Methods and apparatus for allocating resources in hybrid TDMA communication systems

• US 6,631,124 B1
• Filed: 11/03/1999
• Issued: 10/07/2003
• Est. Priority Date: 11/03/1999
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Koorapaty, Havish, Wang, Yi-Pin Eric, Dent, Paul W.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): RAMPURIA, SHARAD K
• Application Number:
  US09/432,989
• Time in Patent Office: 1,434 Days
• Field of Search: 370/337, 370/336, 370/343, 370/347, 370/348, 370/329, 370/330, 370/335, 370/342, 370/465, 370/321, 370/468
• US Class Current: 370/337
• CPC Class Codes: H04B 7/2618 using hybrid code-time division multiple access [CDMA-TDMA]
• CPC Class Codes: H04W 48/06 based on traffic conditions
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

A wireless communications system including at least one base station operative to communicate with terminals on a plurality of carrier frequencies in repetitive time slots defined thereon is operated by assigning an entire time slot or a spreading-code defined subchannel of a time slot to a terminal based on a communications constraint associated with the terminal. The communications constraint may include a performance requirement, such as an information rate or an error rate, and a signal reception condition, such as signal to noise ratio. According to another aspect, a wireless communications system determines a communications constraint associated with a terminal. The system assigns a time slot, a spreading code, a coding rate and a bandwidth to the terminal based on the determined communications constraint. Preferably, the system assigns a time slot, a spreading code, a coding rate and a bandwidth to the terminal such that at least one of an available bandwidth, a number of available time slots, and a number of available spreading codes is optimized. Related apparatus are also described.

Claims

1. A method of operating a wireless communications system including at least one base station operative to communicate on a plurality of carrier frequencies in repetitive time slots defined thereon, the method comprising:

defining a normal channel that comprises a first plurality of time slots and that provides a first level of error correction coding redundancy;

defining a high-penetration channel that comprises a second plurality of time slots and that provides a second level of error correction coding redundancy that is greater than the first level of error correction coding redundancy, the high-penetration channel including a plurality of spreading code defined subchannels; and

determining which of an entire time slot of the normal channel or a spreading-code defined subchannel of a time slot of the high-penetration channel to assign to a terminal based on a communications constraint associated with the terminal.

2. A method according to claim 1, wherein the communications constraint comprises a performance requirement and a signal reception condition.

3. A method according to claim 2, wherein the performance requirement comprises at least one of an information rate requirement or an error rate requirement.

4. A method according to claim 2, wherein the signal reception condition comprises a signal to noise ratio.

5. A method according to claim 1:

wherein said step of determining which of an entire time slot of the normal channel or a spreading-code defined subchannel of a time slot of the high-penetration channel to assign to a terminal is preceded by the steps of;

identifying a single terminal;

identifying a plurality of terminals;

determining a communications constraint associated with the single terminal; and

determining respective communications constraints associated with respective ones of the plurality of terminals;

wherein said step of determining which of an entire time slot of the normal channel or a spreading-code defined subchannel of a time slot of the high-penetration channel to assign to a terminal comprises the steps of;

exclusively assigning a first time slot to the single terminal based on the communications constraint associated with the single terminal; and

assigning a second time slot to the plurality of terminals based on the communications constraints associated with the plurality of terminals; and

wherein the method further comprises the steps of;

communicating with the single terminal in the first time slot; and

communicating with respective ones of the plurality of terminals in the second time slot using a plurality of subchannels, wherein respective ones of the plurality of subchannels are encoded according to respective spreading codes.

6. A method according to claim 5:

wherein said step of communicating with the single terminal comprises the step of communicating with the single terminal at a first information rate; and

wherein said step of communicating with the plurality of terminals comprises the step of communicating with a terminal of the plurality of terminals at a second information rate less than the first information rate.

7. A method according to claim 6:

wherein said step of communicating with the single terminal comprises the step of communicating at least one of voice information or high bit rate data; and

wherein said step of communicating with a terminal of the plurality of terminals comprises the step of communicating low bit rate data.

8. A method according to claim 5, wherein said step of communicating with respective ones of the plurality of terminals comprises the step of communicating with one terminal of the plurality of terminals over a group of subchannels of the second time slot.

9. A method according to claim 1, wherein said step of communicating with the plurality of terminals comprises the step communicating with one terminal of the plurality of terminals over a group of the subchannels.

10. A method according to claim 5:

wherein said step of communicating with the single terminal comprises the step of communicating with the single terminal using a first bandwidth; and

wherein said step of communicating with respective ones of the plurality of terminals comprises the step of communicating with one of the terminals of the plurality of terminals using a second bandwidth greater than the first bandwidth.

11. A method according to claim 5, wherein a respective one of the subchannels is encoded according to a respective scrambling mask.

12. An operating method for a wireless communications system that is operative to communicate using a plurality of time slots on a plurality of carrier frequencies, to communicate on respective subchannels on a time slot according to respective spreading codes and to communicate over a channel with a variable coding rate and a variable bandwidth, the method comprising:

determining a communications constraint associated with a terminal; and

assigning a time slot, a spreading code, an error correction coding redundancy level and a bandwidth to the terminal based on the determined communications constraint.

13. A method according to claim 12, wherein the communications constraint comprises a performance requirement and a signal reception condition.

14. A method according to claim 13, wherein the performance requirement comprises at least one of an information rate or an error rate.

15. A method according to claim 13, wherein the signal reception condition comprises a signal to noise ratio.

16. A method according to claim 12, wherein said step of assigning comprises the step of assigning a time slot, a spreading code, an error correction coding redundancy level and a bandwidth to the terminal such that at least one of an available bandwidth, a number of available time slots, a number of available spreading codes, or a transmit power is optimized.

17. A method according to claim 12, wherein the spreading code comprises a scrambling mask.

18. A wireless communications system operative to communicate on a plurality of carrier frequencies in repetitive time slots defined thereon, the system comprising:

means for defining a normal channel that comprises a first plurality of time slots distributed over the series of frames and that provides a first level of error correction coding redundancy;

means for defining a high-penetration channel that comprises a second plurality of time slots distributed over the series of frames and that provides a second level of error correction coding redundancy that is greater than the first level of error correction coding redundancy, the high-penetration channel including a plurality of spreading code defined subchannels;

means for determining a communications constraint associated with a terminal;

means, responsive to said means for determining a communications constraint, for determining which of an entire time slot of the normal channel or a spreading-code defined subchannel of a time slot of the high-penetration channel to assign to the terminal based on the determined communications constraint; and

means for communicating with the terminal on the determined entire time slot or subchannel.

19. A system according to claim 18, wherein the communications constraint comprises a performance requirement and a signal reception condition.

20. A system according to claim 19, wherein the performance requirement comprises at least one of an information rate requirement or an error rate requirement.

21. A system according to claim 19, wherein the signal reception condition comprises a signal to noise ratio.

22. A system according to claim 18:

wherein said means for determining a communications constraint comprises;

means for determining a communications constraint associated with a single terminal; and

means for determining respective communications constraint associated with respective ones of a plurality of terminals;

wherein said means for determining which one of an entire time slot of the normal channel or a spreading-code defined subchannel of a time slot of the high-penetration channel to assign to the terminal comprises;

means for exclusively assigning a first time slot to the single terminal based on the communications constraint associated with the single terminal;

means for assigning a second time slot to the plurality of terminals based on the communications constraints associated with the plurality of terminals; and

wherein said means for communicating comprises;

means for communicating with the single terminal in the first time slot; and

means for communicating with the plurality of terminals in the second time using a plurality of subchannels, wherein respective ones of the plurality of subchannels are encoded according to respective spreading codes.

23. A system according to claim 22:

wherein said means for communicating with the single terminal comprises means for communicating with the single terminal at a first information rate; and

wherein said means for communicating with respective ones of the plurality of terminals comprises means for communicating with one terminal of the plurality of terminals at a second information rate less than the first information rate.

24. A system according to claim 23:

wherein said means for communicating with the single terminal comprises means for communicating at least one of voice information or high bit rate data; and

wherein said means for communicating with a terminal of the plurality of terminals comprises means for communicating low bit rate data.

25. A system according to claim 22, wherein said means for communicating with respective ones of the plurality of termninals comprises means for communicating with one terminal of the plurality of terminals over a group of subchannels of the second time slot.

26. A system according to claim 22, wherein said means for communicating with respective ones of the plurality of terminals comprises means for communicating with one terminal of the plurality of terminals over a group of the subchannels.

27. A system according to claim 22:

wherein said means for communicating with the single terminal comprises means for communicating with the single terminal using a first bandwidth; and

wherein said means for communicating with respective ones of the plurality of terminals comprises means for communicating with one of the terminals of the plurality of terminals using a second bandwidth greater than the first bandwidth.

28. A system according to claim 18, wherein a respective one of the subchannels is encoded according to a respective scrambling mask.

29. A wireless communications system operative to communicate using a plurality of time slots on a plurality of carrier frequencies, to communicate on respective subchannels on a time slot according to respective spreading codes and to communicate over a channel with a variable coding rate and a variable bandwidth, the wireless communication system comprising:

means for determining a communications constraint associated with a terminal; and

means, responsive to said means for determining a communications constraint, for assigning a time slot, a spreading code, an error correction coding redundancy level and a bandwidth to the terminal based on the determined communications constraint.

30. A system according to claim 29, wherein the communications constraint comprises a performance requirement and a signal reception condition.

31. A system according to claim 30, wherein the performance requirement comprises at least one of an information rate or an error rate.

32. A system according to claim 30, wherein the signal reception condition comprises a signal to noise ratio.

33. A system according to claim 29, wherein said means for assigning comprises means for assigning a time slot, a spreading code, an error correction coding rate and a bandwidth to the terminal such that at least one of an available bandwidth, a number of available time slots, a number of available spreading codes, or a transmit power is optimized.

34. A system according to claim 29, wherein the spreading code comprises a scrambling mask.

35. A wireless communications system, comprising:

a base station operative to communicate using a plurality of time slots on a plurality of carrier frequencies, to communicate on respective subchannels on a time slot according to respective spreading codes and to communicate over a channel with a variable coding rate and a variable bandwidth; and

a resource allocator operatively associated with the base station and operative to determine a communications constraint associated with a terminal and to assign a time slot, a spreading code, an error correction coding redundancy level and a bandwidth to the terminal based on the determined communications constraint,

wherein said base station is responsive to said resource allocator to communicate with the terminal according to the assigned time slot, spreading code, coding rate and bandwidth.

36. A system according to claim 35, wherein the communications constraint comprises a performance requirement and a signal reception condition.

37. A system according to claim 36, wherein the performance requirement comprises at least one of an information rate or an error rate.

38. A system according to claim 36, wherein the signal reception condition comprises a signal to noise ratio.

39. A system according to claim 35, wherein the resource allocator is operative to assign a time slot, a spreading code, an error correction coding redundancy level and a bandwidth to the terminal such that at least one of an available bandwidth, a number of available time slots, a number of available spreading codes, or a transmit power is optimized.

40. A system according to claim 35, wherein the spreading code comprises a scrambling mask.

41. A wireless communications terminal for communicating with a wireless communications system, the terminal comprising:

means for informing the system of a communications constraint associated with the terminal; and

means for communicating with the system using a time slot, a spreading code, an error correction coding redundancy level and a bandwidth assigned to the terminal by the system based on the determined communications constraint.

42. A terminal according to claim 41, wherein the communications constraint comprises a performance requirement and a signal reception condition.

43. A terminal according to claim 42, wherein the performance requirement comprises at least one of an information rate or an error rate.

44. A terminal according to claim 42, wherein the signal reception condition comprises a signal to noise ratio.

45. A terminal according to claim 41, wherein said means for communicating comprise means for communicating with the system using an entire time slot or a subchannel of a time slot defined by a spreading code.

46. A system according to claim 45, wherein the spreading code comprises a scrambling mask.