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Research Group Communications Engineering - Project Description

Orthogonal and Non-Orthogonal Relay Protocols

The deployment of relay nodes in cellular mobile radio networks is intensively discussed in the upcoming LTE-Advanced standard.

In particular, relays shall improve coverage and outage capacity at cell borders. Although the capacity of relay networks is generally unknown, upper bounds can be obtained by applying the max-flow min-cut theorem. These bounds illuminate substantial gains of non-orthogonal compared to orthogonal relay protocols and emphasize the importance of optimizing the time sharing for a 2-hop communication. Contrarily, most of the literature as well as practical implementations deal with orthogonal protocols using fixed time slot lengths. Based on the max-flow min-cut bounds, the project shall evaluate if and how the theoretical gains are achievable in a system using with discrete modulation schemes, imperfect coding and discrete rates. Appropriate transmission strategies have to be developed for non-orthogonal relay protocols and corresponding detection algorithms have to be optimized. The achievable performance has to be compared with the upper bounds as well as standard approaches. Within the project, an OFDM-based system with half-duplex relays will be considered.


German National Science Foundation (DFG), 2013 - 2015


Kern, D.; Kühn, V.:
Practical Aspects of Compress and Forward with BICM in the 3-Node Relay Channel. 20th International ITG Workshop on Smart Antennas (WSA 2016), München, Deutschland, 2016
Kern, D.; Kühn, V.:
On Superposition Multilevel Coding for the 3-Node Relay Channel Exploiting Decode and Forward. IEEE 82nd Vehicular Technology Conference (VTC 2015 Fall), pp. 1-5, Boston, USA, 2015
Kern, D.; Kühn, V.:
Achievable Decode and Forward Rates for the 3-Node Relay Channel Considering Different Energy Constraints and Synchronization Errors. 12th International Symposium on Wireless Communication Systems (ISWCS'15), pp. 1-5, Brussels, Belgium, 2015
Kern, D.; Kühn, V.:
Practical Aspects of Decode and Forward in the Classical Relay Channel Exploiting Non-Orthogonal Channel Access. 10th International ITG Conference on Systems, Communications and Coding (SCC'2015), Hamburg, Germany, 2015