Methods for wirelessly communicating time division multiple access (TDMA) data using adaptive multiplexing and coding

• US 6,873,613 B1
• Filed: 10/16/2000
• Issued: 03/29/2005
• Est. Priority Date: 10/16/2000
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dent, Paul Wilkinson
• Primary Examiner(s): PHAN, MAN U
• Application Number:
  US09/688,770
• Time in Patent Office: 1,625 Days
• Field of Search: 370/321, 370/331, 370/318, 370/336, 370/337, 370/345, 370/347, 370/350, 370/441, 370/442, 370/509, 455/69, 455/127, 455/522, 455/561, 455/562, 455/436, 455/450, 342/372, 342/360, 342/450, 342/457
• US Class Current: 370/347
• CPC Class Codes: H04B 7/2659 for data rate control
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0007 by modifying the frame length

Abstract

Data is wirelessly transmitted from a base station, and/or wirelessly received at a plurality of subscriber stations that are at a plurality of distances from the base station using a Time Division Multiple Access (TDMA) frame by transmitting a same amount of data to each of the subscriber stations at a same power level during the TDMA frame while varying at least one other parameter as a function of the distance of the respective subscriber station from the base station. The at least one other parameter may be an amount of error correction coding, a sub-period duration in the TDMA frame, a number of modulation symbols from a set of modulation symbols and/or a number of sub-periods of the TDMA frame.

Claims

1. A method of wirelessly transmitting data from a base station to a plurality of subscriber stations, comprising:

dividing a multiplex time period into sub-periods of graduated duration;

coding data for transmission to a nearest subscriber station to occupy a sub-period of shortest duration;

coding data for transmission to a farthest subscriber station to occupy a sub-period of longest duration;

coding data for transmission to subscriber stations lying at intermediate distances to occupy sub-periods of duration between the longest and the shortest sub-period duration; and

wirelessly transmitting the multiplex time period including the coded data from the base station to the plurality of subscriber stations.

2. The method of claim 1 in which a same amount of data is coded into each sub-period and the coding is varied as a function of the sub-period duration.

3. The method of claim 1 in which the coded data is transmitted at the same modulation symbol rate for each of the sub-periods.

4. The method of claim 3 in which the modulation symbol rate comprises a succession of modulation symbols, each symbol representing a number N of coded data bits using a signal constellation of two to the power N signal points.

5. The method of claim 4 in which the number N of bits represented by each of the modulation symbols varies as a function of the duration of the sub-periods.

6. The method of claim 5 in which the sub-period of the shortest duration uses modulation symbols from a constellation with a highest value of N and the sub-period of the longest duration uses symbols from a constellation with a lowest value of N.

7. The method of claim 6 in which the highest value of N is three and the lowest value is one.

8. The method of claim 4 in which each of the data signals is coded using a rate K/NM code, where M is the number of modulation symbols in a sub-period and K is the number of data bits to be transmitted in a sub-period.

9. A method of claim 1 wherein the multiplex time period is a Time Division Multiple Access (TDMA) frame that is repeatedly transmitted from the base station to the plurality of subscriber stations.

10. A method of claim 1 wherein the multiplex time period including the coded data is transmitted at a constant power level.

11. A method of wirelessly transmitting data from a base station to a plurality of subscriber stations, comprising:

defining a time division multiplex frame period in which a number M of modulation symbols are transmitted;

coding data for transmission to a nearest subscriber station to occupy a smallest subset M1 of the M modulation symbols;

coding data for transmission to a farthest subscriber station to occupy a largest subset M2 of the M modulation symbols,

coding data for transmission to subscriber stations lying at intermediate distances to occupy subsets of the M modulation symbols containing a number of symbols intermediate between the smallest and the largest subsets of symbols; and

wirelessly transmitting the time division multiplex frame period including the coded data from the base station to the plurality of subscriber stations.

12. The method of claim 11 in which a same quantity of data bits is coded into each subset of modulation symbols and the coding is varied as a function of the number of modulation symbols in the subset.

13. The method of claim 12 in which the modulation symbols comprise a succession of modulation symbols, each symbol representing a number N of coded data bits using a signal constellation of two to the power N signal points.

14. The method of claim 13 in which the number N of bits represented by each of the modulation symbols varies as a function of the subset of symbols to which it belongs.

15. The method of claim 14 in which signal constellation points used to represent a smaller number of bits are a subset of the signal constellation points used to represent a greater number of bits.

16. The method of claim 13 in which each of the data bits is coded using a rate K/NM code, where K is the number of data bits to be transmitted to a subscriber station during the time division multiple frame period.

17. The method of claim 11 in which the symbols belonging to a same subset are transmitted sequentially.

18. The method of claim 11 in which modulation symbols of different subsets are interleaved over the time division multiplex frame period using a predetermined symbol placement pattern for each subset.

19. The method of claim 18 further comprising:

interleaving modulation symbols with known synchronization or pilot symbols.

20. A method of claim 11 wherein the multiplex time period is a Time Division Multiple Access (TDMA) frame that is repeatedly transmitted from the base station to the plurality of subscriber stations.

21. A method of claim 11 wherein the-multiplex time period including the coded data is transmitted at a constant power level.

22. A method of wirelessly transmitting data from a base station to a plurality of subscriber stations, comprising:

dividing a time division multiplex frame period into a number M of time slots in each of which a number L of modulation symbols are transmitted;

coding data for transmission to a nearest subscriber station to occupy a smallest subset M1 of the M time slots;

coding data for transmission to a farthest subscriber station to occupy a largest subset M2 of the M time slots;

coding data for transmission to subscriber stations lying at intermediate distances to occupy subsets of the M time slots containing a number of time slots intermediate between the smallest and the largest subsets of slots; and

wirelessly transmitting the time division multiplex frame period including the coded data from the base station to the plurality of subscriber stations.

23. The method of claim 22 in which a same quantity of data bits is coded into each subset of time slots and the coding is varied as a function of the number of time slots in the subset.

24. The method of claim 23 in which the number L of symbols in each time slot each represents a number N of coded data bits using a signal constellation of two to the power N signal points.

25. The method of claim 24 in which the number N of bits represented by each of the modulation symbols varies as a function of the subset of slots in which it is contained.

26. The method of claim 25 in which signal constellation points used to represent a smaller number of bits are a subset of the signal constellation points used to represent a greater number of bits.

27. The method of claim 24 in which each of the data bits is coded using a rate K/LMN code, where L is the number of time slots in the assigned subset of slots, N is the number of bits carried by each modulation symbol and K is the number of data bits to be transmitted using the assigned subset of slots.

28. The method of claim 27 in which the rate K/LMN code is formed by puncturing a code of lower rate having smaller integers in the numerator and denominator.

29. The method of claim 22 further comprising:

interspersing synchronization or pilot symbols among the modulation symbols of each of the time slots.

30. The method of claim 22 further including interspersing a plurality of synchronization or pilot symbols among the modulation symbols of each of the time slots.

31. A method of claim 22 wherein the multiplex time period is a Time Division Multiple Access (TDMA) frame that is repeatedly transmitted from the base station to the plurality of subscriber stations.

32. A method of claim 22 wherein the multiplex time period including the coded data is transmitted at a constant power level.