Reduced-Complexity Radio Resource Management Algorithms for Heterogeneous MIMO Cellular Networks

  • Author / Creator
    Purmehdi, Hakimeh
  • Multiuser multiple-input multiple-output (MU-MIMO) antenna techniques and heterogeneous network (HetNet) layouts are two promising approaches to dramatically increase throughput in future cellular networks to meet the exploding demand for ever higher data rates. HetNets increase capacity of cellular systems by employing dense layouts of various types of base stations (BSs) in the coverage area. MU-MIMO techniques increase spectral efficiency by enabling spatial multiplexing of data streams transmitted to/from different users. However, effective MIMO spatial multiplexing is achievable only at relatively high signal-to-interference-plus-noise ratios (SINRs). To maximize their capacity, conventional cellular networks are designed to operate at low SINRs. Hence, mitigation of inter-cell interference is required to obtain the benefits of MIMO spatial multiplexing. The most promising approach to achieve it is network coordination. In this thesis, downlink transmission in a coordinated MU-MIMO HetNet is considered. We investigate the application of simulated annealing (SA) and particle swarm (PS) algorithms to perform user scheduling in a cluster of coordinated network nodes. Our proposed SA and PS algorithms are able to perform in discrete value search space to select users and determine their encoding order for various precoding methods. Moreover, a hybrid algorithm combining the traits of PS and a greedy scheduler is also proposed. We demonstrate that performance of the proposed algorithms, in terms of the achievable sum rate, is close to that of the optimal search at much lower complexity. To mitigate inter-cluster interference, we develop a rotating clustering scheme, which increases average achievable throughput to cluster-edge users. Considering two different cellular layouts, different rotating patterns of clusters are introduced and the performance of the network with the proposed clustering patterns is investigated. Our simulations demonstrate the effectiveness of the proposed cluster rotation approach and determine the speed of rotation, beyond which any further performance gains become negligible. Lastly, we investigate the behaviour of our proposed user scheduling algorithms with temporally correlated channel gains. We further develop our user scheduling algorithms to take advantage of temporal correlation of channel gains to improve their convergence rate and achievable throughput. Our user scheduling algorithms designed specifically for temporally correlated channels perform very close to the optimal exhaustive search at significantly reduced complexity.

  • Subjects / Keywords
  • Graduation date
    2016-06:Fall 2016
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Electrical and Computer Engineering
  • Specialization
    • Communications
  • Supervisor / co-supervisor and their department(s)
    • Witold A. Krzymien (Electrical and Computer Engineering)
  • Examining committee members and their departments
    • Abraham Fapojuwo (Electrical and Computer Engineering)
    • Chintha Tellambura (Electrical and Computer Engineering)
    • Pedram Mousavi (Electrical and Computer Engineering)
    • Yindi Jing (Electrical and Computer Engineering)
    • Hai Jiang (Electrical and Computer Engineering)