JP2908991B2 - Wireless channel allocation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio channel allocating method in a mobile communication system for performing communication between a radio base station and a mobile station.

[0002]

2. Description of the Related Art In a mobile phone or car phone system that is currently widely used, a radius of a wireless zone served by one wireless base station is set to several kilometers, and a large number of wireless base stations are arranged in a service area. Cellular systems that provide services through are well known.

In general, in a cellular system, a so-called geographically repetitive use of a radio channel in which the same radio channel is used by different radio base stations geographically separated for the purpose of effectively using a finite radio channel. Is performed. By making the distance between the radio base stations using the same radio channel as small as possible, high frequency utilization efficiency can be obtained, and the system capacity can be increased under the condition that the frequency bandwidth given to the system is constant. .

On the other hand, when the repetition distance of a radio channel is reduced, interference from the same radio channel or FDM
In the A method, interference between adjacent wireless channels occurs in the interleaving method in which the overlapping of the powers of the sidebands of the wireless channel is allowed to form the wireless channel, and the communication quality is significantly reduced. The size cannot be reduced, and it is necessary to repeatedly use the same radio channel in radio base stations that are sufficiently far apart spatially so that the interference does not exceed a certain allowable value. Methods for realizing repeated use of a wireless channel satisfying such conditions are roughly classified into a fixed channel allocation method and a dynamic channel allocation method. There is an assignment method.

[0005] The fixed channel allocation method is a method in which the radio wave propagation situation and the traffic distribution are obtained by actual measurement or theoretical calculation, and the radio channels are fixedly arranged at each radio base station. In general, there is a drawback in that the design for determining the fixed arrangement requires enormous effort, and further, re-design is necessary even when additional equipment is added. In addition, since a radio channel usable as the whole system is divided into several groups and assigned to each radio base station, there is a disadvantage that a division loss occurs and high frequency use efficiency cannot be obtained.

On the other hand, the dynamic channel assignment method is as follows:
It is possible to allocate the wireless channel with some flexibility to the temporal variation of traffic, spatial bias, etc.
Since the radio channels usable in the entire system can be used by any radio base station, a large grouping effect is obtained, and the frequency use efficiency is improved as compared with the fixed channel allocation method.

However, in order to minimize the call loss rate or the probability of occurrence of interference, a large amount of information and complicated control are generally required. In the centralized control type dynamic channel allocation scheme, each radio base station and control station are required. In the autonomous decentralized dynamic channel assignment scheme, there are many processes up to channel assignment, and the connection delay is increased.However, the control load is low and high frequency use efficiency is reduced. It is very important to realize a radio channel allocation scheme that can be obtained.

As a wireless channel allocation method for realizing autonomous distributed dynamic channel allocation by a relatively simple control method, the allocation priority of each wireless channel is calculated from a past allocation availability history, and the allocation priority is high. The assignment of the wireless channel is determined in order from the wireless channel. If the assignment is determined to be possible, the wireless channel is assigned. Otherwise, the wireless channel with the next highest priority is assigned, and the assignment is determined. (Japanese Patent Laid-Open Nos. 61-244137 and 62-91033) have been proposed.

For example, in the radio communication system disclosed in Japanese Patent Application Laid-Open No. 61-244137, priorities that are variably determined based on past history of channel use are given to each channel, and channels used with higher priority are used sequentially. The transmission channel control method disclosed in Japanese Patent Application Laid-Open No. 62-91033 stores a transmission success rate for each channel, and sequentially uses the channels having the higher transmission success rates for transmission. The success rate is updated based on the transmission result.

[0010]

The above-mentioned conventional fixed channel allocation method has the drawbacks that it has low adaptability to system expansion and high frequency use efficiency cannot be obtained.

In the centralized control type dynamic channel allocation scheme of the dynamic channel allocation schemes, signal traffic between each radio base station and the control station increases.
In addition, the autonomous distributed dynamic channel assignment method has a drawback that a large amount of processing is required up to channel assignment and connection delay is increased.

Further, as described above, a conventional autonomous distributed dynamic channel allocation method in which the allocation priority of each wireless channel is calculated from the past allocation availability history and the wireless channel is allocated based on the allocation priority. Since only one priority is assigned to each wireless channel, the repeated use of the wireless channel is limited to the repeated use in units of the wireless zone, and the frequency use efficiency is lower than that of the fixed channel allocation method. However, there is a drawback in that the improvement is limited to the large grouping effect obtained by making the wireless channels available for the entire system available to each wireless base station.

The present invention has been made in view of the above,
It is an object of the present invention to provide an autonomous decentralized wireless channel allocation method that has a small control load and can obtain high frequency use efficiency.

[0014]

In order to achieve the above object, a radio channel allocating method according to the present invention is directed to a mobile communication system for performing communication between a mobile station and a radio base station, wherein the radio base station is an entire system. A function of transmitting / receiving one or more arbitrary radio channels among radio channels usable as a radio channel, and a function of measuring whether or not the selected radio channel is usable; One or a plurality of radio channels are selected from the radio channels available as the entire system by referring to the allocation priority assigned to each of them, and whether the radio channels can be used in order from the radio channel with the highest allocation priority A radio channel assignment method for deciding whether or not to assign a radio channel, wherein the radio base station manages N assignment priority tables. By the N number of allocation priority assigned to one radio channel, the state of the mobile station to be assigned a radio channel, the mobile station N
The gist is that the wireless channels are divided into groups and the radio channels are allocated according to the allocation priorities recorded in the allocation priority table corresponding to the groups.

[0015] Further, the radio channel assignment method of the present invention comprises:
In the above description, the gist is that the assignment priority of the wireless channel is adaptively determined based on the past usage history of the wireless channel in the group.

[0016] In addition, the radio channel assignment method of the present invention comprises:
In the above, the gist is that the assignment priority of the wireless channel is adaptively determined based on the past use history of the wireless channel in the group and other groups.

In the wireless channel allocating method of the present invention, when allocating a wireless channel, a distance of a mobile station from a wireless base station is provided as a state of the mobile station for grouping.

Further, the radio channel assignment method according to the present invention comprises:
In the above description, when assigning a wireless channel, the gist is that the direction in which a mobile station moves is provided as a state of the mobile station and is used for grouping.

Further, the radio channel allocating method of the present invention comprises:
In the above description, when assigning a wireless channel, the gist is that the moving speed of the mobile station is provided to the grouping as the state of the mobile station.

In the wireless channel allocation method according to the present invention, the wireless channel is allocated by arbitrarily combining the distance of the mobile station from the wireless base station, the moving direction of the mobile station, and the moving speed of the mobile station. Of the mobile station as a state of the mobile station.

In the wireless channel allocation method according to the present invention, at the time of wireless channel allocation, at least one of the mobile station itself and the base station measures the state of the mobile station.

[0022]

According to the radio channel assignment method of the present invention, the radio base station manages N assignment priority tables,
N allocation priorities are assigned to one radio channel, and upon allocating radio channels, the radio base station divides the mobile stations into N groups based on the extracted characteristics of the mobile stations, and Radio channels are allocated according to the allocation priority recorded in the corresponding allocation priority table.

Further, in the radio channel assignment method of the present invention, the assignment priority of the radio channel is adaptively determined based on the past use history of the radio channel in the group.

Further, in the radio channel allocating method of the present invention, the allocation priority of the radio channel is adaptively determined based on the past usage histories of the radio channels in the group and other groups.

In the radio channel assignment method of the present invention, when assigning a radio channel, the distance of the mobile station from the radio base station is measured as the state of the mobile station.

In the radio channel assignment method of the present invention, the direction in which the mobile station moves is measured as the state of the mobile station when assigning a radio channel.

Further, in the radio channel allocating method of the present invention, when allocating the radio channel, the moving speed of the mobile station is measured as the state of the mobile station.

According to the radio channel allocation method of the present invention, when allocating a radio channel, a combination of any combination of the distance of the mobile station from the radio base station, the moving direction of the mobile station, and the moving speed of the mobile station is used. Measure as station status.

In the radio channel allocating method of the present invention, when allocating a radio channel, the mobile station itself, the base station, or both of them measures the state of the mobile station. Assign wireless channels according to the degree.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a mobile communication system to which the wireless channel assignment method of the present invention is applied.
The mobile communication system shown in FIG.
1 and a plurality of mobile stations 12 connected to and communicating with the radio base station 11 using one or more radio channels.

In the entire mobile communication system thus configured, M radio channels can be used, and the i-th radio base station 11 in this mobile communication system
Ki transceivers capable of transmitting and receiving on any of the M radio channels are provided, and each mobile station 12 connected to and communicating with this mobile communication system is provided with any of the M radio channels. It is assumed that a transceiver capable of transmitting and receiving on a channel is provided.

FIG. 2 is a block diagram functionally showing a configuration of the radio base station 11 used in the mobile communication system shown in FIG. 1, particularly a configuration of a portion related to radio channel allocation. In the wireless base station 11 shown in the figure, Ki transceivers 1, 2,...
And the transceiver control device 13 is connected to the radio channel control device 14. Also, the radio base station
A mobile device characteristic measuring device 15 for extracting characteristics of a mobile station is provided, and the mobile device characteristic measuring device 15 is a mobile device characteristic measuring device control device 16 for controlling the mobile device characteristic measuring device 15.
Is connected to the radio channel controller 14 through
Further, the radio channel control device 14 is
And a memory 18.

The radio channel controller 14 reads, updates, and writes data stored in the memory 18 in response to a request from the call processing controller 17, and reads the radio currently used by the radio base station. Manage channels.
The transceiver control device 13 manages the transceivers 1, 2,... Ki, and determines whether or not the wireless channel specified by the wireless channel control device 14 can be allocated.

FIG. 3 conceptually shows an example of data stored in the memory 18. In this example, when assigning a wireless channel, the mobile stations are grouped according to characteristics of the distance, the moving direction, and the moving speed of the mobile station from the wireless base station. The memory 18 has a flag indicating whether the M radio channels are in use or unused in the radio base station, N allocation priorities for one radio channel, and N mobile stations to which the radio channel is to be allocated. Thresholds, such as distance, moving direction, and moving speed, for sorting into individual groups are recorded.

FIG. 4 is a flowchart showing a processing procedure of the radio channel assignment method of the first embodiment in the mobile communication system shown in FIGS. The processing procedure of the radio channel assignment method will be described with reference to the flowchart shown in FIG. In FIG. 4, first, when there is a request to allocate a wireless channel for a new call or wireless channel switching from the call processing control device 17, the wireless channel control device 14 checks whether there is a wireless channel that is not currently in use. Perform (Step 110). If all the radio channels are in use, the fact is notified to the call processing control device 17 and the process is terminated.

On the other hand, if there is a usable radio channel in step 110, the radio channel controller 1
4 make an inquiry to the transceiver control device 13 as to whether there are any transceivers 1, 2,... Ki that are not currently in use (step 120). If there is no usable transceiver, the transceiver controller 13 notifies the call processing controller 17 of the fact via the radio channel controller 14 and ends the process.

If there is a transceiver that can be used in step 120, the process proceeds to step 130, where the radio channel controller 14 determines the characteristics of the mobile station to which the radio channel is to be assigned to the mobile device characteristic measuring device controller 16. An extraction command is issued, and the mobile device characteristic measuring device control device 16 causes the mobile device characteristic measuring device 15 to perform characteristic measurement of the mobile station. Then step 1
Proceeding to 40, upon receiving the measurement result from the mobile device characteristic measuring device 15, the mobile device characteristic measuring device control device 16 notifies the wireless channel control device 14 of the measurement result. The radio channel controller 14 compares the notified measurement result with a threshold value stored in the memory 18 for determining a priority table number, and determines a priority table number.

In step 150, the radio channel controller 1
4 refers to the allocation priority of the priority table number determined in step 140 in the memory 18 and selects the wireless channel number having the highest allocation priority among the wireless channels that are not currently in use, and Notify the control device 13. In step 160, the transceiver control device 13 determines whether or not the wireless channel can be used as described later, and returns the result to the wireless channel control device 14.

The radio channel controller 14 increases the allocation priority for the radio channel on the priority table if the result of the judgment on availability in the transceiver controller 13 indicates that the radio channel can be used (step 170). The above value is updated, and the wireless channel number is updated to the call processing control device 1.
7 is set, the used / unused flag of the wireless channel is set as being used, and the wireless channel is allocated (step 175).

If the result of the determination as to whether or not the wireless channel can be used in step 160 is unusable, the priority assigned to the wireless channel in the priority table is reduced (step 180), and the value in the memory is updated. And
Next, a radio channel with the highest priority is selected (step 1).
90, 200), and returns to step 160 to repeat the same processing.

If the results of the determination as to whether the wireless channels are not currently in use are not available, the wireless channel control device 14 notifies the processing control device to that effect.
The process ends (step 190).

Various methods are conceivable as a method of determining whether or not to allocate a wireless channel in the processing of steps 150 and 160 in the above-described wireless channel allocating method. Set to a radio channel, receive, and, if the reception level, that is, the interference wave level is equal to or less than a predetermined threshold value, determine that allocation is possible. Notify and send on that wireless channel,
This is received by the radio base station, and the power ratio of the desired wave and the interference wave in the radio channel is measured. A method in which the mobile station is notified of the provisional setting of the radio channel and measures the interference wave level or the power ratio between the desired wave and the interference wave and compares the result with a predetermined threshold value. There is.

The threshold value of the interference wave level and the threshold value of the power ratio between the desired signal and the interference signal may be the same for all groups, or different threshold values may be used for each group. Good. For example, the power ratio of the desired wave and the interference wave, the mobile station with a low moving speed is considered to have a small fluctuation in the communication state, so take a small margin for the required value, and conversely, for a mobile station with a high moving speed, A method of increasing a margin for a required value can be considered. Similarly, for the interference wave level, the interference wave level threshold for the mobile station near the radio base station is increased and the interference wave level threshold for the mobile station at the cell edge is decreased so as to satisfy the required communication quality. It can be set.

FIGS. 2 and 4 show an example in which the radio base station measures the state of the mobile station when allocating a radio channel. The measurement of the state of the mobile station may be configured to be performed by the mobile station. In this case, for example, the mobile station measures the state of its own station according to a command from the radio base station at the time of an outgoing / incoming call, and reports it to the radio base station. A method of measuring the status and reporting the status to the radio base station is conceivable. In any case, the present invention can be applied, and the same effects can be obtained.

In the above-described control flow, the method of determining the assignment priority from the result of the assignment permission / non-permission judgment in the group has been described. However, a method of setting the assignment priority from the result of the assignment permission / non-permission judgment of the group and the other group can be considered. . For example, when the result of the assignment permission / inhibition judgment is “OK”, by performing an operation of increasing the assignment priority of the group to the wireless channel and simultaneously decreasing the assignment priority of the other group to the wireless channel, The convergence time of the degree can be shortened. By performing the above processing, the radio channel is automatically used properly in the radio base station according to the characteristics of the mobile station, and the radio channel is properly used properly between the radio base stations. A high quality wireless channel allocation method can be realized with simple control.

Examples of assignment priorities for each radio base station and each group will be described based on the results of computer simulation. As shown in FIG. 5, there are two adjacent wireless base stations, and the number of wireless channels is five in total. The number of priority tables, that is, the number of groups is three,
As a feature of the mobile station, grouping was performed by measuring only the distance from the radio base station. The distance of the mobile station from the radio base station was estimated by measuring the reception level of radio waves transmitted by the mobile station at the radio base station. Further, it is assumed that the occurrence of the call follows the Poisson distribution, and the call is uniformly distributed in the wireless zone. The applied call volume in the two wireless zones was assumed to be equal. As a method of determining whether or not allocation is possible, it is determined that allocation is possible if the ratio between the desired wave and the interference wave in the uplink and downlink is equal to or greater than a threshold. As interference waves, only co-channel interference was considered.

FIG. 6 shows the assignment priorities of the two radio base stations after a sufficient time has elapsed from the start of the simulation. FIG. 6A shows the assignment priority of the priority table # 1.
6 (b) is an assignment priority used for a mobile station close to the radio base station, FIG. 6 (c) is an assignment priority used for a mobile station at a medium distance from the radio base station, and FIG. This is an assignment priority used for a mobile station that is far from the mobile station. In each assignment priority graph, the higher the value on the vertical axis, the higher the priority.

In FIG. 6A, in both base stations, channel 0 has the highest allocation priority.
It can be seen that the same wireless channel is used with a high priority in the adjacent wireless zone for a mobile station that is short from the wireless base station. FIG. 6B and FIG.
In (c), the wireless base station 1 and the wireless base station 2 have different wireless channels with high allocation priorities. For example, FIG.
In (c), the wireless channel 2 has the highest allocation priority in the wireless base station 1 and the wireless channel 4 in the wireless base station 2. It can be seen that different radio channels are used to avoid interference from other radio zones.

Further, it can be seen that, even within the same radio base station, the use of radio channels with other groups is automatically performed. For example, in the wireless base station 1 of FIG. 6A, the assignment priority of the channel 0 is high, and in the wireless base station 1 of FIGS. 6B and 6C, the assignment priority of the channel 0 is low. 6 (b), the assignment priority of channel 3 is high, and the assignment priority of channel 3 of the wireless base station 1 in FIGS. 6 (a) and 6 (c) is high. The degree is low.

Generally, in the case of a mobile station that is far from the radio base station and located at the end of the radio zone, the reception level of the desired wave is low in both the uplink and downlink, so the radio channel allocated to such a mobile station is In addition, in order to prevent the degradation of the communication quality, it is necessary to repeatedly use the wireless base station at a relatively large distance so that the level of interference waves from nearby radio base stations or mobile stations can be kept low. Conversely, in the case of a mobile station that is short in distance from the radio base station, a certain level of desired wave reception level is secured, so even if a wireless channel with a small repetition distance is used compared to a mobile station located at the end of the radio zone. The communication quality does not deteriorate.

Accordingly, the frequency use efficiency can be improved by selectively using a radio channel having a large repetition distance and a radio channel having a small repetition distance according to the distance between the radio base station and the mobile station. According to the radio channel assignment method of the present invention, the use of the radio channel in the radio base station and between the radio base stations according to the characteristics of the mobile station are automatically performed by autonomous distributed control of the base station. A high wireless channel allocation method can be realized with simple control.

A description will now be given of a computer simulation performed to quantitatively confirm the effects of the present invention and the results thereof. In this simulation, the wireless zone is a hexagonal omnicell, and the service area is composed of 61 wireless zones. Call generation follows the Poisson distribution and occurs spatially uniformly within the wireless zone. Average call hold time is 1
Assume an exponential distribution of 20 seconds. In addition, it is assumed that the call behavior in each wireless zone is the same. It is assumed that a mobile station that intends to make or receive a call selects a wireless zone by measuring the reception power of a perch channel (control channel) previously transmitted at a constant transmission power from a wireless base station. . Also, the number of wireless channels that can be used in the entire system was 35, and only co-channel interference was considered as interference. The number of priority tables, that is, the number of groups was set to 7, and as a feature of the mobile station, only the distance from the radio base station was measured to perform grouping. The distance of the mobile station from the radio base station was estimated by measuring the reception level of radio waves transmitted by the mobile station at the radio base station. As a method of determining whether or not allocation is possible, it is determined that allocation is possible if the ratio between the desired wave and the interference wave in the uplink and downlink is equal to or greater than a threshold.

FIGS. 7 and 8 show the results of the computer simulation. The accommodated call volume is defined as an applied traffic volume per wireless zone at a call loss rate of 3%. FIG. 7 shows the call loss rate. The horizontal axis indicates the applied traffic volume, which is standardized by the accommodated traffic volume in the conventional wireless channel allocation method using a single allocation priority. FIG. 8 shows the number of times of deciding whether or not allocation is required for allocating one call, which is standardized by the value of the accommodated traffic in the conventional method. The horizontal axis is the call blocking rate.

According to the result of the computer simulation, according to the wireless channel assignment method of the present invention, the accommodated traffic volume is improved by about 25% as compared with the conventional wireless channel assignment method using a single assignment priority. In addition, it was confirmed that the number of times of determining whether or not the allocation required for allocating the wireless channel to one call was reduced by about 10% in the capacity of the accommodated call, and the number was largely improved.

From the above computer simulation results,
ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional radio channel assignment method using a single assignment priority, it is possible to greatly increase the accommodated traffic volume and sufficiently suppress the control load, and to reduce the control load. It is possible to realize a radio channel assignment method that is small and can obtain high frequency use efficiency.

In the above computer simulation, the distance of the mobile station from the radio base station is extracted as a feature of the mobile station. However, even when the moving speed and the moving direction of the mobile station are extracted as the features of the mobile station, the same simple operation is performed. The same effect can be obtained. In a method of allocating a radio channel without considering a moving direction and a moving speed of the mobile station, when the mobile station moves at a high speed, the frequency of the mobile station moving in the wireless zone increases, and the wireless station moves to the wireless zone of the migration destination. The rate of forced disconnection that occurs because channels are not allocated increases, and the control load for switching wireless channels increases on both the wireless base station side and the mobile station side.

Further, since there are mobile stations that move at high speed, the interference conditions fluctuate greatly with time, and the probability of occurrence of interference is increased for both mobile stations that move at high speed and mobile stations that move at low speed. . Therefore, when mobile stations having different moving speeds are mixed in the service area, the moving speed of the mobile station,
It is necessary to use the radio channel to be used depending on the moving direction.

In the radio channel allocating method of the present invention, the mobile stations are divided into groups according to the moving direction and the moving speed of the mobile stations, and the radio channels are allocated using the allocation priorities corresponding to the groups. As in the case where the distance to the mobile station is extracted, the proper use of the channel is automatically performed, and it is possible to minimize a decrease in control load and frequency use efficiency.

As a radio channel, a radio frequency in an FDMA system, a radio frequency and a time slot in a TDMA system, and a repeated use of a spreading code or a frequency hopping pattern in a CDMA system can be considered. Even when a wireless channel is configured by any method such as a time slot and a spreading code, the present invention can determine whether or not a wireless channel can be allocated by measuring an interference level or a power ratio of a desired wave to an interference wave. Is applicable, and a similar effect can be obtained.

Next, a second embodiment will be described. In the above-described first embodiment, the method of determining the allocation priority based on the allocation result in the own group has been described. In the second embodiment, a specific method for adaptively determining the assignment priority of the wireless channel based on the past usage history of the wireless channel in the group and other groups will be described. This second
The method shown in the third embodiment differs from the method of the first embodiment only in the method of updating the assignment priority of the wireless channel of each group.

First, referring to FIG. 1, in the second embodiment, like the first embodiment, M radio channels can be used in the whole system, and i in the mobile communication system is used. The wireless base station 11 has Ki transceivers capable of transmitting and receiving on any of the M wireless channels, and each mobile station 12 connected to and communicating with this mobile communication system has the M It is assumed that a transceiver capable of transmitting and receiving an arbitrary wireless channel among the wireless channels is provided.

FIGS. 9 and 10 are flowcharts showing the processing procedure of the radio channel assignment method of the second embodiment in the mobile communication system shown in FIGS. Hereinafter, with reference to the flowcharts shown in FIG. 9 and FIG.
The processing procedure of the wireless channel assignment method according to the embodiment will be described. In FIG. 9, first, when there is a request from the call processing control device 17 for a new call or a radio channel allocation request for radio channel switching, the radio channel control device 14
Checks whether there is a wireless channel that is not currently in use (step 310). If all the radio channels are in use, the call processing control device 17
And terminates the process.

On the other hand, if there is a usable radio channel in step 310, the radio channel controller 1
4 makes an inquiry to the transceiver control device 13 as to whether there are the transceivers 1, 2,..., Ki that are not currently in use (step 320). If there is no usable transceiver, the transceiver controller 13 notifies the call processing controller 17 of the fact via the radio channel controller 14 and ends the process.

If there is a transceiver that can be used in step 320, the process proceeds to step 330, where the radio channel controller 14 determines the characteristics of the mobile station to which the radio channel is to be assigned to the mobile device characteristic measuring device controller 16. An extraction command is issued, and the mobile device characteristic measuring device control device 16 causes the mobile device characteristic measuring device 15 to perform characteristic measurement of the mobile station. Then step 3
Proceeding to 40, upon receiving the measurement result from the mobile device characteristic measuring device 15, the mobile device characteristic measuring device control device 16 notifies the wireless channel control device 14 of the measurement result. The radio channel controller 14 compares the notified measurement result with a threshold value stored in the memory 18 for determining a priority table number, and determines a priority table number.

At step 350, the radio channel controller 1
4 refers to the priority table number determined in step 340 and refers to the allocation priority on the memory 18 to select the wireless channel number with the highest allocation priority among the wireless channels that are not currently in use, and perform transmission and reception. To the machine control device 13. In step 360, the transceiver control device 13 determines whether the wireless channel can be used by the same method as that described in the first embodiment, and returns the result to the wireless channel control device 14.

If the result of the determination on availability in the transceiver control device 13 is that the wireless channel control device 14 is available, the radio channel control device 14 updates the assignment priority stored in the memory 18 shown in FIG. 10 (step 370). ). FIG.
Is a conceptual diagram of an assignment priority table used for explaining a method of updating the assignment priority in this case, in which a horizontal axis indicates a group number and a vertical axis indicates a channel number.
In the flowchart showing the processing procedure of FIG.
The determined group number will be described as G, and the number of the wireless channel determined to be usable will be described as CH.

Step 371: In the group whose group number is less than G, the allocation priority is raised for all the channels whose channel numbers are less than CH. The target radio channel is a radio channel in the range of I in FIG. Step 373: In the group whose group number is larger than G, lower the allocation priority for all the channels whose channel numbers are equal to or less than CH. The target wireless channel is a wireless channel in the range of II in FIG. Step 375: In the group whose group number is less than G, lower the allocation priority for all the channels whose channel numbers are equal to or higher than CH. The target wireless channel is a wireless channel in the range of III in FIG. Step 377: In the group whose group number is larger than G, increase the allocation priority for all the channels whose channel number is larger than CH. The target wireless channel is a wireless channel in the range of IV in FIG. Step 379: Increase the allocation priority of the channel G of the group G.

Based on the above five steps, the value in the memory 18 is updated with the obtained assignment priority, the wireless channel number is notified to the call processing control device 17, and the use / unused flag of the wireless channel is used. Is set as in use, and the wireless channel is allocated. At this time,
The above five steps need not be performed in this order, and even if they are performed one after the other, the resulting allocation priorities are equal.

Returning again to the flowchart of FIG. 9, if the result of the determination as to whether or not the wireless channel is usable indicates that the wireless channel is unusable, the priority assigned to the wireless channel in the priority table is reduced (step 390), and 18
The above value is updated, the next radio channel having the highest allocation priority is selected, and the same processing is repeated (steps 400 and 41).
0). If the results of the availability determination for all the wireless channels not currently in use are unavailable, the wireless channel control device 14 notifies the call processing control device 17 to that effect,
The process ends (Step 400).

As described in the first embodiment, the interference wave level threshold value and the threshold value of the power ratio between the desired wave and the interference wave used at this time may be the same threshold value for all groups. Separate thresholds may be used for each group.

Further, in the second embodiment, an example in which the radio base station measures the state of the mobile station when allocating the radio channel has been described. However, as described in the first embodiment,
The measurement of the state of the mobile station may be configured to be performed by the mobile station.

By executing the above processing, the radio channel is automatically used in the radio base station according to the characteristics of the mobile station, and the radio channel between the radio base stations is automatically used properly. Furthermore, by appropriately determining the assignment priority of the wireless channel based on the past use history of the wireless channel in the group and other groups, the use of the channel in the wireless base station becomes more clear, A wireless channel allocation method with higher frequency use efficiency than the embodiment can be realized with simple control.

A computer simulation performed to quantitatively confirm the effects of the method according to the second embodiment of the present invention and the results thereof will be described. In this simulation, the wireless zone is a hexagonal omnicell, the service area is composed of 61 wireless zones, and calls are generated uniformly and spatially within the wireless zone according to Poisson distribution. Hold time follows an exponential distribution with an average of 120 seconds. In addition, it is assumed that the call behavior in each wireless zone is the same. It is assumed that a mobile station that intends to make or receive a call selects a wireless zone by measuring the reception power of a perch channel (control channel) previously transmitted at a constant transmission power from a wireless base station. .
Also, the number of wireless channels available in the entire system is 7
There were no channels, and only co-channel interference was considered as interference. The number of priority tables, ie, the number of groups, was 30, and the distance of the mobile station from the radio base station was estimated by measuring the reception level of radio waves transmitted by the mobile station at the radio base station. As a method of determining whether or not allocation is possible, it is determined that allocation is possible if the ratio between the desired wave and the interference wave in the uplink and downlink is equal to or greater than a threshold value.

FIG. 7 shows the result of the computer simulation. FIG. 7 shows the call loss rate characteristics. The horizontal axis represents the applied traffic per wireless zone, which is standardized by the capacity accommodated by the conventional wireless channel allocation method using a single allocation priority. The accommodated call volume is defined as an applied traffic volume per wireless zone at a call loss rate of 3%.

According to the result of the computer simulation, according to the radio channel assignment method of the second embodiment according to the present invention, compared with the conventional radio channel assignment method using a single assignment priority, the accommodated traffic volume Has been improved by about 60%, and it has been confirmed that it has been improved by about 28% as compared with the radio channel assignment method of the first embodiment according to the present invention.

From the results of the above computer simulation, according to the method of the second embodiment, the capacity of accommodated traffic is greatly increased as compared with the conventional wireless channel allocation method using a single allocation priority. Therefore, a radio channel assignment method capable of obtaining high frequency use efficiency can be realized with simple control.

In the above computer simulation,
Although the distance of the mobile station from the radio base station is extracted as the feature of the mobile station, the same applies to the case where the moving speed and direction of the mobile station are extracted as the features of the mobile station, as in the method of the first embodiment. The same effect can be obtained with a simple operation.

As the radio channel, the radio frequency in the FDMA system, the radio frequency and time slot in the TDMA system, and the repeated use of the spreading code or the frequency hopping pattern in the CDMA system can be considered. Similarly to the method, the method of the second embodiment can be applied to the case where the radio channel is configured by any method such as radio frequency, time slot, spreading code, and frequency hopping pattern. By determining whether wireless channel assignment is possible or not by measuring the power ratio or the like, the present invention can be applied and the same effect can be obtained.

[0079]

As described above, according to the present invention,
The radio base station manages the N allocation priority tables, thereby assigning N allocation priorities to one radio channel, and measuring the state of the mobile station when allocating the radio channel. To extract mobile device features,
By dividing the mobile stations into N groups based on the result and allocating the radio channels according to the allocation priority recorded in the allocation priority table corresponding to the group,
Calculates the allocation priority of each radio channel from the past allocation availability history, and based on the allocation priority, compares the frequency allocation efficiency with the conventional autonomous distributed dynamic channel allocation method of allocating radio channels. It is possible to realize a radio channel allocation method capable of greatly increasing the control load and suppressing the control load sufficiently, achieving a small control load and achieving high frequency use efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mobile communication system to which a wireless channel assignment method of the present invention is applied.

2 is a block diagram functionally showing a configuration of a radio base station used in the mobile communication system shown in FIG. 1, particularly a configuration of a portion related to radio channel assignment.

FIG. 3 is a conceptual diagram of data stored on a memory used in the wireless base station shown in FIG.

FIG. 4 is a flowchart showing a processing procedure of a radio channel assignment method in the mobile communication system shown in FIGS. 1 to 3;

FIG. 5 is a diagram illustrating a computer simulation model performed to show the learning effect of the assignment priority.

FIG. 6 is a diagram illustrating an example of a learning result of an assignment priority.

FIG. 7 is a call blocking rate characteristic diagram showing the results of computer simulation performed to confirm the effects of the first embodiment and the second embodiment.

FIG. 8 is a diagram showing the results of a computer simulation performed to confirm the effects of the present invention.

FIG. 9 is a flowchart illustrating a processing procedure of a wireless channel assignment method according to the second embodiment of the present invention.

FIG. 10 is a flowchart illustrating a processing procedure of a wireless channel assignment method according to the second embodiment of the present invention.

FIG. 11 is a conceptual diagram of an allocation priority table used for explaining an allocation priority updating method.

[Explanation of symbols]

 1, 2,..., Ki Transceiver 11 Radio base station 12 Mobile station 13 Transceiver controller 14 Radio channel controller 15 Mobile device characteristic measuring device 16 Mobile device characteristic measuring device controller 17 Call processing controller 18 Memory

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04B 7/24-7/26 H04Q 7/00-7/38

Claims (8)

(57) [Claims] 1. A mobile communication system for performing communication between a mobile station and a wireless base station, wherein the wireless base station can transmit and receive one or a plurality of arbitrary wireless channels among wireless channels usable as the entire system. And a function for measuring whether or not the selected radio channel is usable. The radio base station can refer to the assignment priority given to each radio channel in the radio base station, thereby making the radio usable for the entire system. A radio channel allocation method for selecting one or more radio channels from among the channels, sequentially determining whether the radio channel can be used from a radio channel having a higher allocation priority, and allocating the radio channel, The radio base station manages the N assignment priority tables, thereby assigning N assignment priorities to one radio channel, The mobile station is divided into N groups according to the state of the mobile station to which the line channel is to be allocated, and the radio channel is allocated according to the allocation priority recorded in the allocation priority table corresponding to the group. Channel assignment method. 2. The wireless channel assignment method according to claim 1, wherein the assignment priority of the wireless channel is adaptively determined based on the past usage history of the wireless channel in the group. 3. The wireless communication apparatus according to claim 1, wherein the assignment priority of the wireless channel is adaptively determined based on the past use history of the wireless channel in the group and other groups.
The wireless channel allocation method described in the above. 4. The wireless communication system according to claim 1, wherein when allocating the wireless channel, the distance of the mobile station from the wireless base station is provided to the grouping as the state of the mobile station. Channel assignment method. 5. The radio channel allocating method according to claim 1, wherein the direction in which the mobile station moves is provided to the grouping as the state of the mobile station when allocating a radio channel. . 6. The mobile station according to claim 1, wherein when allocating the radio channel, the moving speed of the mobile station is provided to the grouping as the state of the mobile station.
The wireless channel allocation method described in the above. 7. When allocating a radio channel, any combination of the distance of the mobile station from the radio base station, the moving direction of the mobile station, and the moving speed of the mobile station is grouped as the state of the mobile station. The wireless channel allocation method according to claim 1, 2 or 3, wherein the method is provided. 8. The mobile station according to claim 1, wherein at the time of radio channel allocation, at least one of the mobile station itself and a base station measures a state of the mobile station.
Or the wireless channel assignment method according to claim 3.