H. Burchardt, Z. Bharucha, G. Auer, and H. Haas, “ Uplink Interference Protection and Scheduling for Energy Efficient OFDMA Networks” in EURASIP Journal on Wireless Communications and Networking, to appear.
One of the key challenges for future orthogonal frequency division multiple access (OFDMA)-based networks is inter-cell interference coordination (ICIC). With full frequency reuse and small inter-site distances, coping with co-channel interference (CCI) in such networks has become increasingly important. Here, 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 serve to decrease the total system uplink power, resulting in a greener system. This is of great significance for future networks, in which energy efficiency (especially at the mobile-side, where battery lifetimes are struggling to keep up with enhanced data applications) will play a huge role in the development of wireless technologies. It is shown through analytic derivation that the introduction of ULIP guarantees an increase in energy efficiency for all MSs in the network, and hence also a substantial improvement for the system as a whole. Furthermore, it is shown that the system capacity may be augmented depending on the locations and channel-states of individual users. Extensive system level simulations validate these findings.
a pre-print of the paper can be found here.