Uplink power control message indexing in wireless OFDMA systems

• US 20110199945A1
• Filed: 09/30/2010
• Published: 08/18/2011
• Est. Priority Date: 02/12/2010
• Status: Active Grant

• Current Assignee: HFI Innovation, Inc. (MediaTek, Inc.)
• Original Assignee: MediaTek, Inc.
• Inventors: Chang, Yu-Hao, Chen, Yih-Shen
• Granted Patent: US 8,588,205 B2
• Time in Patent Office: Days
• US Class Current: 370/281
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo

Abstract

A method of power control message indexing is provided in a wireless Orthogonal Frequency Division Multiple Access (OFDMA) network. A base station configures fast feedback channels (FFBCHs) and mobile stations report downlink channel information via the configured FFBCHs. Based on the received channel information, the base station estimates uplink channel quality and detects any channel variation. In response to uplink channel variation, the base station delivers power offsets to adjust the transmit power levels of the mobile stations. In one advantageous aspect, the power control commands for mobile stations are aggregated and the indexing scheme of the power control commands is implicitly based on the configured FFBCHs. For example, if a FFBCH is located at a first location in an uplink frame, then a following power control command in response to the FFBCH is located at a second location in a downlink frame, the second location is located after the first location with a predefined fixed delay time.

Claims

1. A method, comprising:

estimating uplink channel quality based on a fast feedback channel transmitted by a mobile station in a wireless OFDMA system, wherein the fast feedback channel is allocated at a first location in an uplink subframe; and

transmitting a power control message by a base station to the mobile station, wherein the power control message is transmitted in response to the estimated uplink channel information and is allocated at a second location in a downlink subframe, and wherein the second location is located after the first location with a delay time.

2. The method of claim 1, wherein the delay time is predefined in the wireless OFDMA system.

3. The method of claim 1, wherein the delay time is independently signaled from the base station to the mobile station.

4. The method of claim 1, wherein the first location is associated with a first frame index, a first subframe index, and a first channel index, wherein the second location is associated with a second frame index, a second subframe index, and a second channel index, and wherein the second frame index, the second subframe index, and the second channel index are determined based on the first frame index, the first subframe index, the first channel index, and the delay time.

5. The method of claim 4, wherein each frame contains N unit of subframes, wherein the delay time equals to X unit of subframes, and wherein N is a positive integer while X is a decimal number.

6. The method of claim 1, wherein the power control message comprises a power offset for adjusting the uplink transmitting power of the mobile station.

7. The method of claim 1, wherein the wireless OFDMA system is either a frequency division duplex (FDD) system or a hybrid frequency division duplex (H-FDD) system.

8. A base station, comprising:

a receiver that estimates uplink channel quality based on a fast feedback channel transmitted by a mobile station in a wireless OFDMA system, wherein the fast feedback channel is allocated at a first location in an uplink subframe;

a power control module that generates a power control message in response to the estimated uplink channel information; and

a transmitter that transmits the power control message to the mobile station, wherein the power control message is allocated at a second location in a downlink subframe, and wherein the second location is located after the first location with a fixed delay time.

9. The base station of claim 8, wherein the delay time is predefined in the wireless OFDMA system.

10. The base station of claim 8, wherein the delay time is independently signaled from the base station to the mobile station.

11. The base station of claim 8, wherein the first location is associated with a first frame index, a first subframe index, and a first channel index, wherein the second location is associated with a second frame index, a second subframe index, and a second channel index, and wherein the second frame index, the second subframe index, and the second channel index are determined based on the first frame index, the first subframe index, the first channel index, and the delay time.

12. The base station of claim 11, wherein each frame contains N unit of subframes, wherein the delay time equals to X unit of subframes, and wherein N is a positive integers while X is a decimal number.

13. The base station of claim 8, wherein the power control message comprises a power offset for adjusting the uplink transmitting power of the mobile station.

14. The base station of claim 8, wherein the wireless OFDMA system is either a frequency division duplex (FDD) system or a hybrid frequency division duplex (H-FDD) system.

15. A method, comprising:

receiving downlink channel information via a plurality of fast feedback channels transmitted by a plurality of mobile stations in a wireless OFDMA system;

estimating uplink channel quality based on the received fast feedback channels by a base station in the wireless OFDMA system; and

transmitting a plurality of power control messages in response to the estimated uplink channel responses by the base station to the plurality of mobile stations, wherein each power control message is allocated with respect to each fast feedback channel such that each mobile station is able to locate each power control message based on each corresponding fast feedback channel and a delay time.

16. The method of claim 15, wherein each frame contains N unit of subframes, wherein the delay time equals to X unit of subframes, and wherein N is a positive integer while X is a decimal number.

17. The method of claim 15, wherein each fast feedback channel is transmitted every P unit of subframes, wherein P is a positive integer, and wherein the delay time is unrelated to the value of P.

18. The method of claim 17, wherein the delay time is predefined such that resource is efficiently utilized for transmitting the power control messages when the number of plurality of mobile stations is large.

19. The method of claim 17, wherein the delay time is predefined such that the delay time is substantially shorter than the periodicity of each fast feedback channel when P is a large number.

20. The method of claim 17, wherein the delay time is predefined such that the power control message is allocated in downlink subframe in a hybrid frequency division duplex (H-FDD) system.

21. The method of claim 15, wherein each power control message comprises a power offset for adjusting the uplink transmitting power of the plurality of mobile stations.