Apparatus and method for allocating subchannel and power in an orthogonal frequency division multiple access system

• US 20060078059A1
• Filed: 10/11/2005
• Published: 04/13/2006
• Est. Priority Date: 10/11/2004
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ok, Kwang-Man, Kang, Chung-Gu, Kim, Min-Goo, Rho, Wi-Sang
• Application Number:
  US11/246,566
• Publication Number:
  US 20060078059A1
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

An apparatus and method for allocating transmission power of a subchannel for each individual user in an orthogonal frequency division multiple access (OFDMA) system. The apparatus and method comprises determining the number-of-transmission bits per symbol approximating an estimated signal-to-interference ratio (SIR) for each of subchannels when transmission power is uniformly allocated to the subchannels; and calculating a required SIR corresponding to the number-of-transmission bits per symbol, and allocating transmission power to each of the subchannels according to the required SIR.

Claims

1. A method for allocating transmission power of a subchannel for each individual user by a base station in an orthogonal frequency division multiple access (OFDMA) system, the method comprising the steps of:

determining a required signal-to-interference (SIR) approximating an estimated SIR for each of subchannels when transmission power is uniformly allocated to the subchannels; and

finding the number-of-transmission bits per symbol corresponding to the required SIR, and allocating transmission power to each of the subchannels such that the required SIR is satisfied.

2. The method of claim 1, wherein the estimated SIR represents an estimated SIR measured when transmission power is uniformly allocated to the subchannels for the individual users at a present time.

3. The method of claim 1, wherein the estimated SIR is calculated by dividing a measured SIR by previously allocated transmission power and multiplying the division result by average power allocable to a corresponding subchannel.

4. The method of claim 1, wherein the transmission power allocation to each of the subchannels is performed within a range of the total transmission power of the base station.

5. The method of claim 1, wherein the number-of-transmission bits per symbol is determined as a positive real number when it satisfies data rates required by all users.

6. The method of claim 1, wherein the number-of-transmission bits per symbol is determined as a zero or positive real number when it maximizes the full data rate of the base station.

7. A base station apparatus for allocating transmission power of a subchannel for each individual user in an orthogonal frequency division multiple access (OFDMA) system, the apparatus comprising:

means for determining a required signal-to-interference ratio (SIR) approximating an estimated SIR for each of subchannels when transmission power is uniformly allocated to the subchannels; and

means for finding the number-of-transmission bits per symbol corresponding to the required SIR, and allocating transmission power to each of the subchannels such that the required SIR is satisfied.

8. A method for allocating, by a base station, transmission power and a subchannel used by a mobile station of each user in a cell of an orthogonal frequency division multiple access (OFDMA) system that both a non-real-time data user and a real-time data user access, the method comprising:

a first allocation step of sequentially allocating the subchannels having the highest measured signal-to-interference ratio (SIR) to each individual user, and allocating the transmission power to each individual user such that the number-of-transmission bits has a positive value; and

a second allocation step of allocating the remaining subchannels to at least one non-real-time data user selected for every remaining subchannel left after the allocation in the order of the subchannel having the highest measured SIR.

9. The method of claim 8, wherein the step of allocating the transmission power in the first and second allocation steps comprises the steps of:

determining a required SIR when the transmission power is uniformly allocated to the subchannels; and

finding the number-of-transmission bits per symbol corresponding to the required SIR, and allocating transmission power to each of the subchannels such that the required SIR is satisfied.

10. The method of claim 9, wherein the transmission power allocated to the subchannel in the second allocation step is determined such that the number-of-transmission bits has a zero or positive real number.

11. The method of claim 8, wherein the real-time data user has a required data rate of a positive value, the non-real-time data user has a required data rate of a zero or positive value, and the first allocation step is repeatedly performed in the predetermined user'"'"'s order until data rates required by all users are satisfied.

12. The method of claim 8, wherein the real-time data user has a required data rate of a positive value, the non-real-time data user has a required data rate of a zero or positive value, and the first allocation step is performed on a user with the next order in the same manner after a data rate required by a user with the previous order is satisfied.

13. The method of claim 8, wherein the allocation is performed in a downlink, and the base station receives a required data rate and a measured SIR of each subchannel from a mobile station of each user and performs the first and second allocation steps using the received required data rate and measured SIR.

14. The method of claim 8, wherein the allocation is performed in an uplink, and the base station receives a required data rate from a mobile station of each user, measures an SIR of each subchannel, and performs the first and second allocation steps using the received required data rate and the measured SIR.

15. The method of claim 8, wherein the first allocation step is performed when a user acquired data rate is lower than a required data rate.

16. A subchannel and power allocation apparatus in a base station, for allocating a subchannel and transmission power to a mobile station of each user in an orthogonal frequency division multiple access (OFDMA) system that both a non-real-time data user and a real-time data user access, the apparatus comprising:

a first allocator for sequentially allocating the subchannels having the highest measured signal-to-interference ratio (SIR) to each individual user, and allocating the transmission power to each individual user such that the number-of-transmission bits has a positive value; and

a second allocator for allocating the remaining subchannels to at least one non-real-time data user selected for every remaining subchannel left after the allocation in the order of the subchannel having the highest measured SIR.

17. The apparatus of claim 16, wherein in a downlink, the base station further includes a receiver for receiving a required data rate and a measured SIR of each subchannel from the mobile station, and delivering the received required data rate and measured SIR to the first and/or second allocator.

18. The apparatus of claim 16, wherein in an uplink, the base station further includes:

a receiver for receiving a required data rate from the mobile station, and delivering the received required data rate to the first and/or second allocator; and

a measurer for measuring an SIR of each subchannel.

19. The apparatus of claim 16, wherein the first and second allocators determine a required SIR approximating an estimated SIR when transmission power is uniformly allocated to the subchannels, find the number-of-transmission bits corresponding to the required SIR, and allocate transmission power to each of the subchannels such that the required SIR is satisfied.

20. The apparatus of claim 19, wherein the real-time data user has a required data rate of a positive value, the non-real-time data user has a required data rate of a zero or positive value, and the first allocator repeatedly performs the channel and power allocation in the predetermined user'"'"'s order until data rates required by all users are satisfied.

21. The apparatus of claim 19, wherein the real-time data user has a required data rate of a positive value, the non-real-time data user has a required data rate of a zero or positive value, and the first allocator performs the channel and power allocation on a user with the next order in the same manner after a data rate required by a user with the previous order is satisfied.

22. A base station apparatus for allocating a subchannel and transmission power to a mobile station of each user in an uplink of an orthogonal frequency division multiple access (OFDMA) system that both a non-real-time data user and a real-time data user access, the apparatus comprising:

a subchannel and power allocator for sequentially allocating the subchannels having the highest measured signal-to-interference ratio (SIR) to each individual user, allocating the transmission power to each individual user such that the number-of-transmission bits has a positive value, allocating the remaining subchannels to at least one non-real-time data user selected for every remaining subchannel left after the allocation in the order of the subchannel having the highest measured SIR, and outputting the allocation result;

an adaptive demodulator for demodulating received data on each subchannel with a demodulation method corresponding to the transmission power and the number-of-transmission bits based on the allocation result of the subchannel and power allocator; and

a bit extractor for extracting data bits demodulated by the adaptive demodulator.

23. The base station apparatus of claim 22, wherein the subchannel and power allocator determines a required SIR approximating an estimated SIR when transmission power is uniformly allocated to the subchannels, find the number-of-transmission bits corresponding to the required SIR, and allocates transmission power to each of the subchannels such that the required SIR is satisfied.