1 Resource Allocation for Downlink Cellular OFDMA Systems: Part I—Optimal Allocation Nassar Ksairi(1), Pascal Bianchi(2), Philippe Ciblat(2), Walid Hachem(2) Abstract In this pair of papers (Part I and Part II in this issue), we investigate the issue of power control and subcarrier assignment in a sectorized two-cell downlink OFDMA system impaired by multicell interference. As recommended for WiMAX, we assume that the first part of the available bandwidth is likely to be reused by different base stations (and is thus subject to multicell interference) and that the second part of the bandwidth is shared in an orthogonal way between the different base stations (and is thus protected from multicell interference). Although the problem of multicell resource allocation is nonconvex in this scenario, we provide in Part I the general form of the global solution. In particular, the optimal resource allocation turns out to be “binary” in the sense that, except for at most one pivot-user in each cell, any user receives data either in the reused bandwidth or in the protected bandwidth, but not in both. The determination of the optimal resource allocation essentially reduces to the determination of the latter pivot-position. Index Terms OFDMA Networks, Multicell Resource Allocation, Distributed Resource Allocation. arXiv:0811.1108v3 [cs.IT] 28 Aug 2009 I. INTRODUCTION We consider the problem of resource allocation in the downlink of a sectorized two-cell OFDMA system with incomplete Channel State Information (CSI) at the Base Station (BS) side. In principle, performing resource allocation for cellular OFDMA systems requires to solve the problem of power and subcarrier allocation jointly in all the considered cells, taking into consideration the interaction between (1)Sup´elec, Plateau de Moulon 91192 Gif-sur-Yvette Cedex, France (
[email protected]).