Link adaptation method for links using modulation schemes that have different symbol rates

• US 5,909,469 A
• Filed: 08/29/1997
• Issued: 06/01/1999
• Est. Priority Date: 08/29/1997
• Status: Expired due to Term

• Current Assignee: Telefonktiebolaget L.M. Ericsson
• Original Assignee: Telefonktiebolaget L.M. Ericsson
• Inventors: Skold, Johan, Hook, Mikael, Schramm, Peter, Muller, Frank, Frodigh, Carl Magnus
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): Tran, Khai
• Application Number:
  US08/921,319
• Time in Patent Office: 641 Days
• Field of Search: 375/302, 375/334, 375/222, 375/223, 375/308, 375/261, 375/279, 375/208, 370/465, 370/468, 370/206, 370/207, 370/203, 455/552, 455/553
• US Class Current: 375/302
• CPC Class Codes: H04W 28/22 Negotiating communication rate

Abstract

A communication system supports multiple modulation schemes having differing symbol rates. The system supports two modulation schemes that have the same symbol rate and at least one modulation scheme that does not have the same symbol rate. For as long as communication can be carried out using the modulation schemes with the same symbol rate, the system avoids using the modulation scheme with different symbol rate, even if communication can be carried out using this scheme.

Claims

1. A method of communication between a mobile station and a base station comprising the steps of:

determining whether the base station and the mobile station can communicate with each other using at least a first, a second, or a third modulation schemes, wherein the second and third modulation schemes have the same symbol rate that is different from the symbol rate of the first modulation scheme; and

using the second modulation scheme, if the mobile station and the base station can not communicate with each other with acceptable performance using the third modulation scheme, even if the mobile station and the base station can communicate with each other using the first modulation scheme.

2. The method of claim 1 further including the step of using the first modulation scheme, if the mobile station and the base station can not communicate with each other with acceptable performance using the second and third modulation schemes.

3. The method of claim 1 further including the step of using the third modulation scheme, if the mobile station and the base station can communicate with each other with acceptable performance using the third modulation schemes.

4. The method of claim 1, wherein the first modulation scheme is a non-linear modulation scheme, and the second and third modulation schemes are linear modulation scheme.

5. The method of claim 4, wherein the second modulation scheme is a linear modulation scheme with a lower level than the third modulation scheme.

6. The method of claim 5, wherein the first modulation scheme is GMSK scheme, the second modulation scheme is QPSK modulation scheme, and the third modulation scheme is 16QAM modulation scheme.

7. The method of claim 4, wherein the second modulation scheme and the third modulation scheme use the same pulse shaping.

8. The method of claim 4, wherein the second modulation scheme uses a reduced signal set of third modulation scheme.

9. The method of claim 4, wherein the second and third modulation schemes use the same burst format.

10. The method in claim 4, wherein the second and third modulation schemes use the same training sequences.

11. A method for communicating within a communication system, comprising:

communicating with a mobile station that supports at least a first, a second, and a third modulation schemes, wherein the second and third modulation schemes have the same symbol rate, which is different from the symbol rate of the first modulation scheme;

communicating with the mobile station using the third modulation scheme within a first coverage area that provides acceptable communication performance for the first, second, and third modulation schemes; and

communicating with the mobile station using the second modulation scheme within a second coverage area that provides acceptable communication performance for both the first and second modulation schemes but not the third modulation scheme.

12. The method of claim 11, wherein the first modulation scheme is a non-linear modulation scheme, and the second and third modulation schemes are linear modulation schemes.

13. The method of claim 12, wherein the second modulation scheme is a lower level linear modulation scheme than the third modulation scheme.

14. The method of claim 13, wherein the first modulation scheme is GMSK scheme, the second modulation scheme is QPSK modulation scheme, and the third modulation scheme is 16QAM modulation scheme.

15. The method of claim 12, wherein the second modulation scheme and the third modulation scheme use the same pulse shaping.

16. The method of claim 12, wherein the second modulation scheme uses a reduced signal set of third modulation scheme.

17. The method of claim 12, wherein the second and third modulation schemes use the same burst format.

18. The method of claim 12, wherein the second and third modulation schemes use the same training sequences.

19. A cellular communication system, comprising:

at least one base station that covers a first cell using at least a first modulation scheme, a second modulation scheme, and a third modulation scheme, wherein the second and the third modulation schemes have the same symbol rate, which is different from the symbol rate of the first modulation scheme; and

at least one mobile station supporting the first, second, and third modulation schemes, and wherein the mobile station uses the second modulation scheme when using the third modulation scheme does not provide acceptable communication performance, even if the first modulation scheme provides acceptable communication performance.

20. The cellular system of claim 19 further including another base station that covers a second cell using the first modulation scheme only, wherein the mobile station uses the first modulation scheme when it travels from the first cell to the second cell.

21. The cellular system of claim 19, wherein the first modulation scheme is a non-linear modulation scheme, and the second and third modulation schemes are linear modulation scheme.

22. The cellular system of claim 21, wherein the second modulation scheme is a lower level linear modulation scheme than the third modulation scheme.

23. The cellular system of claim 21, wherein the first modulation scheme is GMSK scheme, the second modulation scheme is QPSK modulation scheme, and the third modulation scheme is 16QAM modulation scheme.

24. The cellular system of claim 21, wherein the second modulation scheme and the third modulation scheme use the same pulse shaping.

25. The cellular system of claim 21, wherein the second modulation scheme uses a reduced signal set of third modulation scheme.

26. The cellular system of claim 21, wherein the second and third modulation schemes use the same burst format.

27. The cellular system of claim 21, wherein the second and third modulation schemes use the same training sequences.