JP2012029318A - Mobile communication method - Google Patents

Abstract

A load on a sector device is reduced according to the load on the sector device.
A first communication device that transmits to a mobile station device, a second communication device in the vicinity of the first communication device, and information indicating a transmission load in the first communication device Notification means for notifying the other communication apparatus, and handing over the mobile station apparatus 1 to a communication apparatus with a light load.
[Selection] Figure 4

Description

  The present invention relates to a mobile communication method.

  For example, in a mobile communication system such as a cellular phone system, a mobile station apparatus receives a large number of receivable pilot signals transmitted from each sector apparatus of a base station apparatus. And it communicates with the sector apparatus with the best reception state of the pilot signal. In this way, communication can be performed in the most favorable state.

  In Patent Document 1, in a wireless communication system including a plurality of wireless base stations and a plurality of wireless terminals, the roaming frequency of the wireless terminals is reduced, the communication load is distributed to the plurality of wireless base stations, and the wireless terminals As a final effect, an invention relating to obtaining an improvement in the throughput of a wireless communication system is disclosed by always connecting a wireless base station with a high reception strength and performing stable communication.

JP 2003-235069 A

  However, in the conventional method, the load for each sector device may be biased. That is, there are cases where many of the mobile station devices communicate with one sector device even though they can communicate with other sector devices, such as when a large number of mobile station devices exist locally. In such a case, the load on the sector device may increase and processing capacity may be insufficient. As a result, the transmission waiting data amount (total amount of untransmitted information codes) in the sector device is accumulated, and the communication throughput is reduced.

  The present invention has been made in view of the above problems, and an object thereof is to provide a communication system, a communication device, and a communication control method capable of reducing the load on the sector device according to the load on the sector device. It is in.

  In order to solve the above-described problem, the present invention provides a step in which a first base station apparatus requests measurement from a second base station apparatus, and the second base station apparatus includes the first base station apparatus. And a step of notifying a measurement result of the state of the second base station apparatus measured by the second base station apparatus in response to a measurement request from the second base station apparatus, and in the step of notifying, The measurement result of the state of the communication area is notified.

  In this way, when the load of the sector device (first communication device) exceeds a predetermined threshold, another sector device (second communication) that can communicate with the mobile station device in communication with the sector device. Device) and the load of the sector device whose load exceeds a predetermined threshold can be reduced.

  According to the feature of the present invention, it is possible to reduce the load of the sector device whose load exceeds a predetermined threshold.

1 is a configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a block diagram of the configuration of a base station apparatus according to an embodiment of the present invention. FIG. 2 is a configuration block diagram of a mobile station apparatus according to an embodiment of the present invention. 1 is a functional block diagram of a mobile communication system according to an embodiment of the present invention. It is a sequence diagram of processing according to an embodiment of the present invention. It is explanatory drawing of the handover destination candidate sector list which concerns on embodiment of this invention. It is explanatory drawing of the peripheral sector throughput list which concerns on embodiment of this invention. It is explanatory drawing about the sector apparatus structure of the base station apparatus which concerns on embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings. A mobile communication system 4 according to the present embodiment includes a plurality of mobile station apparatuses 1, a plurality of base station apparatuses 2, and a communication network 3, as shown in FIG. The base station device 2 normally communicates with a plurality of mobile station devices 1.

  As shown in FIG. 3, the mobile station apparatus 1 includes a control unit 11, a communication unit 12, a storage unit 13, an operation unit 14, and a display unit 15. The control unit 11 controls each unit of the mobile station device 1 and executes processing related to a call and data communication. Moreover, the control part 11 is also performing the process for determining the transmission rate, when transmitting the packet for communication used in data communication via the communication part 12. FIG. The communication unit 12 includes an aerial line, and in accordance with an instruction input from the control unit 11, modulates a voice signal, a communication packet, and the like and outputs the modulated signal or the voice signal arriving at the aerial line. It receives and demodulates and outputs it to the control unit 11.

  The storage unit 13 operates as a work memory for the control unit 11. The storage unit 13 holds programs and parameters related to various processes performed by the control unit 11.

  The operation unit 14 is, for example, a numeric keypad, and receives a telephone number or a character string from a user and outputs it to the control unit 11. The display unit 15 is configured to include, for example, a liquid crystal display device, and displays and outputs information according to a signal input from the control unit 11.

  Next, as shown in FIG. 2, the base station apparatus 2 includes three sector apparatuses 101d, 102d, and 103d. The number of sector devices is not limited to three, and is usually configured by one to six. Each of the sector devices 101d, 102d, and 103d includes a sector control unit 21, a network interface unit 22, a wireless communication unit 23, and a storage unit 24. The sector control unit 21 controls each unit of the sector device, and executes processing related to telephone calls and data communication. The network interface unit 22 is connected to the communication network 3 and receives an audio signal, a communication packet, and the like from the communication network 3 and outputs them to the sector control unit 21, or according to an instruction from the sector control unit 21 A communication packet or the like is transmitted to the communication network 3. The wireless communication unit 23 includes an antenna, receives and demodulates a voice signal, a communication packet, and the like from at least one mobile station apparatus 1 and outputs the received signal to the sector control unit 21 or input from the sector control unit 21. In accordance with the instruction, the voice signal or communication packet input from the sector control unit 21 is modulated and output via the antenna. The storage unit 24 operates as a work memory for the sector control unit 21. Further, the storage unit 24 holds programs and parameters related to various processes performed by the sector control unit 11.

  As shown in FIG. 8, each sector device included in the base station device 2 forms a wireless communication area, that is, a first sector 101a, a second sector 102a, and a third sector 103a in each direction around the base station device 2. To do. Each sector sometimes overlaps with other sectors. Then, the sector device 101d communicates with a plurality of normal mobile station devices 1 located in the corresponding first sector 101a. The sector device 102d communicates with a plurality of normal mobile station devices 1 located in the corresponding second sector 102a. Further, the sector device 103d communicates with a plurality of normal mobile station devices 1 located in the corresponding third sector 103a. In the figure, since the mobile station apparatus 1 is in both the first sector 101a and the third sector 103a of the base station apparatus 2, the first sector apparatus 101d and the third sector apparatus 103d of the base station apparatus 2 are used. It is possible to communicate with any of these. In such a case, in the prior art, the mobile station apparatus 1 performs communication by selecting a sector apparatus with a better pilot signal reception state. In the figure, a single base station apparatus 2 is shown. However, when there is another base station apparatus 2 and communication with the sector apparatus of the other base station apparatus 2 is possible, the sector A pilot signal from the apparatus is also received, and a sector apparatus having the best pilot signal reception state is selected to perform communication.

  Furthermore, the base station apparatus 2 includes a base station apparatus control unit 25 and a storage unit 26 that are common to the sector apparatuses. The base station device control unit 25 controls the sector control unit 21 of each sector device. The storage unit 26 operates as a work memory for the base station apparatus control unit 25. Further, the storage unit 26 holds programs and parameters related to various processes performed by the base station apparatus control unit 25.

  When each sector device of the base station device 2 communicates with the mobile station device 1 using the wireless communication unit 23, a traffic channel and a control channel can be used as logical channels. Traffic channels include uplink and downlink communication channels and power control channels. Voice signals and communication packets are transmitted and received on the upstream and downstream communication channels. Uplink means communication from the mobile station apparatus 1 to each sector apparatus of the base station apparatus 2, and downlink means communication from each sector apparatus of the base station apparatus 2 to the mobile station apparatus 1. The power control channel is a channel for each sector device of the base station device 2 to control the antenna power of the mobile station device 1. The control channel includes an uplink access channel, a downlink pilot channel, a synchronization channel, and a paging channel. The access channel is a channel for transmitting a signal from the mobile station device 1 to each sector device of the base station device 2, and includes an uplink dedicated control channel. The pilot channel and the synchronization channel are channels for synchronizing each sector device of the base station device 2 and the mobile station device 1. The paging channel is a channel for each sector device of the base station device 2 to transmit control information of the mobile station device 1 to the mobile station device 1, and is transmitted to all mobile station devices 1 that can communicate at the same time. Common downlink control channels and downlink individual control channels for communicating with individual mobile station apparatuses 1 are included. In the common control channel, specifically, information indicating the amount of interference and information such as transmission restrictions are broadcast to all mobile station apparatuses that can communicate. In the dedicated control channel, various signals used in the communication sequence for controlling each mobile station apparatus are transmitted and received.

  FIG. 4 is a functional block diagram of mobile station apparatus 1 and base station apparatus 2 used in the present embodiment. The mobile station device 1 is functionally configured to include a data receiving unit 41, a handover control unit 43, a reception intensity measuring unit 45, and a data transmitting unit 47. On the other hand, the base station apparatus 2 includes a data transmission unit 40, a schedule management unit 42, a pilot signal transmission unit 44, and a data reception unit 46 in each sector device. Furthermore, the base station apparatus 2 includes a load state management unit 48 that is common to the sector apparatuses. In addition to the base station apparatus 2, the load state management unit 48 can be provided in an exchange or SCP (Service Control Point) installed on the communication network 3. In this way, handover by the process shown in the present embodiment can be performed not only between sector devices of the same base station device, but also between sector devices straddling different base stations and exchanges. For the sake of simplicity in the present embodiment, the load state management unit 48 will be described as being provided in the base station apparatus 2. That is, when the mobile station apparatus 1 exists in a portion where areas overlap each other in each sector apparatus in the same base station apparatus 2, the processing according to the present embodiment is performed. In the initial state of the present embodiment, it is assumed that mobile station apparatus 1 is communicating with first sector apparatus 101d of base station apparatus 2.

  Hereinafter, a specific example of processing performed in this embodiment will be described in detail with reference to FIGS. 4 to 7. FIG. 5 is a sequence diagram of processing according to the present embodiment.

  The data transmitting unit 40 of the first sector device 101d uses each downlink communication channel as a modulated wave obtained by modulating / spreading the information code for each mobile station device 1 received from an exchange or the like included in the communication network 3. It transmits to the apparatus 1. At this time, the transmission rate of the information code is notified from the handover control unit 43 of the mobile station apparatus 1 by a process described later. Further, the transmission order of the information codes is notified from the schedule management unit 42 by a process to be described later, and the transmission wait information codes are stored in the buffer of the data transmission unit 40 as a transmission wait data amount. That is, when transmitting the information code using the downlink communication channel, the data transmission unit 40 temporarily stores the information code in the storage device for each mobile station device 1 and reads out the information code stored in the storage means. Send. At this time, the amount of information code stored in the buffer is the amount of data waiting to be transmitted. Then, the transmitted modulated wave is received by the data receiving unit 41 included in the mobile station device 1, and the data receiving unit 41 despreads / demodulates the modulated wave transmitted from the first sector device 101d. By doing so, the information code is acquired.

  Next, the pilot signal transmission unit 44 of each sector device transmits a pilot signal to all mobile station devices 1 that can communicate using the pilot channel (S102, S103, S104). Then, the reception intensity measuring unit 45 of the mobile station apparatus 1 that has received the pilot signal from each sector apparatus of each base station apparatus 2 associates the reception intensity of the pilot signal with the sector apparatus identification information in FIG. This is stored in the illustrated table (handover destination candidate sector list). The sector device identification information is usually a sector number uniquely determined in the communication network 3 for each sector. However, it is a sector device that spans different base stations or exchanges within its own base station device, and can be handed over to a sector device that uses a different frequency band, in which case, in order to identify the sector device, In addition to the sector number, information indicating a frequency band is preferably added to the list in the sector device identification information.

  The reception strength measurement unit 45 further determines the transmission rate and antenna power when the data transmission unit 47 transmits the information code using the uplink communication channel based on the reception strength of the pilot signal from the communicating sector device. Decide and notify the data transmitter 47.

  The data transmission unit 47 transmits the information code of the transmission rate to the first sector device 101d as a modulated wave obtained by modulating / spreading. Then, the data receiving unit 46 of the first sector device 101d receives the transmitted modulated wave and performs despreading / decoding, etc., thereby obtaining an information code, transmitting the information code to the communication network 3, etc. Data processing is performed.

  The transmission / reception of the information code, the transmission / reception of the pilot signal, and the update of the handover destination candidate sector list (S105) between the first sector device 101d of the base station device 2 and the mobile station device 1 are performed according to the present embodiment. (S101, S102, S103, S104).

  Next, the schedule management unit 42 of the first sector device 101d assigns the transmission priority of the information code for each mobile station device 1 transmitted by the data transmission unit 40. This allocation is performed based on the transmission rate of the information code of the downlink communication channel notified from the handover control unit 43 of the mobile station apparatus 1 by the process described later. The schedule management unit 42 measures the information code transmission amount (total throughput) within a certain time in the data transmission unit 40. Then, the total throughput is transmitted to the load state management unit 48 included in the base station apparatus 2 when there is a throughput inquiry (S115) from the load state management unit 48. Here, the schedule management unit 42 may measure the total throughput at all times, and send the latest total throughput when there is an inquiry, or measure the total throughput after the inquiry. Also good. The load state management unit 48 stores the total throughput from each sector device in the table (peripheral sector throughput list) illustrated in FIG. 7 in association with the sector device identification information. Similarly to the handover destination candidate sector list, the peripheral sector throughput list is a sector device in the own base station device or across different base stations and exchanges, and when handing over to a sector device using a different frequency band, In order to specify, it is desirable to add information indicating the frequency band to the list in addition to the sector number to the sector device identification information. It can be said that the higher the total throughput, the higher the load on the sector device. Further, instead of the total throughput, a total transmission waiting data amount described later may be used.

  Furthermore, the schedule management unit 42 constantly measures the amount of data waiting for transmission for each mobile station device. Then, when the total transmission waiting data amount (total transmission waiting data amount) of all mobile station devices in communication exceeds a threshold value, it is determined that the sector device has become overloaded (S106). The determination may use a statistical quantity other than the total amount of data waiting to be transmitted, or may use an amount based on the throughput such as the total throughput. If it is determined that an overload has occurred, the handover controller 43 of the mobile station apparatus 1 is notified of the overload using the common control channel (S108), and the load state manager 48, a peripheral sector status inquiry is performed (S107). The load state management unit 48 creates a new peripheral sector throughput list by performing a throughput inquiry (S115) to each sector device (S116), and notifies the first sector device 101d (S109).

  On the other hand, the handover control unit 43 reads the handover destination candidate sector list stored in the reception strength measurement unit 45 when notified from the schedule management unit 42 of the first sector device 101d that the load is overloaded, and performs individual control. The channel is transmitted to the first sector device 101d (S110). Here, only the sector device identification information included in the list may be transmitted. Then, the first sector device 101d extracts only the sector devices existing in the handover destination candidate sector list received from the handover control unit 43 from the peripheral sector throughput list received from the load state management unit 48, and A similar sector throughput list is created (S111) and notified to the handover control unit 43 (S112). Then, the handover control unit 43 selects the most suitable sector device (a sector device with a good pilot signal reception state and a light load) based on information on the total throughput of each sector device included in the sector throughput list. To do. For example, “a sector device having a pilot signal reception strength of 10 dB or more and a total throughput of 1000 kbps or less” or “a sector device having the highest pilot signal reception strength is within −5 dB and the most total among the sector devices. It is also possible to impose a specific selection condition such as “sector apparatus with small throughput” and select from sector apparatuses that satisfy the selection condition. Then, the data transmission unit 47 of the mobile station apparatus 1 transmits a handover request to the selected sector apparatus (S113). When there is a handover request response from the sector device that transmitted the handover request (S114), a handover process is performed with the sector device.

  The handover control unit 43 also performs a process of determining the transmission rate of the information code in the downlink communication channel from the reception strength of the pilot signal received by the reception strength measurement unit 45. The data transmission unit 47 is notified of the transmission rate. Then, the data transmission unit 47 notifies the transmission rate to the data transmission unit 40 and the schedule management unit 42 via the data reception unit 46 of the first sector device 101d through the uplink communication channel.

  In addition, when notifying the overload state to the mobile station apparatus 1 in S108, the overload state may be notified only to a specific mobile station apparatus. Specifically, for example, notification may be made only to the mobile station device 1 in which the amount of data waiting for transmission in the first sector device 101d exceeds a predetermined amount. Moreover, it is good also as notifying only the mobile station apparatus 1 with much transmission waiting data amount among the mobile station apparatuses 1 in communication. Further, a predetermined threshold is provided for the total transmission waiting data amount, the transmission waiting data amount of the mobile station apparatus 1 having the largest transmission waiting data amount is subtracted from the total transmission waiting data amount in descending order, and the remaining total transmission waiting data amount. May be notified only to the mobile station apparatus 1 that will be below the predetermined threshold. In these cases, the overload state notification in S108 may be performed through the dedicated control channel. As a result, the first sector device 101d can perform handover by designating a specific mobile station device 1.

  According to the present embodiment, when a large number of mobile station devices exist locally, some mobile station devices can be handed over to other sector devices, so that it is possible to reduce the load imbalance for each sector device. it can. As a result, communication throughput in each sector device can be improved. In addition, the mobile station device 1 can continue communication after the handover. In handover, a sector device having the best condition can be selected from communicable sector devices. Further, since the sector device to be handed over is not a handover destination when the load on the own sector device is heavy, the possibility of adversely affecting the processing of the sector device at the handover destination can be reduced. Furthermore, by determining the mobile station apparatus 1 to be handed over from the transmission waiting data amount for each mobile station apparatus 1, an effect of reducing the transmission waiting data amount for each mobile station apparatus 1 can be expected.

  The present invention is not limited to the above embodiment.

  For example, in the processing in S111 and S112 of FIG. 5, the first sector device 101d determines the handover destination from the peripheral sector throughput list received from the load state management unit 48 and the handover destination candidate sector list received from the handover control unit 43. The candidate sector apparatus may be selected and notified to the handover control unit 43. That is, in the first sector device 101d, the most suitable sector device (the reception state of the pilot signal is good) based on information on the sector device with which the mobile station device 1 can communicate and information on the total throughput of each sector device. , A lightly loaded sector device) is selected and notified to the handover control unit 43. When the handover control unit 43 does not notify the first sector device 101d of the handover destination candidate sector list, the first sector device 101d may transmit the peripheral sector throughput list to the handover control unit 43. It should be noted that the criteria for a suitable sector device are based on station data in order to determine an appropriate range according to the circumstances of each base station device, such as the installation location of the sector device, the influence of fading, and the time zone. It is good also as setting.

  DESCRIPTION OF SYMBOLS 1 Mobile station apparatus, 2 Base station apparatus, 3 Communication network, 4 Mobile communication system, 11 Control part, 12 Communication part, 13 Storage part, 14 Operation part, 15 Display part, 21 Sector control part, 22 Network interface part, 23 wireless communication unit, 24 storage unit, 25 base station apparatus control unit, 26 storage unit, 40 data transmission unit, 41 data reception unit, 42 schedule management unit, 43 handover control unit, 44 pilot signal transmission unit, 45 reception strength measurement Unit, 46 data reception unit, 47 data transmission unit, 48 load state management unit, 101a, 102a, 103a sector, 101d, 102d, 103d sector device

Claims (1)

A step in which a first base station device requests measurement from a second base station device;
The second base station apparatus notifying the measurement result of the state of the second base station apparatus measured by the second base station apparatus in response to a measurement request from the first base station apparatus;
With
In the notification step,
A mobile communication method comprising: notifying a measurement result of a communication area state of the second base station apparatus.

Images