Iterative interference cancellation and channel estimation for mobile OFDM

Abstract

Abstract-In mobile reception, the reliability of orthogonal frequency division multiplexing (OFDM) is limited because of the time-varying nature of the channel. This causes intercarrier interference (ICI) and increases inaccuracies in channel tracking. In this paper, we model the ICI using derivatives of the channel amplitude. This allows us to design a relatively simple receiver scheme that iteratively cancels the ICI. The design of the canceler aims at maximizing the signal-to-noise-plus-ICI ratio at the detector input. We also propose a new channel estimator, and we show that it achieves reliable mobile reception in practical situations that are relevant to terrestrial Digital Video Broadcasting (DVB-T). Extensive simulations for a receiver with one or two antennas show that a small number of iterations between ICI cancellation and channel estimation allow a reliable reception at vehicle speeds above 100 km/h. Index Terms-Channel estimation, interference cancellation, mobile communications, orthogonal frequency division multiplexing (OFDM).

Equalization of Time-Varying Channels

“…Gorokhov and Linnartz [GL04] proposed O(KD) approximate LMMSE and DFE-like schemes using a first-order Taylor series approximation of the K × K LMMSE matrix inverse. Tomasin, Gorokhov, Yang, and Linnartz [TGYL05] extended the techniques in [GL04] to incorporate iterative hard interference cancellation. Hou and Chen [HC05] proposed an O(KD 2 ) nonlinear estimator of the formâ = E FF y − E FB D A (E FF y), where E FF and E FB are both narrowly banded.…”

Partial FFT Demodulation: A Detection Method for Doppler Distorted OFDM Systems

“…The channel is modeled using six independent Rayleigh fading paths, each with a Jakes' spectrum specified by a normalized Doppler spread of f d T = 0.2, and a delay spread of 6µs [13]. Fig.…”

Low-Complexity Time-Domain ICI Equalization for OFDM Communications Over Rapidly Varying Channels

“…An example of recent practical relevance is the mobile reception of DVB-T (e.g. [7]), which was originally conceived for fixed receivers. …”

“…An iterative MMSE equalizer preceded by an "ICI-shaping" stage that concentrates the ICI power within a small band of the channel matrix is described in [14]. Alternative frequency-domain equalization approaches that model the channel variations using a firstorder polynomial are described in [7,15].…”