An Analytical Evaluation Approach for Control Plane Operations of a Multi-RAT Mobility Procedures in a User Equipment

Abstract

It is evident that the present and future deployment of multiple radio access technology (RAT), e.g., WLAN, LTE, WiMAX, etc., will advent multi-RAT user equipment (UE). There will be four major challenges due to multi-RATs existence, i.e., fast-reliable signaling, fast-reliable mobility with Quality of Service (QoS), security and reasonable cost. In this paper we deal with performance modeling signaling plane. Most of the reported works present signaling performance between two RATs e.g., EUTRAN to CDMA2000 etc., and vice versa (or single RAT scenarios e.g., UMTS to UMTS). To the best of our knowledge, there has been no analytical modeling approach available for performance analysis of entire control plane operations in a multi-RAT UE, right from cell search to completion of mobility procedures in case of more than two RATs, i.e., a generic model for N-number of RATs. This paper proposes a generic Discrete Time Markov Chain (DTMC) based analytical method for evaluation of control plane operations for multi-RAT mobility procedures. Using the case of UE initiated multi-RAT mobility procedures, for presenting our analytical model we propose an algorithm, integrating and extending some of the known approaches which were mostly limited to single RAT. For this algorithm a generic analytical relationship is derived between time taken by each signaling process in each layer involved in the multi-RAT mobility procedure and the probability of success of the same. Finally, using the above analytical model a case study is presented where the performance of UE initiated mobility procedure for WLAN interworking with LTE supported by Proxy Mobile IP (PMIP) and Media Independent Handover (MIH). With our analytical model, results show that, for a target LTE cell, the increase in probability of successful completion of mobility procedure is 11 % from existing procedures. For target WLAN cell, the same is around 9 %. Notably, the results show how our analytical approach helps in modeling most of the control plane operations in multi-RAT mobility procedures, in a holistic manner.