Modeling And Cost Analysis Of Location Management With User Status Tracking

Location management plays an indispensable role in mobile communications.By dynamically tracking users' locations in networks,a user's position can be located timely and accurately when a call arrives,which can ensure the quality of wireless communication services.The existing location management schemes can be divided into three main classes,i.e.,static location management schemes,dynamic location management schemes and TAL-based location management schemes.Due to the issues of unbalanced signal load and the inability to adapt to the user's mobility in the static scheme,dynamic location management and TAL-based location management has attracted more attention from the research community.Dynamic location management schemes can be mainly classified as distance-based location management scheme,time-based location management scheme and movement-based location management scheme.Among them,distance-based location management scheme owns the lowest cost.Although time-based location management scheme is not very efficient,the system is simple and the user's status in the network can be tracked periodically.TAL-based location management scheme is the location management scheme in 4G which can solve the issue in static location management.Firstly,the existing works on distance-based location management mainly focused on the reduction of the signal cost.However,when the distance-based location management scheme is applied for 2G/3G networks,it must be incorporated with time-based location management to detect the users' presence.Moreover,when a user crosses the boundary of the LA in the HLR/VLR architecture,its location update will impact the location management inside the LA.There is a similar situation in LTE networks.To solve this issue,we propose to combine the time-based location management scheme and the distance-based location management scheme,so that the new location management scheme has the capability to detect the users' presence.Also,we consider the HLR/VLR architecture in the analysis.By applying Erlang distribution to approximate the time threshold and modeling the movement model by using embedded Markov chain,we derive the signal cost between the two continuous incoming calls,and analyze the impact of different parameters on the propose location management.Furthermore,we provide simulation results to verify the ability of the proposed location management to reduce the paging failure rate in the networks.Secondly,TAL-based location management in LTE networks also needs to detect the users' presence.In the performance analysis of TAL-based location management schemes,one must take into account the impact of periodic location update,but this factor was neglected in most of existing studies.In this work,in order to analyze this impact,we modify the original embedded Markov chain and derived an expression for the signal cost between the two consecutive incoming calls.What's more,the accuracy of the theoretical results is verified by simulations and the impact of different parameters on the location management is analyzed.