Mobility support for IEEE 802.16d wireless networks

The IEEE 802.16d standard (now called 802.162004) has been proposed to provide last-mile connectivity to fixed locations by radio links. Despite this original objective, we study in this paper whether mobility can be supported by the 802.16d network without any change in the specification. Mobility enhancements are considered in a later standard (IEEE 802.16e). However we expect that 802.16d devices will be widely deployed in the field before the 802.16e standard is finalized. Thus our proposed techniques can be useful regardless of the final acceptance of the new 802.16e standard. Mobility capability involves two main issues: connection handoff and correct reception for moving terminals. We find that seamless connection handoff can be achieved within the 802.16d standard by: 1) applying some of the existing functionalities defined for the terminal initialization process, 2) devising a set of protocols for message exchanges for handoff, and 3) forwarding some of the operational parameters from the current base station to a new one via the backhaul network, instead of over the radio link As for reception at moving terminals, our analysis of bit error rate for the 802.16d OFDMA mode shows that under typical radio conditions, the 802.16d link can provide satisfactory error performance for terminal speed up to tens of kilometers per hour. As a result we show that the current 802.16d standard with our proposed technique can support user mobility.