System Level Analysis of ACK/NACK Bundling for Multi-Component Carrier LTE-Advanced

This paper focuses on reducing the uplink overhead caused by Acknowledgement (ACK)/Non-acknowledgement (NACK) signaling in an Long Term Evolution (LTE)-Advanced system. Such a system typically aggregates multiple Component Carrier (CC)s to obtain a wide bandwidth. Usually it has much larger feedback overhead than the single-CC system, and hence reducing the overhead is of special importance. A technique called ACK/NACK bundling has been used for the overhead reduction of the ACK/NACK signaling. Along with the overhead reduction, the downlink performance is also degraded. The tradeoff between the downlink performance and the overhead is analyzed under various load conditions and antenna configurations. The presented results can be used for selecting the proper bundling scheme based on specific system setting.