Methods and systems for channel estimation in a collaborative multi input multiple output (MIMO) communication system

A system for estimating channel in a collaborative Multiple Input Multiple Output (MIMO) communication system, the system comprising:

• a plurality of Mobile Stations (MSs), wherein each MS comprises a transmit antenna configured to transmit signal;
• and
• a Base Transceiver Station (BTS) comprising:
• a plurality of receiver antennas, each receiver antenna configured to receive signal from a transmit antenna of a first MS and a second MS at a BTS, wherein a signal comprises a plurality of tiles, each tile comprises a plurality of pilot sub-carriers and a plurality of data sub-carriers corresponding to at least one of the first MS and the second MS;
• and
• a base station receive processor configured to:
• compute a plurality of conjugate products for each of the first MS and the second MS using signal received at the plurality of receiver antennas of the BTS from the first MS and the second MS, wherein a conjugate product is computed for the plurality of pilot sub-carriers in a tile of a signal received at a receiver antenna of the BTS from a MS;
• determine an average of the plurality of conjugate products for each of the first MS and the second MS;
• divide a phase determined based on the average of the plurality of conjugate products for each of the first MS and the second MS into a first phase and a second phase;
• determine a channel estimate for each tile in the signal for the first MS and the second MS at each receiver antenna of the BTS, wherein a channel estimate corresponding to a MS for a tile at a receiver antenna of the BTS is determined based on the phase and a plurality of pilot sub-carriers corresponding to the MS in the tile;
• and
• perform predefined computations on the channel estimate of each tile of the first MS and the second MS at each receiver antenna of the BTS using the corresponding first phase and the corresponding second phase;
• wherein the predefined computations performed on a channel estimate of a tile for a MS at each receiver antenna of the BTS comprises:
• generating a combined phase for each pilot sub-carrier and each data sub-carrier in the tile by weighting the corresponding first phase and the corresponding second phase;
• applying the combined phase corresponding to each pilot sub-carrier and each data sub-carrier in the tile to the channel estimate determined for the tile.