OFDM SYSTEMS

Modified SNR gap approximation for resource allocation in LDPC-coded multicarrier systems

The signal-to-noise ratio (SNR) gap approximation provides a closed-form expression for the SNR required for a coded modulation system to achieve a given target error performance for a given constellation size. This approximation has been widely used …

On the pilot carrier placement in multicarrier-based systems

In traditional multicarrier systems, the pilot carriers used to estimate the channel are placed as uniform as possible over the bandwidth. However, with the raise of cognitive radio systems, where the multicarrier system is used by the secondary …

Feedforward data-aided phase noise estimation from a DCT basis expansion

This contribution deals with phase noise estimation from pilot symbols. The phase noise process is approximated by an expansion of discrete cosine transform (DCT) basis functions containing only a few terms. We propose a feedforward algorithm that …

PAPR reduction by symbol nulling

As a multicarrier signal can exhibit large peaks in the time domain, the amplifier used to transmit the multicarrier signal must be highly linear, and thus expensive, to avoid non-linear signal distortion. To reduce the high peak-to-average power …

Code-aided channel tracking and frequency offset-phase noise elimination for multicarrier systems

In this contribution, we propose a novel code-aided channel tracking and carrier frequency offset (CFO) and/or phase noise (PN) estimation algorithm for orthogonal frequency-division multiplexing (OFDM) systems. Starting from the maximum-likelihood …

Turbo estimation and equalization for asynchronous uplink MC-CDMA

In this contribution, we propose a new code-aided synchronization and channel estimation algorithm for uplink MC-CDMA. The space alternating generalized expectation-maximization (SAGE) algorithm is used to estimate the channel impulse responses, …