JPH09275585A - Mc/tdma mobile satellite communication system and its communication channel assignment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assign efficiently a communication channel while avoiding interference between adjacent zones. SOLUTION: A satellite exchange 1 is provided with a space time switch that makes exchange connection of a signal received by each RF transmitter 12 in the unit of time slots and provides an output of the result to each RF transmitter 14. Then a control section 16 compares a channel with a communication channel used in its adjacent zones in response to a communication channel assignment request from a mobile station 2 and selects a communication channel whose carrier frequency or time slot at least differs as a new communication channel and informs the result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MC / TDMA mobile satellite communication system and a communication channel allocation method therefor, and more particularly to a plurality of carrier frequencies provided on a plurality of carrier frequencies in response to a channel allocation request from an arbitrary mobile station. The present invention relates to an MC / TDMA mobile satellite communication system that allocates any one of the time slots as a communication channel and a communication channel allocation method.

[0002]

2. Description of the Related Art Conventionally, multiple carrier / time division multiple access (hereinafter, MC / TD) using a plurality of time slots provided on a plurality of carrier frequencies as communication channels.
In a mobile satellite communication system using a mobile communication system (hereinafter referred to as MA), each radio base station having a transceiver having a variable transmission / reception frequency is provided in each zone provided by dividing a coverage space (service area) of a mobile satellite. Every time a call from an arbitrary mobile station is generated, a predetermined free communication channel is allocated from a satellite exchange provided for a mobile satellite to a radio base station in a zone where the mobile station is located. ing.

In particular, in a satellite exchange, a communication channel is exchanged for each carrier frequency. In addition, in consideration of communication quality, the communication channel assignment requesting unit allocates a communication channel of a carrier frequency having no interference with a communication channel of a predetermined carrier frequency used in a zone adjacent to a zone in which a mobile station in which a request is made is located. (For example, JP-A-3-175828).

FIG. 3 is an explanatory diagram showing an example of MC / TDMA mobile satellite communication channel assignment, and shows channel assignment of a communication channel composed of a time axis, a space axis, and a carrier frequency axis. Carriers 1 to 3 of a predetermined frequency are provided on the carrier frequency axis, and time slots 1 to 3 are repeatedly provided on the time axis.

Zones 1 to N are provided as zones in the coverage space on the space axis. In each zone,
Each time slot 1 provided on these carrier frequencies
3 are shared as communication channels. When a predetermined mobile station located in zone 1 requests allocation of a communication channel in response to an outgoing call, the request is transmitted to the satellite exchange via the zone 1 radio base station using the predetermined control communication channel. A vacant channel of a carrier frequency which is transferred and has no interference with a zone adjacent to zone 1, for example, zone 2, is selected.

[0006] Here, in the case where all of the carrier frequencies other than the carrier 1 have been allocated, all the time slots of the carrier 1 in the zone 1 are vacant, so the satellite exchange selects, for example, the time slot 2. However, it is assumed that the time slot 2 of the carrier 1 is assigned to the radio base station of the zone 1. Subsequently, when there is a communication channel allocation request from a mobile station located in zone 2, the satellite exchange selects an empty time slot other than time slot 2 of carrier 1 in order to avoid interference with an adjacent zone.

In this case, time slot 1 of carrier 1
Although 3 and 3 are empty, the satellite exchange performs the exchange process for each carrier frequency, so that an empty time slot is actually selected from other than the carrier frequencies used in the adjacent zones. Here, since all the time slots of the carriers 2 and 3 other than the carrier 1 are used, the fact that there is no free communication channel is notified to the radio base station of the zone 2.

[0008]

Therefore, in such a conventional MC / TDMA mobile satellite communication system,
Since the switching process is performed for each carrier frequency in the satellite exchange, even if time slots of the same carrier frequency are vacant in adjacent zones,
There is a problem that the vacant time slot cannot be allocated as a communication channel, and the utilization efficiency of the communication channel is reduced.

The present invention has been made to solve such a problem, and can avoid mutual interference between adjacent zones, efficiently allocate communication channels, and effectively use network resources. It is an object of the present invention to provide an MC / TDMA mobile satellite communication system and a communication channel allocation method thereof.

[0010]

In order to achieve the above object, an MC / TDMA mobile satellite communication system and a communication channel assignment method according to the present invention are provided for a satellite exchange, a multicarrier / time division multiple access. A space / time switch that switches and connects a plurality of time slots provided for each carrier frequency as a processing unit based on the
In response to a communication channel assignment request from any mobile station, communication that is different from at least one of the carrier frequency and the time slot compared to the communication channel used in the zone adjacent to the zone where the mobile station is located. It has a control unit for selecting and notifying a channel as a new communication channel.

Therefore, the control section of the satellite exchange
In response to a communication channel allocation request from any mobile station, a communication channel having at least one of a carrier frequency and a time slot different from the communication channel used in the adjacent zone is selected as a new communication channel. In addition to notification to the mobile station, switching processing is performed for each time slot.

[0012]

Next, the present invention will be described with reference to the drawings. FIG. 1 shows an MC according to an embodiment of the present invention.
It is an explanatory view showing a / TDMA mobile satellite communication system, in which (a) is a system configuration and (b) is a block diagram of a satellite exchange.

In FIG. 1 (a), reference numeral 1 denotes a satellite exchange which centrally manages communication channels and allocates time slots free of mutual interference between adjacent zones as communication channels directly to mobile stations, and 4 denotes a coverage space (service area). 2) A plurality of zones 2 provided in 3 are mobile stations located in an arbitrary zone 4 and communicating by transmitting and receiving a predetermined carrier signal in a time slot of a carrier frequency allocated from the satellite exchange 1.

In FIG. 1 (b), reference numeral 12 denotes various signals received at an arbitrary time slot of an arbitrary carrier frequency transmitted from a mobile station 2 located in a specific zone 4 via a receiving antenna 11. The RF receiver 14 is a mobile station 2 located in a specific zone 4 via a transmitting antenna 15.
An RF transmitter 13 for transmitting a predetermined carrier signal in an arbitrary time slot of an arbitrary carrier frequency exchanges and connects a signal received by each RF transmitter 12 in units of a time slot. This is a space / time switch that outputs to

Numeral 16 manages all communication channels in a unified manner, and in response to a communication channel allocation request from the mobile station 2 received by the RF receiver 12 on a predetermined control communication channel, causes mutual interference between adjacent zones. An empty time slot without a channel is selected as a new communication channel, and the RF transmitter 14 notifies the mobile station of the allocation of the selected new communication channel through a control communication channel, and sets the space / time switch 13 A control unit that controls and exchanges and connects predetermined communication channels.

Next, the operation of the present invention will be described with reference to FIG. FIG. 2 is an explanatory diagram showing an example of communication channel assignment according to an embodiment of the present invention, and shows channel assignment of a communication channel composed of a time axis, a space axis, and a carrier frequency axis.

Carriers 1 to 3 of a predetermined frequency are provided on the carrier frequency axis, and time slots 1 to 3 are repeatedly provided on the time axis. Zones 1 to N are provided on the spatial axis as zones in the service area. In each zone, the time slots 1 to 3 provided at these carrier frequencies are shared as communication channels.

When a predetermined mobile station located in zone 1 requests allocation of a communication channel via a control communication channel, the request is received by a predetermined RF receiver 12 and notified to a control unit 16. Then, a free time slot that does not interfere with a zone adjacent to the zone where the mobile station is located is selected. When mobile stations residing in adjacent zones have the same carrier frequency and use the same time slot as a communication channel, interference occurs.

Therefore, the control unit 16 selects a communication channel different from at least one of the carrier frequency and the time slot as compared with the communication channel used in the adjacent zone. In FIG. 2, when all the frequencies except for the carrier 1 among the carrier frequencies have been allocated, the time slot 1 of the carrier 1
Since the time slots 1 and 3 are empty, the control unit 16 selects, for example, time slot 1, and the predetermined RF transmitter 14
To the mobile station in zone 2.

Further, in parallel with this, the control unit 18 selects the communication channel for the called mobile station, which is received together with the above-mentioned communication channel allocation request, in the same manner as described above based on the existing zone, The communication channel is notified according to the response from the calling side, and the space / time switch 13 is controlled to switch and connect the communication channels assigned to both. Thus, communication between the two is started.

As described above, the satellite exchange 1 is provided with a space / time switch for switching and connecting the signals received by the respective RF transmitters 12 in units of time slots and then outputting the signals to the respective RF transmitters 14. Accordingly, in response to a communication channel assignment request from the mobile station 2, a communication channel having at least one of a carrier frequency and a time slot different from that of a communication channel used in an adjacent zone is selected as a new communication channel. Notification.

Therefore, as compared with the conventional system in which the switching process is performed for each carrier frequency in the satellite exchange,
If different time slots are vacant even at the same carrier frequency in adjacent zones, the vacant time slots can be allocated as communication channels, and mutual interference between adjacent zones can be avoided. At the same time, communication channels can be efficiently allocated, and network resources can be used effectively.

[0023]

As described above, according to the present invention, space and time are switched and connected to a satellite exchange using a plurality of time slots provided for each carrier frequency as a processing unit based on multiple carrier / time division multiple access. A switch is provided, and in response to a communication channel allocation request from any mobile station, at least a carrier frequency or a time slot is compared with a communication channel used in a zone adjacent to the zone where the mobile station is located. One of them selects a different communication channel as a new communication channel.

Therefore, as compared with the conventional one in which the switching processing is performed for each carrier frequency in the satellite exchange,
If different time slots are vacant even at the same carrier frequency in adjacent zones, the vacant time slots can be allocated as communication channels, and mutual interference between adjacent zones can be avoided. At the same time, communication channels can be efficiently allocated, and network resources can be used effectively.

[Brief description of drawings]

FIG. 1 shows MC / TDMA according to an embodiment of the present invention.
It is a block diagram of an explanatory view showing a mobile satellite communications system.

FIG. 2 is an explanatory diagram showing an example of communication channel assignment according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of conventional communication channel assignment.

[Explanation of symbols]

1 ... satellite exchange, 2 ... mobile station, 3 ... service area, 4
... Zone, 11 ... Reception antenna, 12 ... RF receiver, 1
3 ... space / time switch, 14 ... RF transmitter, 15 ... transmission antenna, 16 ... control unit.

Claims (2)

[Claims] 1. A service area in which a communication service can be provided by a mobile satellite is divided into a plurality of zones, and based on multiple carriers / time division multiple access via a satellite switch provided in the mobile satellite. In an MC / TDMA mobile satellite communication system that provides various communication services to mobile stations located in each zone using a predetermined communication channel selected in the above, each carrier frequency is determined based on multiple carriers / time division multiple access. A space / time switch that switches and connects a plurality of time slots provided as processing units, and is used in a zone adjacent to a zone in which the mobile station is located in response to a communication channel allocation request from an arbitrary mobile station. Communication channels that differ at least in either carrier frequency or time slot compared to MC / T, characterized in that it comprises a satellite switch and a control unit which notifies to the mobile station selects a channel as a new communication channel
DMA mobile satellite communication system. 2. A service area in which a mobile satellite can provide a communication service is divided into a plurality of zones, and based on multiple carrier / time division multiple access via a satellite exchange provided in the mobile satellite. In a MC / TDMA mobile satellite communication system that provides various communication services to mobile stations located in each zone using a predetermined communication channel selected in the above, a satellite exchange uses a multicarrier / time division multiple access. A space / time switch for switching and connecting a plurality of time slots provided in each carrier frequency as a processing unit, and in response to a communication channel assignment request from any mobile station, to a zone in which the mobile station is located. At least either carrier frequency or time slot compared to the communication channel used in the adjacent zone A communication channel allocation method for an MC / TDMA mobile satellite communication system, wherein a communication channel of which one is different is selected as a new communication channel and notified to the mobile station.