Winning by Successive Failures - Enhanced Link Adaptation for Cellular Networks

Link adaptation algorithm that tailors the data transmission coding-rate to the dynamic channel state is an essential ingredient in any (modern) cellular network. Current link adaptation schemes are based on the usage of periodic pilots sent by the base station. The mobile terminal determines the optimal coding-rate to be employed based on processing the received pilots, and then reports its findings back to the base station. Herein, we show that these schemes perform far from optimal and do not come close to achieving the channel capacity. To address this shortcoming, we propose enhanced link adaptation scheme based on a rateless-like coding approach. According to the proposed scheme, the base station sends multiple re-transmissions, effectively combined at the receiver side, until decoding is successful. It is demonstrated that the proposed scheme can closely track the channel capacity, even for highly mobile terminals, hence achieving significant gains over current link adaptation schemes. From the practical side, we address several implementation-related issues thus paving the way for the adaptation of the proposed scheme to the use of 5G networks.