Estimating frequency-offsets and multi-antenna channels in MIMO OFDM systems
AssigneeRegents of the University of Minnesota
InventorsGeorgios B. Giannakis, Xiaoli Ma
Life of this patent
Estimating the term…
Abstract
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.
Claims43
A method comprising:
- forming, by a wireless communication device, two or more blocks of symbols by inserting training symbols within each of two or more blocks of information-bearing symbols;
- applying, by the wireless communication device, a hopping code to each of the two or more blocks of symbols to insert a null subcarrier at a different position within each of the two or more blocks of symbols;
- and
- outputting, by the wireless communication device, a wireless transmission signal in accordance with the two or more blocks of symbols,
- wherein the hopping code is applied to insert the null subcarriers at different positions in the two or more blocks of symbols such that a second wireless communication device is operable to receive a wireless signal from the outputted wireless transmission signal and to estimate a carrier frequency offset of the received wireless signal based on the positions of the null subcarriers.
A method comprising:
- receiving, by a wireless communication device, a wireless signal transmitted from a stream of two or more blocks of symbols, wherein each of the two or more blocks of symbols includes one or more information-bearing symbols, one or more training symbols, and at least one null subcarrier at a different position within each of the two or more blocks of symbols;
- estimating, by the wireless communication device, a carrier frequency offset of the received wireless signal based on the positions of the null subcarriers in the two or more blocks of symbols;
- and
- outputting, by the wireless communication device, estimated symbols based on the received wireless signal and the estimated carrier frequency offset.
A wireless communication device comprising:
- a training symbol insertion module to form two or more blocks of symbols by inserting training symbols within each of two or more blocks of information-bearing symbols, wherein the training symbol insertion module applies a hopping code to each of the two or more blocks of symbols to insert a null subcarrier at a different position within each of the two or more blocks of symbols;
- and
- a modulator to output a wireless transmission signal in accordance with the two or more blocks of symbols,
- wherein the wireless communication device applies the hopping code to insert the null subcarriers at different positions in the two or more blocks of symbols such that a second wireless communication device is operable to receive a wireless signal from the outputted wireless transmission signal and to estimate a carrier frequency offset of the received wireless signal based on the positions of the null subcarriers.
A wireless communication device comprising:
- one or more antennas that receive a wireless signal transmitted from a stream of two or more blocks of symbols, wherein each of the two or more blocks of symbols includes one or more information-bearing symbols, one or more training symbols, and at least one null subcarrier at a different position within each of the two or more blocks of symbols;
- a carrier frequency offset estimator to estimate a carrier frequency offset of the received wireless signal based on the positions of the null subcarriers in the two or more blocks of symbols;
- and
- a decoder to output a stream of estimated symbols based on the received wireless signal and the estimated carrier frequency offset.
A non-transitory computer-readable storage medium, comprising instructions that cause a processor of a wireless communication device to:
- form two or more blocks of symbols by inserting training symbols within each of two or more blocks of information-bearing symbols;
- apply a hopping code to each of the two or more blocks of symbols to insert a null subcarrier at a different position within each of the two or more blocks of symbols;
- and
- output wireless transmission signal in accordance with the two or more blocks of symbols,
- wherein the hopping code is applied to insert the null subcarriers at different positions in the two or more blocks of symbols such that a second wireless communication device is operable to receive a wireless signal from the outputted wireless transmission signal and to estimate a carrier frequency offset of the received wireless signal based on the positions of the null subcarriers.
A non-transitory computer-readable storage medium, comprising instructions that cause a processor of a wireless communication device to:
- receive a wireless signal transmitted from a stream of two or more blocks of symbols, wherein each of the two or more blocks of symbols includes one or more information-bearing symbols, one or more training symbols, and at least one null subcarrier at a different position within each of the two or more blocks of symbols;
- estimate a carrier frequency offset of the received wireless signal based on the null subcarriers included in the two or more blocks of symbols;
- and
- output estimated symbols based on the received wireless signal and the estimated carrier frequency offset.
Dependencies are inferred from the claim text.