New European Patent: Channel estimation in a multi-user MIMO-OFDM system in the presence of user terminal symbol specific phase offsets
Disclosed is an OFDM wireless communication system comprising an access point, and a plurality of remote user terminals.
The access point receives one or more training symbols transmitted by the user terminals, each training symbol comprising pilot symbols associated with phase offset estimation OFDM sub-carriers of said training symbol, the phase offset estimation sub-carriers comprising subsets of sub-carriers associated with respective user terminals, wherein each subset is used exclusively by the associated user terminal during channel estimation, and further symbols associated with channel estimation OFDM sub-carriers of said training symbol, wherein the channel estimation sub-carriers are used by all user terminals.
The access point estimates, for each user terminal, symbol-specific phase offsets specific to the user terminal using the received pilot symbols associated with the user specific subset of the phase offset estimation sub-carriers; and estimates the uplink channel using the user-terminal-symbol-specific phase offset estimates and the received further symbols.
About the Patent
Method of estimating uplink channels in wireless communication system, involves estimating symbol specific phase offsets by received pilot symbols and user-terminal-symbol-specific phase offset estimates and other symbols
The method (300) involves receiving training symbols at the access point by the user terminals. The subsets of sub-carriers are used by the associated user during channel estimation and the channel estimation sub carriers are used by all user terminals and are comprised by training symbols. The symbol specific phase offset is estimated (330) by received pilot symbols associated with the subset of phase offset estimation sub-carriers associated with the user terminal. The uplink channel carrier is estimated (320) by user-terminal-symbol-specific phase offset estimates and other symbols.
Method of estimating uplink channels in wireless communication system.