Unique-Word-Based OFDM


Overview

In Charge: Dipl.-Ing. Jakob Rettelbach
Project Funding: DFG
Duration: 04/12 -- 04/15
Keywords: OFDM, Peak-to-Average Power Ratio, Unique-Word

Motivation

One of the most challenging problems in high data rate wireless communications is to overcome the distortions caused by multipath propagation.

UW_OFDM_BSB.jpg

Mobile radio channels in indoor or cellular environments can exhibit large relative time dispersions, i.e. intersymbol interference (ISI) smears each individual data symbol over several subsequent symbols. The solution to the ISI problem in single carrier systems is the employment of an equalizer, which can either be implemented in time- or in frequency domain. A completely different approach to overcome the problems of time dispersion is the use of the multicarrier technique OFDM (Orthogonal Frequency Division Multiplexing). In conventional OFDM subsequent symbols are separated by guard intervals which are usually implemented as cyclic prefixes (CPs). In this project we investigate a novel OFDM signaling concept, where the CPs are replaced by deterministic sequences which we call unique words (UWs). Since UWs are known sequences, they can advantageously be used for system parameter estimation purposes in a receiver.

Major Goals

  • Non-linear methods of data estimation
    MMSE equalization, decision feedback equalization, sphere decoding
  • Data estimation exploiting noise correlation
    Noise correlations due to receiver structure
  • PAPR reduction methods
    PAPR behaviour of UW-OFDM, PAPR-reduction schemes

Persons Involved

Project Members

  • Institute for Information Transmission at FAU Erlangen-Nürnberg
  • Institute of Networked and Embedded Systems University of Klagenfurt, Austria