Mobile relay and group mobility for 4G WiMAX networks

Relay is one of the key features being considered for IMT-Advanced systems. The relay architectures defined in IEEE 802.16m and 3GPP LTE-Advanced are optimized only for non-mobile relay, i.e., the Relay Station is attached to a designated Base Station and becomes a part of the fixed access network. A mobile relay architecture, where relay may switch attached BS according to operation demand, will promise more resilient relay deployment. In this paper, we first highlight three use cases where mobile relays can offer useful deployment options. Next, we propose an enhanced handover mechanism for relay-based group mobility by extending the IEEE 802.16m specification on relay. To this end, we describe the handover architecture for mobile relay highlighting the C-plane and U-plane enhancements required in order to support group mobility of mobile stations. Using illustration and comparisons, we show that mobile relay will offer significant benefits of signaling overhead reduction and provide users seamless mobility experience compared to fixed relays.