JP2002064857A - Multicell system and base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve CIR of an incoming slot signal at a base station in a multicell system, in which base stations are linearly arranged in a sequential manner, the base stations repeatedly reusing a frequency of a limited number of frequencies, communication is carried out by causing the base station to allocate a specified slot to a mobile station from a plurality of slots, and the mobile station has a single traveling direction. SOLUTION: The base station manages the using start time of a slot of the mobile station in communication and allocates a slot to the mobile station based on the using start time of the slot. It is expected that the mobile station with an early using start time of a slot has traveled along a traveling direction. Thus, it is possible to predict a current position of the mobile station based on an entry time of the mobile station in the base station and to allocate a slot so as to improve CIR of an incoming slot signal at the base station.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

According to the present invention, a base station that repeatedly reuses a frequency from a finite number of frequencies is arranged so that each area of the base station overlaps linearly such as a road, and a communication area formed by the base station. The present invention relates to a multi-cell system that provides a continuous communication service to mobile stations running in a linear manner by using a CIR (Carrier to Interface), which is a power ratio between a desired wave and an interference wave in a base station and a mobile station.
technology for improving the rence power ratio).

[0002]

2. Description of the Related Art As a conventional multi-cell system for performing communication by allocating a slot to each mobile station, a PDC (Personal Computer) is known.
al Digital Cellular) and PHS (Personal Handy Phon)
e System) is known. In these multi-cell systems, a plurality of base stations that repeatedly reuse frequencies from a finite number of frequencies are arranged so that their communication areas overlap, and continuous communication services are provided to mobile stations. Each base station allocates uplink and downlink slots to the mobile station on the time axis at the frequency allocated to the base station. The mobile station communicates with the base station by using these slots. When the mobile station transits the communication area formed by the base station, the base station performs a handover process and allocates a new base station slot to the mobile station. As for these multi-cell systems, for example, "Books Understand Mobile Data Communication", Mainichi Communications, 1999, p. Normally, the base station randomly selects a slot to be newly assigned. An example of a method of selecting an empty slot to be allocated to these mobile stations is disclosed in Japanese Patent Application Laid-Open No. 9-322.
There are 25.

[0003] The following describes the conventional technology with reference to the drawings.
Give an explanation. FIG. 8 is a configuration diagram of a conventional multi-cell system. 8, 81 is a control station, 82, 83,
84 is a base station, and 85 and 86 are mobile stations. The operation of the conventional multi-cell system configured as described above will be described below. As shown in FIG. 8, in the conventional multi-cell system, the base station configures a communication area by radio and arranges the base station so that the communication area is formed without gaps, thereby enabling continuous communication with the mobile station. I will provide a. Adjacent base stations use different frequencies to avoid radio wave interference. In FIG. 8, the base station 83 uses a frequency F2 different from the frequency F1 of the adjacent base station 84. The same frequency is reused at base stations at some distance. In FIG. 8, the base station 8
The frequency F1 of 2 is reused by the base station 84. The base station is connected to the control station 81, and the multi-cell system operates by the control station 81 integrating and controlling the base stations.

[0004] Base stations and mobile stations in the communication area of each base station have a T.sub.T at a frequency assigned to that base station.
It is assumed that communication is performed by DMA / TDD. Here, 1
It is assumed that four transmission slots and four reception slots exist in one base station. In FIG. 8, from T1 to T4
Indicates a transmission slot, R1 to R4 indicate reception slots, and it is assumed that the mobile station 85 uses the transmission slot T3 and the reception slot R3.

[0005] When the mobile station moves to the base station (at the time of handover) or when the mobile station newly makes a call, a new uplink slot and a new downlink slot are allocated from the base station to the mobile station. For example, when the mobile station moves from the base station 82 to the base station 83, the destination base station 83 selects a transmission slot and a reception slot which are not currently used at the frequency of the base station, and moves. Assign to mobile stations. The determination of the necessity of the handover is performed on the basis that the mobile station observes the radio wave intensity and the radio wave intensity from the base station with which the mobile station is currently communicating falls below a predetermined threshold value.
The determination of the base station after the handover can be performed by observing the radio wave intensity at the mobile station and selecting a base station having a strong radio wave intensity. As described above, the base station randomly selects a slot to be newly allocated.

[0006] In a multi-cell system, the base station repeatedly reuses the same frequency, so that there is a problem of interference between base stations using the same frequency. For example, in FIG. 8, the base station 82 and the base station 84 use the same frequency F1, but the downlink signal from the base station 84 in the mobile station 85 communicating with the base station 82 becomes an interference wave.
In the base station 84, the uplink signal from the mobile station 85 becomes an interference wave.

As shown in FIG. 8, when a base station and a mobile station are communicating with each other by TDMA / TDD, between base stations using the same frequency, mobile stations using the same slot can communicate with each other. The signals interfere. In a conventional multi-cell system, for a mobile station to which a new slot is to be allocated, the base station randomly selects a slot that is not currently used and allocates it to the mobile station. For this reason, the CIR of the uplink slot signal at the base station and the CIR of the downlink slot signal at the mobile station become small, and the communication quality may deteriorate. Here, the CIR of the uplink slot signal in the base station is obtained by communicating the desired wave from the mobile station using the uplink slot allocated by the base station with the surrounding base station using the same uplink slot using the same uplink slot. This is the power ratio of the interference wave from the mobile station. On the other hand, the CIR of the downlink slot signal in the mobile station is the ratio of the power ratio of the desired wave of the downlink slot from the base station to the power ratio of the interference wave of the same downlink slot of the base station using the same surrounding frequency.

FIG. 9 is a diagram for explaining a problem of the conventional multi-cell system. In FIG. 9, reference numeral 91 denotes a control station;
2, 93 and 94 are base stations, and 95 and 96 are mobile stations.

In FIG. 9, a mobile station 96 communicating with a base station 93 moves to the communication area of the base station 94, and
It is assumed that the uplink slot T2 and the downlink slot R2 in the frequency F1 have been allocated. At this time, in the base station 92 using the same frequency F1, the uplink slot T
2. When the mobile station 95 using the downlink slot T2 is located at a position close to the base station 94 as shown in FIG. CIR2 of the signal of the downlink slot of the base station 92 in the station 95 is degraded.

CIR1 is represented by CIR1 = (L2 / L3) ＾ α, and CIR2 is represented by CIR2 = (L2 / L1) ＾ α. L1 is the distance between the mobile station 95 and the base station 92, L2 is the distance between the mobile station 95 and the base station 94, L3 is the distance between the mobile station 96 and the base station 94, and α is the attenuation coefficient of the radio wave. .

From these equations, the position of the mobile station 95 using the same slot of the same frequency is closer to the mobile station 96,
When L2 is short, CIR1 of the signal of the upstream slot deteriorates. Further, the position of the mobile station 95 that uses the same slot of the same frequency is close to the mobile station 96, L1 is long, and L1 is long.
When 2 is short, the CIR of the downlink slot signal is degraded. That is, when a slot is randomly selected in the base station when a slot is assigned to a mobile station, the CIR of the uplink slot signal in the base station and the CIR of the downlink slot signal in the mobile station deteriorate in some cases.

[0012]

As described above, there are the following problems in the conventional multi-cell system. In a multi-cell system, since the base station repeatedly reuses the same frequency, interference between base stations using the same frequency becomes a problem. In a conventional multi-cell system, T
When a base station and a mobile station communicate with each other by DMA / TDD, the base station assigns a new slot to the mobile station.
A slot that is not currently used is randomly selected and assigned to a mobile station. For this reason, the CIR of the uplink slot signal at the base station and the CIR of the downlink slot signal at the mobile station become small, and the communication quality may deteriorate.

In view of the above, in the present application, in a multi-cell system in which base stations using repetition frequencies are continuously arranged and the base station allocates slots to mobile stations and performs communication, the base station and the mobile station use slot signals of the mobile stations. An object is to provide a multi-cell system that improves CIR. Note that the present application is particularly directed to a multi-cell system in which base stations are arranged on a line.

[0014]

[Means for Solving the Problems]

[0015] In the multi-cell system according to the first invention of the present application, base stations that use a repetition frequency from a finite number of frequencies are continuously arranged on a line, and the base station has a plurality of slots for a mobile station. Communicates with the mobile station by allocating a specific slot in the multi-cell system in which the traveling direction of the mobile station is one-way, and manages the use start time of the slot of the mobile station communicating with the base station; Is to allocate a slot to a mobile station based on the use start time of the.

Thus, in the multi-cell system according to the first aspect of the present invention, it is possible to improve the CIR of the uplink slot signal in the base station. The base station predicts the position of the mobile station based on the use start time of the slot of the mobile station communicating with the adjacent base station using the same frequency, and based on this, improves the CIR of the uplink slot signal. This is because slots can be allocated as described above. For example, for a base station to which a slot is assigned, in a base station that uses the same frequency one position behind the traveling direction of the mobile station, a mobile station that has an earlier slot use start time is:
Since it is predicted that the mobile station exists in a short distance, the base station can predict the current position of the mobile station from the entry time of the mobile station, and can allocate slots so that the CIR of the uplink slot signal in the base station is improved. And can be.

In the multi-cell system according to the second aspect of the present invention, a base station using a repetition frequency from a finite number of frequencies is continuously arranged on a line, and the base station has a plurality of slots for a mobile station. In a multi-cell system that communicates with a mobile station by allocating a specific slot within, when a mobile station is managing a slot in use at each base station and newly allocating a slot to a mobile station, Slots that are not used in the base station and are unused in adjacent base stations that use the same frequency are preferentially allocated.

Thus, in the multi-cell system according to the second aspect of the present invention, the mobile station in a certain base station preferentially uses an unused slot in an adjacent base station using the same frequency, and , And the CIR of the downlink slot signal in the mobile station can be improved.

[0019]

Embodiment 1 Hereinafter, a multi-cell system according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a multi-cell system according to Embodiment 1 of the present invention.
In FIG. 1, 11 is a control station, 12 is a base station A,
13 is a base station B, 14 is a base station C, 15 is a base station D, 1
6 is a base station E, 17 is a base station F, 18 is a base station G, 1
9, 110, 111, 112 and 113 are mobile stations, 114
Is a road.

The operation of the multi-cell system according to the first embodiment configured as described above will be described below. As shown in FIG. 1, in the multi-cell system according to the first embodiment, base stations are continuously arranged along a road 114, and the base stations transmit and receive radio waves. The communication area of the base station is set so that an area partially overlaps with an adjacent base station. Here, the communication area is an area where the base station and the mobile station can communicate. As a result, road 11
4 can communicate with the base station continuously in time.

Each base station is connected to the control station 11 by wire, and each base station is centrally controlled by the control station. Since communication areas formed by adjacent base stations interfere with each other, the adjacent base stations use radio waves of different frequencies, and the same frequency is reused by base stations that are distant to some extent. In FIG. 1, the repetition frequency is 3, the base station A, the base station D, and the base station G use F1, the base station B and the base station E use F2, and the base stations C and F use F3. When the mobile station moves to a communication area of a different base station, a handover is required. Also,
In the present embodiment, the traveling direction of the mobile station is one direction. In this embodiment, it is assumed that the antenna of the base station has directivity in a direction of 45 degrees with respect to the reverse direction of travel of the mobile station as shown in the portion of base station B in FIG. .

Next, the configurations of the base station and the mobile station will be described. FIG. 2 is a configuration diagram of a mobile station and a base station according to the first embodiment of the present invention. In FIG. 2, reference numeral 21 denotes a mobile station, which includes an antenna 211, a receiving device 212, and a control device 2.
13, a transmission device 214, 22 is a base station, and an antenna 221, a reception device 222, a control device 223,
The transmission / reception device 224 and the transmission device 225 are configured.

The mobile station 21 includes an antenna 211, a receiving device 212 for receiving data from the base station using the antenna 211, a transmitting device 214 for transmitting data to the base station using the antenna 211, and a receiving device 212. The control unit 213 is configured to transmit and receive data to and from the base station 22 using the transmitting device 214 in a predetermined procedure.

The base station 22 includes an antenna 221, a receiving device 222 for receiving data from the mobile station using the antenna 221, a transmitting device 225 for receiving data from the mobile station using the antenna 221, and a receiving device 222. The control device 223 performs data transmission / reception with the mobile station 21 using the transmission device 225 in a predetermined procedure, and performs communication with the control station using the wired transmission / reception device 224. And a wired transmission / reception device 224. The base station 22 transmits and receives data to and from the control station by the wired transmission / reception device 224. The control station performs transmission of data to be transmitted to the mobile station, reception of data from the mobile station, and transmission of control data to each base station.

The communication system according to the present embodiment
In both downlinks, the base station allocates a specific slot among a plurality of slots to the mobile station and performs data transmission.

FIG. 3 is a diagram showing a communication frame configuration according to the first embodiment of the present invention. In FIG. 3, 3
1 is a communication frame. FIG. 3 shows one communication frame, and communication is performed by continuously exchanging the communication frame 31 between the base station and the mobile station. The frame control slot is a slot for controlling the entire frame transmitted from the base station to the mobile station. The frame control slot includes data for frame synchronization, ID of the base station, data of the frequency of the next base station, and the like. By receiving the frame control slot from the base station, the mobile station can synchronize the frames and know the characteristics of the entire multi-cell system.

The downlink slot is a slot allocated to a mobile station in the base station, and is a slot used for data transmission from the base station to each mobile station. Notification of allocation of uplink slots to each mobile station at the time of handover is also performed using the downlink slots. Uplink slots are slots allocated to mobile stations in the base station, and are used for data transmission from each mobile station to the base station. A handover request from the mobile station to the base station is also performed using this slot.

In this embodiment, in the case of the up slot 1
Is downlink slot 1 and uplink slot 2 is downlink slot 2.
Thus, it is assumed that the uplink slot and the downlink slot having the same slot number are allocated to the mobile station as a pair. In the present embodiment, it is assumed that frame synchronization is established between base stations. That is, it is assumed that the transmission timings of the frame control slot, each uplink slot, and each downlink slot are the same in all base stations.

When the mobile station moves and changes the communication area formed by the base station, a handover process is performed. In determining the handover, the mobile station observes the radio wave intensity of the next base station, and performs the handover process when the radio wave intensity of the next base station becomes stronger than the current radio wave intensity from the base station. In the handover process, the mobile station issues a handover request to the base station, and the base station allocates a new uplink slot to the mobile station. Thereafter, the mobile station communicates with the next base station in the assigned uplink slot.

The sequence of the handover will be described below with reference to the drawings. FIG. 4 is a diagram showing a handover sequence according to the first embodiment of the present invention. In FIG. 4, reference numeral 41 denotes a handover sequence. FIG. 4 shows a handover sequence when the mobile station 111 in FIG. 1 moves from the base station C to the base station D. Before the handover, the mobile station 111 exists in the communication area configured by the base station C, and performs data communication with the base station C according to the frame structure described with reference to FIG. Mobile station 111
Communicates with the base station C and simultaneously receives the frame control slot of the base station D which is the next base station in the traveling direction. The mobile station can know the frequency of the adjacent base station uniquely if the frequency repetition pattern is predetermined, or each base station notifies the mobile station of the frequency of the adjacent base station. It may be.

The mobile station 111 compares the radio field intensity of the frame control slot from the base station C which is the current base station with the base station D which is the next base station, and compares the radio field intensity of the frame control slot from the base station D. Is stronger than that of the base station C, it is determined that the mobile station 111 has entered the communication area of the base station D, and a handover request is made to the base station C. The handover request is made using an uplink slot. Upon receiving this handover request, the base station C sends a handover request to the next base station, the base station D.
The request for the handover is made via the control station 11. The mobile station ID of the mobile station performing the handover is included in the handover request.
Is included. The base station D allocates a slot currently unused in the base station D, and transmits a new slot number to the base station C as handover data. A method of allocating slots in the base station D at this time will be described later. Note that the base station D uses the data of the slot use state in the base station A, which is one base station behind the mobile station that uses the same frequency as the base station D, in allocating slots. However, it is assumed that these data are received from the base station A via the control station 11. When notified of the new slot number from the base station D as handover data, the base station C further notifies the mobile station of this data.

When receiving the handover data, the mobile station 111 transmits a handover completion notification to the base station D to notify that the handover has been completed. The transmission of the handover completion notification at this time is performed using the newly allocated uplink slot. The base station D that has received the handover completion notification transmits a handover completion notification to the base station C, and the base station C releases the slot used by the mobile station 111 so far. Thereafter, the mobile station 111 becomes the base station D
Data communication is performed using the slot assigned.

As described above, when the mobile station moves in the communication area of the base station, it can receive the allocation of the uplink slot of the next base station and communicate with the next base station. Next, base station D
Will be described below.
When allocating slots, each base station refers to the slot usage status in the base station that is one step behind the mobile station using the same frequency, and assigns a newly used slot. decide. At this time, if there is a vacant slot in the base station immediately behind the traveling direction of the mobile station, it is preferentially used. In addition, the slot whose use start time is earlier is used without priority. Specifically, if there is a slot that is unused in base station D and unused in base station A, that slot is used. The base station A communicates with the base station D using an unused slot, so that the base station D
Is improved in the CIR of the upstream slot signal. Further, among mobile stations communicating with the base station A, there are mobile stations whose CIR is improved because there is no interference wave from the base station D in receiving the downlink slot signal.

When there is no vacant slot in both the base station A and the base station D, the slot which is unused in the base station D and whose use start time is latest in the base station A is used. A mobile station using an upstream slot whose use start time is early,
Is expected to move forward, so that when this uplink slot is used, it is expected that the CIR of the signal of the uplink slot in the base station D will deteriorate.
For this reason, by using the slot whose use start time is late in the base station A, it is possible to improve the CIR of the uplink slot signal in the base station D.

Hereinafter, a method for allocating slots in the base station D will be described in detail. First, the slot management table in each base station will be described with reference to the drawings. FIG. 5 is a diagram illustrating an example 1 of the slot management table. In FIG. 5, reference numeral 51 denotes a slot management table of the base station A, and 52 denotes a slot management table of the base station D.

In the slot management table of each base station as shown in FIG.
Two items are managed. In the present embodiment, it is assumed that each base station has five slots. The use state indicates whether or not the base station is currently using the slot, and includes an unused state and a used state. The use start time is valid only when the slot is being used, and indicates the time when the slot is started to be used in the base station. In this embodiment, it is assumed that ms is managed as a unit.

Each base station allocates a slot by referring to the slot management table in the base station one immediately behind the mobile station using the same frequency in the traveling direction. The method of allocating slots in each base station will be described with reference to the drawings. FIG. 6 is a diagram illustrating a slot assignment method in the base station. In FIG. 6, 61, 62, 6
Steps 3 and 64 are steps.

Hereinafter, a method of allocating slots in the base station will be described with reference to FIG. The base station to which the uplink slot is assigned is a slot that is unused in the base station (base station A in the case of base station D) which is one base station in the direction of travel of the mobile station that is unused and uses the same frequency. Check if it exists. (Step 62) If the slot exists, the slot is used. (Step 63) If there is no slot, the slot that is unused in the base station and is used by the base station one step behind in the traveling direction of the mobile station using the same frequency is used as the slot with the latest use start time. select. (Step 64)

As an example, a description will be given of a method of allocating slots in base station D that has received a handover request from mobile station 111 in FIG. 1 when the use state of the slots is as shown in FIG. The base station D checks in the slot management table 52 of the base station D that the slots 1 and 4 are unused. Next, the base station D checks the slot management table 51 of the base station A, and checks that the slot 1 is empty. Therefore, base station D
Assigns slot 1 to mobile station 111.

In FIG. 1, it is assumed that the mobile station using slot 4 in base station A is mobile station 19. When slot 4 is allocated to mobile station 111, the signal of uplink slot 4 from mobile station 19 becomes an interference wave with the signal of uplink slot 4 from mobile station 111 in base station D. When slot 1 is allocated to mobile station 111, there is no mobile station communicating with base station A and transmitting an interference wave to base station D. On the other hand, in the signal reception of the downlink slot 4 in the mobile station 19, when the base station D uses the downlink slot 4, it becomes an interference wave, but when the base station D uses the downlink slot 1,
The base station D does not transmit a downlink slot serving as an interference wave to the mobile station communicating with the base station A.

As another example, the case where the use state of the slot is the state shown in FIG. 7 will be described. FIG. 7 is a diagram illustrating an example 2 of the slot management table. 7, reference numeral 71 denotes a slot management table of the base station A, and reference numeral 72 denotes a slot management table of the base station D. 7 differs from the slot management table of FIG. 5 in that slot 1 of base station A is used.

As in the first example, the mobile station 1 in FIG.
A description will be given of a method of allocating slots in the base station D that has received the handover request from the terminal 11. Base station D
Checks that slot 1 and slot 4 are unused in slot management table 72 of base station D. Next, the base station D checks the slot management table 71 of the base station A, and checks that both the slots 1 and 4 are in use. Further, the use start time of slot 1 and slot 4 in base station A is checked, and since the use start time of slot 4 is later,
The slot 4 is determined as an uplink slot to be allocated to the mobile station 111.

In the base station A, the mobile station whose slot use start time is earlier is moving from the base station D. Therefore, in the base station to which the slot is allocated, the radio wave intensity of these mobile stations is stronger than the radio wave intensity from other mobile stations of base station A. Therefore, by making the uplink slots of these mobile stations non-prioritized, it is possible to improve the CIR of the uplink slot signal at the base station D.

In FIG. 1, in the base station A, it is assumed that the mobile station 19 uses the slot 4 whose use start time is late, and the mobile station 110 uses the slot 1 whose use start time is early. Since the use start time of the mobile station 110 is earlier, L2 <L3. Therefore, when the uplink slot 4 in use of the mobile station 19 is allocated to the mobile station 111, the CIR of the signal of the uplink slot of the mobile station 111 in the base station D is CIR1 = (L3 / L1) ＾ α, A larger CIR is realized as compared with CIR2 = (L2 / L1) ＾ α, which is the CIR of the signal of the uplink slot of the mobile station 111 in the base station D when the uplink slot 1 in use by the mobile station 110 is allocated. be able to. (Normally, α is about 2-3)

As described above, in a multi-cell system in which a base station using a repetition frequency is intermittently arranged on a line and the base station performs communication by allocating slots to mobile stations, a base station using the same frequency is used. By using the slot use, non-use state, and slot use start time, the CIR of the uplink slot signal in the base station and the CIR of the downlink slot signal in the mobile station are used.
IR can be improved. The addition of the configuration in the mobile station and the base station also increases the management of the use start time of the slot of the mobile station in the base station, and can realize a multi-cell system with a simple configuration.

In this embodiment, when allocating slots, the slots are determined by referring to the use state of the slots of the base station that is one step behind the mobile station that uses the same frequency. It is also conceivable to refer to the use state of the slot of the base station which is one ahead of the traveling direction of the mobile station using. In this case, slots used by the base station immediately ahead of the traveling direction of the mobile station using the same frequency and whose use start time of the slot of the mobile station being used is late are assigned with non-priority. . This is because, when viewed from the base station to which the slot is assigned, a mobile station having a later use start time of the slot in the front base station is located closer. Regarding an empty slot, one slot is set in the traveling direction of a mobile station using the same frequency.
By not using the slot of the base station in front of the mobile station, the influence of the interference wave of the downstream slot from the base station of the same frequency in front of one in the reception of the downlink slot of the mobile station in the base station is eliminated. It is possible to eliminate the influence of the interference wave of the uplink slot from the mobile station of the base station of the same frequency one back in the reception of the uplink slot in the base station of the same frequency ahead.

[0047]

As described above, according to the multi-cell system according to the first aspect of the present invention, base stations using repetition frequencies from a finite number of frequencies are continuously arranged on a line, and The mobile station communicates with the mobile station by allocating a specific one of a plurality of slots to the mobile station, and in a multi-cell system in which the traveling direction of the mobile station is one-way, the slot of the mobile station communicating with the base station. The base station uses the same frequency to communicate with an adjacent base station using the same frequency, since the use start time is managed and the slot is assigned to the mobile station based on the use start time of the slot. The position of the mobile station is predicted on the basis of the use start time of the slot, and the slot can be allocated so that the CIR of the uplink slot signal can be improved based on the predicted position. It takes an effect capable of improving the CIR of the uplink slot signal.

Further, according to the multi-cell system according to the second aspect of the present invention, base stations that use repetition frequencies from a finite number of frequencies are continuously arranged on a line, and In a multi-cell system in which communication with a mobile station is performed by allocating a specific slot among a plurality of slots, when a base station manages a slot being used by a mobile station and newly allocates a slot to a mobile station. Is configured to preferentially allocate slots that are unused in the base station and unused slots in adjacent base stations that use the same frequency. By preferentially using unused slots in adjacent base stations that use
There is an effect that the IR and the CIR of the downlink slot signal in the mobile station can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a multi-cell system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing configurations of a mobile station and a base station in the multi-cell system according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a communication frame configuration in the multi-cell system according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a handover sequence in the multi-cell system according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a first example of an upstream slot management table.

FIG. 6 is a diagram showing a slot assignment method in a base station.

FIG. 7 is a diagram illustrating an example 2 of an uplink slot management table;

FIG. 8 is a diagram showing a configuration of a conventional multi-cell system.

FIG. 9 is a diagram for explaining a problem of a conventional multi-cell system.

[Explanation of symbols]

11, 81, 91 control station 12 base station A 13 base station B 14 base station C 15 base station D 16 base station E 17 base station F 18 base station G 19, 110, 111, 112, 113, 21, 85,
86, 95, 96 Mobile station 114 Road 211, 221 Antenna 212, 222 Receiving device 213, 223 Control device 214, 225 Transmitting device 22, 82, 83, 84, 92, 93, 94 Base station 224 Wired transmitting / receiving device 31 Communication frame 41 Handover sequence 51, 71 Slot management table of base station A 52, 72 Slot management table of base station D 61, 62, 63, 64 Step

Continued on the front page (72) Inventor ▲ Taka ▼ Hitoshi Ikai 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F term (reference) 5K028 AA01 BB04 CC02 CC05 DD01 DD02 DD03 EE03 EE07 KK01 KK12 KK32 LL12 RR02 5K067 AA03 BB03 BB04 EE02 EE10 EE16 EE44 EE56 EE63 EE71 FF03 FF05

Claims (10)

[Claims] A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged linearly so that the areas of adjacent base stations overlap with each other. A multi-cell system that communicates with the mobile station by allocating a specific one of a plurality of slots to a mobile station entering the mobile station, wherein the arbitrary base station starts using a slot of the mobile station communicating with the mobile station. A multi-cell which manages time and determines a slot assignment based on a slot use start time in another base station using the same frequency when the mobile station requests a slot assignment. system. 2. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged in a line so that areas of adjacent base stations overlap with each other. A base station in a multi-cell system that communicates with a mobile station by allocating a specific one of a plurality of slots to a mobile station that enters the mobile station, and manages the use start time of the slot of the mobile station that is communicating with the base station. A base station, wherein when a request for slot allocation is issued from the mobile station, slot allocation is determined based on a slot use start time in another base station using the same frequency. 3. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged in a linear manner so that areas of adjacent base stations overlap with each other. A multi-cell system in which communication with the mobile station is performed by allocating a specific slot among a plurality of slots to the mobile station entering the mobile station, and the traveling direction of the mobile station is one-way, In an arbitrary base station, the use or non-use state of all slots and the start time of use of the slot of the mobile station with which the mobile station is communicating are managed, and the arbitrary base station allocates a slot from the mobile station. When requested, a slot being used in a second base station that is one back in the direction of travel of the mobile station using the same frequency as the arbitrary base station, and Multi-cell system and allocates the slot use start time is earlier in the mobile station slots in use slots not preferentially. 4. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged linearly so that the areas of adjacent base stations overlap with each other. A mobile station that communicates with the mobile station by allocating a specific one of a plurality of slots to the mobile station, and the mobile station travels in one direction in a multi-cell system. The state of use or non-use, and manages the use start time of the slot of the mobile station that is communicating, when there is a request for slot allocation from the mobile station,
A slot being used by a second base station that is one position behind the mobile station using the same frequency as the base station, and the slot of the mobile station that is using the slot. A base station, wherein a slot whose use start time is earlier is assigned in a non-priority manner. 5. A plurality of base stations that repeatedly reuse frequencies from among a finite number of frequencies are linearly arranged so that areas of adjacent base stations overlap with each other. A multi-cell system in which communication with the mobile station is performed by allocating a specific slot among a plurality of slots to the mobile station entering the mobile station, and the traveling direction of the mobile station is one-way, In an arbitrary base station, the use or non-use state of all slots and the start time of use of the slot of the mobile station with which the mobile station is communicating are managed, and the arbitrary base station allocates a slot from the mobile station. When requested, a slot being used in a second base station that is one ahead of the traveling direction of the mobile station using the same frequency as the arbitrary base station, and Multi-cell system, characterized in that use start time of the slot of the mobile station in use slot allocates slow slot non priority. 6. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged in a linear manner so that areas of adjacent base stations overlap with each other. A mobile station that enters the mobile station, and communicates with the mobile station by allocating a specific one of a plurality of slots to the mobile station, and is a base station in a multi-cell system in which the traveling direction of the mobile station is one-way. Managing the use or non-use state of all the slots and the use start time of the slot of the mobile station with which the mobile station is communicating, and when the mobile station requests a slot allocation, A slot being used by a second base station that is one position ahead of the traveling direction of the mobile station using the same frequency, and a slot of the mobile station that is using the slot. Base station and allocates the use start time is later slot non priority. 7. A plurality of base stations that repeatedly reuse frequencies from among a finite number of frequencies are linearly arranged so that areas of adjacent base stations overlap with each other. A multi-cell system that communicates with the mobile station by allocating a specific slot out of a plurality of slots to the mobile station entering the, the arbitrary base station, the use or non-use state of all slots Managing, when there is a request for slot allocation from the mobile station, a slot that is unused in the arbitrary base station and uses the same frequency as the arbitrary base station. A multi-cell system characterized by preferentially allocating slots not used in a base station. 8. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged in a line so that the areas of adjacent base stations overlap with each other. A base station in a multi-cell system that communicates with the mobile station by allocating a specific one of a plurality of slots to a mobile station entering the base station, and manages the use or non-use state of all slots, A slot that is unused by the base station when a slot allocation request is issued by the mobile station, and that is not used by an adjacent second base station that uses the same frequency as the base station. A base station, wherein the base station is assigned with priority. 9. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged in a line so that areas of adjacent base stations overlap with each other. A multi-cell system in which communication with the mobile station is performed by allocating a specific slot among a plurality of slots to the mobile station entering the mobile station, and the traveling direction of the mobile station is one-way. Manages the use or non-use state of all slots, when there is a request for slot allocation from the mobile station, the slot is an unused slot in the arbitrary base station, and the arbitrary base station A multi-cell system, wherein an unused slot is preferentially allocated in a second base station one position behind the mobile station using the same frequency as that of the mobile station. 10. A plurality of base stations that repeatedly reuse a frequency from a finite number of frequencies are arranged linearly so that the areas of adjacent base stations overlap with each other. A mobile station that enters the mobile station communicates with the mobile station by allocating a specific one of a plurality of slots, and the mobile station travels in one direction in a multi-cell base station, Manages the use or non-use state of the base station, when there is a request for slot allocation from the mobile station, the base station is a slot that is unused, and uses the same frequency as the base station. A base station, wherein an unused slot is preferentially allocated in a second base station one position behind the mobile station in the traveling direction.