Method and apparatus for adaptively allocating transmission power for beam-forming combined with OSTBCs in a distributed wireless communication system

• US 20080102881A1
• Filed: 10/25/2007
• Published: 05/01/2008
• Est. Priority Date: 10/25/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hwang, Seong-Taek, Han, Shuangfeng, Oh, Yun-Je, Kim, Byung-Jik, Lee, Han-Lim
• Granted Patent: US 7,949,360 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H01Q 3/30 varying the relative phase between the radiating elements of an array H01Q3/2605, H01Q3/2658, H01Q3/2682, H01Q3/44 take precedence
• CPC Class Codes: H04B 7/0443 utilizing "waterfilling" technique
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• 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

An apparatus that adaptively allocates transmission power for beam-forming combined with orthogonal space time block codes in a distributed wireless communication system, the apparatus including: sub-arrays for beam-forming, which are geographically distributed and each of which includes a plurality of distributed antennas placed in random groups. A central processing unit provides predetermined combinable power allocation schemes according to subsets in a plurality of the sub-arrays, identifying performances of the schemes by using information on large-scale fading of each of the sub-arrays fed back from a receiving party, setting a subset having best performance as an optimal subset according to the identified performances, and performing power allocation according thereto.

Claims

1. An apparatus for adaptively allocating transmission power for beam-forming combined with orthogonal space time block codes in a distributed wireless communication system, the apparatus comprising:

a plurality of sub-arrays for beam-forming, which are geographically distributed and each of which comprises a respectively plurality of distributed antennas arranged in random groups; and

a central processing unit for applying predetermined combinable power allocation schemes according to subsets in a plurality of the beam-forming sub-arrays, for identifying performances of the schemes by using information on large-scale fading of each of the sub-arrays fed back from a receiving party, for setting a subset comprising a best performance as an optimal subset according to the identified performances, and performing power allocation according thereto.

2. The adaptive transmission power allocation apparatus as recited in claim 1, wherein the predetermined power allocation scheme allocates the transmission power proportional to a Nakagami fading parameter “

m”

for each of the sub-arrays.

3. The adaptive transmission power allocation apparatus as recited in claim 1, wherein the determination of performances comprises a determination of an outage probability, and setting a subset of which the determined outage probability is a lowest to the optimal subset.

4. The apparatus according to claim 1, wherein the beam-forming sub-arrays are independently connected to said central processing unit, wherein a transmission signal and receiving signal of the distributed antennas are processed.

5. The apparatus according to claim 3, wherein a macro and a micro fading of different beam-forming sub-arrays are mutually independent.

6. The apparatus according to claim 4, wherein the distributed antennas are arranged with half-wavelength spacing in each of the sub-arrays.

7. A method for adaptively allocating transmission power for beam-forming combined with one or more orthogonal space time block codes in a distributed wireless communication system comprising sub-arrays for beam-forming which are geographically distributed and each of which comprises a plurality of distributed antennas arranged in random groups, the method comprising the steps of:

estimating a direction-of-arrival (DOA) for each of the sub-arrays and creating an array response vector for each antenna sub-array;

allocating transmission power proportional to a Nakagami fading parameter “

m”

for each of the sub-arrays according to subsets that are combined in a plurality of the sub-arrays by using information regarding large-scale fading of each of the sub-arrays that is fed back from a receiving party and calculating the outage probability according to each of the subsets; and

setting a subset, of which the calculated outage probability is a lowest, as an optimal subset and performing power allocation according thereto.

8. The method according to claim 7, wherein calculating the outage probability includes calculating a quasi-optimal outage probability P_i for a subset A_i by using a quasi-optimal power allocation scheme for allocating the transmission power proportional to the fading parameter “

m”

of each sub-array of the subset A_i, wherein A represents an optimal antenna subset, and P represents a quasi-optimal outage probability.

9. The method according to claim 8, wherein the estimating a direction-of-arrival (DOA) for each of the sub-arrays, and creating the array response vector for each antenna sub-array includes receiving large-scale fading information being fed back to the receiving party by a mobile terminal (MT) which is provided with the large-scale fading information.

10. The method according to claim 9, wherein calculating the outage probability P_i includes determining when P_i≦

P<sub>i−

1</sub>, in which A and P are then set to A_i and P_i respectively.