Mobile communication system

• US 6,160,801 A
• Filed: 12/29/1997
• Issued: 12/12/2000
• Est. Priority Date: 07/14/1997
• Status: Expired due to Term

• Current Assignee: TCL Communication Technology Holdings Ltd. (TCL Technology Group Corp.)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Matsumoto, Shinji, Uchida, Yoshinori
• Primary Examiner(s): Patel, Ajit
• Assistant Examiner(s): NGUYEN, BRIAN D
• Application Number:
  US08/998,732
• Time in Patent Office: 1,079 Days
• Field of Search: 370/335, 370/336, 370/337, 370/344, 370/347, 370/342, 370/319, 370/320, 370/321, 370/441, 370/442, 370/324, 370/331, 370/343, 370/503, 455/436, 455/437, 455/439, 455/442
• US Class Current: 370/337
• CPC Class Codes: H04B 7/2618 using hybrid code-time division multiple access [CDMA-TDMA]

Abstract

A mobile communication system implementing a frequency sharing and a time slot sharing using communication signal including a plurality of TDMA signals and/or the time divided CDMA signals, to supply the mobile communication system with an improved overall communication quality. The system includes the communication signal from a plurality of multiple access method for sharing frequency and time. A TDMA signal identified by synchronization word code has a different synchronization word code from each other, which is assigned to the same frequency and time slot. A time divided CDMA signal is frequency spreaded by spreading codes which is assigned to time divided time slot. The system also includes the stations which regenerate the time divided CDMA shared signal from the received communication signal and after a removal of the shared signal from the communication signal the TDMA signal synchronization word code is regenerated as desired signal.

Claims

1. A mobile communication system for radio communication comprising:

a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method selected from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, wherein each of said communication stations includes;

a receiving unit for receiving a communication signal, said communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method and

a time divided CDMA signal, frequency spread by a spread code and being assigned to a time division time slot, based on a CDMA method;

a shared signal regeneration unit for regenerating the time divided CDMA signal from the received communication signal and for outputting said time divided CDMA signal as a shared signal;

a shared signal removing unit for removing the shared signal from the received communication signal; and

a desired signal regeneration unit for regenerating said TDMA signal after removal of the shared signal from the received communication signal and for outputting said TDMA signal as a desired signal.

2. A mobile communication system for radio communication comprising:

a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, wherein each of said communication stations includes;

a receiving unit for receiving a communication signal, said communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method, and

a time divided CDMA signal, frequency spread by a spread code and being assigned to a time division time slot, based on a CDMA method;

a shared signal regeneration unit for regenerating the TDMA signal from the receive communication signal and for outputting said TDMA signal as a shared signal;

a shared signal removing unit for removing the shared signal from the received communication signal; and

a desired signal regeneration unit for regenerating said time divided CDMA signal after removal of the shared signal from the received communication signal and for outputting said time divided CDMA signal as a desired signal.

3. A mobile communication system for radio communication comprising:

a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, wherein each of said communication stations includes;

a receiving unit for receiving a communication signal said communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method, and

a time divided CDMA signal, frequency spread by a spread code and being assigned to a time division time slot, based on a CDMA method;

a base station control data memory unit for storing information for identifying said predetermined access method as control data showing a spreading code used in creating the time divided CDMA signal and a synchronization word code used in the TDMA signal, for the communication signal used within the service area of said a least one base station; and

a base station access method control unit for controlling multiple access methods between a plurality of mobile stations an said at least one base station, based on said control data.

4. The mobile communication system of claim 3, wherein the base station access method control unit of claim 3 stores control data for each access method identified by information for identifying said predetermined access method showing said spreading code and said synchronization word code, and

wherein the control data has information on transmitting/receiving powers related to transmitting power at said at least one base station, receiving power at said at least one base station, transmitting power at each of said plurality of mobile stations and receiving power at each of said plurality of mobile stations.

5. The mobile communication system of claim 4, wherein the system decides a handoff of the mobile station depending on a receiving power of a communication signal transmitted from a mobile station and received at a base station and a transmitting power of a communication signal transmitted from the base station to the mobile station at the mobile station,

wherein, based on the decision, adjoining base stations from the base station receive communication signal from the mobile station;

and

wherein the system decides a handoff destination of the base station based on the receiving powers at the adjoining base stations.

6. The mobile communication system of claim 3 wherein the station has a plurality of shared signal regeneration units and a plurality of desired signal regeneration units corresponding to multiple access methods;

and wherein the station stores a control data for each access method identified by method using information for identifying access method showing spreading code and synchronization word code, and wherein the control data includes operation information of each of the shared signal regeneration units and each of the desired signal regeneration unit.

7. The mobile communication system of claim 6, wherein the one of the shared signal regeneration unit and the desired signal regeneration unit corresponding to the multiple access method is assigned to the communication signal depending on receiving power of the communication signal transmitted from the mobile station and received at the base station.

8. The mobile communication system of claim 6, wherein the shared signal regeneration unit or the desired signal regeneration unit corresponding to the multiple access method is assigned to the communication signal depending on receiving power of the TDMA signal and the time divided CDMA signals at the handoff destination base station in case of making handoff to TDMA signal sharing frequency and time slot with time divided CDMA signal.

10. The mobile communication system of claim 9, wherein the system access method control unit of claim 4 stores control data for each access method identified by information for identifying access method showing spreading code and synchronization word code, and

wherein the control data has information on transmitting/receiving powers related to transmitting power at base station, receiving power at base station, transmitting power at mobile station and receiving power at mobile station.

9. A mobile communication system for radio communication comprising:

a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, wherein each of said communication stations includes;

a receiving unit for receiving a communication signal, said communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method, and

a time divided CDMA signal, frequency spread by a spread code and being assigned to a time division time slot, based on a CDMA method;

a mobile switching center, connected to said at least one base station, for controlling the multiple access methods use in the mobile communication system, wherein the mobile switching center includes;

a system control data memory unit for storing information for identifying said predetermined access method as control data showing a spreading code used in creating the time divided CDMA signal and a synchronization word code used in the TDMA signal, for the communication signal used within the mobile communication system; and

a system access method control unit for controlling multiple access methods between a plurality of mobile stations and said a least one base station within the mobile communication system, based on the control data.

11. The mobile communication system of claim 9, wherein the station has a plurality of shared signal regeneration units and a plurality of desired signal regeneration units corresponding to multiple access methods;

and wherein the station stores a control data for each access method identified by method using information for identifying access method showing spreading code and synchronization word code, and wherein the control data includes operation information of each of the shared signal regeneration units and each of the desired signal regeneration unit.

12. A mobile communication system for radio communication comprising:

a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method selected from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, wherein each of said communication stations includes;

a receiving unit for receiving a communication signal, said communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method, and

wherein the mobile stations perform communication with said at least one base station using said TDMA signal, and perform communication with an adjoining base station using a TDMA signal identified by a synchronization word code that has a different synchronization word code from the previously used TDMA signal, upon handoff of communication from said at least one base station to said adjoining base station.

13. A mobile communication system for radio communication comprising:

a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method selected from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, wherein each of said communication stations includes;

a receiving unit for receiving a communication signal, said communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method, and

a time divided CDMA signal, frequency spread by a spread code and being assigned to a time division time slot, based on a CDMA method;

wherein the base station divides radio coverage of mobile communications into a plurality of concentric zones centered around the base station, wherein each of the concentric zones correspond to at least a time slot associated with one of;

a TDMA signal, a TDMA signal identified by a synchronization word code, and a time divided CDMA signal, and

wherein, when a mobile station situated inside the concentric zones of radio coverage and assigned a time divided communication signal having a time slot corresponding to a particular concentric zone moves to another concentric zone, the mobile station is assigned a time divided communication signal having a time slot corresponding to said another concentric zone.

14. The mobile communication system of claim 13, wherein when a mobile station is situated at an outermost one of the concentric zones, the mobile station performs handoff to an adjoining base station using a time divided communication signal having a time slot corresponding to the outermost concentric zone of radio coverage of said adjoining base station.

15. The mobile communication system of claim 14, wherein, when a mobile station transmits a communication signal at a maximum transmitting power and a base station receives the communication signal at a minimum receiving signal-strength based on a pre-determined threshold value, the mobile station is determined to be situated at the outermost concentric zone of radio coverage of said base station.

16. The mobile communication system of claim 13, wherein when a number of mobile stations situated inside said concentric zones of radio coverage, each of which is assigned a time divided communication signal having a time slot corresponding to a concentric zone, has exceeded a predetermined maximum number, an additional mobile station moving with said concentric zones is assigned a time divided communication signal having a new time slot that is not corresponding to the concentric zones and that is not a previously assigned time slot.

17. The mobile communication system of claim 13, wherein a mobile station, situated inside the concentric zones of radio coverage, which mobile station is assigned a time divided communication signal having a time slot corresponding to one of the concentric zones, adjusts its transmitting power so that the communication signal is able to be received at said base station within the level of receiving power based on a pre-determined minimum receiving intensity, and

wherein the base station adjusts its transmitting power so that the communication signal is able to be received at a mobile station within the level of receiving power based on a pre-determined minimum receiving intensity.

18. A mobile communication method for radio communication among a plurality of communication stations including a plurality of mobile stations and at least one base station, wherein mobile communication is performed between the stations with a communication signal using a predetermined access method selected from a plurality of frequency sharing or time sharing multiple access methods available to said communication system, the method comprising steps of:

receiving a communication signal including

a TDMA signal identified by a synchronization word code, said TDMA signal transmitted between two stations having a different synchronization word code from other TDMA signals assigned to the same frequency and time slot, based on a TDMA method, and

a time divided CDMA signal, frequency spread by a spread code and being assigned to a time division time slot, based on a CDMA method;

regenerating one of the time divided CDMA signal and the TDMA signal from the receive communication signal and for outputting the regenerated signal as a shared signal;

removing the shared signal from the communication signal; and

regenerating the other of the TDMA signal and the time divided CDMA signal as a desired signal after removal of the shared signal from the communication signal and for outputting the desired signal.