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Driving Advances in Broadband Wireless Communications

Spotlight On:

Witold Krzymień
University of Alberta
Department of Electrical & Computer Engineering

As the global fourth generation (4G) broadband cellular system standard (also known as the LTE-Advanced) has been essentially finalized and its pre-4G version (also known as the LTE, or Long-Term Evolution of the 3rd generation cellular systems) is already deployed by many cellular operators around the world, research work on beyond-4G systems is now progressing rapidly. Researchers at the University of Alberta (UofA) are actively involved in this global research effort using WestGrid’s Orcinus cluster.

Witold Krzymień, Rohit Sharma Professor in Communications & Signal Processing and Professor of Electrical & Computer Engineering at the UofA, is currently leading multiple projects that focus on radio resource management and signal processing techniques underlying the evolution of today’s wireless communication systems.

The projects, which involve several PhD and MSc students and a post-doctoral fellow, are focused on the development of more efficient transmitter precoding and scheduling algorithms to enable even more spectrally efficient transmission and improved coverage in heterogeneous broadband cellular networks employing multiple antennas at network node (base station) and mobile user transceivers.

In order to increase network capacity and quality of service, the heterogeneous cellular networks include cells of significantly different sizes (and hence significantly different transmitter powers), as well as infrastructure-based relays and distributed antenna systems. This heterogeneous network layout (especially when combined with deployment of multiple antennas at network nodes and mobile users to enable capacity gains through spatial multiplexing) gives rise to very severe interference conditions that need to be mitigated with suitable radio resource management and signal processing algorithms.

The development and performance evaluation of these algorithms in a complex wireless network requires very powerful computing resources. The graduate students and the post-doctoral fellow in Prof. Krzymień’s group use the HPC resources of WestGrid’s Orcinus cluster to run extensive simulations to verify new design options and evaluate performance of network-wide interference mitigation algorithms in complex multiple-tier heterogeneous cellular networks employing multiple antennas for transmission and reception.

Recently, the group has obtained very promising results involving the application of simulated annealing as an effective reduced-complexity suboptimal approach to user and date stream scheduling for multi-user multiple-antenna transmission on cellular downlink (from network nodes to mobile users).

The application of very large numbers of antennas known as massive MIMO (multiple-input multiple-output) systems have recently gained considerable attention in the research community as an alternative approach to increasing capacity and improving user experience (by mitigating cell-edge interference problems) in large cellular networks.

Access to WestGrid's HPC resources has allowed Prof. Krzymień’s group to demonstrate performance gains of massive MIMO when novel transmitter precoding algorithms are employed. Publications reporting this and other related work can be found here. The development of advanced wireless technologies facilitated by WestGrid’s HPC resources will help boost the Canadian telecommunication industry’s already significant role in the national economy.

All research projects under way in Prof. Krzymień’s group involve close collaboration with industrial partners, such as TELUS Communications, TRTech and Huawei Canada. This collaboration may lead to the partners’ contributions to the international standards bodies developing future generations of cellular standards and help impact the future direction of the industrial wireless communications research and commercial deployments of wireless networks.