Mobile communication system

1. A mobile communication system, comprising:

at least one base station, including time slot change request means which sends time slot change information to a subscriber station connected thereto by radio when it becomes necessary to change the transmission rate for data to be sent to the subscriber station; and

at least one subscriber station, including time slot changing means which, upon receiving the time slot change information from the change request means of the base station, changes the time slot in which to receive data from the base station in accordance with the time slot change information.

2. The mobile communication system of claim 1 , wherein when having sent the time slot change information to the subscriber station, the change request means of the base station begins to use the new time slot to send data contained in the next frame.

3. The mobile communication system of claim 1 , wherein the change request means of the base station determines the transmission rate in accordance with an instantaneous amount of data sent to the subscriber station.

4. The mobile communication system of claim 3 , wherein the change request means of the base station detects the instantaneous amount of data from that amount of data received from a switching center which has yet to be sent to the subscriber station.

5. The mobile communication system of claim 1 , wherein at the time of sending the time slot change information to the subscriber station, the change request means of the base station obtains the time slot change information from a provisional channel memory provisionally pre-assigned the time slot to be used for the transmission of the next frame.

6. The mobile communication system of claim 1 , wherein at the time of sending the time slot change information to the subscriber station, the change request means of the base station also sends reservation information indicating the time slot change timing to the subscriber station.

7. The mobile communication system of claim 6 , wherein the time slot changing means of the subscriber station determines the time slot change timing in accordance with the reservation information sent from the base station.

8. The mobile communication system of claim 6 , wherein when a desired time slot becomes unusable before the time slot changing means of the subscriber station performs time slot switching after sending the time slot change information and the reservation information to the subscriber station, the change request means of the base station sends time slot change information indicating another time slot to the subscriber station.

9. The mobile communication system of claim 1 , wherein in the case of increasing the data transmission rate, the change request means of the base station determines whether to change the transmission rate by referring to the sendable power of a transmitter in the base station.

10. The mobile communication system of claim 1 , wherein in the case of decreasing the data transmission rate, the change request means of the base station determines whether to change the transmission rate by referring to the sensitivity of a receiver in the subscriber station and the transmission power of a transmitter in the base station.

11. A mobile communication system comprising:

at least one subscriber station, including time slot change request means which sends a time slot change information to a base station connected thereto by radio when it becomes necessary to change the transmission rate for data to be sent to the base station; and

at least one base station, including time slot changing means which, upon receiving the time slot change information from the change request means of the subscriber station, changes the time slot in which to receive data from the subscriber station in accordance with the time slot change information.

12. The mobile communication system of claim 11 , wherein when having sent the time slot change information to the base station, the change request means of the subscriber station begins to use the new time slot to send data contained in the next frame.

13. The mobile communication system of claim 11 , wherein the change request means of the subscriber station determines the transmission rate in accordance with an instantaneous amount of data to be sent to the base station.

14. The mobile communication system of claim 13 , wherein the change request means of the subscriber station detects the instantaneous amount of data from that amount of data received from a man-machine interface which has yet to be sent to the subscriber station.

15. The mobile communication system of claim 11 , wherein at the time of sending the time slot change information to the base station, the change request means of the subscriber station obtains said time slot change information from a provisional channel memory provisionally pre-assigned the time slot to be used for the transmission of the next frame.

16. The mobile communication system of claim 11 , wherein at the time of sending the time slot change information to the base station, the change request means of the subscriber station also sends reservation information indicating the time slot change timing to the base station.

17. The mobile communication system of claim 16 , wherein the time slot changing means of the base station determines the time slot change timing in accordance with the reservation information sent from the subscriber station.

18. The mobile communication system of claim 16 , wherein when a desired time slot becomes unusable before the time slot changing means of the base station performs time slot switching after sending the time slot change information and the reservation information to the base station, the change request means of the subscriber station sends time slot change information indicating another time slot to the base station.

19. The mobile communication system of claim 11 , wherein in the case of increasing the data transmission rate, the change request means of the subscriber station determines whether to change the transmission rate by referring to the sendable power of a transmitter in the subscriber station.

20. The mobile communication system of claim 11 , wherein in the case of decreasing the data transmission rate, the change request means of the subscriber station determines whether to change the transmission rate by referring to the sensitivity of a receiver in the base station and the transmission power of a transmitter in the subscriber station.

21. A mobile communication system, comprising:

at least one base station, including time slot change request means for sending time slot change information to a subscriber station connected to the base station by a radio communication channel, when it becomes necessary to change a transmission rate for data to be sent from said base station to said subscriber station, and time slot changing means for receiving time slot change information from a subscriber station and changing a time slot in which to receive data from said subscriber station; and

at least one subscriber station, including time slot change request means for sending time slot change information to a base station connected to the subscriber station by a radio communication channel, when it becomes necessary to change transmission rate for data to be sent from said at least one subscriber station to said base station; and time slot changing means for receiving time slot change information from a base station and changing a time slot in which to receive data from said base station.