Dynamic channel allocation method

• US 5,260,944 A
• Filed: 08/05/1991
• Issued: 11/09/1993
• Est. Priority Date: 08/09/1990
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tomabechi, Akitaka
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US07/740,511
• Time in Patent Office: 827 Days
• Field of Search: 370/95.1, 370/95.3, 370/85.2, 370/79, 370/24, 370/104.1, 370/29, 370/30, 370/31, 379/59, 379/60, 455/12, 455/33, 455/56, 455/12.1, 455/33.1, 455/33.2, 455/33.3, 455/33.4, 455/56.1
• US Class Current: 370/347
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames

Abstract

A dynamic frequency allocation method of a digital, mobile, portable telephone system wherein in communications between a plurality of base stations which are connected to a public telephone network and/or a private branch exchange and which respectively generate synchronization in an independent manner and mobile stations receiving service therefrom, each base station uses a communication signal transmission channel including a frequency and a time slot pair respectively selected from a plurality of frequencies and a plurality of time slots related thereto to implement a multichannel time division multiplex/time division duplex communication. Each of the base and mobile stations receives a communication signal of a different station communicating with synchronization independent of the pertinent station by use of a different time slot at the same frequency of the channel used by the station to receive a communication sent thereto so as to measure an interval or a distance between the time slot used by the different station and the time slot assigned thereto. Based on the measurement result, a chance of a collision between these two time slots is estimated such that depending on the estimation result, the pertinent station detects free channels not being used by any other stations to conduct a channel transition to one of the detected free channels.

Claims

1. A dynamic channel allocation method in mobile radio communication between a plurality of base stations and mobile stations which receive communication service of the base stations, each of the base stations being connected to a network and independently establishing synchronization for the mobile radio communication and having a plurality of communication signal transmission channels each defined by a combination of a frequency and a pair of time slots for transmitting and receiving a communication signal selected from a plurality of frequencies and a plurality of time slots to achieve a time division multiple access (TDMA)/time division duplex (TDD) communication, comprising steps of;

establishing communication between selected base and mobile stations in respective channels;

causing each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

measuring at each of the selected base and mobile stations, when the communication signal from the different station exists, a difference in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

estimating at each of the selected base and mobile stations, based on a result of the measurement, an occurrence of an overlap in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

2. A dynamic channel allocation method according to claim 1 further comprising steps of:

sensing at each of the selected base and mobile stations, when the communication signal from the different station exists, a reception level of the communication signal from the different station to recognize a rising point of the communication signal reception and a falling point thereof;

sensing, based on the rising and falling points, a leading portion and a tailing portion of the time slot used by the different station;

recognizing a position of the time slot used by the different station depending on the leading and tailing portions thus sensed; and

recognizing a difference in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations.

3. A dynamic channel allocation method according to claim 1 further comprising steps of:

sensing at each of the selected base and mobile stations, when the communication signal from the different station exists, a frame synchronization signal included in the communication signal from the different station;

recognizing a position of the time slot used by the different station depending on the frame synchronization signal included in the communication signal from the different station; and

recognizing a difference in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations.

4. A dynamic channel allocation method according to claim 1 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

sensing at each of the selected base and mobile stations, when the communication signal from the different station exists, a reception signal level of the communication signal destined to said each of the selected base and mobile stations and the communication signal from the different station;

achieving at each of the selected base and mobile stations, when an occurrence of an overlap in time between the time slot used by said each of the selected base and mobile stations and the time slot used by the different station is estimated as a result of the sensing operation, a comparison between the reception levels respectively of the communication signal destined to said each of the selected base and mobile stations and the communication signal from the different station;

achieving at each of the selected base and mobile stations, when it is recognized that the reception level of the communication signal from the different station is strong enough to interfere with the communication signal destined to said each of the selected base and mobile stations, a search through all free channels to detect a free channel not being used by any other station before the occurrence of the overlap in time between the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

5. A dynamic channel allocation method according to claim 2 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot form a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

sensing at each of the selected base and mobile stations, when the communication signal from the different station exists, a reception signal level of the communication signal destined to said each of the selected base and mobile stations and the communication signal from the different station;

achieving at each of the selected base and mobile stations, when an occurrence of an overlap in tie between the time slot used by said each of the selected base and mobile stations and the time slot used by the different station is estimated as a result of the sensing operation, a comparison between the reception levels respectively of the communication signal destined to said each of the selected base and mobile stations and the communication signal from the different station;

achieving at each of the selected base and mobile stations, when it is recognized that the reception level of the communication signal from the different station is strong enough to interfere with the communication signal destined to said each of the selected base and mobile stations, a search through all free channels to detect a free channel not being used by any other station before the occurrence of the overlap in time between the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

6. A dynamic channel allocation method according to claim 3 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

sensing at each of the selected base and mobile stations, when the communication signal from the different station exits, a reception signal level of the communication signal destined to said each of the selected base and mobile stations and the communication signal from the different station;

achieving at each of the selected base and mobile stations, when an occurrence of an overlap in time between the time slot used by said each of the selected base and mobile stations and the time slot used by the different station is estimated as a result of the sensing operation, a comparison between the reception levels respectively of the communication signal destined to said each of the selected base and mobile stations and the communication signal from the different station;

achieving at each of the selected base and mobile stations, when it is recognized that the reception level of the communication signal from the different station is strong enough to interfere with the communication signal destined to said each of the selected base and mobile stations, a search through all free channels to detect a free channel not being used by any other station before the occurrence of the overlap in time between the time slot used by said each of the selected base and mobile stations and time slot used by the different station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

7. A dynamic channel allocation method according to claim 1 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

setting as identification points a point of time prior to a leading portion of a time slot used by each of the selected base and mobile stations to receive a communication signal sent thereto and a point of time posterior to a tailing portion of the time slot;

causing said each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

detecting at each of the selected base and mobile stations, when the communication signal from the different station exists, a state wherein at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station exists at a point in a range between the identification points;

estimating at each of the selected base and mobile stations, at a detection of the state, an occurrence of an overlap in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

8. A dynamic channel allocation method according to claim 2 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

setting as identification points a point of time prior to a leading portion of a time slot used by each of the selected base and mobile stations to receive a communication signal sent thereto and a point of time posterior to a tailing portion of the time slot;

causing said each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

detecting at each of the selected base and mobile stations, when the communication signal from the different station exists, a state wherein at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station exists at a point in a range between the identification points;

estimating at each of the selected base and mobile stations, at a detection of the state, an occurrence of an overlap in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

9. A dynamic channel allocation method according to claim 3 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

setting as identification points a point of time prior to a leading portion of a time slot used by each of the selected base and mobile stations to receive a communication signal sent thereto and a point of time posterior to a tailing portion of the time slot;

causing said each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

detecting at each of the selected base and mobile stations, when the communication signal from the different station exists, a state wherein at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station exists at a point in a range between the identification points;

estimating at each of the selected base and mobile stations, at a detection of the state, an occurrence of an overlap in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

10. A dynamic channel allocation method according to claim 4 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

setting as identification points a point of time prior to a leading portion of a time slot used by each of the selected base and mobile stations to receive a communication signal sent thereto and a point of time posterior to a tailing portion of the time slot;

causing said each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

detecting at each of the selected base and mobile stations, when the communication signal from the different station exists, a state wherein at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station exists at a point in a range between the identification points;

estimating at each of the selected base and mobile stations, at a detection of the state, an occurrence of an overlap in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

11. A dynamic channel allocation method according to claim 5 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

setting as identification points a point of time prior to a leading portion of a time slot used by each of the selected base and mobile stations to receive a communication signal sent thereto and point of time posterior to a tailing portion of the time slot;

causing said each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

detecting at each of the selected base and mobile stations, when the communication signal from the different station exists, a state wherein at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station exists at a point in a range between the identification points;

estimating at each of the selected base and mobile stations, at a detection of the state, an occurrence of an overlap in time between the time slot use by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

12. A dynamic channel allocation method according to claim 6 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

setting as identification points a point of time prior to a leading portion of a time slot used by each of the selected base and mobile stations to receive a communication signal sent thereto and a point of time posterior to a tailing portion of the time slot;

causing said each of the selected base and mobile stations to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

detecting at each of the selected base and mobile stations, when the communication signal from the different station exists, a state wherein at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station exists at a point in a range between the identification points;

estimating at each of the selected base and mobile stations, at a detection of the state, an occurrence of an overlap in time between the time slot used by the different station and the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations, prior to the occurrence of the overlap in time, based on a result of the estimation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

13. A dynamic channel allocation method according to claim 1 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile station a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

14. A dynamic channel allocation method according to claim 2 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

15. A dynamic channel allocation method according to claim 3 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists of not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exits, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

16. A dynamic channel allocation method according to claim 4 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different stations, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel use by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

17. A dynamic channel allocation method according to claim 5 comprising steps of;

establishing communication between a selected base station and a selected mobile station in channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at lest one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

18. A dynamic channel allocation method according to claim 6 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at lest one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

19. A dynamic channel allocation method according to claim 7 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion an the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

20. A dynamic channel allocation method according to claim 8 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency a that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the tie slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

21. A dynamic channel allocation method according to claim 9 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot form a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base ad mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

22. A dynamic channel allocation method according to claim 10 comprising the steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving att each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

23. A dynamic channel allocation method according to claim 11 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations ad transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot from a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations about the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.

24. A dynamic channel allocation method according to claim 12 comprising steps of;

establishing communication between a selected base station and a selected mobile station in a channel;

causing each of the selected base and mobile stations to receive a communication signal destined to said each of the selected base and mobile stations and to check whether a communication signal from a different station exists or not which establishes synchronization independently of the selected base and mobile stations and transmits in a different channel having a same frequency as that of the channel used by the selected base and mobile stations and a different time slot form a time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto;

recognizing at each of the selected base and mobile stations, when the communication signal from the different station exists, at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto and at least one of a leading portion and a tailing portion and a frame synchronization signal field of the time slot used by the different station, whereby recognizing a position of the time slot used by said each of the base and mobile stations and a position of the time slot used by the different station;

detecting at each of the selected base and mobile stations a change with respect to a lapse of time in a relative positional relationship between at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by said each of the selected base and mobile stations and at least one of the leading portion and the tailing portion and the frame synchronization signal field of the time slot used by the different station;

computing at each of the selected base and mobile stations a relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations;

achieving at each of the selected base and mobile stations a computation to estimate a point of time when the time slot used by said each of the selected base and mobile stations to receive a communication signal sent thereto overlaps in time with the time slot used by the different station based on the relative moving speed of the time slot used by the different station in reference to the time slot used by said each of the selected base and mobile stations and on the positions of the time slot used by said each of the selected base and mobile stations and the time slot used by the different station;

achieving at each of the selected base and mobile stations, prior to an occurrence of the overlap in time, based on a result of the computation, a search through all free channels to detect a free channel not being used by any other station;

causing one of the selected base and mobile stations which has detected the free channel to inform the other of the selected base and mobile stations aobut the free channel; and

conducting at the selected base station, when the free channel has been detected, a channel transition from the channel used by the selected base and mobile stations to the free channel, thereby allocating the free channel to the selected base and mobile stations.