Inband Relaying in Long Term Evolution-Advanced Networks

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2014-04-04
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Aalto University publication series DOCTORAL DISSERTATIONS, 32/2014
The set of stringent requirements for 4G radio access networks has triggered the embodiment of new small low-power nodes, e.g. relay, Femto and Pico access nodes, as part of the network infrastructure. Various types of relay nodes are currently supported in IEEE 802.16m and 3GPP LTE-Advanced, e.g. inband Layer 2 or Layer 3 nodes and outband nodes, considering different functional capabilities and backhauling characteristics. In general, relay nodes are characterized by compact physical characteristics, low power consumption, a wireless backhaul link to the core network, and relaxed installation guidelines with respect to radiation and planning regulation. In specific, inband relay nodes, the matter of this study, are Layer 3 access nodes with time-multiplexed transmission and reception on their wireless backhaul and access links, which operate on the same frequency band. These characteristics impose serious challenges on one hand, but allow for significant improvements on the other hand. In this context, the deployment flexibility of relay nodes simplifies the network planning procedure and reduces deployment costs. On the other hand, low power transmission and limited antenna capabilities result in small relay cell coverage areas which will lead to load imbalances. Besides, multiplexing backhaul and access communications on different subframes implies the need for suitable two-hop resource allocation and scheduling. Further challenges are attributed to increased interference levels compared to macrocell deployments, as well as the introduction of a new interference type known as relay-to-relay interference resulting from the misalignment of access and backhaul link dedicated subframes at different relay nodes. The research towards this thesis has addressed these challenges within 3GPP LTE-Advanced context. A feasibility study of different relaying modes is provided and the performance of relay deployments is evaluated in different propagation environments. Thereafter, simple network planning techniques are proposed to alleviate the limitations of the inband backhaul link. Further, novel techniques are investigated to address resource allocation and scheduling, load balancing and interference coordination. The performance of proposed techniques along with the energy efficiency of relay nodes is evaluated. Results show in general significant gains and validate relaying as an efficient enhancement technology.
Supervising professor
Hämäläinen, Jyri, Prof., Aalto University, Department of Communications and Networking, Finland
Thesis advisor
Redana, Simone, Dr., Nokia Solutions and Networks, Germany
inband relaying, network planning, resource allocation, interference coordination, load balancing, energy efficiency, performance evaluation, LTE-Advanced
Other note
  • [Publication 1]: A. Bou Saleh, C. Hausl, R. Kötter. Outage Behavior of Bidirectional Half-Duplex Relaying Schemes. In IEEE Information Theory Workshop ITW 2009, Taormina, Italy, pp. 50-54, October 2009.
  • [Publication 2]: A. Bou Saleh, T. Riihonen, S. Redana, J. Hämäläinen, R. Wichman, B. Raaf. Performance of Amplify-and-Forward and Decode-and-Forward Relays in LTE-Advanced. In IEEE Vehicular Technology Conference VTC-Fall 2009, Anchorage, USA, pp. 1-5, September 2009.
  • [Publication 3]: A. Bou Saleh, S. Redana, J. Hämäläinen, B. Raaf. On the Coverage Extension and Capacity Enhancement of Inband Relay Deployments in LTE-Advanced Networks. Journal of Electrical and Computer Engineering, Volume 2010, Special Issue LTE/LTE-Advanced Cellular Communication Networks", Article ID 894846, pp. 1-12, Vol. 2010, May 2010.
  • [Publication 4]: A. Bou Saleh, Ö. Bulakci, J. Hämäläinen, S. Redana, B. Raaf. Analysis of the Impact of Site Planning on the Performance of Relay Deployments. IEEE Transactions on Vehicular Technology, pp. 3139 - 3150, Vol. 61, NO. 7, September 2012.
  • [Publication 5]: A. Bou Saleh, Ö. Bulakci, Z. Ren, S. Redana, B. Raaf, J. Hämäläinen. Resource Sharing in Relay-enhanced 4G Networks. In European Wireless Conference 2011 - Sustainable Wireless Technologies, Vienna, Austria, pp. 1-8, April 2011.
  • [Publication 6]: A. Bou Saleh, Ö. Bulakci, S. Redana, J. Hämäläinen. On cell range extension in LTE-Advanced Type 1 inband relay networks. Wireless Communications and Mobile Computing, June 2013,
    DOI: 10.1002/wcm.2377. View at publisher
  • [Publication 7]: Z. Ren, A. Bou Saleh, Ö. Bulakci, S. Redana, B. Raaf, J. Hämäläinen. Joint Interference Coordination and Relay Cell Expansion in LTE-Advanced Networks. In IEEE Wireless Communications Networking Conference WCNC 2012, Paris, France, pp. 2874-2878, April 2012.
  • [Publication 8]: A. Bou Saleh, Ö. Bulakci, S. Redana, B. Raaf, J. Hämäläinen. A Divide-and-conquer Approach to Mitigate Relay-to-Relay Interference. In IEEE Personal, Indoor and Mobile Radio Communications PIMRC 2011, Toronto, Canada, pp. 1889-1893, September 2011.
  • [Publication 9]: A. Bou Saleh, Ö. Bulakci, S. Redana, B. Raaf, J. Hämäläinen. Impact of Relay-to-Relay Interference on the Performance of LTE-Advanced Relay Networks. In 17. VDE ITG workshop on Mobile Communications, Osnabrück, Germany, pp. 1-6, May 2012.
  • [Publication 10]: A. Bou Saleh, Ö. Bulakci, S. Redana, B. Raaf, J. Hämäläinen. Evaluating the Energy Efficiency of LTE-Advanced Relay and Picocell Deployments. In IEEE Wireless Communications Networking Conference WCNC 2012, Paris, France, pp. 2335-2340, April 2012.