Realistic Cooperative MIMO Channel Models for 4G and Beyond

Visiting researcher: Dr Cheng-Xiang Wang HWU
Host researcher: Prof. Xiqi Gao (SEU) & Prof. Dongfeng Yuan (SDU)
Duration: 3 months
Status: Ongoing

Biography of the visiting researcher

Cheng-Xiang Wang received the BSc and MEng degrees in Communication and Information Systems from Shandong University, China, in 1997 and 2000, respectively, and the PhD degree in Wireless Communications from Aalborg University, Denmark, in 2004.
He has been with the Joint Research Institute for Signal and Image Processing, Heriot-Watt University, Edinburgh, UK since 2005, first as a Lecturer and then as a Reader in 2009. He is also an Honorary Fellow of the University of Edinburgh, UK. He was a Research Fellow at the University of Agder, Norway, from 2001-2005, a Visiting Researcher at Siemens AG-Mobile Phones, Munich, Germany, in 2004, and a Research Assistant at Technical University of Hamburg-Harburg, Hamburg, Germany, from 2000-2001. His current research interests include wireless channel modelling and simulation, cognitive radio networks, vehicular communication networks, green communications, cooperative communications, MIMO, and (beyond) 4G wireless communications. He has published 1 book chapter and about 130 papers in refereed journals and conference proceedings.
Dr Wang is currently serving as an Editor for Wireless Communications and Mobile Computing Journal (John Wiley & Sons), Security and Communication Networks Journal (John Wiley & Sons), and Journal of Computer Systems, Networks, and Communications (Hindawi). He also served as an Editor for IEEE Transactions on Wireless Communications from 2007 to 2009. He is the leading Guest Editor for IEEE Journal on Selected Areas in Communications, Special Issue on Vehicular Communications and Networks. He served or is serving as a TPC member, TPC Chair, and General Chair for about 60 international conferences. He is a Senior Member of the IEEE, a member of the IET, and a Fellow of the HEA.

Background and motivation

For the design and performance assessment of cooperative MIMO systems, realistic cooperative MIMO channel models with a good trade-off between accuracy and complexity are indispensible. Previous theoretical research on cooperative MIMO systems utilized simple narrowband fading channel models such as Rayleigh, Rician, or Nakagami channel models. These analytical channel models are over-simplified and clearly inappropriate for system-level performance simulations. The existing standardized MIMO channel models, such as the 3GPP spatial channel model (SCM), the WINNER II channel model, and the IEEE 802.16j channel model, can be used to simulate individual point-to-point channels. However, since cooperative MIMO involves multiple point-to-point links, its channel model should consider not only the properties of the individual links, but also the system-level variations (or heterogeneity) and correlation of multiple links in a multi-cell environment. Also, for cooperative MIMO using mobile relays, realistic mobile-to-mobile (M2M) channel models should be developed for channels between mobile users. Although the existing standardized point-to-point MIMO channel models can be applied to a certain extent to model cooperative MIMO channels, many new challenges remain in cooperative MIMO channel modeling.
One challenge is how to implement a channel model that can run multiple scenarios simultaneously to faithfully represent the heterogeneity of different point-to-point links involved in a cooperative transmission. Providing a pool of 13 scenarios, the WINNER II channel model is obviously the best existing channel model to use. However, the current implementation of the WINNER II channel model does not allow simultaneous simulation of multiple links in different scenarios. Therefore the channel models need to be upgraded to support end-to-end channels in cooperative MIMO systems.
Another challenge is how to address the correlations of multiple links in a system level channel model. Existing correlation models for large scale parameters (LSPs) in standardized MIMO channel models are not consistent. It is therefore desirable to develop a unified correlation model for LSPs. In addition, the small scale fading of multiple links in cooperative MIMO systems may also be correlated, necessitating the development of new small scale fading correlation models for cooperative MIMO systems.
The existing scenarios defined in the standardized MIMO channel models need to be expanded to include the mobile-to-mobile (M2M) scenario, which is often seen in cooperative MIMO systems using mobile relays (e.g., vehicles, users). M2M channels differ significantly from conventional fixed-to-mobile channels. Currently, none of the existing standardized point-to-point MIMO channel models includes M2M scenarios.
Finally, realistic channel simulators with good degrees of both efficiency and simplicity need to be developed to support accurate and fast generation of large sets of channel profiles for system level simulations.

Research activities

The aim of this project is to propose new realistic cooperative MIMO channel models with reasonable accuracy-complexity tradeoff. The objectives are:
  1. Develop cooperative MIMO channel models that consider the correlations of multiple links and LSPs and can run multiple scenarios simultaneously;
  2. Develop realistic M2M channel models which can be used for cooperative MIMO systems using mobile relays;
  3. Investigate the computational complexity, such as the number of “real operations”, of the developed cooperative MIMO channel simulators;
  4. Develop a new realistic cooperative MIMO channel model (framework) with the above desirable features while having reasonable complexity;
  5. Investigate and compare the impacts of the proposed cooperative MIMO channel model and existing cooperative MIMO channel models on the performance of cooperative MIMO systems.


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