SYSTEM AND METHOD FOR REDUCING BIT-ERROR-RATE IN ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING

• US 20120236964A1
• Filed: 11/30/2010
• Published: 09/20/2012
• Est. Priority Date: 11/30/2009
• Status: Abandoned Application

• Current Assignee: Ben Gurion University of The Negev
• Original Assignee: Ben Gurion University of The Negev
• Inventors: Wulich, Dov
• Application Number:
  US13/512,360
• Publication Number:
  US 20120236964A1
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/346 distributing total power among users or channels

Abstract

System and method for reducing BER in OFDM based communication system. A cost function relating the power partition coefficients and the average power emitted by the linear power amplifier at the transmitter during quasistatic periods of the channel may be minimized, solved or estimated, based on the received channel partial CSI, and on knowledge of the linear power amplifier gain and linear dynamic range, to get power partition coefficients. The total available power may be divided among the subcarriers according to the resultant power partition coefficients. Additionally, the OFDM signal may amplified by a variable gain calculated based on the resultant power partition coefficients.

Claims

1. A method for reducing Bit Error Rate (BER) in Orthogonal Frequency-Division Multiplexing (OFDM) transmitter, the method comprising:

setting power partition coefficients of said OFDM transmitter by periodically solving a cost function relating said power partition coefficients to average power emitted by a linear power amplifier (LPA) of said OFDM transmitter, said cost function considering partial Channel State Information (CSI) of said channel, and gain and linear dynamic range of said LPA;

setting a gain for a variable gain amplifier based on said linear dynamic range and on said power partition coefficients;

distributing total available power among subcarriers using said power partition coefficients; and

amplifying a transmitted signal of the OFDM transmitter by said gain.

2. The method of claim 1, wherein said cost function is given by:

3. The method of claim 2, wherein solving said cost function is done numerically.

4. The method of claim 2, wherein solving said cost function is done using look-up-table matching possible values of said power partition coefficients and said average power emitted by the LPA.

5. The method of claim 2, wherein a sub optimal solution of said cost function is obtained by solving f(γ

_x)=γ

_x wherein the function y_o=f(γ

_x) is defined by the following chain of equations;

6. The method of claim 1, said gain is calculated by:

7. The method of claim 1, wherein said cost function is solved for every quasistatic period of the channel.

8. An OFDM transmitter comprising:

a modified minimum BER (MM-BER) block to set power partition coefficients of said OFDM transmitter by periodically solving a cost function relating said power partition coefficients to average power emitted by a linear power amplifier (LPA), said cost function considering partial Channel State Information (CSI) of said channel, and gain and linear dynamic range of said LPA;

a variable gain amplifier to amplify a transmitted signal of said OFDM transmitter by a second gain, said second gain to be set based on said linear dynamic range and on said power partition coefficients; and

an OFDM modulator block adapted to distribute total available power among subcarriers using said power partition coefficients.

9. The OFDM transmitter of claim 8, wherein said cost function is given by:

10. The OFDM transmitter of claim 9, wherein solving said cost function is done numerically.

11. The OFDM transmitter of claim 9, wherein solving said cost function is done using look-up-table matching possible values of said power partition coefficients and said average power emitted by the LPA.

12. The OFDM transmitter of claim 9, wherein a sub optimal solution of said cost function is obtained by solving f(γ

_x)=γ

_x where the function γ

_o=f(γ

_x) is defined by the following chain of equations;

13. The OFDM transmitter of claim 8, said gain is calculated by:

14. The OFDM transmitter of claim 8, wherein said cost function is solved for every quasistatic period of the channel.

15. A computer readable medium having stored thereon instructions which when executed by a processor cause the processor to perform the method of:

setting power partition coefficients of an OFDM transmitter by periodically solving a cost function relating said power partition coefficients to average power emitted by a linear power amplifier (LPA) of said OFDM transmitter, said cost function considering partial Channel State Information (CSI) of said channel, and gain and linear dynamic range of said LPA;

setting a gain for a variable gain amplifier based on said linear dynamic range and on said power partition coefficients;

distributing total available power among subcarriers using said power partition coefficients; and

amplifying a transmitted signal of said OFDM transmitter by said gain.

16. The computer readable medium of claim 15, wherein said cost function is given by:

17. The computer readable medium of claim 16, wherein solving said cost function is done numerically.

18. The computer readable medium of claim 16, wherein solving said cost function is done using look-up-table matching possible values of said power partition coefficients and said average power emitted by the LPA.

19. The computer readable medium of claim 16, wherein a sub optimal solution of said cost function is obtained by solving f(γ

_x)=γ

_x were the function γ

_o=f(γ

_x) is defined by the following chain of equations;

20. The computer readable medium of claim 15, said gain is calculated by:

21. The computer readable medium of claim 15, wherein said cost function is solved for every quasistatic period of the channel.