therefore, it is possible to increase the communication opportunity that the base stations 2a to 2c give to the mobile station 3, that is, it is possible to increase the service throughput of the base stations 2a to 2c, and the mobile station 3 The probability of succeeding in sending and receiving can be improved. Therefore, the throughput of communication performed by the mobile station 3 can be further improved.

  When the radio unit 22 of the base stations 2a to 2c transmits a packet including data using the high-speed packet channel, when the directional beam transmission is performed, the control unit 38 is similar to the high-speed packet channel. The reception quality is obtained using the second common pilot channel transmitted by the directional beam that transmits the packet in the direction. According to this, the obtained reception quality matches the reception quality of the high-speed packet channel that performs directional beam transmission. Therefore, the control unit 38 uses the reception quality obtained using the second common pilot channel to select a communication area for communication, thereby taking into account that the high-speed packet channel is transmitted in a directional beam. Based on this, it is possible to select a communication area for communication.

  In addition, the control unit 26 of the base stations 2a to 2c selects the mobile station 3 having the largest ratio between the average value of the reception quality of the mobile station 3 in the short cycle and the average value of the reception quality of the mobile station 3 in the long cycle. When performing Proportional Fairness scheduling in which channel assignment is performed using a channel assignment algorithm, the control unit 38 receives the average value of the reception quality in the short cycle of the signal received by the radio unit 32 and the average of the reception quality in the long cycle. Based on the ratio to the value, a communication area for communication can be selected. That is, the control unit 38 can select a communication area in which communication is performed using a standard similar to the channel allocation standard.

  Therefore, the control unit 38 can select a communication area where a channel is easily assigned, that is, a communication area where a communication opportunity is easily given as a communication area where communication is performed. As a result, the base stations 2a to 2c can increase the opportunity to allocate a high-speed packet channel for transmission of packets to the mobile station 3, and the communication opportunities that the base stations 2a to 2c give to the mobile station 3 can be increased. Can be made. Therefore, it is possible to increase the throughput of communication performed by a mobile station with poor reception quality existing at the end of the communication area, and so-called cell coverage can be increased. Furthermore, since the mobile station 3 calculates the ratio of the average value of the reception quality in the short period and the average value of the reception quality in the long period and selects the communication area for communication, the control load of the base stations 2a to 2c Can be distributed and the control efficiency of the base stations 2a to 2c can be improved, and the throughput of communication performed by the mobile station 3 can be further increased.

(Example of change)
The present invention is not limited to the above embodiment, and various modifications can be made. In the embodiment described above, the cell is used as the unit of the communication area, but the case where the sector is used as the unit of the communication area and the sector is selected as the communication area for performing communication will be described. FIG. 12 is a block diagram showing the configuration of the base station 202 according to the modification of the present invention. The base station 202 includes an antenna 21, a radio unit 222, a baseband processing unit 23, a buffer 24, a network interface unit 25, and a control unit 226. Since the antenna 21, the baseband processing unit 23, the buffer 24, and the network interface unit 25 are the same as those in the above embodiment, the same reference numerals are given and description thereof is omitted.

  The radio unit 222 functions as a transmission unit that transmits data and control signals to the mobile stations 3 that exist in each sector in order to transmit and receive data and control signals in units of sectors, and the mobile station 3 that exists in each sector. A plurality of transmission sectors 222a and 222b functioning as receiving means for receiving data and control signals from the receiver. That is, each transmission sector 222a, 222b covers each sector. In FIG. 12, only two transmission sectors 222a and 222b are shown, but the same number of sectors as the number of sectors obtained by dividing the cell covered by the base station 202 is provided. When receiving an instruction from the control unit 226 to transmit a packet to the mobile station 3, that is, when receiving an instruction to turn on the packet transmission function, the transmission sectors 222a and 222b transmit the packet. On the other hand, when the transmission sectors 222a and 222b receive an instruction from the control unit 226 not to transmit a packet to the mobile station 3, that is, when an instruction to turn off the packet transmission function is received, the transmission sectors 222a and 222b transmit the packet. Absent.

  The transmission sectors 222a and 222b perform substantially the same function as the radio unit 22 according to the above-described embodiment except that transmission of a downlink control channel and a high-speed packet channel is performed in units of sectors. The control unit 226 generates a control signal including the traffic amount in the communication area on a sector basis, or controls the mobile station 3 to perform communication on a communication area selected by the mobile station 3 on a sector basis. Except for this, it is substantially the same as the control unit 26 according to the above embodiment.

  Specifically, the control unit 226 moves the transmission sectors 222a and 222b covering the sectors corresponding to the data indicating the communication area selected by the mobile station 3 included in the control signal transmitted from the mobile station 3. Instructs the station 3 to transmit a packet. That is, the control unit 226 instructs the transmission sectors 222a and 222b to turn on the packet transmission function. On the other hand, the control unit 226 transmits the mobile station 3 to the transmission sectors 222a and 222b that cover sectors that do not correspond to the data indicating the communication area selected by the mobile station 3 included in the control signal transmitted from the mobile station 3. To not send packets. That is, the control unit 226 instructs the transmission sectors 222a and 222b to turn off the packet transmission function. In this way, the control unit 226 performs control so that the mobile station 3 performs communication in the communication area selected by the mobile station 3 in units of sectors.

  FIG. 13 is a flowchart showing the procedure of the communication method according to the modified example of the present invention. In FIG. 13, the procedures performed by the configuration other than the transmission sectors 222a and 222b, such as the control unit 226 and the baseband processing unit 23 of the base station 202, are collectively illustrated as the procedures of the base station 202. The procedure performed by 222b is illustrated separately. First, each of the transmission sectors 222a and 222b transmits a control signal including the traffic volume of the sector covered by the transmission sectors 222a and 222b to the mobile station 3 using the downlink common control channel and the downlink shared control channel, respectively (S801). .

  Each transmission sector 222a, 222b transmits a pilot signal to the mobile station 3 using the common pilot channel (S802).

  The radio unit 32 of the mobile station 3 receives the common pilot channel from each of the transmission sectors 222a and 222b, measures the received power of the received common pilot channel, and transmits it to the control unit 38. The control unit 38 obtains reception quality such as the reception signal power of the pilot signal and the reception signal power to interference wave power ratio in the sectors covered by the transmission sectors 222a and 222b (S803). The control unit 38 communicates transmission sectors 222a and 222b that cover sectors having reception quality within a predetermined threshold from transmission sectors 222a and 222b that cover the sector having the best received quality. The transmission sectors 222a and 222b that cover the sector to be performed are selected as candidates (S804). The control unit 38 selects a sector having the smallest traffic amount included in the control signal transmitted in step (S801) as a sector to perform communication from among the selected candidates for the transmission sectors 222a and 222b. Here, since the unit of the communication area is a sector, the transmission sectors 222a and 222b that cover the selected sector are selected (S805).

  The control unit 38 of the mobile station 3 generates a control signal including the sector ID of the sector covered by the selected transmission sectors 222a and 222b, and the radio unit 32 multiplexes the control signal in the uplink channel, and each base station It transmits to 202 (S806). In each base station 202, the radio unit 222 receives a control signal including the sector ID selected by the mobile station 3 transmitted from the mobile station 3 using the uplink channel, and the baseband processing unit 23 performs data demodulation processing. (S807). The control unit 226 of each base station 202 instructs the transmission sectors 222a and 222b covering the sector corresponding to the sector ID included in the control signal to turn on the packet transmission function, and is included in the control signal. The transmission sectors 222a and 222b that cover sectors not corresponding to the sector ID are instructed to turn off the packet transmission function (S808).

  Each of the transmission sectors 222a and 222b determines whether an instruction to transmit a packet to the mobile station 3 is received from the control unit 226 of the base station 202 (S809). When each transmission sector 222a, 222b receives an instruction to transmit a packet in step (S809), it transmits the packet (S810).

  On the other hand, if each transmission sector 222a, 222b receives an instruction not to transmit a packet in step (S809), it does not transmit the packet (S810). As described above, even when the unit of the communication area is the sector, similarly, the mobile station 3 can select a communication area that is easily given a communication opportunity as a communication area for communication. Therefore, the service throughput of the base station 202 can be increased, and the opportunity for the mobile station 3 to perform communication in the communication area increases.

  Therefore, the throughput of communication performed by the mobile station 3 existing at the end of the communication area can be increased.

  In the communication method according to this modification, the sector is selected based on the traffic amount in the sector included in the control signal and the reception quality in the sector. However, as in the communication method according to the above-described embodiment, A sector can be selected by estimating the amount of traffic, or a sector can be selected based on a ratio between an average value of short-period reception quality and an average value of long-period reception quality.

  In addition, when the control unit 26 of the base stations 2a to 2c performs proportional fairness scheduling using the above-described channel allocation algorithm as a channel allocation method, in the above embodiment, the communication area in which the mobile station 3 performs communication is set. Although selected, base station 2a-2c may select the communication area | region which communicates. In this case, the control unit 38 of the mobile station 3 receives the received signal power such as the received signal power of the pilot signal or the ratio of the received signal power of the pilot signal to the interference wave power, which is the ratio of the received signal power to the interference wave power. A control signal including the reception quality information regarding is generated, and the radio unit 32 is transmitted to the base stations 2a to 2c. And the radio | wireless part 32 of the mobile station 3 transmits the control signal containing reception quality information to base station 2a-2c. The radio units 22 of the base stations 2 a to 2 c receive the control signal including the reception quality information and transmit it to the control unit 26 via the baseband processing unit 23.

  The control unit 26 acquires the reception quality information included in the control signal, and uses the reception quality information, the average value of the reception quality in the short cycle of the signal received by the mobile station 3 and the average of the reception quality in the long cycle. It functions as a calculation means for calculating a value and calculating a ratio between the two. Based on the ratio between the average value of the reception quality in the short period of the signal received by the mobile station 3 and the average value of the reception quality in the long period, the control unit 26 determines the communication area having the largest ratio as follows. The mobile station 3 also functions as a selection means for selecting as a communication area in which communication is performed. When the base stations 2a to 2c covering the selected communication area are own base stations, the control unit 26 of the base stations 2a to 2c uses a high-speed packet channel to transmit a packet to the mobile station 3. Allocation is performed, and the wireless unit 22 transmits a packet. On the other hand, the control unit 26 of the base stations 2a to 2c does nothing when the base stations 2a to 2c covering the selected communication area are not its own base station.

  In the above embodiment, the mobile station 3 shown in FIG. 6 performs communication by estimating the traffic amount in the communication area based on the received power received from the signals transmitted from the base stations 2a to 2c. Also in the communication method in the case of selecting a communication area, a communication area with a small estimated traffic volume is communicated from communication areas having a relatively good reception quality in consideration of the reception quality of the signal received by the mobile station 3. Or a communication area with good reception quality can be selected as a communication area in which communication is performed from communication areas in which the estimated traffic volume is small to some extent.

  In addition, in the communication methods shown in FIGS. 7, 8, and 12, a candidate for a communication area for communication is selected in consideration of the reception quality of the signal received by the mobile station 3, and the candidate is selected from the candidates. A communication area with a small amount of traffic was selected as a communication area for communication, but a communication area candidate for communication was first selected in consideration of the traffic volume, and a communication area with good reception quality was selected from the candidates. May be selected as a communication area for communication. Similarly, in the communication method shown in FIG. 11, first, communication area candidates for communication are selected in consideration of the traffic volume, and an average value of reception quality in a short cycle and reception of a long cycle are selected from the candidates. A communication area with a large ratio to the average quality value was selected as a communication area for communication, but first a communication area with a large ratio between the average value of the reception quality in the short period and the average value of the long period of reception quality. A candidate may be selected, and a communication area with a small traffic volume may be selected from the candidates as a communication area for communication.

It is explanatory drawing which shows the structure of the communication system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the base station which concerns on embodiment of this invention. It is a block diagram which shows the structure of the mobile station which concerns on embodiment of this invention. It is a graph which shows the received power of the signal which the mobile station which concerns on embodiment of this invention received. It is a flowchart which shows the procedure of the communication method in the case of selecting the communication area | region which performs communication based on the traffic amount in the communication area | region contained in the control signal which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the communication method in the case of estimating the traffic amount in the communication area which concerns on embodiment of this invention, and selecting the communication area which communicates. It is a flowchart which shows the procedure of the communication method in the case of selecting the communication area | region which performs communication based on the traffic amount and signal reception quality in the communication area which concerns on embodiment of this invention. The procedure of the communication method in the case of selecting the communication area | region which performs communication based on the traffic amount and signal reception quality in a communication area | region, when directional beam transmission is performed on the high-speed packet channel which concerns on embodiment of this invention is shown. FIG. It is a flowchart which shows the procedure of the communication method in the case of performing the scheduling using the algorithm of the predetermined channel allocation which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the communication method in the case of performing directional beam transmission of the high-speed packet channel which concerns on embodiment of this invention, and performing the scheduling using the algorithm of a predetermined channel allocation. FIG. 6 is a flowchart showing a procedure of a communication method when selecting a communication area in which communication is performed in consideration of the traffic amount in the communication area when performing scheduling using a predetermined channel allocation algorithm according to the embodiment of the present invention. is there. It is a block diagram which shows the structure of the base station which concerns on the example of a change of this invention. It is a flowchart which shows the procedure of the communication method which concerns on the example of a change of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication system 2a, 2b, 2c, 202 Base station 3 Mobile station 4 Network 21 Antenna 22, 222 Radio | wireless part 23 Baseband process part 24 Buffer 25 Network interface part 26,226 Control part 31 Antenna 32 Radio | wireless part 33 Baseband process part 34 Input unit 35 Output unit 36 Card interface unit 37 Buffer 38 Control unit 222a, 222b Transmission sector

Claims (4)

A mobile station that communicates with a plurality of base stations configured to perform scheduling based on a ratio between an average value of mobile station reception quality in a short cycle and an average value of mobile station reception quality in a long cycle. ,
Receiving means for receiving signals transmitted from each of the plurality of base stations;
Calculation means for calculating, for each of the plurality of base stations, as a reception quality of the signal received by the reception means, a ratio between an average value of the reception quality in a short period and an average value of the reception quality in a long period;
Based on the ratio between the average value of the reception quality in the short period calculated by the calculation means and the average value of the reception quality in the long period, and the traffic volume of a plurality of communication areas in which the reception means can receive the signal Selecting means for selecting a communication area for communication from the plurality of communication areas,
Each of the plurality of communication areas corresponds to each of the plurality of base stations. A base station configured to perform scheduling based on a ratio between an average value of mobile station reception quality in a short period and an average value of mobile station reception quality in a long period, and communicating with the mobile station. ,
As the reception quality at the mobile station of the signal transmitted from each of the plurality of base stations to the mobile station, the ratio of the average value of the reception quality in a short period to the average value of the reception quality in a long period is A calculation means for calculating for each base station;
Based on the ratio between the average value of the reception quality in the short period calculated by the calculation means and the average value of the reception quality in the long period, and the traffic volume of a plurality of communication areas in which the reception means can receive the signal Selecting means for selecting a communication area in which the mobile station performs communication from the plurality of communication areas,
Each of the plurality of communication areas corresponds to each of the plurality of base stations. A plurality of base stations configured to perform scheduling based on a ratio between an average value of the reception quality of the mobile station in a short cycle and an average value of the reception quality of the mobile station in a long cycle; and communication with the plurality of base stations A communication system comprising a mobile station for performing
As the reception quality at the mobile station of a signal transmitted from each of the plurality of base stations to the mobile station, a ratio between the average value of the reception quality in a short period and the average value of the reception quality in a long period is Calculating means for calculating each base station of
Based on the ratio between the average value of the reception quality in the short period calculated by the calculation means and the average value of the reception quality in the long period, and the traffic volume of a plurality of communication areas in which the reception means can receive the signal Selecting means for selecting a communication area in which the mobile station performs communication from the plurality of communication areas,
Each of the plurality of communication areas corresponds to each of the plurality of base stations. A plurality of base stations configured to perform scheduling based on a ratio between an average value of the reception quality of the mobile station in a short cycle and an average value of the reception quality of the mobile station in a long cycle; and communication with the plurality of base stations A communication method using a communication system comprising a mobile station for performing
As the reception quality at the mobile station of the signal transmitted from each of the plurality of base stations to the mobile station, the ratio of the average value of the reception quality in a short cycle to the average value of the reception quality in a long cycle is For each base station,
Based on the ratio between the calculated average value of the reception quality in the short period and the average value of the reception quality in the long period, the mobile station is selected from a plurality of communication areas in which the mobile station can receive the signal. Select the communication area for communication,
Each of the plurality of communication areas corresponds to each of the plurality of base stations.

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