A disturbed resource reservation structure for mobility and QoS support in WiMedia networks

A Distributed Meduim Access Control (D-MAC) protocol had been proposed to support High Rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operation Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device\´s mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a "mobile" hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while other DRP reservations must be terminated and DRP negotiations for them have to be restarted although only a few Mass are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mecahnism to provent and resolve multi-hop range DRP conflicts due to each device\´s mobility in D-MAC environment.