Cell range extension in LTE in-band relays: Analysis of radio link, subframe allocation and protocol perfornance of FTP traffic model

Self backhauled in-band relays are an integral component of LTE-Advanced. In this paper, we have investigated the effect on user as well as system performance when UEs in the coverage edge between a macro Donor eNB (DeNB) and Relay Node (RN) are biased to select the RN as its serving cell. For the studied load point, our results indicate that relay deployment improves system capacity along with improved bit rates for cell-edge users. Introducing relay cell range extension enhances the offloading gain for macro users, thereby improving overall bit rates in the system. However, range extension with offsets beyond 6 dB degrades system capacity as well as bit rates; due to increased imbalance in DL received powers, higher protocol related latency in time-multiplexed multi-hop transmission etc. The highly detailed radio and protocol modeling in the simulator provides insight about the gains and challenges of range extension in possibly one of the most realistic simulation settings.