ABSTRACT
Th e IEEE 802.16-2004 standard (formerly called 802.16d) has been proposed to provide last-mile connectivity to fi xed locations by radio links. Despite this original objective, we study in this paper whether mobility can be supported by the 802.16-2004 network without any change in the specifi cation. Mobility enhancements are considered in a later standard (IEEE 802.16e). However, we anticipate that 802.16-2004 devices will be deployed in the fi eld before the 802.16e standard does. Th us, our proposed techniques can be useful independent of the new 802.16e standard. Mobility capability involves two main issues: connection handoff and correct reception for moving terminals. We fi nd that seamless connection handoff can be achieved within the 802.16-2004 standard by: (i) applying some of the existing functionalities defi ned for the terminal initialization process, (ii) devising a set
of protocols for message exchanges for handoff , and (iii) forwarding some of the operational parameters from the current Base Station (BS) 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 (BER) for the 802.16-2004 orthogonal frequency division multiplexing access (OFDMA) mode shows that under typical radio conditions, the 802.16-2004 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. 16-2004 standard with our proposed technique can support user mobility.
