Opportunistic Feedback in OFDMA Downlink

This paper presents an opportunistic feedback (OF) protocol that reduces the amount of channel-state-information (CSI) feedback for the OFDMA downlink system. The OF protocol associates a channel value instead of a user to each feedback slot. The users access the slots opportunistically based on their channel state measurement for each tone. This allows the base station (BS) to deduce the channel state from the slot index without explicit channel-state feedback, and also solve the resource allocation problem on the fly. The OF protocol is designed to support heterogeneous traffic, where users with deadline-sensitive (DS) applications are prioritized over best- effort (BE) users. The proposed OF protocol (a) requires finite number of feedback slots upper bounded by a small number, (b) is fully distributed, and (c) provides QoS to the DS applications.