METHOD AND APPARATUS FOR USING MBSFN SUBFRAMES TO SEND UNICAST INFORMATION

• US 20090252077A1
• Filed: 04/02/2009
• Published: 10/08/2009
• Est. Priority Date: 04/07/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhushan, Naga, Palanki, Ravi, Montojo, Juan, Ji, Tingfang, Khandekar, Aamod D.
• Granted Patent: US 8,675,537 B2
• Time in Patent Office: Days
• US Class Current: 370/312
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/244 Interferences in heterogeneous networks, e.g. among macro and femto or pico cells or other sector / system interference [OSI]
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

Techniques for sending information in a wireless network are described. The network may support (i) regular subframes used to send unicast information and (ii) multicast/broadcast single frequency network (MBSFN) subframes used to send broadcast information and having lower overhead than the regular subframes. In an aspect, MBSFN subframes may be used to mitigate interference. A first base station may cause high interference to stations (e.g., UEs) served by a second base station. The first base station may reserve a subframe for the second base station, send system information conveying the reserved subframe as an MBSFN subframe to its stations, and transmit in a first part of the reserved subframe in accordance with an MBSFN subframe format. The second base station may skip the first part and may send unicast information to its stations in the remaining part of the reserved subframe. In another aspect, MBSFN subframes may be used to support additional base station capabilities.

Claims

1. A method of sending information in a wireless communication network, comprising:

sending a reference signal in a first part of a subframe in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

sending unicast information in a second part of the subframe to at least one station recognizing the subframe as carrying unicast information.

2. The method of claim 1, further comprising:

sending system information conveying the subframe as an MBSFN subframe.

3. The method of claim 1, further comprising:

sending signaling conveying the subframe as carrying unicast information for the at least one station.

4. The method of claim 1, wherein the sending the reference signal comprises sending the reference signal in the first part of the subframe to stations expecting the subframe to be an MBSFN subframe.

5. The method of claim 1, further comprising:

sending control information in the first part of the subframe in accordance with the MBSFN subframe format to stations expecting the subframe to be an MBSFN subframe.

6. The method of claim 1, further comprising:

sending the reference signal from at most four antennas in the first part of the subframe, and

sending the reference signal from at least one additional antenna in the second part of the subframe.

7. The method of claim 1, wherein the sending unicast information in the second part of the subframe comprises sending at least one of unicast data and control information in the second part of the subframe to the at least one station.

8. The method of claim 1, wherein the sending unicast information in the second part of the subframe comprises sending a dedicated reference signal in the second part of the subframe to a station among the at least one station.

9. The method of claim 1, wherein the sending unicast information in the second part of the subframe comprises

sending a dedicated reference signal with beamforming in the second part of the subframe to a station among the at least one station, and sending unicast information for the station with beamforming in the second part of the subframe.

10. The method of claim 1, further comprising:

sending a channel quality indicator (CQI) reference signal in the second part of the subframe.

11. The method of claim 1, further comprising:

sending unicast information in the first part of the subframe.

12. The method of claim 1, wherein the at least one station supports a release later than 3GPP Release 8.

13. An apparatus for wireless communication, comprising:

means for sending a reference signal in a first part of a subframe in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

means for sending unicast information in a second part of the subframe to at least one station recognizing the subframe as carrying unicast information.

14. The apparatus of claim 13, further comprising:

means for sending system information conveying the subframe as an MBSFN subframe.

15. The apparatus of claim 13, further comprising:

means for sending signaling conveying the subframe as carrying unicast information for the at least one station.

16. The apparatus of claim 13, further comprising:

means for sending the reference signal from at most four antennas in the first part of the subframe, and

means for sending the reference signal from at least one additional antenna in the second part of the subframe.

17. The apparatus of claim 13, wherein the means for sending unicast information in the second part of the subframe comprises

means for sending a dedicated reference signal with beamforming in the second part of the subframe to a station among the at least one station, and

means for sending unicast information for the station with beamforming in the second part of the subframe.

18. The apparatus of claim 13, further comprising:

means for sending a channel quality indicator (CQI) reference signal in the second part of the subframe.

19. A method of receiving information in a wireless communication network, comprising:

receiving a first part of a subframe carrying a reference signal sent in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format;

receiving a second part of the subframe carrying unicast information for a station; and

processing the second part of the subframe to recover the unicast information for the station.

20. The method of claim 19, further comprising:

receiving signaling conveying the subframe as carrying unicast information for the station.

21. The method of claim 19, further comprising:

processing the first and second parts of the subframe to recover the reference signal, wherein the reference signal is sent from at most four antennas in the first part of the subframe and is sent from at least one additional antenna in the second part of the subframe.

22. The method of claim 19, further comprising:

processing the second part of the subframe to recover a dedicated reference signal sent to the station, wherein the dedicated reference signal and the unicast information are sent with beamforming to the station.

23. The method of claim 19, further comprising:

receiving a channel quality indicator (CQI) reference signal in the second part of the subframe; and

estimating channel quality based on the CQI reference signal.

24. An apparatus for wireless communication, comprising:

means for receiving a first part of a subframe carrying a reference signal sent in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format;

means for receiving a second part of the subframe carrying unicast information for a station; and

means for processing the second part of the subframe to recover the unicast information for the station.

25. The apparatus of claim 24, further comprising:

means for receiving signaling conveying the subframe as carrying unicast information for the station.

26. The apparatus of claim 24, further comprising:

means for processing the first and second parts of the subframe to recover the reference signal, wherein the reference signal is sent from at most four antennas in the first part of the subframe and is sent from at least one additional antenna in the second part of the subframe.

27. The apparatus of claim 24, further comprising:

means for processing the second part of the subframe to recover a dedicated reference signal sent to the station, wherein the dedicated reference signal and the unicast information are sent with beamforming to the station.

28. The apparatus of claim 24, further comprising:

means for receiving a channel quality indicator (CQI) reference signal in the second part of the subframe; and

means for estimating channel quality based on the CQI reference signal.

29. An apparatus for wireless communication, comprising:

at least one processor configured to receive a first part of a subframe carrying a reference signal sent in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format, to receive a second part of the subframe carrying unicast information for a station, and to process the second part of the subframe to recover the unicast information for the station.

30. The apparatus of claim 29, wherein the at least one processor is configured to receive signaling conveying the subframe as carrying unicast information for the station.

31. The apparatus of claim 29, wherein the at least one processor is configured to process the first and second parts of the subframe to recover the reference signal, and wherein the reference signal is sent from at most four antennas in the first part of the subframe and is sent from at least one additional antenna in the second part of the subframe.

32. The apparatus of claim 29, wherein the at least one processor is configured to process the second part of the subframe to recover a dedicated reference signal sent to the station, and wherein the dedicated reference signal and the unicast information are sent with beamforming to the station.

33. The apparatus of claim 29, wherein the at least one processor is configured to receive a channel quality indicator (CQI) reference signal in the second part of the subframe, and to estimate channel quality based on the CQI reference signal.

34. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to receive a first part of a subframe carrying a reference signal sent in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format,

code for causing the at least one computer to receive a second part of the subframe carrying unicast information for a station, and

code for causing the at least one computer to process the second part of the subframe to recover the unicast information for the station.

35. A method of mitigating interference in a wireless communication network, comprising:

reserving a subframe by a first base station for a second base station;

sending a reference signal in a first part of the reserved subframe in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

sending no transmissions or transmissions at a low transmit power level in a remaining part of the reserved subframe to reduce interference to stations served by the second base station.

36. The method of claim 35, further comprising:

sending system information conveying the reserved subframe as an MBSFN subframe to stations served by the first base station.

37. The method of claim 35, wherein the sending the reference signal comprises sending the reference signal in first M symbol periods of the reserved subframe, where M is one or greater and is dependent on number of antennas at the first base station.

38. The method of claim 35, wherein the first base station is a high-power base station and the second base station is a low-power base station.

39. The method of claim 35, wherein the first base station has restricted access and the second base station has restricted or unrestricted access.

40. An apparatus for wireless communication, comprising:

means for reserving a subframe by a first base station for a second base station;

means for sending a reference signal in a first part of the reserved subframe in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

means for sending no transmissions or transmissions at a low transmit power level in a remaining part of the reserved subframe to reduce interference to stations served by the second base station.

41. The apparatus of claim 40, further comprising:

means for sending system information conveying the reserved subframe as an MBSFN subframe to stations served by the first base station.

42. The apparatus of claim 40, wherein the means for sending the reference signal comprises means for sending the reference signal in first M symbol periods of the reserved subframe, where M is one or greater and is dependent on number of antennas at the first base station.

43. A method of sending information in a wireless communication network, comprising:

receiving an indication of a subframe reserved by a first base station for a second base station;

sending no transmissions in a first part of the reserved subframe, the first part comprising a reference signal sent by the first base station in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

sending transmissions in a second part of the reserved subframe to stations served by the second base station.

44. The method of claim 43, wherein the sending transmissions in the second part of the reserved subframe comprises

sending a reference signal in the second part of the reserved subframe,

sending control information in at least one symbol period in the second part of the reserved subframe, and

sending unicast information in remaining symbol periods in the second part of the reserved subframe to the stations served by the second base station.

45. The method of claim 43, wherein the first part of the reserved subframe comprises M symbol periods, where M is one or greater and is dependent on number of antennas at the first base station.

46. An apparatus for wireless communication, comprising:

means for receiving an indication of a subframe reserved by a first base station for a second base station;

means for sending no transmissions in a first part of the reserved subframe, the first part comprising a reference signal sent by the first base station in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

means for sending transmissions in a second part of the reserved subframe to stations served by the second base station.

47. The apparatus of claim 46, wherein the means for sending transmissions in the second part of the reserved subframe comprises

means for sending a reference signal in the second part of the reserved subframe,

means for sending control information in at least one symbol period in the second part of the reserved subframe, and

means for sending unicast information in remaining symbol periods in the second part of the reserved subframe to the stations served by the second base station.

48. A method of receiving information in a wireless communication network, comprising:

receiving by a station a subframe reserved by a first base station for a second base station, the subframe comprising a first part and a second part, the first part comprising a reference signal sent by the first base station in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

processing the second part of the subframe to recover unicast information sent by the second base station to the station.

49. The method of claim 48, further comprising:

receiving signaling conveying the subframe as carrying unicast information for the station.

50. The method of claim 48, wherein the processing the second part of the subframe comprises

recovering a reference signal from the second part of the subframe,

recovering control information from at least one symbol period in the second part of the subframe, and

recovering the unicast information from at least one remaining symbol period in the second part of the subframe.

51. The method of claim 48, further comprising:

skipping first M symbol periods of the subframe, where M is one or greater and dependent on number of antennas at the first base station.

52. An apparatus for a wireless communication station, comprising:

means for receiving by a station a subframe reserved by a first base station for a second base station, the subframe comprising a first part and a second part, the first part comprising a reference signal sent by the first base station in accordance with a multicast/broadcast single frequency network (MBSFN) subframe format; and

means for processing the second part of the subframe to recover unicast information sent by the second base station to the station.

53. The apparatus of claim 52, further comprising:

means for receiving signaling conveying the subframe as carrying unicast information for the station.

54. The apparatus of claim 52, wherein the means for processing the second part of the subframe comprises

means for recovering a reference signal from the second part of the subframe,

means for recovering control information from at least one symbol period in the second part of the subframe, and

means for recovering the unicast information from at least one remaining symbol period in the second part of the subframe.