Carrier Frequency Oset Estimation for OFDM-Based Cooperative Communications Systems

M. PUZIO; G. GONZÁLEZ; F. GREGORIO; J. E. COUSSEAU

Oro Verde, Entre Rios

Congreso; XIV Reunión de Trabajo en Procesamiento de la Información y Control; 2011

Universidad Nacional de Entre Rios

We analyze in this work the carrier frequency oset (CFO) estimation issue ofOFDM-based cooperative communications systems. We focus on the relaying phase of thisscenario, where one or more relaying nodes decode and forward data, originated by a sourcenode, to a single destination node. For an OFDM symbol to be decoded correctly, all itssubcarriers must be orthogonal. If any relay node introduce a frequency oset in the assigned subcarriers subset, orthogonality is lost in the whole symbol and data cannot be recovered. A recently proposed training sequence, which consits of one OFDM block with a tilestructure and a number of nulled subcarriers, is studied here. By using this subcarrier arrangement, CFO can be estimated with conventional subspace-based methods, such as ESPRIT and MUSIC. In particular, the later achieves a better performance over a wider range of SNR. Despite their low computational complexity, these techniques evidence a high sensitivity to eigenvalue spread, which can be the subject of a future work.