Distributed Scheduling and Discrete Power Control for Energy Efficiency in Multi-Cell Networks

Distributed resource allocation for energy efficiency is an important issue in wireless cellular networks. While most of the existing works in literature consider continuous transmit power, in practical systems such as 3GPP LTE networks, the downlink transmit power is quantized into discrete levels. Moreover, how to apply those power control schemes into such systems is not specified, so one can consider a simple rounding scheme, however, the optimality, convergence, and uniqueness may not be preserved. Therefore, in this letter, we propose a distributed resource allocation for energy efficiency in multi-cell wireless networks, considering discrete power control. We formulate the problem as a fractional discrete optimization problem, show its NP-hardness, and propose a suboptimal polynomial time solution by exploiting the convenience of non-linear fractional programming. The algorithm is executed before each transmission interval, and in each iteration, each base station first assigns the user for the radio resource and then updates the transmit power using a randomized procedure. Simulations are provided to evaluate the convergence and advantages of the proposed algorithm.