A Software Defined Radio based implementation of the “Tower Overlay over LTE-A+” system

The basic idea of the “Tower Overlay over LTE-A⁺” system (TOoL⁺) is to offload popular services, especially live video, from cellular networks, thereby decreasing the operational cost of such networks. This can be realized by using High Tower High Power (HTHP) transmitters whose signals can be seen as an overlay to the cellular networks. For the integration of HTHP signals into the cellular networks, the Carrier Aggregation (CA) mechanism known from LTE-A is used. Future Extension Frames (FEFs) provided by the terrestrial broadcast standard DVB-T2 are used to generate a time-division multiplex of signals according to either DVB-T2 or LTE-A. This approach provides a backward compatible migration path from classical TV broadcast to TOoL⁺ as well as co-operative spectrum usage and the reuse of existing transmitter sites. After introducing the proposed system, this paper presents a demonstrator to show the technical feasibility of the concept. This demonstrator is based on the flexible Software Defined Radio (SDR) approach and covers both a Hybrid Modulator, an unmodified TV set and a prototype of an LTE-A⁺ terminal.