An Improved Scheme for Initial Ranging in OFDMA-based Networks

TL;DR

This paper introduces a novel initial ranging scheme for OFDMA networks that estimates timing errors and carrier frequency offsets of subscriber stations, accounting for misalignments in both time and frequency, improving synchronization accuracy.

Contribution

The work presents a new OFDMA ranging method that jointly estimates timing errors and CFOs considering signal misalignments, enhancing existing synchronization techniques.

Findings

Effective CFO estimation using subspace methods

Accurate timing recovery via least-squares approach

Superior performance demonstrated through simulations

Abstract

An efficient scheme for initial ranging has recently been proposed by X. Fu et al. in the context of orthogonal frequency-division multiple-access (OFDMA) networks based on the IEEE 802.16e-2005 standard. The proposed solution aims at estimating the power levels and timing offsets of the ranging subscriber stations (RSSs) without taking into account the effect of possible carrier frequency offsets (CFOs) between the received signals and the base station local reference. Motivated by the above problem, in the present work we design a novel ranging scheme for OFDMA in which the ranging signals are assumed to be misaligned both in time and frequency. Our goal is to estimate the timing errors and CFOs of each active RSS. Specifically, CFO estimation is accomplished by resorting to subspacebased methods while a least-squares approach is employed for timing recovery. Computer simulations are used to assess the effectiveness of the proposed solution and to make comparisons with existing alternatives.