Use this URL to cite or link to this record in EThOS:
Title: Hybrid precoding algorithms for millimeter-wave massive MIMO systems
Author: Alluhaibi, Osama
ISNI:       0000 0004 7223 8587
Awarding Body: University of Kent
Current Institution: University of Kent
Date of Award: 2018
Availability of Full Text:
Access from EThOS:
Full text unavailable from EThOS. Thesis embargoed until 01 May 2023
Access from Institution:
The large available spectrum efficiency and wider bandwidth at millimeter wave (mm-Wave) frequencies can enable the gigabit-per-second data rates needed for next generation wireless systems. To compensate for the high propagation loss at mm-Wave bands, multiple-input multiple-output (MIMO) with a large number of antennas are usually employed to enable beamforming. Therefore, a combination of the large number of antennas which can be called massive MIMO technology with mm-Wave bands are considered as one solution for substantially increasing the data rate for future wireless communication systems. The theoretical benefits of large antenna array systems are based on the fact that the number of radio frequency (RF) chains is equivalent to the number of antennas in the conventional wireless communication system which is known as the fully digital system. Nevertheless, implementing a large number of RF chains can be problematic since it increases the system cost, power consumption, high complexity and lowers power efficiency The overall objective of this thesis is to provide simple and effective hybrid D/A precoding and combing for mm-Wave large antenna array systems. Firstly, hybrid D/A precoding with a small number of RF chains is being considered for mm-Wave large antenna array systems. Currently, two types of antenna structures, fully-connected antenna array and partially-connected antenna array structures are adopted in the literature. Considering that each antenna array structure has its own practical advantage, in this thesis, by addressing both structures hybrid D/A precoding algorithms are proposed with target of maximizing the system's spectral efficiency with low computational complexity. For a fully-connected antenna array structure, the precoding design is formulated as an optimization problem to minimize the Euclidean distance between the hybrid D/A and the fully digital system. For a partially-connected antenna array structures, the hybrid D/A precoding is formulated as a joint D/A optimization to maximize the spectral efficiency of the system. This work further develops hybrid D/A precoding designs for mm-Wave multi-user systems based on maximizing the sum rate of the system directly. It will be shown that the proposed algorithms outperform the existing hybrid D/A precoding algorithms for the two types of structures, in terms of the spectral efficiency. Secondly, energy efficient and low complexity hybrid D/A system for mm-Wave large antenna array systems is proposed to reduce the power consumption at the system. The energy efficiency criteria is formulated as fractional programming maximization problem. The target is to find the optimal number of RF chains as the RF chains consume a high energy at the system. Therefore, the effective optimal number of RF chains of the system is found by proposing a simple search algorithm. Then, two methods are proposed for designing low complexity analog and digital precoders and combiners. The presented solutions for the hybrid D/A system are shown to be effective, as these approaches can achieve high energy efficiency, and low computational complexity as compared to the existing algorithms in hybrid D/A paradigms. Ultimately, the proposed D/A precoders and combiners based on the fully-connected antenna array attain an asymptotically optimal achievable spectral efficiency to that of the fully digital system. Thirdly, uplink multi-user hybrid D/A precoding and combining design for mm-Wave large antenna array systems is investigated. The intrinsic focus of this work is to reduce the interference of the system in the analog and digital precoders and combiners. Considering the possibility that uplink transmissions from different users can go through the paths sharing the same physical scatters, some transmission paths of different users may have overlapped angle of arrivals (AoAs) at the base station. Under this circumstance, the correlation between the channel vectors also increases highly, which affects the achievable uplink rate severely. The underlying concentrate of this work is to reduce the interference caused by users sharing the same scatterers during simultaneous uplink transmission. Therefore, in this thesis, by taking account the channel correlation between users sharing the overlapped AoAs, the genuine focus is on substantially maximizing the desired signal of a piratical user while reducing the system interference. Furthermore, the channel estimation is investigated by designing a two-step procedure. The strongest power point in each scattering point is detected and the accuracy is improved by employing an angler domain scheme. Extensive simulations demonstrate that the achievable uplink rate of our proposed algorithms surpasses the achievable uplink rate of the existing algorithms in hybrid D/A paradigms in the practical scenarios.
Supervisor: Wang, Jiangzhou Sponsor: Not available
Qualification Name: Thesis (Eng.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available