System performance of Soft Frequency Reuse in LTE railway networks

With the higher and higher communication requirements on railways, the present railway mobile communication systems-GSM for railway (GSM-R) needs to be upgraded. Long Term Evolution (LTE), which is the standard of next generation mobile communication systems proposed by The 3rd Generation Partnership Project (3GPP), has implemented some novel and advanced technologies to supply high data rate, high spectral efficiency, low latency, and so on. Although LTE keeps high spectral efficiency, it suffers serious inter-cell interference, which will affect the system performance especially the cell-edge performance. As an effective frequency planning strategy, Soft Frequency Reuse (SFR) is proposed in LTE systems for inter-cell interference coordination as well as maintaining spectrum efficiency. In this paper, we analysis the theoretical inter-cell interference about SFR briefly, and then investigate the system performance of SFR for LTE on railway scenario by varying power ratio, carrier frequency, Component Carrier load balance. With the simulation results, the advantages and limitations of SFR are comprehensively analyzed and compared against the traditional frequency reuse (TFR) as a reference. We give some meaningful conclusions on the performance of SFR scheme, especially the performance improvement when varying the carrier frequency offers the opportunity to implement Carrier Aggregation in LTE. The future work will focus on evaluating the performance of SFR when adopting Carrier Aggregation in the system simulator.