Communication over the noncoherent additive white Gaussian noise (AWGN) channel is considered, where the transmitted signal undergoes a phase rotation, unknown to the transmitter and the receiver. The effects of phase dynamics are explicitly taken into account by considering a block-independent model for the phase process: the unknown phase is constant for a block of N complex symbols and independent from block to block. In the first part of the paper, the capacity-achieving input distribution is characterized. In particular, it is shown that the maximizing density has circular symmetry, is discrete in amplitude with infinite number of mass points, and always has a mass point at zero. Furthermore, asymptotic expressions and bounds for the capacity are derived. Based on these results, the capacity is evaluated through numerical optimizations for unconstrained and modulation-constrained input distributions. In the second part of this paper, inspired by the capacity results, two classes of coding and modulation schemes are proposed for fast and moderate phase dynamics. In the case of fast phase dynamics (i.e., small N), optimized modulation alphabets are designed having exponential complexity with N at the demodulator. In the case of moderate phase dynamics (i.e., moderate values of N), specially designed modulation alphabets are utilized that have linear complexity with N. These alphabets are used together with optimized irregular low-density parity-check (LDPC) codes. Simulation results show that these codes can achieve close-to-capacity performance with moderate complexity, and outperform the best known codes so far.

Transmission over the noncoherent additive white Gaussian noise channel is considered, where the transmitted signal undergoes a phase rotation, unknown to the transmitter and the receiver. The effects of phase dynamics are explicitly taken into account by considering a block-independent model for the phase process: the unknown phase is constant for a block of N complex symbols and independent from block to block. In the first part of the paper, a summary of the analytic results on related work regarding the capacity achieving input distribution is presented, followed by some numerical and asymptotic results. In the second part of this paper, inspired by the capacity results, two classes of coding and modulation schemes are proposed for fast and moderate phase dynamics. Due to the complexity issues, these two cases are treated separately. In the first case, serially concatenated turbo codes are utilized, while in the second, irregular low-density parity-check codes are used in conjunction with channel-matched modulation schemes. Simulation results show that these codes can achieve close-to-capacity performance with moderate complexity, and outperform the best known codes so far.

In this paper, pilot-symbol-assisted transmission in conjunction with high-performance coding over the block-independent noncoherent additive white Gaussian noise channel is investigated. Several approximate iterative receivers are proposed, which either perform carrier-phase estimation separately from detection, or joint carrier-phase estimation/decoding in an iterative fashion. The performance of the proposed receivers is analyzed using density evolution. The power allocation to the pilot symbol is quantified, and it is shown that an optimal allocation scheme exists that minimizes the overall information bit signal-to-noise ratio required for error-free communication. This optimal power allocation, which could be utilized in code design, is found to be sensitive to the channel coherence interval, as well as to the particular receiver used. In addition, a simple upper bound on the performance of any receiver that performs joint iterative carrier-phase estimation and detection, is derived. The obtained results are compared with the simulated performance of the proposed receivers.

The paper investigates the design and robustness of rotationally invariant (RI) codes. First, RI codes are extended to the case of serially concatenated (SC) trellis-coded modulation (TCM) and several high-rate powerful RI-SCTCM codes are designed over 8-phase-shift keying and 16-quadrature amplitude modulation alphabets. The investigation continues by considering more realistic channels that introduce cycle slips during phase estimation, and thus rotate only part of the transmitted codeword. It is proven that RI codes with small state space are robust in these channels, even when traditional coherent decoders are utilized. Furthermore, it is demonstrated through simulations that the addition of a simple stopping criterion to the coherent iterative decoding algorithm is sufficient for robustness of the more powerful RI-SCTCM codes when partial codeword rotations are considered. Finally, it is investigated whether RI codes are useful for transmission in the noncoherent channel. It is proved that RI codes are as good as any other good codes for this channel when the phase dynamics are low, and optimal decoding is performed. However, it is shown that for a certain class of receivers, RI codes are also robust to partial phase rotations in this channel.

Pilot-symbol-assisted transmission of coded data over the block independent noncoherent AWGN channel is considered in this paper. Several iterative receivers are proposed and their performance is analyzed using density evolution. Upper and lower performance bounds are derived for the receiver based on the sum-product algorithm, and the optimal allocation of power to the pilots and coded bits is investigated. It is discovered that the optimal power allocation affects considerably the achievable performance, and depends highly on the phase dynamics. These results are verified by simulating practical codes and iterative receivers.

This paper deals with the analysis and design of rotationally invariant (RI) serially concatenated trellis coded modulation (SCTCM) over AWGN channels. Several powerful RI-SCTCM codes are designed which are close to the capacity limit of the modulation constrained channel. Invariance to partial phase rotations is also investigated. Although it is shown that standard (i.e., non-concatenated) TCM codes are provably robust to phase rotations that only affect part of the coded sequence, this property is demonstrated for SCTCM codes only through simulations. A number of experiments were run to verify the expected performance of the designed codes. High order constellations, like 8-PSK and 16-QAM are used to obtain overall throughput on the order of 2-3 bits per channel use.