SINR order statistics in OFDMA systems

Abstract

In orthogonal frequency division multiple access downlink, the signal-to-interference-noise ratio (SINR) of every subband at each user is estimated with the aid of pilots and the channel quality (some function of SINR's) is fed back to the base station (BS). This information is utilized by the BS for downlink scheduling. However, the SINR of the bands at each user are correlated due to the common interfering BSs. In this paper, we obtain the order statistics of band SINR's by considering the the co-channel interference and taking the correlations of interference across the bands into consideration. The order statistics are then used to analyse a best-m band feedback scheme, in which every users reports the index of their best-m bands to the BS. The BS utilizes this information and does greedy allocation of the bands to the users. We observe that utilizing the partial ordering of SINR's for channel allocation provides substantial gains over random allocation of bands to the users even in the presence of interference.