Method for radio resource control (RRC) connection re-establishment after switching failure and user equipment (UE)

Abstract

The invention discloses a method for RRC connection re-establishment after switching failure and UE. The method comprises the steps that: a source cell makes a switching judgment after receiving a measurement report of the UE and if the switching is allowed according to the result of judgment, enters a switching preparation stage; in the switching preparation stage, the source cell acquires an RRC preparation set cell list and sends the RRC preparation set cell list to the UE; and when switching to a target cells fails, the UE searches for a best cell capable of initiating RRC connection re-establishment in the target cell, the resource cell and the cells in the RRC preparation set cell list and initiates RRC connection re-establishment to the searched cell. The technical scheme in the invention can improve the success rate of the RRC connection re-establishment.

Description

technical field [0001] The invention relates to the technical field of mobile communication, in particular to a method for re-establishing an RRC connection after handover failure and a UE. Background technique [0002] A Long Term Evolution (LTE, Long Term Evolution) system adopts a flat network structure. figure 1 It is the structure diagram of LTE network. like figure 1 As shown, the Evolved Universal Terrestrial Radio Access Network (E-UTRAN, Evolved Universal Terrestrial Radio Access Network) is composed of base stations (eNB, evolved NodeB), and the eNBs are interconnected by the X2 interface; the evolved packet core network ( Evolved Packet Corenet work (EPC) includes a Serving Gateway (S-GW, Serving Gateway) and a Mobility Management Entity (MME, Mobility Management Entity), and interacts with the eNB through the S1 interface. Each eNB includes multiple cells. [0003] Mobility is the main feature in wireless communication systems, and it is mainly realized by ce...

AI Technical Summary

Problems solved by technology

[0018] 1) In Scenario 1, the UE is in cell 3 and starts to move towards cell 1. When the UE just crosses the boundary between cell 1 and cell 3, the UE starts to report measurement at point A. The handover is issued, and the UE initiates random access to the target cell 1 at point C. At this time, because it has entered the coverage of cell 2, the signal of cell 1 is relatively weak, and the UE is likely to fail in random access, resulting in handover failure. At this time, the UE will trigger the RRC connection re-establishment process, but the current best signal for the UE should be the signal of cell 2, and the UE cannot normally obtain the information of cell 2, and cannot initiate re-establishment on cell 2, but can only send to cell 1 Or cell 3 initiates reconstruction, it is very likely that the reconstruction fails, resulting in call drop

[0019] 2) In Scenario 2, the trajectory of the UE moving in the opposite direction to cell 3 at point B may cause handover failure, but since it continues to move to cell 1 afterwards, the final reconstruction should be performed on cell 1, but also because the UE does not have an exact Obtaining the signal strength comparison between cell 1 and cell 3 may cause re-establishment failure

[0020] 3) In Scenario 3, the UE should be reestablished in Cell 3 at the end, and since the UE cannot know whether it is reestablished in Cell 1 or Cell 3, the re-establishment will also fail

[0023] First of all, for the performance of the UE itself, the full-band search is time-consuming and power-consuming;

[0024] Secondly, in terms of the recovery performance achieved by the re-establishment process, the cells searched in the full frequency band may not have UE context information, so the re-establishment may not be successful, thus delaying the performance of service recovery

[0025] To sum up, in the existing protocol, there is no clear regulation on which cell to re-establish after the handover fails, but according to the existing capabilities of the UE, it can only be re-established on the source cell or the target cell, so blind re-establishment may lead to re-establishment. It will switch immediately or the wireless link will fail and be rebuilt. It will not achieve the effect of re-establishing and restoring the wireless link, and there will even be a scene of continuous switching and rebuilding in a short period of time.

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