Detection and correction of channel swap in spatial division multiple access systems

• US 6,894,993 B2
• Filed: 12/27/2002
• Issued: 05/17/2005
• Est. Priority Date: 12/27/2002
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: ArrayComm LLC (Ygomi LLC)
• Inventors: Kasapi, Athanasios A., Persson, Lars Johan, Zeng, Xiangzhong, Yu, Xiaoming
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): Hyun, Soon D.
• Application Number:
  US10/330,639
• Publication Number:
  US 20040125767A1
• Time in Patent Office: 872 Days
• Field of Search: 370329-331, 370334-337, 370/339, 370/341, 370/345, 455/562
• US Class Current: 370/329
• CPC Class Codes: H04B 7/06 at the transmitting station
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

Embodiments of the invention provide various methods for detecting a spatial division multiple access (SDMA) channel swap. A first SDMA communication channel is assigned to a first user terminal that initially transmits its signal over the first SDMA communication channel. A second SDMA communication channel is assigned to a second user terminal that initially transmits its signal over the second SDMA communication channel. The first user terminal'"'"'s signal and the second user terminal'"'"'s signal are analyzed to determine that the first user terminal is transmitting its signal over the second SDMA communication channel and the second user terminal is transmitting its signal over the first SDMA communication channel.

Claims

1. A method comprising:

assigning a first spatial division multiple access (SDMA) communication channel to a first user terminal, the first user terminal initially transmitting a first signal over the first SDMA communication channel, the first signal having one or more characteristics associated therewith;

assigning a second SDMA communication channel to a second user terminal, the second user terminal initially transmitting a second signal over the second SDMA communication channel, the second signal having one or more characteristics associated therewith; and

analyzing each of a signal transmitted from the first user terminal and a signal transmitted from the second user terminal to determine that the first user terminal is transmitting a signal having one or more characteristics associated with the first signal over the second SDMA communication channel and the second user terminal is transmitting a signal having one or more characteristics associated with the second signal over the first SDMA communication channel.

2. The method of claim 1 wherein the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel due to proximity of the first user terminal to the second user terminal.

3. The method of claim 1 wherein the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel due to instability of one or both of the first SDMA communication channel and the second SDMA communication channel.

4. The method of claim 1 further comprising:

interchanging a communication channel of the first signal with a communication channel of the second signal.

5. The method of claim 1 wherein the first signal and the second signal are encoded using an encoding scheme in which specified outputs are invalid and wherein analyzing the first signal and the second signal includes:

determining if a data stream of the first signal or a data stream of the second signal contains an invalid bit; and

determining that a cyclic redundancy check of both the first SDMA communication channel and the second SDMA communication channel does not indicate a communication channel error.

6. The method of claim 5 wherein the encoding scheme is adaptive differential pulse code modulation.

7. The method of claim 6 wherein the invalid output contains a zero bit.

8. The method of claim 7 further comprising:

repeatedly analyzing the first signal and the second signal to increase reliability of the determination that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel.

9. The method of claim 1 wherein analyzing the first signal and the second signal includes analyzing one or more physical characteristics of the first signal and the second signal.

10. The method of claim 9 wherein the one or more physical characteristics are selected from the group consisting of frequency offset, time of arrival at a base station, spatial signature, signal spectrum, direction-of-arrival of signals and modulation error vector magnitude.

11. The method of claim 10 further comprising:

repeatedly analyzing the first signal and the second signal to increase reliability of the determination that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel.

12. The method of claim 4 wherein the first signal and the second signal are data communication signals and wherein analyzing the first signal and the second signal includes comparing a result of a first communication layer error detection process with a result of a second communication layer error detection process.

13. The method of claim 12 wherein determining that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel includes determining that the result of the first communication layer error detection process is inconsistent with the result of the second communication layer error detection process.

14. The method of claim 13 wherein the first communication layer is a physical layer and the second communication layer is a data-link layer, the first communication layer error detection process indicating no error and the second communication layer error detection process indicating an error.

15. The method of claim 12 wherein the operation of interchanging a communication channel of the first signal with a communication channel of the second signal is accomplished at a communication layer selected from the group consisting of the physical layer, the data-link layer, and a subsequent communication layer of a communication layer hierarchy.

16. A cellular radio communications network comprising:

a mobile switching center;

at least one base station controller, coupled to the mobile switching center; and

a plurality of base stations coupled to the at least one base station controller, each base station assigning

assigning a first spatial division multiple access (SDMA) communication channel to a first user terminal, the first user terminal initially transmitting a first signal over the first SDMA communication channel, the first signal having one or more characteristics associated therewith;

assigning a second SDMA communication channel to a second user terminal, the second user terminal initially transmitting a second signal over the second SDMA communication channel, the second signal having one or more characteristics associated therewith; and

analyzing each of a signal transmitted from the first user terminal and a signal transmitted from the second user terminal to determine that the first user terminal is transmitting a signal having one or more characteristics associated with the first signal over the second SDMA communication channel and the second user terminal is transmitting a signal having one or more characteristics associated with the second signal over the first SDMA communication channel.

17. The cellular radio communications network of claim 16 wherein a signal from each of the two user terminals is encoded using an encoding scheme in which specified outputs are invalid and wherein analyzing a signal of one or both of the two user terminals includes:

determining if a data stream of the signal of either of the two user terminals contains an invalid bit; and

determining that a cyclic redundancy check of both SDMA communication channels does not indicate a communication channel error.

18. The cellular radio communications network of claim 17 wherein the encoding scheme is adaptive differential pulse code modulation.

19. The cellular radio communications network of claim 18 wherein the invalid output contains a zero bit.

20. The cellular radio communications network of claim 19 wherein the base station repeatedly analyzes the signal from each of the two user terminals to increase reliability of the determination that one or both of the two user terminals is transmitting a signal over the SDMA channel assigned to the other of the two user terminals.

21. The cellular radio communications network of claim 16 wherein analyzing a signal of one or both of the two user terminals includes analyzing one or more physical characteristics of the signal from each of the two user terminals.

22. The cellular radio communications network of claim 21 wherein the one or more physical characteristics are selected from the group consisting of frequency offset, time of arrival at a base station, spatial signature, signal spectrum, direction-of-arrival of signals, and modulation error vector magnitude.

23. The cellular radio communications network of claim 22 wherein the base station repeatedly analyzes the signal from each of the two user terminals to increase reliability of the determination that one or both of the two user terminals is transmitting a signal over the SDMA channel assigned to the other of the two user terminals.

24. The cellular radio communications network of claim 16 wherein the signal from each of the two user terminals is a data communication signal and wherein analyzing the signal from each of the two user terminals includes comparing a result of a first communication layer error detection process with a result of a second communication layer error detection process.

25. The cellular radio communications network of claim 24 wherein determining that one or both of the two user terminals is transmitting a signal over the SDMA channel assigned to the other of the two user terminals includes determining that the result of the first communication layer error detection process is inconsistent with the result of the second communication layer error detection process.

26. The cellular radio communications network of claim 25 wherein the first communication layer is a physical layer and the second communication layer is a data-link layer, the first communication layer error detection process indicating no error and the second communication layer error detection process indicating an error.

27. A machine-readable medium having one or more executable instructions stored thereon, which when executed by a digital processing system cause the digital processing system to perform a method, the method comprising:

assigning a first spatial division multiple access (SDMA) communication channel to a first user terminal, the first user terminal initially transmitting a first signal over the first SDMA communication channel, the first signal having one or more characteristics associated therewith;

assigning a second SDMA communication channel to a second user terminal, the second user terminal initially transmitting a second signal over the second SDMA communication channel, the second signal having one or more characteristics associated therewith; and

analyzing each of a signal transmitted from the first user terminal and a signal transmitted from the second user terminal to determine that the first user terminal is transmitting a signal having one or more characteristics associated with the first signal over the second SDMA communication channel and the second user terminal is transmitting a signal having one or more characteristics associated with the second signal over the first SDMA communication channel.

28. The machine-readable medium of claim 27 wherein the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel due to proximity of the first user terminal to the second user terminal.

29. The machine-readable medium of claim 27 wherein the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel due to instability of one or both of the first SDMA communication channel and the second SDMA communication channel.

30. The machine-readable medium of claim 27 wherein the method further comprises:

interchanging a communication channel of the first signal with a communication channel of the second signal.

31. The machine-readable medium of claim 27 wherein the first signal and the second signal are encoded using an encoding scheme in which specified outputs are invalid and wherein analyzing the first signal and the second signal includes:

determining if a data stream of the first signal or the a data stream of the second signal contains an invalid bit; and

determining that a cyclic redundancy check of both the first SDMA communication channel and the second SDMA communication channel does not indicate a communication channel error.

32. The machine-readable medium of claim 31 wherein the encoding scheme is adaptive differential pulse code modulation.

33. The machine-readable medium of claim 32 wherein the invalid output contains a zero bit.

34. The machine-readable medium of claim 33 wherein the method further comprises:

repeatedly analyzing the first signal and the second signal to increase reliability of the determination that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel.

35. The machine-readable medium of claim 27 wherein analyzing the first signal and the second signal includes analyzing one or more physical characteristics of the first signal and the second signal.

36. The machine-readable medium of claim 35 wherein the one or more physical characteristics are selected from the group consisting of frequency offset, time of arrival at a base station, spatial signature, signal spectrum, direction-of-arrival of signals and modulation error vector magnitude.

37. The machine-readable medium of claim 36 wherein the method further comprises:

repeatedly analyzing the first signal and the second signal to increase reliability of the determination that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel.

38. The machine-readable medium of claim 30 wherein the first signal and the second signal are data communication signals and wherein analyzing the first signal and the second signal includes comparing a result of a first communication layer error detection process with a result of a second communication layer error detection process.

39. The machine-readable medium of claim 38 wherein determining that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel includes determining that the result of the first communication layer error detection process is inconsistent with the result of the second communication layer error detection process.

40. The machine-readable medium of claim 39 wherein the first communication layer is a physical layer and the second communication layer is a data-link layer, the first communication layer error detection process indicating no error and the second communication layer error detection process indicating an error.

41. The machine-readable medium of claim 40 wherein the operation of interchanging a communication channel of the first signal with a communication channel of the second signal is accomplished at a communication layer selected from the group consisting of the first communication layer, the second communication layer, and a subsequent communication layer of a communication layer hierarchy.

42. A method comprising:

transmitting a first signal to a first user terminal over a first spatial division multiple access (SDMA) communication channel, the first signal having one or more characteristics associated therewith;

transmitting a second signal to a second user terminal over a second spatial division multiple access (SDMA) communication channel, the second signal having one or more characteristics associated therewith; and

analyzing each of a signal transmitted from the first user terminal and a signal transmitted from the second user terminal to determine that the first user terminal is receiving a signal having one or more characteristics associated with the first signal over the second SDMA communication channel and the second user terminal is receiving a signal having one or more characteristics associated with the second signal over the first SDMA communication channel.

43. The method of claim 42 wherein the first user terminal is receiving the first signal over the second SDMA communication channel and the second user terminal is receiving the second signal over the first SDMA communication channel due to proximity of the first user terminal to the second user terminal.

44. The method of claim 42 wherein the first user terminal is receiving the first signal over the second SDMA communication channel and the second user terminal is receiving the second signal over the first SDMA communication channel due to instability of one or both of the first SDMA communication channel and the second SDMA communication channel.

45. The method of claim 42 further comprising:

interchanging a communication channel of the first signal with a communication channel of the second signal.

46. The method of claim 42 wherein the first signal and the second signal are encoded using an encoding scheme in which specified outputs are invalid and wherein analyzing the first signal and the second signal includes:

determining if a data stream of the first signal or the a data stream of the second signal contains an invalid bit; and

determining that a cyclic redundancy check of both the first SDMA communication channel and the second SDMA communication channel does not indicate a communication channel error.

47. The method of claim 46 wherein the encoding scheme is adaptive differential pulse code modulation.

48. The method of claim 47 wherein the invalid output contains a zero bit.

49. The method of claim 48 further comprising:

repeatedly analyzing the first signal and the second signal to increase reliability of the determination that the first user terminal is receiving the first signal over the second SDMA communication channel and the second user terminal is receiving the second signal over the first SDMA communication channel.

50. The method of claim 42 wherein analyzing the first signal and the second signal includes analyzing one or more physical characteristics of the first signal and the second signal.

51. The method of claim 50 wherein the one or more physical characteristics are selected from the group consisting of frequency offset, time of arrival at a base station, spatial signature, signal spectrum, direction-of-arrival of signals and modulation error vector magnitude.

52. The method of claim 51 further comprising:

repeatedly analyzing the first signal and the second signal to increase reliability of the determination that the first user terminal is receiving the first signal over the second SDMA communication channel and the second user terminal is receiving the second signal over the first SDMA communication channel.

53. The method of claim 45 wherein the first signal and the second signal are data communication signals and wherein analyzing the first signal and the second signal includes comparing a result of a first communication layer error detection process with a result of a second communication layer error detection process.

54. The method of claim 53 wherein determining that the first user terminal is receiving the first signal over the second SDMA communication channel and the second user terminal is receiving the second signal over the first SDMA communication channel includes determining that the result of the first communication layer error detection process is inconsistent with the result of the second communication layer error detection process.

55. The method of claim 54 wherein the first communication layer is a physical layer and the second communication layer is a data-link layer, the first communication layer error detection process indicating no error and the second communication layer error detection process indicating an error.

56. The method of claim 53 wherein the operation of interchanging a communication channel of the first signal with a communication channel of the second signal is accomplished at a communication layer selected from the group consisting of the physical layer, the data-link layer, and a subsequent communication layer of a communication layer hierarchy.