Guidelines for designing OFDM overlay systems

Due to the increasing demand in mobile communications it is necessary to use the available spectrum as efficiently as possible. In this paper we focus on the concept of overlay scenarios where two different systems operate independently in the same frequency band. We describe a general set of characteristic parameters for licensed systems using FDMA (frequency division multiple access). In the context of these licensed systems especially OFDM (orthogonal frequency-division multiplexing) is a suitable technique to operate an additional system in a coexistence mode. Based on the parameter sets of both systems we derive constraints and guidelines on the design of OFDM overlay systems