Allocation of Resources for HARQ Retransmission in Mobile Networks Based on C-RAN

The radio resources are utilized for both transmissions of new data and for retransmission(s) of erroneous data to handle errors due to transmission over the wireless link. Hence, the more retransmissions occur, the fewer resources remain available for transmission of new data resulting in a lower goodput. This problem is even emphasized in cloud radio access networks (C-RAN), where remote radio heads (RRHs) cooperate with baseband unit (BBU) over fronthaul imposing additional delay and limiting goodput. In this article, we propose a flexible and dynamic Hybrid Automatic Repeat reQuest (HARQ) resource pre-allocation based on the actual retransmission needs of individual user equipments (UEs). This is managed by two algorithms, first exploiting information on the error rate experienced by individual UEs and the second using the length of the scheduling period of the UEs. Both algorithms are further integrated together to improve the efficiency of the HARQ retransmissions resource pre-allocation. Simulation results show the proposed solution provides goodput close to the theoretical upper-bound while outperforming existing approaches by up to 39%. Furthermore, the transport block loss rate and mean absolute percentage error of the amount of pre-allocated resources for the HARQ are notably decreased by around 38% and 57%, respectively.