FREQUENCY DOMAIN EQUALIZATION FOR 2-11 GHZ BROADBAND WIRELESS SYSTEMS
David Falconer(1) and Lek Ariyavisitakul(2)
(1)Dept. of Systems and Computer Engineering
Ottawa, Ont., Canada K1S 5B6
(2)Broadband Wireless Solutions, Atlanta
IEEE 802.16 meeting 11, Ottawa
Broadband wireless sy stems deployed in outdoor non-line of sight environments may encounter delay spreads of over 5 to 10 µs - which can cause
potential intersy mbol interference over 50 or more data symbol intervals. OFDM (orthogonal frequency division multiplexing) has been suggested to combat this ISI
problem with reasonable complexity. However OFDM systems generate high transmitted peak-to-average ratios and are sensitive to phase noise; this can increase RF
subsy stem cost and complexity.
In this tutorial we survey recent advances in frequency domain equalization (FDE) for single carrier (SC) sy stems. SC modulation sy stems have lower
peak-to average-ratios than OFDM, and when combined with FDE, their performance is at least as good as OFDM sy stems (in some cases better); furthermore, they have the
same reduced signal processing complexity enjoyed by OFDM systems.
We introduce linear and decision feedback equalization versions of SC-FDE, and present some comparative performance results. We briefly explore the
possible interoperability of OFDM and SC-FDE sy stems, and also present a proposal for reducing subscriber unit cost and complexity by employ ing OFDM in the downlink
and SC-FDE in the uplink.
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.