Patent ID: 7773681
Filing Date: 2010-08-10
Classification: H04B,H04L

Abstract:
1. A method for noise estimation of a received OFDM communication signal, comprising: receiving by a wireless transmit/receive unit (WTRU) a signal having a data frame with a preamble having at least one long training field (LTF) containing two substantially similar OFDM symbols and independent signal noise samples; examining by the WTRU the at least one LTF for substantially similar OFDM symbols; estimating by the WTRU the noise power in the signal based on the substantially similar OFDM symbols, wherein the estimating includes squaring differences between the independent signal noise samples and averaging them, and wherein the estimating is performed in accordance with the following equation: where r (1) (t) represents the first received symbol, r (2) (t) represents the second received symbol, a represents the automatic gain control (AGC) gain, n 1 (t) and n 2 (t) represent independent noise samples, and σ n 2 is the noise variance; determining by the WTRU the received signal power; calculating by the WTRU the signal to noise ratio to determine signal noise; and determining by the WTRU the signal power by subtracting the noise power from the received signal noise.