Resource Allocation and Scheduling in FDD Multihop Cellular Systems

Cellular radio systems of the next generation aim to make the most out of the available radio resources in the dimensions bandwidth, time and space. The division of time into slots, frames and superframes is standard, both for TDD and FDD duplex modes. OFDMA allows the individual disposition of subchannels as a subdivision of the bandwidth but an aggregation of subcarriers. A basic resource unit is hence a brick in this two-dimensional grid. Space is important both as the location of the base station in whose surrounding the resources are used and in spatial diversity channels. These resources are the scarce good in future radio communications, because they are required proportionally to the traffic demand per area. Due to adaptive modulation and coding schemes and large ranges of possible SINR values, the required resources for a transmission may differ by a factor ten depending on the distances. In this paper we discuss the resource allocation and scheduling mission. We introduce a control system view on the topic, taking adaptive algorithms for modulation, power, subchannel usage and channel quality indication into account.