Patent ID: 8131306
Filing Date: 2012-03-06
Classification: H04B,H04L,H04W

Abstract:
1. In a wireless-access network, a method for allocating time-frequency units of a downlink subframe to user stations, the method comprising: receiving feedbacks indicative of channel state transmitted from at least some of the user stations, classifying each of the user stations based on the feedbacks, wherein classifying comprises classifying user stations with a known channel state that have provided the feedback as closed-loop user stations and classifying open-loop user stations are user stations with an unknown channel state due to a lack of said feedback as open-loop user stations; based on a predetermined radio frequency (RF) spacing threshold, identifying contiguous groups of subcarriers from group of subcarriers within a system bandwidth available for allocation by comparing each group's RF spacing against said threshold, and determining groups of subcarriers that have RF spacing no more than the predetermined threshold; allocating at least some of the contiguous groups of data subcarriers of the downlink subframe from the available contiguous groups to the closed-loop user stations by allocating adjacent groups of data subcarriers to the closed-loop user stations for at least a predetermined number of OFDMA symbols of the downlink subframe; and after the allocation of the contiguous groups of data subcarriers to the closed-loop user stations, allocating remaining groups of data subcarriers of the downlink subframe to the open-loop user stations for each OFDMA symbol including by reallocating different groups of the remaining data subcarriers to the open-loop user stations for at least the predetermined number OFDMA symbols of the downlink subframe, wherein the remaining groups of subcarriers that are allocated to the open-loop user stations comprise groups of subcarriers that have frequency spans exceeding the predetermined spacing threshold by at least a group of subcarriers.