Relay-Assisted User Scheduling in Wireless Networks with Hybrid-ARQ


Caleb K. Lo, John J. Hasenbein, Sriram Vishwanath and Robert W. Heath, Jr.


IEEE Transactions on Vehicular Technology, vol. 58, no. 9, pp. 5284-5288, Nov. 2009.


This paper studies the problem of relay-assisted user scheduling for downlink wireless transmission. The base station or access point employs hybrid automatic-repeat-request (HARQ) with the assistance of a set of fixed relays to serve a set of mobile users. By minimizing a cost function of the queue lengths at the base station and the number of retransmissions of the head-of-line packet for each user, the base station can schedule an appropriate user in each time slot and an appropriate transmitter to serve it. It is shown that a priority-index policy is optimal for a linear cost function with packets arriving according to a Poisson process and for an increasing convex cost function where packets must be drained from the queues at the base station.