JP2011087247A - Mobile communication system, control apparatus of the same and mobile terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a channel usage rate from being deteriorated and to achieve performance improvement, by performing channel allocation by taking into account influences of interference caused by a mobile terminal device. <P>SOLUTION: In a mobile communication system in which a plurality of base stations autonomously perform interference avoidance, based on a mobile terminal device and a position of a base station, channel allocation, by taking into account influences of interference to be exerted on the other base stations, is performed, and thereby a channel usage rate over all the system is improved. Namely, the number of base stations, which the mobile terminal device includes within a communication range, is defined as an index to evaluate the influences of interference. Then, a number of channels are preferentially allocated to a mobile terminal device which covers only a single base station and is present at a position not to exert influences of interference on the other base stations. On the contrary, only minimum channels are allocated to a mobile terminal device being present at such a position that a plurality of base stations are included within a communication range, and only when an excessive channel is generated, an additional channel is allocated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement in a mobile communication system that forms an area by, for example, a microcell system.

  Methods for forming an area of a mobile communication system are roughly classified into a macro cell method and a micro cell method. A typical example of the former is a so-called cellular phone system, and the radius of a radio cell extends to several kilometers. On the other hand, PHS (Personal Handy-phone System) and XGP (eXtended Global Platform) adopt the latter method, and the cell radius is very small, about several hundred meters at most.

  Since a large number of base stations are required in the micro cell system, it is desired to be able to install a base station without a station design. Therefore, a method (autonomous distributed control method) is adopted in which inter-cell interference can be avoided by autonomous control for each base station. In XGP, a plurality of channels can be assigned to one mobile terminal device, and it is possible to realize best-effort communication by controlling the number of assigned channels to the maximum.

  In the autonomous decentralized control method, interference is avoided by assigning an unused channel at that time by autonomous determination of the base station in response to a channel request from a mobile terminal device. However, when one mobile terminal device occupies a large number of channels, there may be no channel remaining for assignment to other mobile terminal devices. For example, when one mobile terminal device is connected to a certain base station, other base stations in the range (hereinafter referred to as communication range) from which the radio terminal device can reach are allocated to that mobile terminal device. Cannot use the channel. Under such circumstances, the autonomous distributed control method tends to cause deterioration of the channel usage rate, and as a result, the channel usage rate of the entire system may be lowered.

  Japanese Patent Application Laid-Open No. H10-228688 discloses a technique for changing the allocation of time slots in a TDD cellular communication system to increase the use efficiency of communication resources. However, the technique of this document does not consider the above-mentioned circumstances peculiar to the autonomous distributed control system in which the base station autonomously performs carrier sense and performs channel allocation based on the result.

JP 2003-333646 A

  In an existing mobile communication system that employs an autonomous distributed control method, each base station performs channel assignment under autonomous control without considering the influence on other base stations. Therefore, if the same channel assignment as that of other mobile terminal apparatuses is performed to a mobile terminal apparatus that can be an interference source depending on the position, the channel usage rate as seen in the entire system deteriorates and the performance decreases. This problem becomes significant in a best effort type mobile communication system. In an extreme example, it is assumed that one base station (base station A) allocates all channels to a mobile terminal apparatus that includes two base stations (base stations A and B) in the communication range. Then, due to autonomous interference avoidance of the other base station (base station B), the base station B cannot use all channels as a result.

  The present invention has been made for the above-mentioned circumstances, and its purpose is to enable channel assignment in consideration of the influence of interference by the mobile terminal apparatus, thereby preventing deterioration of the channel usage rate and improving performance. It is an object of the present invention to provide a mobile communication system, its control device, and a mobile terminal device.

  In order to achieve the above object, according to one aspect of the present invention, in a mobile communication system comprising a plurality of base stations arranged in a cell in an autonomous distributed manner, a base station position that acquires position information of the plurality of base stations Information acquisition means, location information of a mobile terminal device that moves between cells formed for each base station, and communication range information that indicates a range of radio waves transmitted from the mobile terminal device for each mobile terminal device Based on terminal information acquisition means to acquire, position information of the base station, position information of the mobile terminal apparatus, and communication range information of the mobile terminal apparatus, the number of base stations included in the communication range is Calculating means for calculating for each mobile terminal device; and channel control means for dynamically varying the number of allocated channels for each mobile terminal device based on the number of base stations included in the communication range. Mobile communication system is provided, wherein.

  By taking such means, the number of allocated channels is dynamically varied for each mobile terminal device, using the number of base stations included in the communication range as an index. The number of base stations included in the communication range serves as an index indicating an area where interference by the mobile terminal apparatus occurs. That is, the greater the number of base stations included in the communication range, the lower the channel assignment priority and the smaller the number of assigned channels, the smaller the range affected by interference. In other words, channel usage rates are prevented from deteriorating by reducing the number of channel assignments for mobile terminal devices that include multiple base stations in the communication range and increasing the number of channel assignments for mobile terminal devices that do not interfere with other base stations. It becomes possible to improve the performance of the entire system.

  According to the present invention, it becomes possible to perform channel assignment in consideration of the influence of interference by the mobile terminal apparatus, and therefore, the mobile communication system, its control apparatus, and mobile device that prevent deterioration of the channel usage rate and improve performance A terminal device can be provided.

1 is a system diagram showing an embodiment of a mobile communication system according to the present invention. The functional block diagram which shows 1st Embodiment of the mobile communication system concerning this invention. The figure for demonstrating the channel allocation in XGP. The figure for demonstrating the channel allocation in XGP. The figure for demonstrating the channel allocation in XGP. The figure for demonstrating the channel allocation in XGP. The figure which shows the example of the channel allocation priority according to the position of a mobile terminal device. The figure which shows an example of the channel allocation determined based on the channel allocation priority. The flowchart which shows the process sequence which determines the channel allocation number to a mobile terminal device. The flowchart which shows an example of the procedure in a channel addition allocation process. The figure which shows an example which collects the positional information on a base station, and the positional information on a mobile terminal device. The figure which shows the other example which collects the positional information on a base station, and the positional information on a mobile terminal device. The functional block diagram which shows 2nd Embodiment of the mobile communication system concerning this invention. The functional block diagram which shows 3rd Embodiment of the mobile communication system concerning this invention. The sequence diagram which shows the process sequence in the case where base station BS11, BS12 is provided with the channel control part 206.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, description is made assuming XGP, but the present invention is not limited to this type of system. XGP cell design extends the traditional PHS system, divides one control channel frequency into several tens of times in the time direction, and autonomously discovers and uses timings not used by other base stations. It is designed to be shared between base stations. Therefore, even if the cells (base station areas) overlap each other, no interference occurs, and the overlapped portion is automatically made into a micro cell by selection on the mobile terminal device side. However, if a large number of channels are occupied by a mobile terminal device that reaches a plurality of base stations, channel resources allocated to other mobile terminal devices decrease, and the performance of the entire system decreases. Hereinafter, embodiments capable of solving this will be described.

[First Embodiment]
FIG. 1 is a system diagram showing an embodiment of a mobile communication system according to the present invention. This system is formed with a communication network 100 and control devices G11 and G12 connected thereto as a core. The communication network 100 is, for example, a private network of a carrier, and specifically, a packet communication network such as an IP (Internet Protocol) network, an IP-VPN (IP-Virtual Private Network) connection service, or an ISDN (Integrated Service Digital Network). Etc. A gateway 200 is provided to connect the communication network 100 to the Internet 300. In addition, the communication network 100 is provided with a server device 400 for remotely controlling the control devices G11 and G12 and providing various communication services.

  The control device G11 accommodates the base station BS11 via an individual line. The control device G12 accommodates the base station BS12 via another individual line. That is, the base stations BS11 and BS12 are under the control of different control devices. Of course, each control device G11, G12 accommodates a plurality of base stations as well as the base stations BS11, BS12. That is, a plurality of base stations are distributed and accommodated in one of the control devices G11 and G12.

  Each base station including BS11 and BS12 forms a radio zone (hereinafter referred to as a cell) and accommodates mobile terminal devices MS (MS11 and MS12) located in the cell via a radio channel. The mobile terminal devices MS11 and MS12 perform handover between the cells as they move, and switch the connection destination base station. The control devices G11 and G12 can also form a communication link between each other via the communication network 100, and the mobile terminal devices MS11 and MS12 can communicate with each other via this link. Furthermore, it is possible to access the Internet 300 via the gateway 200.

  In addition to this, the system of FIG. 1 is provided with a relay unit for connecting a personal computer (PC) or a fixed telephone (TEL) to the control devices G11 and G12. In particular, if voice call software is installed, a PC can be used as a telephone. Furthermore, an access point (not shown) compliant with a wireless LAN (Local Area Network) standard may be connected to the control devices G11 and G12.

  The control devices G11 and G12 perform various controls such as exchange processing or protocol conversion between opposing devices (such as the gateway 200 and the control device of the communication partner) in order to realize end-to-end communication between communication terminals. Bear. The control devices G11 and G12 specify signals (digital signals such as audio data, video and image data, data for performing various services, etc.) communicated via the base station via the communication network 100. Process according to the communication type.

  FIG. 2 is a functional block diagram showing an embodiment of a mobile communication system according to the present invention. In FIG. 2, mobile terminal apparatuses MS11 and MS12 include a position acquisition unit 101 that acquires a current position. The position acquisition unit 101 applies GPS (Global Positioning System), for example, and the acquired terminal position information is notified to the base stations (BS11, BS12) in the area by the wireless communication unit 102.

  The base stations BS11 and BS12 include a position acquisition unit 201 that acquires the current position. Further, the base stations BS11 and BS12 include another base station information acquisition unit 202 that acquires position information of other base stations, and a terminal information acquisition unit 203 that acquires position information of the mobile terminal device and transmission radio wave range information. The base station BS11 acquires the position information of the base station BS12 by the other base station information acquisition unit 202, and acquires the position information and transmission radio wave range of the mobile terminal device MS11 by the terminal information acquisition unit 203. These pieces of information are held in the position information management unit 204. Similarly, the base station BS12 holds the position information of the base station BS11 and the transmission radio wave range of the mobile terminal device MS12 in the position information management unit 204. The base stations BS11 and BS12 include a radio communication unit 205, and communicate with the radio communication unit 102 of the mobile terminal apparatuses MS11 and MS12 via a radio channel.

  The control device G11 includes an information collection unit 301, a channel control unit 302, and a channel assignment notification unit 303. The information collecting unit 301 collects and holds the position information of the base stations BS11 and BS12, the position information of the mobile terminal devices MS11 and MS12, and the transmission radio wave range from the position information management unit 204 of the base stations BS11 and BS12. The channel control unit 302 determines the number of channels to be assigned to each of the mobile terminal devices MS11 and MS12 based on the information collected by the information collecting unit 301. The determined number of channels is notified to the base stations BS11 and BS12 by the channel allocation notification unit 303. The radio communication unit 205 of the base stations BS11 and BS12 and the radio communication unit 102 of the mobile terminal apparatuses MS11 and MS12 perform radio communication based on the number of assigned channels notified from the channel assignment notification unit 303.

  3 to 6 are diagrams for explaining channel assignment in XGP. In XGP, (frequency axis direction: 900 kHz) × (time axis direction: 625 μs) is defined as a minimum unit for communication, and this minimum unit is referred to as a PRU (Physical Resource Unit). Channel allocation is performed in units of this PRU. As shown in FIG. 3, four PRUs are arranged in the time direction, nine or ten in the frequency direction, and a total of a maximum of 40 PRUs are arranged.

  As shown in FIG. 4, it is assumed that, for example, some of 40 PRUs are allocated to communication with a mobile terminal apparatus and are being used in a certain base station. From this state, for example, when a message requesting three PRUs is given from the mobile terminal device to the base station, the base station performs carrier sense and confirms the PRU used by itself and the PRUs used by neighboring base stations. To do. After that, as shown in FIG. 5, the base station performs control to allocate three of the unused PRUs to the requesting mobile terminal apparatus. However, as shown in FIG. 6, when all PRUs are allocated to one mobile terminal apparatus, it becomes impossible to cope with a new allocation request.

  Therefore, in this embodiment, channel allocation in consideration of the influence of interference on other base stations based on the mobile terminal device and the position of the base station is performed, thereby improving the channel usage rate in the entire system. That is, the number of base stations included in the communication range of the mobile terminal apparatus is used as an index for evaluating the influence of interference. Thus, a large number of channels are preferentially allocated to mobile terminal apparatuses that cover only a single base station and exist at positions that do not affect other base stations. On the contrary, the mobile terminal apparatus existing in a position including a plurality of base stations is limited to the minimum necessary channel allocation, and an additional channel is allocated only when a surplus channel is generated.

  In this way, the mobile terminal device that becomes the interference source is determined from the positions of the mobile terminal device and the base station, and channel allocation to the mobile terminal device of the interference source is suppressed, thereby preventing the channel utilization rate from being lowered and improving the overall system performance. It can be realized. This will be specifically described below.

  FIG. 7 is a diagram illustrating an example of channel assignment priority according to the position of the mobile terminal apparatus. In FIG. 7, the communication ranges of the mobile terminal apparatuses MS1, MS2, MS3, and MS4 are indicated by A1, A2, A3, and A4, respectively, and the width of each range is determined by, for example, the transmission power of each mobile terminal apparatus. The mobile terminal device MS1 is connected to the base station BS1, the mobile terminal devices MS2 and MS3 are connected to the base station BS3, and the mobile terminal device MS4 is connected to the base station BS2.

  In the example of FIG. 7, the mobile terminal apparatus MS1 includes the base station BS1, the mobile terminal apparatus MS3 includes the base station BS3 in the communication range, and both include a single base station in the communication range. Therefore, the priority of channel assignment to the mobile terminal device MS1 is the highest. On the other hand, since the mobile terminal apparatus MS2 includes both the base stations BS2 and BS3 in the communication range, if the mobile terminal apparatus MS2 is connected to the base station BS3, the base station BS2 uses the channel assigned to the mobile terminal apparatus MS2. Can not do. That is, the mobile terminal device MS2 becomes an interference source for the base station BS2. Therefore, in this embodiment, the mobile terminal device MS2 that is an interference source is set to have a lower channel allocation priority than the MS1 and MS3 that include a single base station in the communication range.

  Furthermore, since the mobile terminal apparatus MS4 includes three base stations BS1, BS2, and BS3 in the communication range, the influence level of interference is the highest, so the priority is set to the lowest. In this way, the number of mobile terminal devices including the base station in the communication range is calculated from the positions of the base station and the mobile terminal device and the communication range of the mobile terminal device, and movement with a small degree of interference influence on other base stations is calculated. The channel allocation priority is determined so that the terminal device has a high priority.

  FIG. 8 is a diagram illustrating an example of channel assignment determined based on channel assignment priority. Depending on the number of base stations covered by the communication range (the number of base station covers), channel assignment priority is set in three stages of high, medium, and low. Regardless of the channel priority, a minimum necessary channel (1ch in the example) defined by the system is always assigned to all mobile terminal apparatuses.

  Since the mobile terminal devices MS1 and MS3 including a single base station in the communication range have a high channel assignment priority, the requested number of channels are preferentially assigned. At this time, when there are a plurality of mobile terminal apparatuses having the same priority and the channel resource is less than the total number of requested channels, the mobile terminal apparatuses having the same priority perform channel allocation equally.

  For the mobile terminal devices MS2 and MS4 that include a plurality of base stations in the communication range, the channel allocation priority only when the channel allocation to the mobile terminal devices MS1 and MS3 having a high channel allocation priority is completed and there is a surplus channel. Assign additional channels according to In FIG. 8, since the mobile terminal apparatus MS2 has a higher channel assignment priority than the mobile terminal apparatus MS4, the channel addition assignment to the mobile terminal apparatus MS2 is performed with priority. While the required number of channels of the mobile terminal device MS2 is 3 ch, channel resources are insufficient, so channel allocation is 2 ch (circled). Further, since the mobile terminal device MS4 has the lowest priority, additional channel allocation is not performed for the requested number of channels 3ch, and only 1ch which is the minimum necessary channel is allocated (circled).

  In the example of FIG. 8, the priority is set to three levels of high, middle, and low. However, the priority is not limited to three, but may be two, or conversely, the priority may be determined over multiple levels of four or more. . The number of stages can be determined by system conditions and environment.

  FIG. 9 is a flowchart showing a processing procedure for determining the number of channels allocated to the mobile terminal apparatus. When the processing is started, the base station first assigns the minimum number of channels defined by the system to each mobile terminal apparatus (step S101). Next, the base station calculates the number of base stations included in the communication range for each mobile terminal apparatus based on the information held by the location information management unit 204, and sets the channel allocation priority based on the number of base stations included in the communication range. Determine (step S102). At this time, equal channel assignment can be realized by counting and holding the number of mobile terminal apparatuses having the same priority in advance.

  When the necessary minimum channel allocation (step S101) and priority determination (step S102) processing are completed for all mobile terminal devices (No in step S103), it is confirmed whether there is a surplus channel, that is, whether there is an unused PRU. (Step S104). If there is a surplus channel, additional channel allocation processing based on channel allocation priority is performed (step S105). When the additional channel assignment is completed, the base station instructs to change the number of channels at the timing of notification in wireless communication with each mobile terminal device (step S106), and starts communication on the newly assigned number of channels. . On the other hand, if there is no surplus channel in step S104 (No), the channel additional allocation process is not performed, and the communication between the base station and the mobile terminal device is continued.

  FIG. 10 is a flowchart illustrating an example of a procedure in the additional channel assignment process. The channel addition assignment process is performed based on the channel assignment priority set for each mobile terminal apparatus. In a situation where a channel can be added to a mobile terminal apparatus having a high channel allocation priority, no additional channel allocation is performed for a mobile terminal apparatus having a low priority.

  In FIG. 10, if there is another mobile terminal apparatus that has a higher priority than the selected mobile terminal apparatus (determination target mobile terminal apparatus) and the number of allocated channels is less than the requested channel number (Yes in step S201), the selected mobile terminal apparatus is selected. The channel addition to the mobile terminal device is suspended (step S202). If there is a remaining surplus channel (Yes in step S203) and there is a mobile terminal device that has not reached the required number of channels (Yes in step S204), the channel additional allocation process is continued. If there is no surplus channel or if the allocation of the requested number of channels is completed for all mobile terminal apparatuses, the channel additional allocation process is terminated.

  On the other hand, if there is no other mobile terminal apparatus having a higher priority than the selected mobile terminal apparatus in step S201, or if all the requested channel numbers have been allocated to the mobile terminal apparatus having a higher priority (in step S201). No), additional channel assignment processing is performed (step S205). In this step, based on the number of mobile terminal devices having the same priority, additional channels are allocated to be equal to the mobile terminal devices having the same priority. After additional channel assignment, the surplus channels are confirmed (step S203) and the mobile terminal apparatus that has not reached the required number of channels (step S204) as in the case of unassigned channels, and the processing is continued until no additional channel assignment is possible. The

  FIG. 11 is a diagram illustrating an example of collecting base station position information and mobile terminal apparatus position information. In this example, each of the mobile terminal devices MS1, MS2, MS3, and MS4 acquires current position information using GPS and the like, and the radio interface IF1 of a prescribed transmission radio wave with respect to the connected base stations BS1, BS2, and BS3, Current position information is notified via IF2, IF3, and IF4. Each base station holds the collected information in the location information management unit 204, calculates the number of base stations included in the communication range from the location information of surrounding base stations for each mobile terminal device, and based on the number Determine channel assignment priority.

  FIG. 12 is a diagram illustrating another example of collecting position information of a base station and position information of a mobile terminal device. In this example, the mobile terminal device itself detects surrounding base stations, and directly reports base station information included in its communication range to a connection destination base station. In FIG. 12, the mobile terminal device MS1 detects base stations BS1, BS3, BS4 that can be connected in its transmission radio wave range, and notifies the number of base stations included in its communication range instead of its own location information. Thus, when determining the channel priority in the channel control unit 302, the channel based on the number of base stations included in the communication range notified from each mobile terminal device without using the location information of the mobile terminal device. Allocation priority can be determined.

  As described above, in this embodiment, in a mobile communication system in which a plurality of base stations autonomously avoid interference, the influence of interference on other base stations is considered based on the position of the mobile terminal device and the base station. By performing channel assignment, the channel usage rate in the entire system is improved. That is, the number of base stations included in the communication range of the mobile terminal apparatus is used as an index for evaluating the influence of interference. Thus, a large number of channels are preferentially allocated to mobile terminal apparatuses that cover only a single base station and exist at positions that do not affect other base stations. On the contrary, the mobile terminal apparatus existing in a position including a plurality of base stations is limited to the minimum necessary channel allocation, and an additional channel is allocated only when a surplus channel is generated.

  In this way, the mobile terminal device serving as the interference source can be identified from the positional relationship between the mobile terminal device and the base station, and the channel usage rate can be reduced by lowering the priority of channel assignment to the mobile terminal device serving as the interference source. Can be prevented. This makes it possible to improve the performance of the entire system.

[Second Embodiment]
FIG. 13 is a functional block diagram showing a second embodiment of the mobile communication system according to the present invention. In FIG. 13, parts common to FIG. 2 are denoted by the same reference numerals, and only different parts will be described below. The gateway 200 shown in FIG. 13 includes an information collection unit 401, a channel control unit 402, and a channel assignment notification unit 403. The information collecting unit 401 collects and holds the position information of the base stations BS11 and BS12, the position information of the mobile terminal devices MS11 and MS12, and the transmission radio wave range from the position information management unit 204 of the base stations BS11 and BS12 via the control device G11. To do. The channel control unit 402 determines the number of channels allocated to each of the mobile terminal devices MS11 and MS12 based on the information collected by the information collecting unit 401. The determined number of channels is notified to the base stations BS11 and BS12 by the channel allocation notification unit 403 via the control device G11.

  That is, in this embodiment, the gateway 200 includes the information collection unit, the channel control unit, and the channel assignment notification unit in FIG. Even with such a configuration, as in the first embodiment, the priority of the number of assigned channels based on the location information of the mobile terminal apparatus can be determined, and the same effect as in the first embodiment can be obtained. become.

[Third Embodiment]
FIG. 14 is a functional block diagram showing a third embodiment of the mobile communication system according to the present invention. In FIG. 14, portions common to FIGS. 2 and 13 are denoted by the same reference numerals, and only different portions will be described below. In this embodiment, each base station BS11, BS12 is provided with a channel control unit 206. The channel control unit 206 determines the number of channels to be allocated to the mobile terminal device based on the information held in the location information management unit 204. That is, in this embodiment, each base station BS11, BS12 includes the channel control unit in FIG.

  FIG. 15 is a sequence diagram illustrating a processing procedure in the case where the base stations BS11 and BS12 include the channel control unit 206 as illustrated in FIG. In FIG. 15, it is assumed that there are a plurality of base stations BS1 to BS4. Among these, the mobile terminal apparatus accommodated in the base station BS1 is targeted. Further, mobile terminal apparatuses accommodated in the base station BS1 are grouped into those that include only BS1 in the transmission range (MS group 1) and those that include a plurality of base stations in the transmission range (MS group 2). explain.

  The base station BS1 acquires base station position information in advance in order to perform channel control in cooperation with adjacent base stations. The base station BS1 transmits a base station position information acquisition request (S301) to the surrounding base stations (BS2 to BS4) at the first activation or at a periodic confirmation timing with a sufficiently long interval. When receiving the base station location information acquisition response (S302) as the response, the base station BS1 grasps the adjacent base station based on the base station location information included in the response (S302) (S303). Note that the base stations (BS2 to BS4) that transmit the base station position acquisition information (S301) are base station groups that are partitioned into the same area as BS1 by an IP address or the like. In the example of FIG. 15, description will be made assuming that all base stations BS2 to BS4 are determined as adjacent base stations.

  The base station BS1 starts channel control for the mobile terminal device at the notification timing (S304), and transmits a terminal location information acquisition request (S305) to all the mobile terminal devices accommodated in the BS1. The mobile terminal device accommodated in BS1 receives the terminal location information acquisition request (S305) as a trigger, and receives the terminal location information acquired by the GPS or the like built in the mobile terminal device in the terminal location information acquisition response (S306). Notify the station BS1.

  Base station BS1 groups mobile terminal devices into MS group 1 and MS group 2 based on the notified location information of each mobile terminal device and adjacent base station location information. The base station BS1 secures the minimum channel necessary for communication to all mobile terminal devices, notifies the mobile terminal device by channel assignment notification (S307), and includes only the base station BS1 in the transmission radio wave range 1 As for the mobile terminal apparatus, additional channel allocation is performed as long as there is an empty channel of BS1 (S308).

  The channel assignment notification notifies the mobile terminal device of channel numbers that can be used by notifying the mobile terminal device of bitmap information corresponding to the channel number. In this way, a channel is preferentially given to the MS group 1 including only the base station BS1 in the transmission radio wave range.

  When the base station BS1 has a free channel remaining in the state where the additional channel assignment has been completed for all the mobile terminal devices of the MS group 1 (S309), the base station BS1 adds the additional channel for the MS group 2 including a plurality of base stations in the transmission radio wave range. Perform the assignment.

  For mobile terminal devices included in the MS group 2, the mobile terminal device determines priority based on the number of base stations included in the transmission radio wave range, and assigns additional channels in order from the mobile terminal devices with the smaller number of base stations included in the transmission radio wave range. Do. Here, the priority of the mobile terminal apparatus is uniquely determined by the number of base stations included in the transmission radio wave range of the mobile terminal apparatus.

  The base station BS1 transmits to the adjacent base stations (BS2 to BS4) a channel reservation request (S310) to which terminal information including the priority of the mobile terminal apparatus that performs the additional channel assignment is added. Neighboring base stations (BS2 to BS4) that transmit the channel securing request (S310) are base station groups included in the transmission radio wave range by the mobile terminal device that performs the additional channel assignment. These adjacent base stations (BS2 to BS4) are a base station group in which an unusable channel is generated because BS1 is affected by interference due to channel assignment.

  The adjacent base station that has received the channel reservation request (S310) determines whether or not to allow addition of a channel based on its own channel usage status, and returns a response to BS1 in a channel reservation response (S311). The determination as to whether or not channel addition is permitted is whether there is an empty channel, and whether there is a mobile terminal device that has not been assigned an additional channel and has a higher priority than the mobile terminal device specified in the channel reservation request (S310). Decide on the basis.

  When each of the adjacent base stations (BS2 to BS4) has an empty channel and there is no mobile terminal apparatus having a higher priority than the mobile terminal apparatus specified by the channel reservation request (S310), the channel reservation response (OK) ) Is transmitted (S311). When the base station BS1 receives a channel reservation response (OK) from all the adjacent base stations (BS2 to BS4) that transmitted the channel reservation request (S310) (S312), the base station BS1 notifies the mobile terminal device of an additional channel assignment notification. Transmit (S313).

  If adjacent base stations (BS2 to BS4) do not have an empty channel, these base stations (BS2 to BS4) transmit an additional channel assignment (NG). When at least one additional channel assignment (NG) is received, the base station BS1 does not perform the channel addition assignment operation to the mobile terminal apparatus. For the mobile terminal apparatus that has received the channel reservation response (NG), the base station BS1 is excluded from the additional channel allocation candidates because the additional channel allocation is not possible due to the channel usage status of the adjacent base station.

  Further, when there is a mobile terminal device having a higher priority than the mobile terminal device designated by the channel reservation request (S310), a channel reservation response (S311) until the additional channel assignment to the mobile terminal device having a higher priority is completed. Suspend sending In this way, additional channel allocation is performed in order from the mobile terminal apparatus with the highest priority in cooperation between adjacent base stations. The above additional channel assignment operation is repeated until there is no free channel in BS1 or there are no mobile terminal devices that require additional channel assignment in the mobile terminal devices included in MS group 2.

  By the above processing procedure, the priority of the number of allocated channels based on the location information of the mobile terminal apparatus can be determined as in the first embodiment, and the same effect as in the first embodiment can be obtained. become.

  As described above, according to the first to third embodiments, it becomes possible to perform channel assignment in consideration of the influence of interference by the mobile terminal apparatus, thus preventing deterioration of the channel usage rate and improving performance. It is possible to provide the mobile communication system, its control device, and mobile terminal device.

The characteristic matters of the present invention are summarized below.
(1) Whether each mobile terminal device includes a plurality of base stations in its communication range is determined from the location information of the mobile terminal device and the base station and the transmission radio wave range of the mobile terminal device, and based on the result To change the channel allocation number for each mobile terminal. The positions of the mobile terminal device and the base station can be acquired using GPS or the like. Since the position of the base station is fixed, it may be stored in the system in advance.

(2) A minimum number of channels are allocated to a mobile terminal apparatus including a plurality of base stations in the communication range.
(3) A channel is assigned with high priority to a mobile terminal apparatus including a single base station (single base station) in the communication range.
(4) A mobile terminal that includes a plurality of base stations in the communication range only when there is no mobile terminal device that includes a single base station in the communication range or when the number of channels requested from these mobile terminal devices has been allocated. Allocate additional channels for the device.

(5) For mobile terminal devices that include a plurality of base stations in the communication range, priority is determined according to the number of base stations included in the communication range, and priority is given to mobile terminal devices that cover a small number of base stations. Perform additional channel assignment. That is, the higher the number of base stations included in the communication range, the lower the channel allocation priority.
(6) The number of channel assignments of the mobile terminal apparatus is changed at each radio channel broadcast timing. It is also possible to dynamically change the timing of changing the number of channels based on the system conditions.
(7) Instead of the location information of the base station and the mobile terminal device, the mobile terminal device may directly notify the system of the number of base stations that can be confirmed within its communication range.
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 100 ... Communication network, 200 ... Gateway, 300 ... Internet, 400 ... Server apparatus, G11, G12 ... Control apparatus, BS11, BS12 ... Base station, MS11, MS12 ... Mobile terminal apparatus, 101 ... Location acquisition part, 102 ... Wireless communication , 201 ... location acquisition unit, 202 ... other base station information acquisition unit, 203 ... terminal information acquisition unit, 204 ... location information management unit, 205 ... wireless communication unit, 206 ... channel control unit, 301 ... information collection unit, 302 ... Channel control unit, 303 ... Channel allocation notification unit, 401 ... Information collection unit, 402 ... Channel control unit, 403 ... Channel allocation notification unit

Claims (12)

In a mobile communication system comprising a plurality of base stations arranged in a cell in an autonomous distributed manner,
Base station location information acquisition means for acquiring location information of the plurality of base stations;
Terminal information acquisition for acquiring, for each mobile terminal device, location information of mobile terminal devices moving between cells formed for each base station and communication range information indicating a range of radio waves transmitted from the mobile terminal devices Means,
Calculation for calculating the number of base stations included in the communication range for each mobile terminal device based on the location information of the base station, the location information of the mobile terminal device, and the communication range information of the mobile terminal device Means,
A mobile communication system comprising: channel control means for dynamically changing a channel allocation number for each mobile terminal apparatus based on the number of base stations included in the communication range. 2. The mobile communication system according to claim 1, wherein the channel control unit sets a higher priority for the channel allocation number for a mobile terminal device having a smaller number of base stations included in the communication range. The mobile communication system according to claim 2, wherein the channel control means allocates a predetermined minimum number of channels to each mobile terminal apparatus regardless of the priority. The mobile communication system according to claim 2, wherein the channel control means allocates the required number of channels to the mobile terminal apparatus having the highest priority as much as possible. The mobile communication system according to claim 2, wherein the channel control means equally adds the channel to mobile terminal devices having the same priority. In a control system provided in a mobile communication system including a plurality of base stations arranged in a cell in an autonomous distributed manner and connected to the plurality of base stations,
Base station location information acquisition means for acquiring location information of the plurality of base stations;
Terminal information acquisition for acquiring, for each mobile terminal device, location information of mobile terminal devices moving between cells formed for each base station and communication range information indicating a range of radio waves transmitted from the mobile terminal devices Means,
Calculation for calculating the number of base stations included in the communication range for each mobile terminal device based on the location information of the base station, the location information of the mobile terminal device, and the communication range information of the mobile terminal device Means,
A control apparatus comprising: channel control means for dynamically varying a channel allocation number for each mobile terminal apparatus based on the number of base stations included in the communication range. 7. The control apparatus according to claim 6, wherein the channel control means sets a higher priority for the channel allocation number in a mobile terminal apparatus having a smaller number of base stations included in the communication range. 8. The control apparatus according to claim 7, wherein the channel control means allocates a predetermined minimum number of channels to each mobile terminal apparatus regardless of the priority. 8. The control apparatus according to claim 7, wherein the channel control means allocates the required number of channels to the mobile terminal apparatus having the highest priority to the maximum extent. The control apparatus according to claim 7, wherein the channel control means adds the channel equally to mobile terminals having the same priority. Comprising a plurality of base stations arranged in cells in an autonomous distributed manner;
Base station location information acquisition means for acquiring location information of the plurality of base stations;
Terminal information acquisition for acquiring, for each mobile terminal device, location information of mobile terminal devices moving between cells formed for each base station and communication range information indicating a range of radio waves transmitted from the mobile terminal devices Means,
Calculation for calculating the number of base stations included in the communication range for each mobile terminal device based on the location information of the base station, the location information of the mobile terminal device, and the communication range information of the mobile terminal device Means,
Provided in a mobile communication system comprising channel control means for dynamically varying the number of channel assignments for each mobile terminal apparatus based on the number of base stations included in the communication range, and formed for each base station In a mobile terminal device that moves between cells,
Notification means for notifying the mobile communication system of the position information of the own device;
A mobile terminal apparatus comprising: wireless communication means for communicating with the base station using the number of channels allocated from the mobile communication system. The mobile terminal apparatus according to claim 11, wherein the notifying means notifies the mobile communication system of the number of base stations included in a communication range of the own apparatus.

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