A Belief Propagation Based Framework for Soft Multiple-Symbol Differential Detection

Soft noncoherent detection, which relies on calculating the \textit{a posteriori} probabilities (APPs) of the bits transmitted with no channel estimation, is imperative for achieving excellent detection performance in high-dimensional wireless communications. In this paper, a high-performance belief propagation (BP)-based soft multiple-symbol differential detection (MSDD) framework, dubbed BP-MSDD, is proposed with its illustrative application in differential space-time block-code (DSTBC)-aided ultra-wideband impulse radio (UWB-IR) systems. Firstly, we revisit the signal sampling with the aid of a trellis structure and decompose the trellis into multiple subtrellises. Furthermore, we derive an APP calculation algorithm, in which the forward-and-backward message passing mechanism of BP operates on the subtrellises. The proposed BP-MSDD is capable of significantly outperforming the conventional hard-decision MSDDs. However, the computational complexity of the BP-MSDD increases exponentially with the number of MSDD trellis states. To circumvent this excessive complexity for practical implementations, we reformulate the BP-MSDD, and additionally propose a Viterbi algorithm (VA)-based hard-decision MSDD (VA-HMSDD) and a VA-based soft-decision MSDD (VA-SMSDD). Moreover, both the proposed BP-MSDD and VA-SMSDD can be exploited in conjunction with soft channel decoding to obtain powerful iterative detection and decoding based receivers. Simulation results demonstrate the effectiveness of the proposed algorithms in DSTBC-aided UWB-IR systems.Comment: 14 pages, 12 figures, 3 tables, accepted to appear on IEEE Transactions on Wireless Communications, Aug. 201

Low Complexity Noncoherent Iterative Detector for Continuous Phase Modulation Systems

This paper focuses on the noncoherent iterative detection of continuous phase modulation. A class of simplified receivers based on Principal-Component-Analysis (PCA) and Exponential-Window (EW) is developed. The proposed receiver is evaluated in terms of minimum achievable Euclidean distance, simulated bit error rate and achievable capacity. The performance of the proposed receiver is discussed in the context of mismatched receiver and the equivalent Euclidean distance is derived. Analysis and numerical results reveal that the proposed algorithm can approach the coherent performance and outperforms existing algorithm in terms of complexity and performance. It is shown that the proposed receiver can significantly reduce the detection complexity while the performance is comparable with existing algorithms

Serially Concatenated Coded Continuous Phase Modulation for Aeronautical Telemetry

This thesis treats the development of bandwidth-efficient serially concatenated coded (SCC) continuous phase modulation (CPM) techniques for aeronautical telemetry. The concatenated code consists of an inner and an outer code, separated by an interleaver in most configurations, and is decoded using relatively simple near-optimum iterative decoding algorithms. CPM waveforms such as shaped-offset quadrature phase shift keying (SOQPSK) and pulse code modulation/frequency modulation (PCM/FM), which are currently used in military satellite and aeronautical telemetry standards, can be viewed as inner codes due to their recursive nature. For the outer codes, this thesis applies serially concatenated convolutional codes (SCCC), turbo-product codes (TPC) and repeat-accumulate codes (RAC) because of their large coding gains, high code rates, and because their decoding algorithms are readily implemented. High-rate codes are of special interest in aeronautical telemetry applications due to recent reductions in available spectrum and ever-increasing demands on data rates. This thesis evaluates the proposed coding schemes with a large set of numerical simulation results and makes a number of recommendations based on these results

Detection of Linear Modulations in the Presence of Strong Phase and Frequency Instabilities

Noncoherent sequence detection algorithms, recently proposed by the authors, have a performance which approaches that of coherent detectors and are robust to phase and frequency instabilities. These schemes exhibit a negligible performance loss in the presence of a frequency offset, provided this offset does not exceed an order of 1 % of the signaling frequency. For higher values, the performance rapidly degrades. In this paper, detection schemes are proposed, characterized by high robustness to frequency offsets and capable of tolerating offset values up to 10 % of the signaling frequency. More generally, these detection schemes are very robust to rapidly varying phase and frequency instabilities. The general case of coded linear modulations is addressed, with explicit reference to-ary phase shift keying and quadrature amplitude modulation