Estimating frequency-offsets and multi-antenna channels in MIMO OFDM systems

摘要

Techniques are described for carrier frequency offset (CFO) and channel estimation of orthogonal frequency division multiplexing (OFDM) transmissions over multiple-input multiple-output (MIMO) frequency-selective fading channels. A wireless transmitter forms blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols. The transmitter applies a hopping code to each of the blocks of symbols to insert a null subcarrier at a different position within each of the blocks of symbols, and a modulator outputs a wireless signal in accordance with the blocks of symbols. A receiver receives the wireless signal and estimates the CFO, and outputs a stream of estimated symbols based on the estimated CFO.

主权项

1. A method comprising:
forming, with a wireless communication device, blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols; applying, with the wireless communication device, a hopping code to each of the blocks of symbols to insert a null subcarrier within each of the blocks of symbols, wherein the hopping code causes a position of the null subcarrier to change from block to block, wherein the position change caused by the hopping code is based, at least, on a block length and a cyclic prefix length, wherein the cyclic prefix length is based, at least, on a characteristic of a wireless communication channel; and outputting, via Nt antennas of the wireless communication device, a wireless transmission signal in accordance with the blocks of symbols, the wireless transmission signal being configured to be received via Nr antennas, wherein each of Nt and Nr is an integer, and wherein at least one of Nt and Nr is an integer greater than one.