Polar Coded Faster-than-Nyquist (FTN) Signaling with Symbol-by-Symbol Detection

Reduced complexity faster-than-Nyquist (FTN) signaling systems are gaining increased attention as they provide improved bandwidth utilization for an acceptable level of detection complexity. In order to have a better understanding of the tradeoff between performance and complexity of the reduced complexity FTN detection techniques, it is necessary to study these techniques in the presence of channel coding. In this paper, we investigate the performance a polar coded FTN system which uses a reduced complexity FTN detection, namely, the recently proposed successive symbol-by-symbol with go-backK sequence estimation (SSSgbKSE) technique. Simulations are performed for various intersymbol-interference (ISI) levels and for various go-back-K values. Bit error rate (BER) performance of Bahl-Cocke-Jelinek-Raviv (BCJR) detection and SSSgbKSE detection techniques are studied for both uncoded and polar coded systems. Simulation results reveal that polar codes can compensate some of the performance loss incurred in the reduced complexity SSSgbKSE technique and assist in closing the performance gap between BCJR and SSSgbKSE detection algorithms

Machine Learning Approaches for Faster-than-Nyquist (FTN) Signaling Detection

There will be a significant demand on having a fast and reliable wireless communication systems in future. Since bandwidth and bit rate are tightly connected to each other, one approach will be increasing the bandwidth. However, the number of wireless devices are growing exponentially, and we don't have infinite bandwidth to allocate. On the other hand, increasing the bit rate for a given bandwidth, i.e., improving the spectral efficiency (SE), is another promising approach to have a fast and reliable wireless communication systems. Faster-than-Nyquist (FTN) is one of the candidates to improve the SE while this improvement comes at the expense of complexity of removing the introduced inter-symbol interference (ISI). In this thesis, we propose two algorithms to decrease the computational complexity regarding removing the ISI in FTN signaling. In the first main contribution of the thesis, we introduce an equivalent FTN signaling model based on orthonormal basis pulses to transform the non-orthogonal FTN signaling transmission to an orthogonal transmission carrying real-number constellations. Then we propose a deep learning (DL) based algorithm to decrease the computational complexity of the known list sphere decoding (LSD) algorithm. In essence, the LSD is one of the algorithm that can be used for the detection process of the FTN signaling; however, at huge computational complexity. Simulation results show the proposed DL-based LSD reduces computational complexity by orders of magnitude while maintaining close-to-optimal performance. In the second main contribution of the thesis, we view the FTN signaling detection problem as a classification problem, where the received FTN signaling signal viewed as an unlabeled class sample that is an element of a set of all potential classes samples. Assuming receiving $N$ samples, conventional detectors search over an $N$-dimensional space which is computationally expensive especially for large value of $N$. However, we propose a low-complexity classifier (LCC) that performs the classification in $N_p$ dimensional space where $N_p\ll N$. The proposed LCC's ability to balance performance and complexity is demonstrated by simulation results

Optimal Pilot Sequences for Phase and Timing Synchronization in FTN Systems

In this paper, we study the joint phase and timing estimation problem in Faster-than-Nyquist (FTN) systems. We use the Cramér-Rao lower bound (CRB) as a cost function to design optimal pilot sequences subject to an energy constraint. We rely on harmonic approximations of the bound to establish closed-form relations between the ultimate synchronization performance and the transmitted waveform characteristics (i.e., pulse shaping filter and signaling density). We show that increasing the symbol rate at fixed bandwidth is beneficial to phase estimation and detrimental to timing synchronization. Therefore, we propose a joint timing/phase pilot design to accommodate this trade-off. Lastly, we illustrate the strengths of the proposed pilots with respect to traditional Zadoff-Chu sequences in presence of a residual carrier frequency offset

Interference Exploitation via Symbol-Level Precoding: Overview, State-of-the-Art and Future Directions

Interference is traditionally viewed as a performance limiting factor in wireless communication systems, which is to be minimized or mitigated. Nevertheless, a recent line of work has shown that by manipulating the interfering signals such that they add up constructively at the receiver side, known interference can be made beneficial and further improve the system performance in a variety of wireless scenarios, achieved by symbol-level precoding (SLP). This paper aims to provide a tutorial on interference exploitation techniques from the perspective of precoding design in a multi-antenna wireless communication system, by beginning with the classification of constructive interference (CI) and destructive interference (DI). The definition for CI is presented and the corresponding mathematical characterization is formulated for popular modulation types, based on which optimization-based precoding techniques are discussed. In addition, the extension of CI precoding to other application scenarios as well as for hardware efficiency is also described. Proof-of-concept testbeds are demonstrated for the potential practical implementation of CI precoding, and finally a list of open problems and practical challenges are presented to inspire and motivate further research directions in this area

Advancements of MultiRate Signal processing for Wireless Communication Networks: Current State Of the Art

With the hasty growth of internet contact and voice and information centric communications, many contact technologies have been urbanized to meet the stringent insist of high speed information transmission and viaduct the wide bandwidth gap among ever-increasing high-data-rate core system and bandwidth-hungry end-user complex. To make efficient consumption of the limited bandwidth of obtainable access routes and cope with the difficult channel environment, several standards have been projected for a variety of broadband access scheme over different access situation (twisted pairs, coaxial cables, optical fibers, and unchanging or mobile wireless admittance). These access situations may create dissimilar channel impairments and utter unique sets of signal dispensation algorithms and techniques to combat precise impairments. In the intended and implementation sphere of those systems, many research issues arise. In this paper we present advancements of multi-rate indication processing methodologies that are aggravated by this design trend. The thesis covers the contemporary confirmation of the current literature on intrusion suppression using multi-rate indication in wireless communiquE9; networks