Research On Cell Selection For Idle Mode Users In LTE

The project of Long Term Evolution is a further step of3G, which enhances the interface on-air technology of3G. On comparison with3G, the LTE technology increases the data transmission rate and the wireless resource usage rate. In3GPP LTE, there is a user mode defined as the idle mode, which indicates that the user is powered on while still not allocated any particular wireless channel resources yet. The idle mode is introduced for its three advantages; firstly, optimizing the access technology: By designing suitable cell selection and reselection algorithms, the user terminals can choose the cell of highest receiving power for camping, which gives a good channel quality for wireless communication; Further, by choosing the proper cell selection parameters, the user terminals can be sure to select the same cell under same wireless environment no matter in idle mode or connected mode; Secondly, decreasing the paging load:we can design the proper paging and cell selection strategies to offload unnecessary paging burden; Thirdly, decreasing idle users’power consumption. Above all, the idle users’cell selection problem is a hot topic among the research region.For erasing the disadvantages of idle users’ cell selection problem in current researches, I dig into the problems of coll selection based on the users’mode status, the purpose of decreasing the call blocking rate, increasing the wireless resource blocks’using rate and proper cell selection parameters.To the best of our knowledge, effect of idle users’ cell selection parameters on different key performance indicators in3GPP LTE for a realistic scenario has no extensive studies in the open literature. The cell selection parameters which the residential users choose to use have a crucial impact on the users’servie experience and new call outage probability. My paper studies the main parameters of the standard idle mode user cell selection, such as reselection time interval, the reference signal received power (RSRP, Reference Signal Received Power) measurement bandwidth, reselection threshold and so on.Further, based on the idle mode’s own characteristics, this paper proposes a new cell selection algorithm, taking into account the load of the target cell during cell selection, for the sake of reducing the rate of new call blocking rate.Simulation results also indicate that the cell selection parameter added load information of the target cell, thus, the user can effectively reduce the outage probability of new calls.In current LTE protocol, the cell selection mechanism based on only the Reference Signal Received Power (RSRP) would easily bring high call dropping rate due to ignoring the cell load status. This paper gives full consideration to the user’s state, propose a cell selection strategy with load balancing feature.Then this paper also uses n-dimensional chain model to analyze the proposed strategy theoretically. Theoretical analysis and simulation results show the proposed strategy is effective in reducing new call blocking rate and the handoff call dropping rate, at the same time, make the loads in different cells more balanced..