Feedback interval control

A user equipment for use in a wideband multiple-input multiple-output (MIMO) wireless communication system in which a plurality of adjacent cells, or sectors of cells, are provided each containing one or more base stations operable to transmit signals to, and receive signals transmitted from, the user equipment, wherein the user equipment is operable to:

• feed back to the relevant base station(s) channel state information relating to channel(s) between the relevant base station(s) and the user equipment, thereby enabling the base station(s) to adapt signals for transmission to the user equipment, based on the fed back channel state information;
• obtain information related to time-variation in channel spatial structure by determining a value of a parameter related to time variation in channel spatial structure that indicates the extent of the change in time of a correlation matrix distance of spatial correlation matrices, the spatial correlation matrices being based on an averaged channel correlation matrix over a bandwidth of the wideband MIMO wireless communication system;
• and adjust the timing with which channel state information is fed back based on the time variation in channel spatial structure.

A wideband multiple-input multiple-output (MIMO) wireless communication system in which:

• a plurality of adjacent cells or sectors of cells are provided, each containing one or more base stations operable to transmit signals to, and receive signals transmitted from, one or more users, one or more users are operable to feed back to the relevant base station(s) channel state information relating to channel(s) between the relevant base station(s) and each said user;
• base stations are operable to adapt signals for transmission to users, based on fed back channel state information, to account for channel variations, wherein information related to time-variation in channel spatial structure is obtained by determining a value of a parameter related to time variation in channel spatial structure that indicates the extent of the change in time of a correlation matrix distance of spatial correlation matrices, the spatial correlation matrices being based on an averaged channel correlation matrix over a bandwidth of the wideband MIMO wireless communication system;
• and the timing with which a user feeds back channel state information is adjusted based on time variation in channel spatial structure.