Base station cooperation for queue stability in wireless heterogeneous cellular networks

We propose a base station (BS) cooperation scheme for heterogeneous wireless cellular networks, with multiple small-cells overlaid on top of a macrocell network. Our scheme can guarantee that each BS´s queue is stable, while satisfying minimum signal-to-interference and noise ratio (SINR) targets. We achieve queue stability by employing a stochastic scheduling technique, where the realizations of tuned random variables determine whether each BS transmits, in addition to the minimum SINR target. We develop a new algorithm to tune the random variables in our proposed scheme, which approximately maximizes the probability that each BS transmits-to reduce queue lengths-subject to the constraint that each BS´s queue is stable. In particular, we approximate the non-convex signomial optimization problem arising from the queue stability constraints as a convex optimization problem. We demonstrate that our scheme can achieve queue stability at each BS, even when BS queues are unstable for the standard fractional frequency reuse scheme.