An Energy Aware MobileControlled Handover Method for Natural Disaster Situations Sayan Kumar Ray 1 , William Liu 2 , Harsha Sirisena 3 , Swapan Kumar Ray 4 , Devatanu Deka 5 1 Faculty of Business and IT, Manukau Institute of Technology, Auckland, New Zealand 2 School of Computing and Mathematical Sciences, Auckland University of Technology, Auckland, New Zealand 3 Dept of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand 4 Dept of Computer Science and Engineering, Jadavpur University, Kolkata, India 5 Dynamic Controls, Christchurch, New Zealand sayan.ray@manukau.ac.nz, william.liu@aut.ac.nz, harsha.sirisena@canterbury.ac.nz, skray@ieee.org, deva.deka@gmail.com                                     !"                      #     $        $       %    &#$’ &#$’"      (" $         #)"              !  )   )"      (*    #           +       ,! !      $  ! +     !                         I. INTRODUCTION Natural disasters such as earthquakes or hurricanes often cause breakdown of the AC power grid in the affected areas hampering telecommunication service. Immediately after the Haiti and Christchurch earthquakes in Jan 2010 and Feb 2011, respectively, and the Japan tsunami in March 2011, the ability to make calls was adversely impacted by electricity outages, cable failures and traffic congestion. Telecommunication systems in the affected areas become heavily congested immediately after the disaster owing to the sudden substantial increase in call attempts. The extreme congestion resulting from calling spikes was exacerbated as battery backups died after a few hours causing almost a total collapse of the cellular coverage. Not only did the telecommunication network fail to provide an added emergency assistance to people in the affected areas but it also badly hampered the postdisaster searching and rescue activities by the relief teams. However, the incoming text facilities were available up to a certain time and the telecommunication equipments like the eNBs remained undamaged. Overloading of the eNBs in the affected areas was actually caused by two main factors, namely, (a) the sudden increase in incoming and outgoing voice calls to and from the people stuck in the affected areas and (b) the addition of new communication traffic generated by the rescue and relief team members and other people coming to the affected areas for rendering help. Natural disasters cannot be prevented but their occurrences should spur researchers to delve into areas like creating a sustainable communication infrastructure, reducing and controlling traffic congestion in eNBs, devising appropriate disaster warning systems, etc. In the present paper we propose a mobile stationcontrolled (i.e., UEcontrolled) reliable handover (HO) method to discourage the arrival of new traffic to an already overloaded eNB after a natural disaster. The basic goal is to prolong the overall lifetime of the battery backup in the BSs to maximize the possible number of voice calls and text messages during and after a disaster by properly utilizing the left over power (LoP) of the backup batteries. We have considered an LTEA network environment for our proposed HO scheme but the scheme can be adapted to any cellular network system. In the proposed scheme, when an LTEA UE needs a HO during its journey, it selfselects the particular neighbouring BS (i.e., a neighbouring eNB or NeNB) for handover that obtains the highest weighted average score (WAS) based on two parameters, namely, the UE's Direction of Motion (DoM) relative to the NeNB and the maximum Leftover Power (LoP) of the NeNBs. The UE assigns the score on the DoM and the LoP to each NeNB and the chosen target eNB (TeNB) is the one with the highest WAS. It should be noted that the NeNB towards which the UE is moving the most will provide the UE with the maximum signal strength and will thus receive the highest score against the DoM. Similarly, the NeNB which has the highest LoP will provide the UE with the highest Quality of Service (QoS) and will receive the highest score against the LoP. This scheme offers multiple benefits. First, by diverting the newly arrived 2013 Australasian Telecommunication Networks and Applications Conference (ATNAC) 978-1-4799-1081-6/13/$31.00 ©2013 IEEE 130