Question

2. (30 points) Describe the steps of the handover procedure in LTE, including handover preparation, handover execution, and handover completion.

Answer 1

SOLUTION:-

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SOLUTION:- Handover is a procedure for changing the serving cell of a UE. The two eNodeBs involved in the process are typically called the source eNB (S-eNB) and the target eNB (T-eNB). In NetSim, handover procedure is triggered automatically by the serving eNodeB of the UE. Steps of Handover procedure in LTE are given below:- (1) A data call is established between the UE, S-eNB (Source-eNB) and the network elements. Data packets are transferred to/from the UE to/from the network in both directions (Downlink as well as Uplink) (2) The network sends the MEASUREMENT CONTROL REQ message to the UE to set the parameters to measure and set thresholds for those parameters. Its purpose is to instruct the UE to send a measurement report to the network as on as it detects the thresholds Serving eNB makes the decision to hand off the UE to a T-eNB (Target-eNB) using the handover algorithm at the target side to the UE as an RRC message to perform/execute the handover. the handover, i.e., RRC CONNECTION RECONFIGURATION message including the mobility Control Information. established in the T-eNB during the HANDOVER REQ message processing (3) The UE sends the MEASUREMENT REPORT to the serving eNB, which contains the RQRS from aⅡ the nearby eNBs. The (4) The S-eNB then initiates the decision to handover using the X2 interface. (5) The S-eNB issues a HANDOVER REQUEST message to the T-eNB passing necessary information to prepare the handover 6) The T-eNB CKNOWLEDGE message including a transparent container to be sent (7) The s-eNB generates the RRC (Radio resource control used for signaling transfer) message to perform/execute (8) The S-eNB starts forwarding the downlink data packets to the T-eNB for all the data bearers which are being (9) The T-eNB now requests the s-eNB to release the resources. Now, the handover procedure is complete. sends back the HANDOVER REQUEST A