METHODS AND APPARATUS FOR NETWORK ENERGY SAVINGS IN A WIRELESS COMMUNICATION SYSTEM

• US 20130188531A1
• Filed: 02/16/2011
• Published: 07/25/2013
• Est. Priority Date: 02/16/2010
• Status: Active Grant

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Zhang, Wenfeng
• Granted Patent: US 9,036,523 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0005 Time-frequency
• 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: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0082 at predetermined intervals
• CPC Class Codes: H04W 52/0203 in the radio access network or backbone network of wireless communication networks
• CPC Class Codes: H04W 52/0206 in access points, e.g. base stations access point devices per se H04W88/08
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Disclosed herein are methods and apparatus for network energy savings in a wireless communication system, such as the 3GPP LTE system. Particularly, one such method reduces power consumption in a base station by selectively muting or disabling downlink transmissions of certain control signal symbols in one or more subframes or frames. The disclosed methods and apparatus can apply independently or in combination in both FDD and TDD systems.

Claims

1. A method for energy savings in a wireless network, comprising:

reducing downlink transmissions of a reference signal by selectively muting reference signal symbols in a plurality of subframes of a frame in accordance with an energy saving (ES) scheme, each subframe divided into a first region and a second region,

wherein the ES scheme is configured to select from the plurality of subframes a first set of subframes having reference signal symbols transmitted in their first region and a second set of subframes having reference symbols transmitted in their second region.

2. The method of claim 1, further comprising:

disabling transmissions of reference signal symbols in the first region of all other subframes outside the first set of subframes in accordance with the ES scheme.

3. The method of claim 1, further comprising:

identifying subframes outside the second set of subframes;

excluding subframes that carry at least a content signal symbol from the identified subframes to determine remaining subframes; and

disabling transmissions of reference signal symbols in the second region of the remaining subframes in accordance with the ES scheme.

4. The method of claim 1, wherein the wireless communication system is configured to provide downlink transmissions of a content signal according to a repetition pattern, and the ES scheme is configured to modify or cancel the repetition pattern for downlink transmitting the content signal.

5. The method of claim 1, wherein the wireless communication system includes a frequency division duplex (FDD) system and a time division duplex (TDD) system.

6. The method of claim 5, wherein the ES scheme is configured to incorporate dynamic adjustments of uplink and downlink allocations in the TDD system.

7. The method of claim 1, wherein the wireless communication system is a long term evolution (LTE) system.

8. The method of claim 7, wherein the reference signal is a cell-specific reference signal (CRS), the first region of each subframe is configured to carry a physical layer control channel (PDCCH), and the second region of each subframe is configured to carry a physical layer shared channel (PDSCH).

9. The method of claim 1, wherein each subframe comprises a plurality of symbols in a time domain, one or more symbols in each frame carrying either a control signal or a content signal, and the reference signal is a type of control signal.

10. The method of claim 7, wherein each subframe is at least one of a regular subframe, a MBSFN subframe and a special subframe used in a TDD system.

11. A method for reducing power consumption in downlink transmissions of one or more frames in a wireless communication system, each frame comprising a plurality of subframes and each subframe divided into at least a first region and a second region in a time domain, the method comprising:

selecting a first group of subframes from the plurality of subframes, each of the first group of subframes having at least a control signal symbol in the first region;

for each subframe not selected in the first group, disabling transmission of any control signal symbol in the first region;

selecting a second group of subframes from the plurality of subframes, each of the second group of subframes having one or more control signal symbols in the second region; and

for each subframe not selected in the second group, disabling transmission of any symbol in the second region unless the subframe carries a particular content signal.

12. The method of claim 11, wherein each subframe comprises a plurality of symbols in the time domain, each symbol configured for carrying a control signal or a content signal.

13. The method of claim 11, wherein the wireless communication system is a long term evolution (LTE) system.

14. The method of claim 13, wherein the control signal symbol carries a cell-specific reference signal (CRS), the particular content signal is PCBH or SIB1, the first region of each subframe is configured to carry a physical layer control channel (PDCCH), and the second region of each subframe is configured to carry a physical layer shared channel (PDSCH).

15. The method of claim 11, wherein the wireless communication system includes a FDD system and a TDD system.

16. The method of claim 15, further comprising adjusting uplink and downlink allocations to further reduce the power consumption in the TDD system.

17. The method of claim 11, further comprising reducing a repetition frequency in downlink transmissions of a content signal in the wireless communication system, the content signal having a predetermined frequency for updating the contents therein.

18. An apparatus for reducing power consumption in downlink transmissions of one or more frames in a wireless communication system, each frame comprising a plurality of subframes and each subframe divided into at least a first region and a second region in a time domain, the apparatus comprising:

means for selecting a first group of subframes from the plurality of subframes, each of the first group of subframes having at least a control signal symbol in the first region;

means for disabling transmission of any control signal symbol in the first region of each subframe not selected in the first group;

means for selecting a second group of subframes from the plurality of subframes, each of the second group of subframes having one or more control signal symbols in the second region; and

means for disabling transmission of any symbol in the second region unless the subframe carries a particular content signal in each subframe not selected in the second group.

19. The apparatus of claim 18, further comprising means for reducing a repetition frequency in downlink transmissions of a content signal in the wireless communication system, the content signal having a predetermined frequency for updating the contents therein

20. The apparatus of claim 18, wherein the wireless communication system is an LTE system including FDD and TDD systems.

21. A computer program product for reducing power consumption in downlink transmissions of one or more frames in a wireless communication system, wherein each frame comprises a plurality of subframes and each subframe is divided into at least a first region and a second region, the computer program product embodied in computer-readable storage medium comprising instructions, while executed, causing a computer to perform:

selecting a first group of subframes from the plurality of subframes, each of the first group of subframes having at least a control signal symbol in the first region;

for each subframe not selected in the first group, disabling transmission of any control signal symbol in the first region;

selecting a second group of subframes from the plurality of subframes, each of the second group of subframes having one or more control signal symbols in the second region; and

for each subframe not selected in the second group, disabling transmission of any symbol in the second region unless the subframe carries a particular content signal.

22. The computer program product of claim 21, incorporated in a base station in the wireless communication system.

23. The computer program product of claim 22, wherein the base station comprises a transmitter configured for downlink transmissions of the frames, subframes and symbols, the transmitter including a power amplifier (PA).

24. A base station in a wireless communication system, comprising:

a transmitter configured for downlink transmissions of a frame comprising a plurality of subframes, each subframe divided into at least a first region and a second region;

a downlink signal processor coupled to the transmitter; and

a controller coupled to the downlink signal processor, the controller comprising a power reduction module configured to selectively disable downlink transmissions of control signal symbols by;

selecting a first group of subframes from a plurality of subframes, each of the first group of subframes having at least a control signal symbol in the first region;

for each subframe not selected in the first group, disabling transmission of any control signal symbol in the first region;

selecting a second group of subframes from the plurality of subframes, each of the second group of subframes having one or more control signal symbols in the second region; and

for each subframe not selected in the second group, disabling transmission of any symbol in the second region unless the subframe carries a particular content signal.

25. The base station of claim 24, wherein the transmitter is coupled to one or more power amplifiers (PAs), and the PA-on time in each PA is reduced by the power reduction module.

26. The base station of claim 24, further comprising a scheduler coupled to the downlink signal processor, the schedule configured to schedule downlink transmissions of each frame, subframe and symbols.

27. The base station of claim 24, further comprising an antenna coupled to the transmitter, the antenna having one or more ports, each port coupled to a power amplifier.

28. The base station of claim 24, further comprising an Input/Output (I/O) interface coupled to the controller, the I/O interface configured to enable the base station communicating with one or more networks.

29. The base station of claim 24, wherein the power reduction module is further configured for reducing a repetition frequency in downlink transmissions of a content signal in the wireless communication system, the content signal having a predetermined frequency for updating the contents therein.

30. The base station of claim 24, wherein the wireless communication system is an LTE system having FDD and TDD systems.