Channel Models

Background

All present-day mobile radio systems offer mobility only at one end, namely the user’s end, while the service provider’s end is fixed. This is in contrast to several emerging wireless communication systems, where mobile users can directly communicate with each other. Such systems form the new family of systems called mobile-to-mobile (M2M) communication systems. The driving force behind M2M communications is the consumer demand for better quality of service (QoS), new applications, and increased mobility support. To improve the network range and the coverage, there might be a relay (repeater) between the original transmitter and the final receiver. Potential applications of M2M communication can be found, e.g., in ad hoc networks, relay based cellular networks, and intelligent communication systems, where the communication links must be extremely reliable.

Relay-based wireless/mobile networks lie under the class of cooperative wireless networks, which are built on the idea of cooperation diversity. The basic concept of cooperation diversity is that single-antenna mobile stations in a multi-user scenario can share their antennas to create a virtual multiple-input multiple-output (MIMO) system. Thus, a cooperative wireless network permits mobile stations to relay signals using other mobile stations in the network to a final destination.

Planned Research

M2M communication in cooperative networks is a rather new concept and there are so far only some few results available for M2M channels. However, to cope with the problems faced within the development and performance investigation of future M2M MIMO communication systems, a solid knowledge of the underlying multipath fading channel characteristics is essential. Thus, the main objective of this project is to develop a deep understanding of the unsolved problems in the physical layer of M2M communication systems. It is planned to do intensive research on modelling and analysis of M2M fading channels for cooperative networks.

In cooperative networks, the mobile relays either decode and retransmit the received signal or simply amplify and forward (A&F) the signal. The overall channel from the transmitter to the receiver via the relay in A&F systems can be modelled as a concatenation of two fixed-to-mobile (F2M) fading channels (Fig. 1.) or two M2M fading channels. It can also be considered as a concatenation of F2M and M2M fading channels (Fig. 2.)

The main goals of the planned research include:

• Development of stochastic reference and simulation models under various propagation conditions
• Analysis of the statistical properties of the developed channel models
• Extensions of the developed channel models w.r.t. frequency-selectivity and to MIMO antennas
• Analysis of the statistical properties of channel capacity of the developed channels
• Overall system level performance analysis in terms of symbol error rate (SER) and throughput using the developed channels

Fig. 1: The overall mobile fading channel as a result of a concatenation of two F2M fading channels, where the BS acts a relay.

Fig. 2: The overall mobile fading channel as a result of a concatenation of F2M and M2M fading channels, where one MS acts as a relay.

PhD Student

The PhD student working on this topic at UiA is Miss Batool Talha.

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