Joint iterative detection and decoding in the presence of phase noise and frequency offset

Abstract

Abstract-We present a new algorithm for joint detection and decoding of iteratively decodable codes transmitted over channels affected by a time-varying phase noise (PN) and a constant frequency offset. The proposed algorithm is obtained as an application of the sum-product algorithm to the factor graph representing the joint a posteriori distribution of the information symbols and the channel parameters given the channel output. The resulting algorithm employs the soft-output information on the coded symbols provided by the decoder and performs forwardbackward recursions, taking into account the joint probability distribution of phase and frequency offset. We present simulation results for high-order coded modulation schemes based on low-density parity-check codes and serially concatenated convolutional codes, showing that, despite its low complexity, the algorithm is able to cope with a strong PN and a significant uncompensated frequency offset, thus avoiding the use of complicated data-aided frequency-estimation schemes operating on a known preamble. The robustness of the algorithm in the presence of a time-varying frequency offset is also discussed.Index Terms-Detection and decoding in the presence of phase noise and frequency offset, factor graphs (FGs), iterative detection and decoding, low-density parity-check (LDPC) codes, serially concatenated convolutional codes (SCCCs), sum-product algorithm (SPA), turbo codes (TCs).

Performance analysis of a mesh satellite system based on linear and continuous phase modulations

“…3, is based on Rife and Boorstyn [9] coarse frequency estimation, with a modification as in [10] to let the estimator operate on different data fields, and on a Gardner timing estimator [11]. The phase noise compensation can be performed by a digital phase locked loop (PLL) [12] operating on both known symbols and hard decisions as in [13], or, when necessary, by the CBC demodulation algorithm [14], which yields finer estimation, being thus advisable for high order modulations, at expense of additional complexity. …”

Factor Graph Framework for Serially Concatenated Coded CPM with Limiter Phase Discriminator Receiver

“…The FG/SPA technique can be also used to inherently cope with the parametric channel introducing nuisance channel parameters of various forms (phase, channel transfer, etc.) [7], [8], [9], [10]. One of the major problems arising from the inclusion of continuous valued channel parameters is the fact that the SPA becomes practically difficult to implement.…”

On the cramer-rao bound for carrier frequency estimation in the presence of phase noise

“…Similarly, the CRB goes as L −1 for a time-varying phase whereas in (20) it goes as L −2 for a constant phase offset. This behavior is due to the fact that increasing the distance between two consecutive pilot symbols has the same effect of increasing the phase noise variance.…”