Antenna-array-assisted frequency offset estimation and data detection in an uplink multiuser MIMO-OFDM interference network

The high-density deployment of access points (APs) and their serious mutual interference have made both frequency acquisition and data detection even more difficult in wireless local area network (WLAN). In light of this, this paper presents an antenna-array-assisted algorithm to solve above problems in a multiuser multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) interference network. The algorithm begins with the estimation of the channel parameters, including the frequency offsets, delays, and angle selectivity. To make a good use of the array signal characteristics, these parameters are estimated in an frequency-angle-frequency (FAF) tree structure, in which two frequency estimations and one angle estimation are employed alternatively. One special feature in the FAF tree structure is that temporal filtering or spatial beamforming is invoked between the parameter estimations to decompose the signals so as to enhance the estimation accuracy. Thereafter, based on these parameter estimates, a data detection procedure is developed to mitigate both multiple access interference (MAI) and co-channel interference (CCI). Simulations show that the proposed algorithm can provide satisfactory performance even in networks with MAIs and CCIs sharing the same frequency band.