Comparison between the midamble and the hopping-pilots schemes for estimation of the downlink mobile channel.

Two possible modifications to the downlink IEEE 802.16a OFDM FFT-256 PHY have been proposed to tackle the issue of estimating the time -varying mobile channel - one is to insert midamble symbols every several 'regular' symbols, the other is to use the already existing pilots by varying their location from symbol to symbol. The document compares the performance, in terms of signal-to-noise ratio, of the two schemes. It is shown that the hopping-pilots scheme outperforms the midamble scheme while requiring no additional overhead. Purpose The document is submitted for consideration in the 802.16e WG. Notice This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE's name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE's sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent