JPH089454A - Radio channel assigning method - Google Patents

Abstract

PURPOSE:To provide a radio channel assigning method for facilitating application and operation to a mobile communication system by deciding a threshold value for groupling with the autonomous processing of a radio base station without requiring any large work or complicated design. CONSTITUTION:At the radio base station, the state of a mobile station such as the distance of the mobile station from the radio base station, moving direction or moving speed is measured by a mobile station feature measuring instrument 16 and recorded or updated in a second memory 19 as the state of the mobile station in the past, the threshold value for grouping is decided based on this recorded and updated state of the mobile station in the past, and the threshold value to be used for grouping is decided from the state of the mobile station in the past based on order statistics.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In the currently popular mobile phone and car phone systems, a radius of a radio zone serviced by one radio base station is set to about several kilometers and a large number of radio base stations are arranged in a service area. Cellular systems that provide services are well known. Generally, in a cellular system, so-called wireless channels are repeatedly used geographically, that is, the same wireless channel is used by different wireless base stations that are spatially separated in order to effectively use a limited wireless channel. . By making the distance between wireless base stations that use the same wireless 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 is reduced, interference from the same radio channel and adjacent radio channels in the interleave system in which the radio channels are configured by allowing overlapping of side band power of the radio channels in the FDMA system are formed. Since the interference quality occurs and the communication quality deteriorates significantly, it is not possible to reduce the repeat distance indefinitely.The wireless base station is sufficiently spatially separated so that these interference limits do not exceed a certain allowable value. It is necessary for the station to repeatedly use the same radio channel.

Methods for repeatedly using radio channels satisfying such conditions are roughly classified into a fixed channel allocation method and a dynamic channel allocation method. Further, the dynamic channel allocation includes a centralized control type dynamic channel allocation method and an autonomous method. There is a distributed dynamic channel allocation method.

The fixed channel allocation method is a method in which radio wave propagation conditions and traffic distributions are obtained by actual measurement or theoretical calculation, and radio channels are fixedly allocated to each radio base station. Generally, a large amount of labor is required for the design for deciding the fixed arrangement, and further, there is a drawback that the adaptability to the system expansion is low because the redesign is required even when the equipment is added. Further, since the wireless channels usable as the entire system are divided into some groups and assigned to each wireless base station, a division loss occurs, and high frequency utilization efficiency cannot be obtained.

On the other hand, the dynamic channel allocation system is
It is possible to allocate radio channels to some extent flexibly with respect to temporal fluctuations of traffic, spatial bias, etc.
Since the wireless channels that can be used in the entire system can be used by any wireless base station, a large grouping effect is obtained, and the frequency utilization 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 method, between wireless base stations and control stations However, the autonomous distributed dynamic channel allocation method has the drawbacks that it requires a lot of processing up to channel allocation and a large connection delay, and thus it has a low control load and high frequency utilization efficiency. It is very important to realize a possible wireless channel allocation method.

As a method for solving such a problem and realizing an autonomous distributed dynamic channel allocation capable of obtaining a high frequency utilization efficiency with a small control load, for example, "Radio channel allocation method (Japanese Patent Application No. 6-134188).
No.) ”and a radio channel allocation method described in“ Mobile communication channel allocation control method (Japanese Patent Application No. 1-306417) ”.

According to the radio channel allocation method described in Japanese Patent Application No. 6-134188, a radio base station manages N allocation priorities to give N allocation priorities to one radio channel. According to this method, the mobile stations are divided into N groups according to the state of the mobile station to which the radio 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. Grouping of mobile stations based on the characteristics extracted from the state of the mobile station, thresholds such as the distance between the radio base station and the mobile station, the moving direction of the mobile station, the moving speed of the mobile station, etc. for each group. It is realized by managing and comparing those threshold values with actual measurement results.

In the radio channel allocation method described in Japanese Patent Application No. 1-306417, all radio communication channels are divided into a plurality of channel groups, and the channels of the channel groups are used in order to selectively use the channel groups according to the reception level in communication. The lower limit value of the reception level required for communication between a mobile station and a base station that uses the wireless communication channel is set for each channel group, and the communication connection request is assigned as a wireless communication channel to be assigned to a communication connection request occurring in each wireless zone. The desired wave-to-interference power when the reception level in the communication obtained from the reception level of the radio control channel between the mobile station and the base station performing the operation belongs to a channel group that satisfies the lower limit and is used for communication connection. This is a method of selecting and allocating a wireless communication channel whose ratio satisfies the quality condition.

[0010]

The threshold value in the above-mentioned conventional method is set so as to minimize the control load on the radio channel allocation, maintain high frequency utilization efficiency, and satisfy the required call quality. , It is necessary to determine the radio wave propagation situation and traffic distribution in the wireless zone by conducting a detailed study by theoretical calculation or actual measurement.
However, there is a problem that enormous amount of labor is required to add detailed examinations to all of the many wireless zones existing in the service area, and further redesign is required due to system expansion such as addition of wireless base stations. . Even if the system is not expanded, the radio wave propagation status and traffic distribution will change significantly due to new construction or destruction of buildings around the radio base station, roads, etc., so redesign to respond to these fluctuations There was a problem that it was necessary.

The present invention has been made in view of the above,
The purpose is to determine the threshold for grouping by the autonomous processing of the radio base station without applying enormous labor and complicated design, and apply and operate it in the mobile communication system. To provide a wireless channel allocation method that is easy to perform.

[0012]

In order to achieve the above object, a radio channel allocation method of the present invention is a mobile communication system in which a mobile communication system performs communication between a radio base station and a mobile station. Mobile stations are divided into groups according to the state of the station, a radio channel is selected according to a predetermined procedure for each group, and availability is determined,
In a wireless channel allocation method for allocating wireless channels, a wireless base station records and updates past mobile station states, and determines a threshold for grouping based on the recorded and updated past mobile station states. The point is to do.

Further, the radio channel allocation method of the present invention is
The gist is to determine the threshold value used for the grouping from the past mobile station states based on order statistics.

Further, the wireless channel allocation method of the present invention is
It is a gist that the state of the mobile station is a measurement of the distance of the mobile station from the radio base station, the moving direction of the mobile station, and the moving speed.

[0015]

According to the radio channel allocation method of the present invention, the radio base station records and updates the past mobile station states, and determines the threshold value for grouping based on the past and updated mobile station states. To do.

Further, in the radio channel allocation method of the present invention, the threshold value used for the grouping is determined from the past states of mobile stations based on order statistics.

Further, in the radio channel allocation method of the present invention, the state of the mobile station is a measurement of the distance of the mobile station from the radio base station, the moving method of the mobile station, and the moving speed.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 11 is an explanatory diagram showing the configuration of a mobile communication system to which the radio channel allocation method of the present invention is applied. This mobile communication system includes a plurality of radio base stations 11.
The mobile station 112 is connected to a radio base station using one and one or a plurality of radio channels and communicates with the radio base station.

FIG. 1 is a block diagram showing the configuration of a radio base station that implements a radio channel allocation method according to an embodiment of the present invention. In particular, only a portion related to the radio channel allocation method is functionally illustrated. Shows.

In the radio base station shown in FIG. 1, K transceivers 15 are controlled by the transceiver controller 14, and the transceiver controller 14 is connected to the radio channel controller 12. A mobile station characteristic measuring instrument 16 for extracting mobile station characteristics is connected to the radio channel controller 12 through a mobile station characteristic measuring instrument controller 13 for controlling it. The wireless channel controller 12 is connected to the call processing controller 11 and the first memory 17. The wireless channel control unit 12 reads, updates, and writes data stored in the first memory 17 in response to a request from the call processing control unit 11, and determines the wireless channel currently used by the wireless base station. to manage.

The transceiver controller 14 manages the transceiver 15 and determines whether or not the wireless channel designated by the wireless channel controller 12 can be assigned. The parameter control unit 18 is connected to the mobile station characteristic measuring instrument control unit 13, and also has a second memory 19 and a first memory 17 for recording measurement results.
Connected with. The parameter control unit 18 receives the measurement result of the mobile station feature from the mobile station feature measuring instrument control unit 13, uses the update of the measurement result stored in the second memory 19 and the measurement result stored in the second memory 19. Then, the threshold value for grouping is calculated, and the threshold value data stored in the first memory 17 is updated. Figure 1
Then, although the first memory 17 and the second memory 19 are functionally distinguished from each other, the same memory may be provided with the functions of both memories in terms of the device configuration.

FIG. 2 conceptually shows an example of data stored in the first memory 17. In this example, when allocating radio channels, mobile stations are grouped according to the characteristics of the distance, the moving direction, and the moving speed of the mobile station from the radio base station. On the first memory 17, a flag indicating whether W wireless channels are in use or unused in the wireless base station, distances for allocating mobile stations to which wireless channels are to be allocated to N groups, Threshold values such as moving speed and moving direction are recorded.

FIG. 3 conceptually shows an example of data stored in the second memory 19. In this example, when allocating radio channels, mobile stations are grouped according to the characteristics of the distance, the moving direction, and the moving speed of the mobile station from the radio base station. The measurement results of the states of the past M mobile stations are recorded on the second memory 19. In this example, the case where the measurement results of the distance, the moving direction, and the moving speed are all recorded for each M is shown. However, recording different numbers of measurement results does not hinder the effect of the present invention. Absent.

Next, the radio channel allocation method of this embodiment will be described with reference to the flowchart shown in FIG.

When there is a request from the call processing controller 11 for a new call or a wireless channel allocation for switching a wireless channel, the wireless channel controller 12 checks whether or not there is a wireless channel that is not currently in use (step). 110). If all the wireless channels are in use, the call processing control unit 11 is notified to that effect and the processing ends. If there is a usable wireless channel, the wireless channel control unit 12 inquires of the transceiver control unit 14 whether there is a transceiver 15 that is not currently in use (step 120). If there is no usable transceiver, the transceiver control unit 14 notifies the call processing control unit 11 of that fact through the wireless channel control unit 12 and ends the process.

If there is a transceiver 15 available,
The radio channel controller 12 is a mobile station characteristic measuring device controller 1
3 is instructed to extract the characteristics of the mobile station to which the wireless channel is to be assigned (step 130). The mobile station characteristic measuring instrument control unit 13 notifies the radio channel control unit 12 and the parameter control unit 18 of the measurement result.

The radio channel controller 12 compares the measurement result notified by the mobile station characteristic measuring instrument controller 13 with the threshold for group determination stored in the first memory 17, and Is determined (step 140).
Further, a wireless channel is selected according to a predetermined procedure for each group, and if there is a usable wireless channel, a wireless channel allocation process is performed (step 15).
0) If there is no available wireless channel, the call processing control unit 11 is notified to that effect, and the processing ends.

The parameter control unit 18 stores the measurement result notified by the mobile station characteristic measuring instrument control unit 13 in the second memory 1.
9 and update the measurement result record (step 1
60). Furthermore, the past measurement result stored in the second memory 19 is read out, and the grouping threshold value is calculated according to a predetermined procedure based on the measurement result,
The calculation result is written in the first memory 17, and the process ends (step 170).

Although FIG. 1 and the above procedure show an example in which the radio base station measures the state of the mobile station when allocating the radio channel, the mobile station measures the state of the mobile station. May be. In this case, for example, a method in which the mobile station measures the state of the own station by a command from the radio base station at the time of an incoming / outgoing call and reports it to the radio base station, or the mobile station autonomously makes the own station at the time of an incoming / outgoing call or idle. There is a method of measuring the status of and reporting to the radio base station. In any case, the present invention can be applied and the same effect can be obtained.

Further, only when the radio channel allocation in step 150 is successful, steps 160, 1
A method is also conceivable in which the measurement result of step 70 is updated and the threshold value is updated, and when the wireless channel allocation in step 150 fails, the processing of steps 160 and 170 is not performed. FIG. 5 shows a control flow in this case. In FIG. 5, the process of step 155 is added. Generally, a call that has not been connected due to an unused transceiver or no available wireless channel is treated as a call loss in an immediate system and a waiting call in a waiting system. . Calls that are lost due to an immediate system, or calls that are not connected due to a long waiting time such as a limited waiting time or an abandoned holding due to a long waiting time, are sent one after another. The phenomenon of repeating occurs.
Such a call is called a recall, but when the system is congested and a large number of recalls occur, the measurement result stored in the second memory 19 may greatly differ from the actual traffic distribution. Only if the wireless channel allocation in step 150 above is successful, step 160,
If the measurement result of 170 and the threshold value are updated, it is possible to prevent such a discrepancy and more accurately determine the threshold value.

Using the model of FIG. 6, step 16 above
The determination of the threshold value of 0,170 will be described. Since it is possible to set the respective thresholds for the characteristics of each mobile unit such as the distance from the mobile station's radio base station, the moving direction of the mobile station, and the moving speed, the radio base station of the mobile station An example is shown only for the distance from. In the model of FIG. 6, the service area is served by nine radio base stations. At the center of high traffic, the cell radius is small and the radio base stations BS1 to BS3
It is serviced at. In the peripheral portion where the traffic is relatively low, the radius is larger than that of the cell in the central portion, and it is served by the radio base stations BS4 to BS9. Even in a real system, a large number of radio base stations are arranged with a small cell radius in a metropolitan area with high traffic,
In the peripheral area where the traffic is relatively low, a cell radius larger than that is often used to provide the service, and FIG. 6 schematically shows such a situation.

FIG. 7 shows an example of the cumulative frequency distribution of the distance from the wireless base station of the mobile station recorded in the central wireless base station BS1 and the peripheral wireless base station BS5. The distance of the mobile station from the radio base station is estimated by the reception level. The horizontal axis is the reception level, which is standardized by the required reception level (reception level required to secure the required thermal noise ratio). Due to the difference in cell radius between BS1 and BS5, BS5 having a larger cell radius records a lower reception level. FIG. 8 and FIG. 9 show the results of obtaining the threshold value using the data recorded in BS1 and BS5. 8 and 9 are examples in which the number of groups is 4, and the threshold values are set so that the sizes of the groups are equal. The recorded data is represented by relative cumulative frequencies, and threshold 2 threshold 3 threshold 4 is determined from the reception levels at which the relative cumulative frequencies are 0.25, 0.5, 0.75.
The threshold value 1 is set equal to the required reception level. As described above, by applying the method of the present invention, it is possible to determine the grouping threshold value according to each situation even if the radio base stations have different situations, by applying the method of the present invention. . 8 and 9 show an example in which the sizes of the groups are the same, the present invention is also applicable to the case where the sizes of the groups are not the same. In that case, the relative cumulative frequency referred to may be changed.

By executing the above processing,
A huge amount of labor is required to make that determination, and a complicated threshold value for grouping that needs to be redesigned due to system expansion and changes in the radio wave propagation situation and traffic distribution around the radio base station is required. It is possible to provide a radio channel allocation method that can be easily applied to and operated in a mobile communication system by automatically making a decision by autonomous processing of a radio base station without doing so.

Next, a method of determining the grouping threshold value based on order statistics from the past measurement results of mobile station characteristics will be described in detail.

FIG. 10 conceptually shows an example of data stored in the second memory 19 in this case. In this example, when allocating the radio channel, it is assumed that the mobile station is characterized by measuring the distance, the moving direction, and the moving speed of the mobile station from the radio base station, and the measurement results of the past M times are stored in the second memory 19. Is recorded. Further, the number of groups grouped by the distance of the mobile station from the radio base station is r, the number of groups grouped by the moving direction of the mobile station is s, and the number of groups grouped by the moving speed of the mobile station is t. L ₁ ~L _M measurement result of the distance from the radio base station of the mobile station, D ₁ to D _M is the moving direction of the measurement results of the mobile station, V ₁
V _M indicates the measurement result of the moving speed of the mobile station. PL _{1 to} PL _r are the size of each group in the grouping according to the distance of the mobile station from the radio base station, PD ₁
˜PD _s represents the size of each group in the grouping according to the moving direction of the mobile station, and PV _{1 to} PV _t represent the size of each group in the grouping according to the moving speed of the mobile station, and these values are all 0. It is a value that is set in advance by a system operator within a range of greater than 1 and less than 1. However, PL ₁ + PL ₂ + ... + PL _r = 1 PD ₁ + PD ₂ + ... + PD _s = 1 PV ₁ + PV ₂ + ... + PV _t = 1. In FIG. 10, r>s> t is drawn, but r,
The effect of the present invention is not hindered by the magnitude relationship between s and t. Further, in this example, the case where the measurement results of the distance, the moving direction, and the moving speed are all recorded by M each is shown. However, in general, when the number of groups is large, a large number of measurement results are required. It is also possible to record a different number of measurement results depending on the size of.

Since it is possible to determine the respective threshold values for the characteristics of each mobile station such as the distance of the mobile station from the radio base station, the moving direction and the moving speed of the mobile station, by the similar calculation method, An example will be shown only in the case of the distance from the wireless base station.

(A) The parameter control unit 18 reads the data L _{1 to} L _M stored in the second memory 19 and determines them in ascending order in order to determine the threshold value.

L ⁽¹⁾ ≤L ⁽²⁾ ≤ ... ≤L ^(M) However, the numbers and symbols shown on the right shoulder of L indicate the order after rearrangement, and It has nothing to do with the order in which it is stored in the memory 19 of.

(B) Next, a natural number j such that j / M <PL ₁ ≤ (j + 1) / M is obtained.

(C) Next, using j obtained in (b),
The threshold value TL ₁ is calculated by the following equation.

[0042]

[Formula 1] TL ₁ = L ^(j) + (PL ₁ × M−j) × (L
^{(j + 1)} -L ^(j) ) (d) Similarly, the above steps (b) and (c) are repeated until PL _r .

The above procedures (a) to (d) are the processes corresponding to the above-mentioned steps 160 and 170. The determination of the threshold value using the order statistics is equivalent to estimating the distribution function of the population based on the observed value obtained from a certain population. The order statistics estimation is a non-parametric estimation that does not depend on the shape of the distribution function of the population. By performing steps (a) to (d), the threshold value can be determined more easily than the method of determining the threshold value from the distribution function shown in FIGS. 8 and 9. Therefore, even if the radio base stations are in different situations, it is possible to determine the grouping threshold value according to each situation without complicated design.

By executing the above processing,
A huge amount of labor is required to make that decision, and a complicated threshold value for grouping that needs to be redesigned due to system expansion and changes in radio wave propagation conditions around the wireless base station and changes in traffic distribution should be designed. Instead, it is possible to provide a radio channel allocation method that can be easily applied to and operated in a mobile communication system by automatically determining by the autonomous processing of the radio base station.

Generally, as the radio channel, it is considered that the radio frequency is used in the FDMA system, the radio frequency and the time slot are used in the TDMA system, and the spread code or the frequency hopping pattern is repeatedly used in the CDMA system. The method of the present invention can be applied to the case where the radio channel is configured by any method such as slot, spreading code or frequency hopping pattern, and the same effect can be obtained.

[0046]

As described above, according to the present invention,
The radio base station records and updates the past mobile station status, determines a threshold value for grouping based on the recorded and updated past mobile station status, and is used for the grouping. Since the threshold value is determined based on the order statistics from the past mobile station status, a huge amount of labor has been required in the past, and it has been redesigned due to system expansion and changes in the radio wave propagation situation and traffic distribution around the radio base station. The threshold for grouping, which was required by the wireless base station, can be automatically determined by the autonomous processing of the wireless base station without the need for complicated design. Can be facilitated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a radio base station that implements a radio channel allocation method according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of data stored in a first memory used in the wireless base station of FIG.

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

FIG. 4 is a flowchart showing an operation of the wireless base station of FIG.

5 is a flowchart showing an operation of the wireless base station of FIG.

FIG. 6 is an explanatory diagram of a service area model showing an operation of the wireless base station of FIG.

7 is a diagram showing a cumulative frequency distribution of distances of mobile stations from a radio base station recorded by the radio base station of the service area model shown in FIG. 6;

8 is a diagram showing an example in which a threshold value is determined for the cumulative frequency distribution of the distance of the mobile station shown in FIG. 7 from the radio base station.

9 is a diagram showing an example in which a threshold value is determined for the cumulative frequency distribution of the distance of the mobile station shown in FIG. 7 from the radio base station.

FIG. 10 conceptually shows data stored in a second memory used in the radio base station of FIG. 1, and in particular, a grouping threshold value is used for order statistics from past mobile station feature measurement results. It is a figure for demonstrating the method to determine based on.

FIG. 11 is an explanatory diagram showing a configuration of a mobile communication system to which the wireless channel allocation method of the present invention is applied.

[Explanation of symbols]

 11 Call Processing Control Unit 12 Radio Channel Control Unit 13 Mobile Station Feature Measuring Device Control Unit 14 Transceiver Control Unit 15 Transceiver 16 Mobile Station Feature Measuring Device 17 First Memory 18 Parameter Control Unit 19 Second Memory

Claims (3)

[Claims] 1. In a mobile communication system for communicating between a radio base station and a mobile station, the mobile stations are divided into groups according to the state of the mobile stations to which radio channels are to be allocated, and a predetermined procedure is set for each group. In the wireless channel allocation method of selecting a wireless channel by using, determining availability, and allocating the wireless channel, the wireless base station records and updates the state of the past mobile station, and records and updates the state of the past mobile station. A method for allocating a radio channel, characterized in that a threshold for grouping is determined based on a state. 2. The radio channel allocation method according to claim 1, wherein the threshold value used for the grouping is determined from the past states of mobile stations based on order statistics. 3. The radio channel according to claim 1, wherein the state of the mobile station is a measurement of a distance of the mobile station from a radio base station, a moving direction of the mobile station, and a moving speed. Allocation method.