ally, the encoding representation and decoding algorithms are described in more detail. Furthermore, IDD for coded FD-SIMO is proposed and applied in the digital domain to provide an additional alleviation of the residual SI, which remains after applying different passive and active SICs. The purpose of using IDD as SIC is to achieve a level of per- formance that is very close to the SI-free case. Moreover, tight and union upper bounds of the proposed system are derived for the performance of rate-1/2 convolutional codes with quadrature phase shift keying (QPSK) modulation scheme in order to validate the simulation results.
In Chapter 5, IDD is exploited this time in the context of coded FD-MIMO to ap- ply effective mitigation of the remaining SI in the digital domain. The aim is to achieve a level of performance very close to that of the SI-free scenario after a particular num- ber of iterations. The proposed system is validated by deriving a tight upper bound on the performance of rate-1/2 convolutional codes withM -ary quadrature amplitude mod- ulation (QAM). Further, an extrinsic information transfer (EXIT) chart is utilized as a semi-analytic tool to show how the IDD components are converging, when the soft in- formation is exchanged between them. It also measures approximately the number of iterations required to satisfy this convergence.
In Chapter 6, the main conclusions of the research and the contributions of this thesis are presented, and proposed future work related to this field of study are outlined.
1.5
Publications Arising From This Research
•
Journal Papers
1. M. A. Ahmed, C. C. Tsimenidis and A. F. Al Rawi, ”Performance analysis of full-duplex-MRC-MIMO with self-interference cancellation using null-space- projection,” in IEEE Transactions on Signal Processing, vol. 64, no. 12, pp. 3093-3105, June 2016.
2. M. A. Ahmed and C. C. Tsimenidis, ”A tight upper bound on the performance of iterative detection and decoding for coded full-duplex SIMO systems,” in IEEE Communication Letters., vol. 20, no. 3, pp. 606-609, March 2016. 3. M. A. Ahmed and C. C. Tsimenidis, ”Tight upper bound performance of full-
duplex MIMO-BICM-IDD systems in the presence of residual self-interference,” submitted to IEEE Transactions on Wireless Communication, Dec. 2016.
1.5 Publications Arising From This Research •
Conference papers
1. M. A. Ahmed, C. C. Tsimenidis and S. Y. Le Goff, ”Performance analysis of full-duplex MIMO-SVD-SIC based relay in the presence of channel estima- tion errors,” in Proc. IEEE 10th International Conference on Wireless and Mo- bile Computing, Networking and Communications (WiMob), Larnaca, 2014, pp. 467-472.
2. M. A. Ahmed and C. C. Tsimenidis, ”Coded full-duplex MIMO with iterative detection and decoding,” in Proc. IEEE International Conference on Commu- nications (ICC), London, 2015, pp. 4859-4864.
3. M. A. Ahmed, C. T. Healy, A. F. Al Rawi, and C. C. Tsimenidis, ”Bi-directional beamforming bit error ratio analysis for wireline backhaul networks,” in Proc. 24th European Signal Processing Conference (EUSIPCO), Budapest, 2016.
Chapter 2
2.1 Introduction
2.1
Introduction
Recently, several research studies have been launched with the aim to mitigate SI in transceivers employing FD operation to complement the evolution of the next standard for wireless communications, the fifth generation (5G), and beyond. This is due to the fact that utilizing FD, where the transmitted and received signals use the same frequency band simultaneously, with perfect SIC can improve the spectral efficiency and the channel capacity by a factor of two with respect to systems using the conventional HD operation. However, implementing perfect SIC is impractical due to the large power differences be- tween a weak desired signal coming from a distant source and the strong SI caused by the FD transceiver’s transmitting antennas. This energy difference between the two signals might exceed tens of decibels (dBs), yielding difficulties in properly detecting the signal of interest. This is because the SI’s power, which is roughly100 dB above the noise floor of the receiver, causes saturation of the FD receivers’ front-end components, such as the low noise amplifier (LNA), the mixer and ADC. Hence, these hardware components need to be designed in such a way that they are able to perform precise signal processing over a huge dynamic range, which consequently leads to an increase in the quantization noise of the desired signal. The suppression of SI can be implemented using different methods passively in the propagation domain and/or actively in the analogue and digital domains; that is, before and after the ADC respectively, as shown in Fig. 2.1. Additionally, utiliz- ing the MIMO technique by using multiple antennas in both the transmitter and receiver, with any FD transceiver topologies, such as relay, bidirectional, or base-station, will pro- vide the systems with an additional DoF in the suppression of SI via the employment of equalization methods like zero-forcing (ZF), MMSE filtering and NSP. Furthermore, em- ploying multiple antennas for transmitting and/or receiving plays a vital role in combating fading without the need to expand the bandwidth of the transmitted signal by achieving spatial diversity. Moreover, utilizing a spatial multiplexing technique for wireless com- munications improves the date rate, since multiple uncorrelated spatial channels can be created to deliver the transmitted signal [48].
In this chapter, an overview of MIMO-based transmission is introduced with brief description and discussion of different systems models, such as spatial multiplexing, pre- coding and diversity coding. Moreover, various equalization and detection approaches are presented to recover the transmitted symbols. Furthermore, the background theory of applying FD mode to wireless communication systems is demonstrated, along with the
2.2 Multiple Antennas