Almost blank subframe in carrier aggregation

• US 9,900,882 B2
• Filed: 01/13/2017
• Issued: 02/20/2018
• Est. Priority Date: 10/29/2011
• Status: Active Grant

• Current Assignee: Comcast Cable Communications LLC (Comcast Corporation)
• Original Assignee: Comcast Cable Communications LLC (Comcast Corporation)
• Inventors: Dinan, Esmael Hejazi
• Primary Examiner(s): Zaidi, Iqbal
• Application Number:
  US15/406,009
• Publication Number:
  US 20170142698A1
• Time in Patent Office: 403 Days
• Field of Search: 370328-339, 370433-473, 375130-140
• CPC Class Codes: H04H 20/33 by plural channels
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 48/12 using downlink control channel
• 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 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/54 based on quality criteria
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A base station transmits a message to a plurality of wireless devices in connected mode. The message comprises a subframe allocation bitmap indicating a plurality of subframes. The plurality of subframes comprises a plurality of almost blank subframes. During majority of symbols of an almost blank subframe of a base station, signals are transmitted at an almost blank subframe power level that is different from a transmit power during a non-almost blank subframe.

Claims

1. A method comprising:

transmitting, by a base station, a first message comprising a subframe allocation bitmap indicating a plurality of Almost Blank Subframes, wherein the plurality of Almost Blank Subframes consists of second, fourth, seventh, and ninth subframes of each radio frame in a plurality of radio frames;

transmitting, to a wireless device, a second message comprising;

a first measurement subframe allocation bitmap indicating a first plurality of measurement subframes of a primary carrier, wherein the first plurality of measurement subframes excludes the plurality of Almost Blank Subframes; and

a second measurement subframe allocation bitmap indicating a second plurality of measurement subframes of the primary carrier, wherein the second plurality of measurement subframes excludes the first plurality of measurement subframes; and

transmitting, by the base station, a first Almost Blank Subframe, wherein the first Almost Blank Subframe is transmitted at a power level that is lower than during a non-Almost Blank Subframe.

2. The method of claim 1, wherein the first Almost Blank Subframe consists essentially of a common reference signal in a control region.

3. The method of claim 1, wherein each radio frame in the plurality of radio frames is assigned a system frame number (SFN).

4. The method of claim 1, wherein the first message further comprises:

a subframe allocation repetition period in terms of n radio frames, n being an integer greater than or equal to one; and

a subframe allocation offset i, i being an integer greater than or equal to zero.

5. The method of claim 4, wherein the subframe allocation bitmap indicates a plurality of subframes in k frames, k being an integer and 1≦

k≦

n, the bitmap applying to subframes in k frames starting from frames whose SFN meets (SFN mod n=i) criterion.

6. The method of claim 4, wherein the subframe allocation repetition period is 1, 2, 4, 8, 16, or 32 radio frames.

7. The method of claim 1, wherein the base station broadcasts:

a system frame number represented by m bits;

the p most significant bits of the system frame number employing a plurality of subcarriers in the middle of a frequency band of a carrier; and

the (m−

p) least significant bits of the system frame number by encoding control blocks in a physical broadcast channel over 2<sup>(m−

p)</sup> frames, wherein the (m−

p) least significant bits are determined by sequential positions of the encoded control blocks.

22. The method of claim 1, wherein the second message further configures measurement subframes of a plurality of neighboring carriers for the wireless device.

23. The method of claim 1, wherein the wireless device periodically reports channel state information for subframes indicated in the first measurement subframe allocation bitmap.

24. The method of claim 1, wherein the wireless device periodically reports channel state information for subframes indicated in the second measurement subframe allocation bitmap.

8. A method comprising:

transmitting, by a base station, a first message comprising a subframe allocation bitmap indicating a plurality of Almost Blank Subframes, wherein the plurality of Almost Blank Subframes consists of third and eighth subframes of each radio frame in a plurality of radio frames;

transmitting, to a wireless device, a second message comprising;

a first measurement subframe allocation bitmap indicating a first plurality of measurement subframes of a primary carrier, wherein the first plurality of measurement subframes excludes the plurality of Almost Blank Subframes; and

a second measurement subframe allocation bitmap indicating a second plurality of measurement subframes of the primary carrier, wherein the second plurality of measurement subframes excludes the first plurality of measurement subframes; and

transmitting, by the base station, a first Almost Blank Subframe, wherein the first Almost Blank Subframe is transmitted at a power level that is lower than during a non-Almost Blank Subframe.

9. The method of claim 8, wherein the second message further configures measurement subframes of a plurality of neighboring carriers for the wireless device.

10. The method of claim 8, wherein the wireless device periodically reports channel state information for subframes indicated in the first measurement subframe allocation bitmap.

11. The method of claim 8, wherein the wireless device periodically reports channel state information for subframes indicated in the second measurement subframe allocation bitmap.

12. The method of claim 8, wherein the first Almost Blank Subframe consists essentially of a common reference signal in a control region.

13. The method of claim 8, wherein each radio frame in the plurality of radio frames is assigned a system frame number (SFN).

14. The method of claim 8, wherein the first message further comprises:

a subframe allocation repetition period in terms of n radio frames, n being an integer greater than or equal to one; and

a subframe allocation offset i, i being an integer greater than or equal to zero.

15. The method of claim 14, wherein the subframe allocation bitmap indicates a plurality of subframes in k frames, k being an integer and 1≦

k≦

n, the bitmap applying to subframes in k frames starting from frames whose SFN meets (SFN mod n=i) criterion.

16. A method comprising:

transmitting, by a base station, a first message comprising a subframe allocation bitmap indicating a plurality of Almost Blank Subframes, wherein the plurality of Almost Blank Subframes consists of second, fourth and eighth subframes of each radio frame in a plurality of radio frames;

transmitting, to a wireless device, a second message comprising;

a first measurement subframe allocation bitmap indicating a first plurality of measurement subframes of a primary carrier, wherein the first plurality of measurement subframes excludes the plurality of Almost Blank Subframes; and

a second measurement subframe allocation bitmap indicating a second plurality of measurement subframes of the primary carrier, wherein the second plurality of measurement subframes excludes the first plurality of measurement subframes; and

transmitting, by the base station, a first Almost Blank Subframe, wherein the first Almost Blank Subframe is transmitted at a power level that is lower than during a non-Almost Blank Subframe.

17. The method of claim 16, wherein the second message further configures measurement subframes of a plurality of neighboring carriers for the wireless device.

18. The method of claim 16, wherein the wireless device periodically reports channel state information for subframes indicated in the first measurement subframe allocation bitmap.

19. The method of claim 16, wherein the wireless device periodically reports channel state information for subframes indicated in the second measurement subframe allocation bitmap.

20. The method of claim 16, further comprising:

transmitting, by the base station and in response to a decrease in traffic load of the base station by an amount greater than a first value, a third message comprising a second subframe allocation bitmap indicating a second plurality of Almost Blank Subframes, wherein the second plurality of Almost Blank Subframes consists of second, fourth, seventh, and ninth subframes of each radio frame in a second plurality of radio frames.

21. The method of claim 16, further comprising:

transmitting, by the base station and in response to an increase in traffic load of the base station by an amount greater than a first value, a third message comprising a second subframe allocation bitmap indicating a second plurality of Almost Blank Subframes, wherein the second plurality of Almost Blank Subframes consists of third and eighth subframes of each radio frame in a second plurality of radio frames.

25. The method of claim 16, wherein the first Almost Blank Subframe consists essentially of a common reference signal in a control region.

26. A method comprising:

transmitting, by a base station, a first message comprising a subframe allocation bitmap indicating a plurality of Almost Blank Subframes, wherein the plurality of Almost Blank Subframes consists of third, seventh, and ninth subframes of each radio frame in a plurality of radio frames;

transmitting, to a wireless device, a second message comprising;

a first measurement subframe allocation bitmap indicating a first plurality of measurement subframes of a primary carrier, wherein the first plurality of measurement subframes excludes the plurality of Almost Blank Subframes; and

a second measurement subframe allocation bitmap indicating a second plurality of measurement subframes of the primary carrier, wherein the second plurality of measurement subframes excludes the first plurality of measurement subframes; and

transmitting, by the base station, a first Almost Blank Subframe, wherein the first Almost Blank Subframe is transmitted at a power level that is lower than during a non-Almost Blank Subframe.

27. The method of claim 26, wherein the second message further configures measurement subframes of a plurality of neighboring carriers for the wireless device.

28. The method of claim 26, wherein the wireless device periodically reports channel state information for subframes indicated in the first measurement subframe allocation bitmap.

29. The method of claim 26, wherein the wireless device periodically reports channel state information for subframes indicated in the second measurement subframe allocation bitmap.

30. The method of claim 26, further comprising:

transmitting, by the base station and in response to a decrease in traffic load of the base station by an amount greater than a first value, a third message comprising a second subframe allocation bitmap indicating a second plurality of Almost Blank Subframes, wherein the second plurality of Almost Blank Subframes consists of second, fourth, seventh, and ninth subframes of each radio frame in a second plurality of radio frames.

31. The method of claim 26, further comprising:

transmitting, by the base station and in response to an increase in traffic load of the base station by an amount greater than a first value, a third message comprising a second subframe allocation bitmap indicating a second plurality of Almost Blank Subframes, wherein the second plurality of Almost Blank Subframes consists of third and eighth subframes of each radio frame in a second plurality of radio frames.

32. The method of claim 26, wherein the first Almost Blank Subframe consists essentially of a common reference signal in a control region.