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Open Access Research

Uplink interference protection and scheduling for energy efficient OFDMA networks

Harald Burchardt1*, Zubin Bharucha2, Gunther Auer2 and Harald Haas1

Author Affiliations

1 Institute for Digital Communications, School of Engineering and Electronics, The University of Edinburgh, EH9 3JL, Edinburgh, UK

2 DOCOMO Euro-Labs, Landsbergerstr. 312, 80687 Munich, Germany

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EURASIP Journal on Wireless Communications and Networking 2012, 2012:180  doi:10.1186/1687-1499-2012-180

Published: 28 May 2012

Abstract

One of the key challenges for future orthogonal frequency division multiple access-based networks is inter-cell interference coordination. With full frequency reuse and small inter-site distances, coping with co-channel interference (CCI) in such networks has become increasingly important. In this article, an uplink interference protection (ULIP) technique to combat CCI is introduced and investigated. The level of uplink interference originating from neighbouring cells (affecting co-channel mobile stations (MSs) in the cell of interest) can be effectively controlled by reducing the transmit power of the interfering MSs. This is done based on the target signal-to-noise-plus-interference ratio (SINR) and tolerable interference of the vulnerable link. Bands are prioritised in order to differentiate those (vulnerable/victim) MSs that are to be protected from interference and those (aggressor/interfering MSs) that are required to sacrifice transmission power to facilitate the protection. Furthermore, MSs are scheduled such that those users with poorer transmission conditions receive the highest interference protection, thus balancing the areal SINR distribution and creating a fairer allocation of the available resources. In addition to interference protection, the individual power reductions also serve to decrease the total system uplink power, resulting in a greener system. It is shown through analytic derivation that the introduction of ULIP guarantees an increase in energy efficiency for all MSs, with the added benefit that gains in overall system throughput are also achievable. Extensive system level simulations validate these findings.

Keywords:
inter-cell interference coordination; uplink interference protection; OFDMA networks; fair scheduling