Method and apparatus for allocating transmission power in communication system with multiple antennas

• US 20070133708A1
• Filed: 12/11/2006
• Published: 06/14/2007
• Est. Priority Date: 12/09/2005
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute, Hanaro Telecom., Inc., KT Corporation, Samsung Electronics Co. Ltd., SK Telecom Co., Ltd.
• Original Assignee: Electronics and Telecommunications Research Institute, Hanaro Telecom., Inc., KT Corporation, Samsung Electronics Co. Ltd., SK Telecom Co., Ltd.
• Inventors: Kwon, Dong-Seung, Choi, In-Kyeong, Lee, Yu-Ro
• Granted Patent: US 8,077,792 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0434 using multiple eigenmodes
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/021 Estimation of channel covariance
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0085 when channel conditions change
• CPC Class Codes: H04L 5/0096 Indication of changes in allocation
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

In a method for allocating transmission power in a communication system including multiple antennas, a plurality of subcarriers are grouped by a plurality of groups, and each group includes at least one subcarrier. A transmission power weight and an antenna transmission vector are calculated for each group by using channel information, a transmission power for each group of each antenna is calculated by using the transmission power weight and the antenna transmission vector for each group, and transmission signals are transmitted through the multiple antennas after determining which signals need to be transmitted from the multiple antennas by using the transmission power.

Claims

1. A method for allocating transmission power in a communication system including multiple antennas including a plurality of subcarriers grouped by a plurality of groups, each group including at least one subcarrier, the method comprising:

calculating a first transmission power weight for each group by using channel information;

calculating an antenna transmission vector for each group by using the channel information;

calculating a transmission power for each group of each antenna by using the first transmission power weight and the antenna transmission vector for each group;

determining transmission signals to be transmitted from the multiple antennas by using the transmission power; and

transmitting the transmission signals through the multiple antennas.

2. The method of claim 1, wherein the transmission power weight for each group is calculated by using normalized power calculated from the channel information.

3. The method of claim 1, wherein, when transmittable power for each antenna is low, the calculating the transmission power comprises:

calculating a first transmission vector by using the first transmission power weight and the antenna transmission vector for each group;

calculating a second transmission power weight for each antenna for allocating the transmission power by using the first transmission power weight for each group and the transmittable power for each antenna; and

calculating a second transmission vector used for the transmission power by using the first transmission vector and the first transmission power weight of each antenna.

4. The method of claim 3, wherein the first transmission vector is calculated by multiplying the antenna transmission vector for each group by a square root of the first transmission power weight for each group.

5. The method of claim 3, wherein the second transmission power weight for each antenna is calculated by comparing the first transmission power weight for each antenna with a maximum transmission power ratio.

6. The method of claim 5, wherein, the second transmission power weight for each antenna is set as the first transmission power weight for each antenna when the first transmission power weight for each of the multiple antennas is less than the maximum transmission power ratio.

7. The method of claim 5, wherein the second transmission power weight for at least one first antenna is determined by the first transmission power ratio and the maximum transmission power ratio, when the first transmission power weight for at least one first antenna of the multiple antennas is greater than the maximum transmission power ratio, and

a difference between the maximum transmission power ratio and the transmission power weight for each antenna is allocated as the transmission power weight for at least a second antenna of the multiple antennas.

8. The method of claim 3, wherein the second transmission vector is calculated by multiplying the first transmission vector by a square root of the second transmission power weight for each antenna.

9. The method for allocating transmission power of claim 1, wherein the transmission power weight for each group is calculated by checking the channel information with the use of channel reversibility or by directly using the channel information.

10. The method of claim 1, wherein the antenna transmission vector for each group is calculated by performing eigenvalue decomposition for an optimal transmission weight vector calculated from the channel information so as to maximize the Signal-to-Noise Ratio (SNR) for each antenna.

11. The method of claim 1, wherein the transmission power is calculated by multiplying the antenna transmission vector for each group by a square root of the first transmission power weight for each group.

12. The method of claim 1, wherein the transmission signals are determined by multiplying the transmission power by signals multiplexed by the transmission data.

13. A method for allocating transmission power in a communication system including multiple antennas, including a plurality of subcarriers grouped by a plurality of groups, and each group includes at least one subcarrier, the method comprising:

receiving a code book index and a power weight from a receiver;

calculating a first transmission power weight for each group from the power weight,

calculating an antenna transmission vector for each group from the code book index;

calculating a transmission power for each group of each antenna by using the first transmission power weight and the antenna transmission vector for each group;

determining transmission signals to be transmitted from the multiple antennas by using the transmission power; and

transmitting the transmission signals through the multiple antennas.

14. The method of claim 13, wherein the code book index is an optimal transmission vector calculated by the receiver from a code book determined between a transmitter and the receiver.

15. The method of claim 13, wherein the power weight is calculated by quantizing a normalized weight for power of a data group having maximum power.

16. The method of claim 15, wherein the normalized weight is calculated by dividing power of groups allocated in the receiver for receiving the transmission signal by the power of the data group having the maximum power.

17. The method of claim 16, wherein the normalized weight is between 0 and 1.

18. The method of claim 13, wherein the transmission power is calculated by multiplying the antenna transmission vector for each group by a square root of the first transmission power weight for each group.

19. The method of claim 13, wherein the transmission signals are determined by multiplying the transmission power by signals multiplexed by transmission data.

20. The method of claim 13, wherein, when transmittable power for each antenna is limited, calculating the transmission power comprises:

calculating a first transmission vector by using the first transmission power weight and the antenna transmission vector for each group;

calculating a second transmission power weight for each antenna for allocating the transmission power by using the first transmission power weight for each group and the transmittable power for each antenna; and

calculating a second transmission vector used for the transmission power by using the first transmission vector and the second transmission power weight for each antenna.

21. An apparatus for allocating transmission power in a communication system including multiple antennas, wherein a plurality of subcarriers are grouped by a plurality of groups, each group including at least one subcarrier, the apparatus comprising:

a channel information module for storing channel information for each group;

a transmission power weight module for calculating a first transmission power weight for each group by using the channel information;

an antenna transmission vector determination module for calculating an antenna transmission vector for each group by using the channel information;

a power allocation module for calculating a transmission power for each group of each antenna by using the first transmission power weight and the antenna transmission vector for each group; and

a transmission signal determination module for determining transmission signals to be transmitted through the multiple antennas by using the transmission power.

22. The apparatus of claim 21, wherein, when a transmittable power for each antenna is low, the power allocation module comprises:

a first transmission vector determination module for calculating a first transmission vector by using the first transmission power weight and the antenna transmission vector for each group;

a transmission power control module for each antenna for calculating a second transmission power weight for each antenna for allocating the transmission power by using the first transmission power weight for each group and the transmittable power for each antenna; and

a second transmission vector determination module for calculating the second transmission vector used for the transmission power by using the first transmission vector and the transmission power weight for each antenna.

23. An apparatus for allocating for transmission power in a communication system including multiple antennas, including a plurality of subcarriers grouped by a plurality of groups, each group including at least one subcarrier, the apparatus comprising:

a transmission power control module for calculating, from a power weight, a first transmission power weight for each group;

an antenna transmission vector determination module for calculating, from a code book index, an antenna transmission vector for each group;

a power allocation module for calculating a transmission power for each group of each antenna by using the first transmission power weight and the antenna transmission vector for each group; and

a transmission signal determination module for determining transmission signals to be transmitted through the multiple antennas by using the transmission power.

24. The apparatus of claim 23, wherein the code book index is an optimal transmission vector calculated by a receiver from a code book determined between a transmitter and the receiver.

25. The apparatus of claim 23, further comprising:

a code book index and quantized weight receiving module for receiving a quantized power weight and the code book index from a receiver; and

a weight restoration module for restoring the quantized power weight, wherein the power weight used for the transmission power control module is a power weight restored by the weight restoration module.

26. The apparatus of claim 23, wherein, when transmittable power for each antenna is low, the power allocation module comprises:

a first transmission vector determination module for calculating a first transmission vector by using the first transmission power weight and the antenna transmission vector for each group;

a transmission power control module for each antenna for calculating a second transmission power weight for each antenna for allocating the transmission power by using the first transmission power weight for each group and the transmittable power for each antenna; and

a second transmission vector determination module for calculating the second transmission vector used for the transmission power by using the first transmission vector and the second transmission power weight for each antenna.