Communications Research at the University of York Interference Aware, Energy Efficient Resource Allocation for Beyond Next Generation Mobile Networks Abimbola Fisusi, David Grace, and Paul Mitchell Communications Research Group Department of Electronics University of York, York United Kingdom

Outline Background Beyond Next Generation Mobile Broadband Network (BuNGee) Impact of BS Choice on Inter-cell Interference Existing Resource Allocation Schemes Interference Aware Clustering Capability Rating (IA-CCR) scheme Simulation Results Conclusion 2013 IEEE PIMRC

Background Beyond 4G networks expected to be ultra-high capacity and energy efficient Small Cell Networks (SCNs) considered as a suitable approach Energy efficiency of dense SCNs may be limited by inter-cell interference The choice of base stations (BSs) will determine inter-cell interference in dense SCNs A resource allocation scheme which reduces interference through base station choice restriction is proposed 2013 IEEE PIMRC

Beyond Next Generation Mobile Broadband Network (BuNGee) High capacity mobile broadband architecture proposed under the FP7 BuNGee project Few high power hub base stations (HBSs) Full scale, dense, small cell, access base stations (ABSs) deployment 2013 IEEE PIMRC

Beyond Next Generation Mobile Broadband Network (BuNGee) II BuNGee is based on dual hop relay approach Directional antennas are utilized at the base stations Source: T. Jiang and D. Grace, Beyond Next Generation Mobile Broadband Network System Capacity, WUN CogCom 7th Technical Meeting, Ottawa, Canada, 2012 2013 IEEE PIMRC

Impact of BS Choice on Inter-cell Interference BSs have different SINR with respect to MSs MS have more than one choice of ABS in dense SCNs The choice of ABS determines inter-cell interference level Lower SINR choices results in higher interference 2013 IEEE PIMRC

Existing Resource Allocation Schemes Highest SINR scheme results in selection of the ABS with the highest SINR value First choice ABS in terms of SINR always selected Supports high QoS but not energy efficient 2013 IEEE PIMRC

Existing Resource Allocation Schemes II Most loaded ABS scheme results in selection of ABS with highest load as long as call admission SINR is satisfied Any choice of ABS can be selected to meet the goal of energy efficiency 2013 IEEE PIMRC

Existing Resource Allocation Schemes III Normalized clustering capability rating (NCCR) prioritizes more central ABSs over less central ones Zone association weight, Za, location weight, Lw, and loading ratio, Lr, are ABS parameters The constants, a = 100, b = 10, and c = 1, are used simply to maintain hierarchy between the ABS parameters 𝐶𝐶𝑅=𝑎 𝑍 𝑎 + 𝑏 𝐿 𝑤 + 𝑐 𝐿 𝑟 𝑁𝐶𝐶𝑅= 𝐶𝐶𝑅 𝐶𝐶𝑅 𝑚𝑎𝑥 ; 𝐶𝐶𝑅 𝑚𝑎𝑥 =111 2013 IEEE PIMRC

Existing Resource Allocation Schemes IV NCCR scheme results in the selection of the any ABS choice with the highest value of NCCR that meets call admission SINR threshold Both the Most Loaded ABS and NCCR schemes favour selection of low SINR ABS choices to achieve high MS clustering and high energy efficiency Both schemes are susceptible to the problem of high interference Idle ABSs are switched to sleep mode and activated when neighbours are highly loaded 2013 IEEE PIMRC

Interference Aware Clustering Capability Rating (IA-CCR) scheme IA-CCR scheme takes both energy efficiency and interference into consideration Interference is mitigated by restricting the choice of ABS within pre-determined high SINR group (e.g. top 3 ABSs) Clustering of MS done with NCCR algorithm to limit the number of active base stations 2013 IEEE PIMRC

Interference Aware Clustering Capability Rating (IA-CCR) scheme II IA-CCR evaluated with different restriction policies (1st, 2nd and 3rd choice restrictions) in this study 2013 IEEE PIMRC

Energy Model Energy model proposed by Han et. al. (2012) used Energy consumed during ABS wake up and in the sleeping, transmitting, receiving and waiting modes are accounted for Highest SINR scheme used as baseline scheme Percentage reduction in energy consumption of other schemes estimated relative to the Highest SINR scheme 𝐸 𝐴𝐵𝑆 = 𝑗=1 𝑛 𝑎𝑏𝑠 𝑡 𝑠𝑙𝑒𝑒𝑝,𝑗 𝑃 𝑠𝑙𝑒𝑒𝑝,𝑗 + 𝑡 𝑅𝑥,𝑗 𝑃 𝑅𝑥,𝑗 𝜇 𝑅𝐹 + 𝑡 𝑇𝑥,𝑗 𝑃 𝑇𝑥,𝑗 𝜇 𝑅𝐹 + 𝑡 𝑤𝑎𝑖𝑡𝑖𝑛𝑔,𝑗 𝑃 𝑤𝑎𝑖𝑡𝑖𝑛𝑔,𝑗 + 𝑛 𝑤𝑎𝑘𝑒𝑢𝑝,𝑗 𝐸 𝑤𝑎𝑘𝑒𝑢𝑝 1 1− 𝜇 𝑐 2013 IEEE PIMRC

Simulation Results I Blocking probability similar for all schemes at low traffic load due to low interference At higher traffic load interference is more severe for the lower SINR choice schemes and they perform relatively poorer 2013 IEEE PIMRC

Simulation Results II Higher SINR choice decisions leads to better delay performance Higher data rates responsible for better delay performance 2013 IEEE PIMRC

Simulation Results III Most Loaded ABS and NCCR schemes outperforms IA-CCR at low load due to higher degree of clustering At higher traffic load IA-CCR is better since interference affects the other schemes more 2013 IEEE PIMRC

Simulation Results IV Effective energy savings is obtained by offsetting energy reduction by delay deterioration IA-CCR balances QoS and energy savings better than the other schemes 2013 IEEE PIMRC

Conclusion Energy efficiency depends on how well interference is managed beyond low traffic load IA-CCR reduces inter-cell interference and improves energy efficiency by restricting BS choices IA-CCR balances QoS and energy savings better than the schemes without interference mitigation There is scope for modifying policies with respect to traffic load to optimize energy efficiency across all traffic load 2013 IEEE PIMRC

THANK YOU 2013 IEEE PIMRC