The Effects of Downlink Transmission Activity on Service Coverage in FDMA Cellular Networks

C.L. Weston, R.M. Whitaker, and S. Hurley (UK)


Channel Assignment Problem; Multiple Interference; Constraints


The channel assignment problem for cellular systems using FDMA requires that transmitters be assigned channels such that users receive adequate signal. Traditionally, the `single inter ferer assumption' has been used to encapsulate the situation in binary channel separation constraints. Such constraint generation considers interference from one source in isolation, not account ing for interfering signals emanating from multiple non-serving sources simultaneously, which will occur in real radiocommuni cations scenarios. In this paper the single and multiple interferer assumptions are investigated in detail; quantifying not only the to tal effects of additional sources of interference on downlink cov erage, but also the proportion caused by interferers which are co channel with the server or separated from it by a certain number of channels. We analyse the performance, when multiple interfer ers operate, of channel assignments which are zero-violation for single source interference, over a range of test problems. Results show that a significant coverage reduction can be experienced in these circumstances, largely due to the combined effects of co channel and first adjacent channel interferers, even when a small number of non-serving transmitters are active. Our conclusions are valuable towards developing solution techniques and models to resolve the problem in channel assignment.

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