JP2669323B2 - Channel allocation method for mobile communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel allocation system for a cellular mobile communication system in which each of a plurality of zones is covered by a corresponding base station, and more particularly to an antenna having different in-plane directivity (hereinafter referred to as a sector antenna). ) Is connected to each of the base stations, and the zone is divided into sector-shaped cells (sector cells) corresponding to the directional gains of the sector antennas, respectively.

[0002]

2. Description of the Related Art In a mobile communication system such as a cellular type mobile telephone system, the same radio channel (channel) is repeatedly used between zones where interference does not occur. In this mobile communication system, the configuration of the zone includes an omni configuration and a sector configuration. In the omni configuration, one omnidirectional antenna (omni-antenna) in the horizontal plane is installed for each base station, and this omni antenna covers one zone centered on the corresponding base station. On the other hand, in the sector configuration, one base station includes a plurality of sector-shaped sector antennas having directivity in a horizontal plane, and each of the sector antennas has a sector-shaped region (sector cell) corresponding to the directivity gain of the antenna. Cover each. In the sector configuration, since the same channel interference is small due to the limited directivity effect of the sector antenna, the repetition distance of the same channel is shorter than in the omni configuration, so that the frequency (channel) utilization efficiency is high. The above two zone configuration methods are described in detail in the literature (Yoshikawa, Nomura, Watanabe, Nagatsu, "Wireless Zone Configuration Method for Car Phones," R & D Report No. 23, No. 8, 1974). The mobile communication system further includes a plurality of fixed or movable wireless terminals in the plurality of zones, and the wireless terminals include another wireless terminal via a wireless channel (communication channel) with a base station in a zone to which the mobile terminal belongs. Alternatively, communication is performed with a public communication network.

[0003] In the above-mentioned mobile communication system, there are a fixed channel allocation method and a dynamic channel allocation method as communication channel allocation methods. In the fixed channel assignment method, a use channel (communication channel) of each zone is fixedly assigned in advance in consideration of interference conditions between zones. On the other hand, in the dynamic channel assignment method, a channel is not fixedly assigned to each zone. That is, the base station sequentially selects a channel from among all the channels for each communication request, and obtains a ratio between the reception power (desired wave power) of the signal from the communication partner (one of the wireless terminals) and the interference wave power (hereinafter, referred to as the interference power) CIR
Abbreviated. ) Are above a predetermined threshold (hereinafter, CIR threshold) in both the uplink (transmission from the radio terminal and the reception by the base station) and the downlink (transmission by the base station and reception by the radio terminal). When a predetermined assignment condition (communication quality) such as is satisfied, a channel satisfying the condition is assigned as a communication channel. In this dynamic channel allocation scheme, channels can be effectively used due to a large grouping effect in which all channels are shared by all base stations. In this allocation method, the same channel can be repeatedly used as long as the CIR threshold is satisfied. Therefore, the same channel can be repeatedly used over a shorter distance than the fixed channel allocation method, and the channel can be used more effectively. Therefore, the dynamic channel allocation scheme can obtain higher frequency (channel) utilization efficiency than the fixed channel allocation scheme.

As one of such dynamic channel allocation methods, for example, Procedures o
f IEEE Vehicular Technical
ySociety, 42nd, VTS Confere
Nature, May 1992, pages 782-785.
nomous Reuse Partitioning
As described in a paper published under the title of in Cellular Systems, a method of selecting channels in the same order in all base stations (hereinafter referred to as AR)
P system) has been proposed. According to this ARP method, the channel to be selected first, that is, the channel having a higher selection order, is used more by the wireless terminal closer to the base station and can be reused at a shorter distance interval. Has been shown to be high.

In order to obtain high frequency (channel) utilization efficiency, it has been considered to use sector cell configuration and dynamic channel allocation in combination. As a dynamic channel assignment method in a sector cell configuration, there is a method of preferentially assigning the same channel to sector cells in the same direction (Japanese Patent Application No. 5-081011). In this method, the channels are divided into channel groups of the number of sector cells per base station, and for wireless terminals in the sector cells with the same directionality of sector antennas, priority is given to the same channel group in all base stations. If a channel that can be allocated does not exist in the channel group, a channel is allocated from another channel group.

It is possible to further improve the frequency utilization efficiency by using the method of preferentially allocating the same channel among the sector cells in the same direction in combination with the above-mentioned ARP method or the like. As a method,
A method is considered in which the order of selecting channels from each channel group is the same for all base stations. With this, the effects of both formulas can be expected to some extent. However, in this method, the channel selection order is the same in the sector cells having the same directivity direction of the sector antenna, but the channel group selection order is different between different sector cells, and thus the channel selection order is significantly different. . For this reason, there is a problem that the effect of ARP becomes relatively small.

[0007]

As described above, in the method in which the order of selecting channels from each channel group is the same in all base stations, the order of selecting channels is determined in advance like the ARP method. Channel allocation method that determines the order of channel selection using the measurement result of the reception level of the desired wave or the interference wave of each channel, and simultaneously allocates the same channel preferentially between sector cells in the same direction. There is a problem that the effect of the method of determining the channel selection order according to the arrival direction of the desired wave, such as the allocation method, cannot be sufficiently obtained.

Therefore, the object of the present invention is to solve the above-mentioned problems of the channel allocation method, and to measure the reception level of the desired wave and the interference wave of each channel, or the channel allocation method in which the channel selection order is determined in advance. It is an object of the present invention to provide a channel allocation method for a mobile communication system that can obtain the effects of both a channel allocation method that uses the result and a method that determines the channel selection order according to the arrival direction of a desired wave.

[0009]

A channel allocation system for a mobile communication system according to the present invention comprises a plurality of wireless zones, a plurality of sector cells covering each of the wireless zones, and bases arranged in each of the wireless zones. Station, a sector antenna corresponding to the sector cell, which is connected to the receiving input end of the base station and has directivity in a horizontal plane with respect to each of the sector cells belonging to the base station, and a plurality of sector antennas located at any of the sector cells. A plurality of wireless terminals that communicate with the base station using the assigned wireless channel of the wireless channels as a communication channel, wherein the base station is common to all sector cells of all base stations.
In the first wireless channel order information that predetermines the order of the wireless channels, and when a communication request occurs between one of the wireless terminals in the sector cell belonging to the own station, the desired wave arriving from the wireless terminal Desired wave arrival direction estimating means for estimating the arrival direction, second wireless channel order information that determines the order of the wireless channels according to the arrival direction of the desired wave, and the order of the first wireless channel order information A wireless channel selection order for determining a selection order based on the value of the first priority function determined according to the value and the value of the second priority function determined according to the order of the second wireless channel order information. Determining means for selecting the wireless channel satisfying a predetermined communication quality in accordance with the selection order of the wireless channels determined by the wireless channel selection order determining means; And a radio channel allocation means for allocating Le as the communication channel.

Further, a channel allocation system for a mobile communication system according to the present invention comprises a plurality of radio zones, a plurality of sector cells covering each of the radio zones, a base station arranged in each of the radio zones, and the base. A sector antenna corresponding to the sector cell, which is connected to a receiving input end of a station and has directivity in a horizontal plane for each of the sector cells belonging to the base station; and a plurality of radio channels located in any of the sector cells. A plurality of wireless terminals that communicate with the base station using the allocated wireless channel as a communication channel, and the base station makes a communication request with one of the wireless terminals in the sector cell belonging to the own station. And each of the radio channels from a sector antenna corresponding to a sector cell where one of the radio terminals is located.
The reception level of each interference wave is measured, and the reception level of the interference wave is measured.
First wireless channel order information that determines the order of the wireless channels according to the bell , desired wave arrival direction estimation means for estimating the arrival direction of the desired wave coming from the wireless terminal, and the arrival direction of the desired wave Second wireless channel order information that determines the order of the wireless channels, a value of a first priority function determined according to the order of the first wireless channel order information, and the second wireless channel Radio channel selection order determining means for determining a selection order based on the value of a second priority function determined according to the order of the order information, and selection of the radio channels determined by the wireless channel selection order determining means Wireless channel allocating means for selecting the wireless channel satisfying a predetermined communication quality according to an order and allocating the selected wireless channel as the communication channel. Configuration may be adopted.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a conceptual diagram of a system according to an embodiment of the present invention. The first embodiment has the system configuration shown in FIG. FIG. 2 is a diagram illustrating a process of determining a selection order in the first embodiment.

[0013] This cellular type mobile communication system comprises:
As shown in FIG. 1, base stations (BS) 11, 12, and 1
It has three zones, each of which has three zones. At the input end of the receiving section of the base station 11, three sector antennas 31 (31a, 31a) having a horizontal
b, 31c, 31d, 31e, and 31f) are connected. These sector antennas 31a, 31b, and 3
1c is a sector cell 41 (41a, 41b, and 4) obtained by equally dividing the periphery of the base station 11 into three in accordance with the horizontal directivity.
1c) respectively. Similarly, the base station 12,
The same three sector antennas 32 (32a, 32b, and 32) are provided at the input terminals of the receiving unit of the base station 13, respectively.
c), 33 (33a, 33b, and 33c) are connected, and these sector antennas 32a, 32b, 32c,
33a, 33b, and 33c are similar to the base stations 12, 1
Sector cell 42 (42a, 42
b, and 42c), 43 (43a, 43b, and 43)
c) respectively. Here, each base station 1
1, 12, and 13 are arranged in the directions shown in the figure, and the sector antennas and sector cells having the same lower case alphabetic code in the constituent codes form directivity and cells in the same direction around the corresponding base station. I have. Further, the wireless terminal 21 is in the sector cell 41a, the wireless terminal 22 is in the sector cell 41b, the wireless terminals 23 and 24 are in the sector cell 41c, the wireless terminal 25 is in the sector cell 42a, and the wireless terminal 26 is in the sector cell 43a.
Are located respectively. Further, this mobile communication system has channels that can be used for communication of six channels CH1 to CH6 and a control channel that is used at the time of channel assignment.

In this mobile communication system, as shown in FIG. 2A, it has predetermined channel order information (first order information). In this embodiment, the channel order information is common to all sector cells of all base stations,
Channels CH1, CH2, CH3, CH4, CH5, C
It is assumed that the order is H6. As shown in FIG. 2B, a priority function P1 (i) for the order information i is defined, and the priority function value for the rank 1 is 200,
For rank 2, 150, below, 100, 30, 20,
It is assumed to be 10. The lower the rank, the smaller the function value, and the lower the rank, the smaller the difference between the ranks. Here, this is referred to as a first function value.

Further, this mobile communication system has order information (second order information) that determines the order of channels according to the direction in which a desired wave from a radio terminal arrives. Here, the order information when the desired wave comes from the directivity directions of the sector antennas 31a, 32a, and 33a is:
As shown in FIG. 2C, the order of CH1, CH4, CH2, CH5, CH3, and CH6, and the order information in the case of arriving from the directivity directions of the sector antennas 31b, 32b, and 33b are CH2, CH5, and CH3. , CH6, CH1,
CH4 order, and sector antennas 31c, 32c,
And 33c, the sequence information when coming from the directional directions is CH3, CH6, CH1, CH4, CH2, CH5.
It is assumed that the order is as follows. The priority function P2 (i) is also defined for this order information i, and as shown in FIG. 2 (d), the priority function values for rank 1 and rank 2 are 50 and rank 3 to rank 6. On the other hand, it is set to 10. This function value is also determined to be smaller as the order is lower. Here, this is referred to as a second function value.

In the mobile communication system shown in FIG. 1, the base station 11 uses the channel CH4 and the wireless terminal 21
And the wireless terminal 22 using the channel CH6 and the base station 1
2 uses the channel CH3 for the wireless terminal 25 and the base station 1
3 are communicating with the wireless terminal 26 using the channel CH2.

At this time, when a communication request is generated between the base station 11 and the wireless terminal 23, the wireless terminal 21 transmits a signal using the control channel. In contrast, base station 11
Measures the reception level (desired wave level) of the signal from the wireless terminal 23 using all the connected sector antennas 31. Here, the desired wave levels received by the receiving unit of the base station 11 from the sector antennas 31a, 31b, and 31c are defined as Da, Db, and Dc, respectively.

Since the radio terminal 23 is located in the directivity direction of the sector antenna 31b of the base station 11, the desired wave levels Da, Db, and Dc from the radio terminal 23 measured by each sector antenna are: Db becomes the maximum.
Therefore, the desired wave of the wireless terminal 23 is transmitted to the sector antenna 31b.
Is determined to come from the directivity direction. As described above, the sequence information when coming from the directivity directions of the sector antennas 31b, 32b, and 33b is CH2, CH5, C.
Since the order is H3, CH6, CH1, CH4, the above-mentioned second function value is CH1, CH2, CH3, CH4,
CH5, CH6 in the order of 10,50,10,10,5
0 and 10. On the other hand, the first function value is 200, 150, 100, 30, 2 in order as shown in FIG.
0,10. In this embodiment, the sum of the first function value and the second function value of each channel is taken in order to determine the channel selection order. At this time, the sum of the priority function values for CH1 to CH6 is 210, 200, 11
0, 40, 70, and 20 (FIG. 2E). And
The order of the channels with the larger sum is determined as the channel selection order. In this case, CH1, CH2, CH3, CH
5, CH4 and CH6 (FIG. 2 (f)).

According to this order, the base station 11 first selects the channel CH1 and measures its interference wave level U1b. If the ratio between the desired wave level Db and the measured interference wave level U1b is greater than or equal to a predetermined value, the channel CH1 is designated to the wireless terminal 23, and the wireless terminal 23 similarly responds to the desired wave level. And the interference wave level, and determines whether or not the channel CH1 can be allocated.
Notify. If it can be assigned, channel CH1
Start communication using. In this case, since the channel CH1 is not used elsewhere, it is determined that allocation is possible, and communication is started using the channel CH1.

Next, consider a case where a communication request occurs between the base station 11 and the wireless terminal 24 immediately after the wireless terminal 23 starts communication. Since the wireless terminal 24 is located in the sector cell 41b similarly to the wireless terminal 23, the desired wave comes from the directivity direction of the sector antenna 31b. Therefore, the channel selection order is the same as that in the case of the wireless terminal 23.
1, CH2, CH3, CH5, CH4, and CH6. The base station 11 first selects the channel CH1, but cannot allocate the channel CH1 because the wireless terminal 23 is in use, and then selects the channel CH2. However, the channel CH2 is set so that the base station 13 has the sector antenna 33a.
Since the channel CH3 is in use, the channel CH3 is similarly determined to be unassignable. Then, the channel CH5 is selected, and it is checked whether the ratio between the reception level of the desired wave and the reception level of the interference wave is equal to or more than a predetermined value in both the base station 11 and the wireless terminal 24 by the above-described procedure. If both are equal to or more than the predetermined value, communication is started by allocating the channel CH5.

The second embodiment has the same system configuration as the first embodiment shown in FIG. FIG. 3 is a diagram illustrating a process of determining a selection order in the second embodiment.

FIG. 1 shows a mobile communication system according to a second embodiment.
As shown in the base station, sector antenna, sector cell,
The configurations of the mobile station, the communication channel, and the control channel are the same as in the first embodiment. Also, as in the first embodiment, the sum of the first function value and the second function value is used to determine the selection order of each channel.

This mobile communication system has channel sequence information (first sequence information) that determines the channel sequence according to the interference wave level. In this embodiment, when a communication request occurs between a base station and a wireless terminal, the base station measures the interference wave level of each communication channel via a sector antenna corresponding to a sector cell in which the wireless terminal to which the channel is to be allocated is located. , Rank the channels in descending order,
Get order information. Channels with large interference wave level measurements
The reason to rank in order from the
The higher the value of the channel, the closer the
Is likely to be used in
The same channel by preferentially using different channels.
Channels are used repeatedly over shorter distances,
This is because the usage efficiency becomes high.

Further, as shown in FIG. 3B, a priority function P1 (i) for this order information i is defined, the priority function value for rank 1 is 30, and the priority function value for rank 2 is 25. , Hereinafter, 20, 15, 10, and 5. This function value is determined to be smaller as the rank is lower. Here, this is referred to as a first function value.

Further, in this mobile communication system, FIG.
As shown in (c) and FIG. 3D, order information (second order information) that determines the order of channels according to the direction in which a desired wave from a wireless terminal arrives, and a priority function value (second order information) for the order information. Two function values). Since these are the same as in the first embodiment, the description will be omitted.

As with the first embodiment, in the mobile communication system shown in FIG.
H4 is in communication with the wireless terminal 21, channel CH6 is in communication with the wireless terminal 22, base station 12 is in communication with the wireless terminal 25 using channel CH3, and base station 13 is in communication with the wireless terminal 26 using channel CH2. Consider a case.

At this time, when a communication request is generated between the base station 11 and the wireless terminal 23, the base station 11 causes the desired wave from the wireless terminal 23 measured by each sector antenna, as in the first embodiment. The levels Da, Db, and Dc are measured, and it is determined that the desired wave of the wireless terminal 23 comes from the directivity direction of the sector antenna 31b, and the second function value is CH
1, CH2, CH3, CH4, CH5, CH6 in the order:
10, 50, 10, 10, 50, and 10.

On the other hand, the base station 11 obtains the first function value via the sector antenna 31b corresponding to the sector cell in which the wireless terminal 23 to which the channel is to be allocated is located, the interference wave level of the communication channels CH1 to CH6. U1b,
U2b, U3b, U4b, U5b and U6b are measured respectively. In this example, since the wireless terminal 26 using the channel CH2 is in the directivity direction of the sector antenna 31b, the interference wave level of the channel CH2 is large, and the wireless terminals 21 and 22 using the channels CH4 and CH6 are in the sector cell 41a. , 41c and close to the base station 11, their interference levels are relatively high and the channel C
Since the wireless terminal 25 using H3 is not in the directivity direction of the sector antenna 31b and is not close to the base station 11, the interference wave level of the channel CH3 is relatively low, and the channels CH1 and CH5 are not used. , The interference wave level is small. Accordingly, here, as a result of the measurement of the interference wave level, the order of the channel having the largest interference wave level is CH
2, CH4, CH6, CH3, CH1, and CH5. As described above, the first order information is ranked in order from the channel with the largest measured value of the interference wave level,
As shown in FIG. 3A, CH2, CH4, CH6, C
The order is H3, CH1, and CH5.

Then, the first order information shown in FIG.
From the first function value shown in FIG. 3B, the second order information shown in FIG. 3C, and the second function value shown in FIG.
When the sum of the first function value and the second function value of each channel is calculated, as shown in FIG.
It becomes 5,35,55,30. Then, the order of channels having the larger sum is determined as the channel selection order. In this case, CH2, CH5, CH4, CH6, CH3, C
The order is H1 (FIG. 3 (f)).

The base station 11 selects a channel in this order, and determines the ratio of the desired wave level Db to the interference wave level (CI
If R) is equal to or greater than a predetermined value, the wireless terminal 23
The channel CH1 is designated. In this case, the channel CH2 is selected first, but since the interference wave level U2b is large, the CIR of the channel CH5 to be selected next becomes equal to or more than a predetermined value, and the channel CH5 is transmitted to the wireless terminal 23.
Is specified. On the other hand, the wireless terminal 23 similarly measures the desired wave level and the interference wave level, determines whether or not the channel CH5 can be allocated, and notifies the base station 11 of it. If the assignment is possible, the communication is started using the channel CH5. In this case, since channel CH5 is not used elsewhere, it is determined that allocation is possible, and communication is started using channel CH5.

In a cellular system for performing dynamic channel allocation, a method of selecting channels in the same order for all base stations and a method of selecting channels in the order of increasing interference wave level have the effect of improving channel utilization efficiency. is there. In particular, in a cellular system having a sector cell configuration, a method of determining a channel selection order according to a direction in which a wireless terminal exists also has an effect of improving channel use efficiency.

The magnitude of the effect of the method of determining the order of channel selection is greatly affected by the order of the channels having the highest priority in channel selection, and the order of channels having almost the same priority is largely affected. I do not receive. Since the channel selection order determined by the two schemes is generally different from each other, the channel selection order is determined based on the priority function values for the priority of the two schemes, for example, the respective priority functions as in the present invention. If the sum is determined by the sum of the values, the order of selection between the channels having the same priority in one scheme A is determined by the other scheme B. At this time, since the selection order according to the scheme A only changes the order of the channels with little difference in priority, the effect is less reduced, while the order of the channels with little difference in priority is less in the scheme A. , And the method B, and the effect of the method B can be obtained. This brings out the effects of the two methods at the same time,
It is possible to further improve the channel use efficiency.

Although the present invention has been described in detail with reference to the embodiment, the present invention is not limited to this embodiment. For example, in the embodiment, the number of sector cells per base station is three, but the present invention can be implemented without any problem regardless of the number of sector cells.

[0034]

As described above, according to the present invention, in a mobile communication system employing a sector configuration and a dynamic channel allocation method, a channel allocation method in which the channel selection order is determined in advance, or interference between a desired wave and each channel. It is possible to simultaneously obtain the effects of both the channel allocation method using the measurement result of the wave reception level and the method of determining the channel selection order according to the arrival direction of the desired wave.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a process of determining a selection order in the first embodiment.

FIG. 3 is a diagram illustrating a process of determining a selection order in a second embodiment.

[Explanation of symbols]

11-13 Base Station 21-26 Wireless Terminals 31a-31c, 32a-32c, 33a-33c
Sector antennas 41a to 41c, 42a to 42c, 43a to 43c
Sector cell

Claims (2)

(57) [Claims] 1. A plurality of radio zones, a plurality of sector cells covering each of the radio zones, a base station arranged in each of the radio zones, and a base station connected to a reception input terminal of the base station. A sector antenna corresponding to the sector cell having directivity in a horizontal plane for each of the sector cells belonging to the sector cell, and a radio channel allocated among a plurality of radio channels located in any of the sector cells as a communication channel. A plurality of wireless terminals that communicate with a base station, wherein the base station is common to all sector cells of all base stations
When a communication request is generated between the first wireless channel order information that predetermines the order of the wireless channels so that and the one of the wireless terminals in the sector cell that belongs to the own station, it comes from the wireless terminal. Desired wave arrival direction estimation means for estimating the arrival direction of the desired wave, second wireless channel order information that determines the order of the wireless channels according to the arrival direction of the desired wave, and the first wireless channel order information Radio that determines the selection order based on the value of the first priority function determined according to the order of and the value of the second priority function determined according to the order of the second wireless channel order information Channel selection order determining means, and selecting the wireless channel satisfying a predetermined communication quality according to the wireless channel selection order determined by the wireless channel selection order determining means; Channel assignment scheme in a mobile communication system, comprising a radio channel allocation means for allocating radio channel as the communication channel. 2. A plurality of radio zones, a plurality of sector cells covering each of the radio zones, a base station arranged in each of the radio zones, and a base station connected to a reception input terminal of the base station. A sector antenna corresponding to the sector cell having directivity in a horizontal plane for each of the sector cells belonging to the sector cell, and a radio channel allocated among a plurality of radio channels located in any of the sector cells as a communication channel. A plurality of wireless terminals that communicate with a base station, wherein the base station supports a sector cell in which one of the wireless terminals is located when a communication request is made with one of the wireless terminals in the sector cell belonging to the own station. Measuring the reception level of each interference wave of the radio channel from the sector antenna
Then, the first wireless channel order information that determines the order of the wireless channels according to the reception level of the interference wave, and a desired wave arrival direction estimation means for estimating the arrival direction of the desired wave coming from the wireless terminal, Second wireless channel order information that determines the order of the wireless channels according to the arrival direction of the desired wave, and a value of the first priority function that is determined according to the order of the first wireless channel order information. And a wireless channel selection order determining means for determining a selection order based on a value of a second priority function determined according to the order of the second wireless channel order information, and the wireless channel selection order determining means. According to the selected order of the selected wireless channel, the wireless channel satisfying a predetermined communication quality is selected, and the selected wireless channel is assigned as the communication channel. Channel assignment scheme in a mobile communication system, comprising a channel allocation unit.