Methods and system for performing handover in a wireless communication system

Abstract

A method and system for performing handover in a third generation (3G) long term evolution (LTE) system are disclosed. A source evolved Node-B (eNode-B) makes a handover decision based on measurements and sends a handover request to a target eNode-B. The target eNode-B sends a handover response to the source eNode-B indicating that a handover should commence. The source eNode-B then sends a handover command to a wireless transmit / receive unit (WTRU). The handover command includes at least one of reconfiguration information, information regarding timing adjustment, relative timing difference between the source eNode-B and the target eNode-B, information regarding an initial scheduling procedure at the target eNode-B, and measurement information for the target eNode-B. The WTRU then accesses the target eNode-B and exchanges layer 1 / 2 signaling to perform downlink synchronization, timing adjustment, and uplink and downlink resource assignment based on information included in the handover command.

Description

technical field [0001] The present invention relates to wireless communication systems. In particular, the present invention relates to a method and system for performing handover in a Long Term Evolution (LTE) system. Background technique [0002] Currently, LTE for fourth generation (4G) systems is being conceived to develop a new radio interface and radio network architecture that provides high data rates, low latency, packet optimization, and improved system capacity and coverage. For LTE systems, it is recommended to use Orthogonal Frequency Division Multiple Access (OFDMA) and Frequency Division Multiple Access (FDMA) in the downlink and uplink transmissions, respectively, rather than the Code Division Multiple Access (CDMA) currently used in 3G systems. address (CDMA). Since many aspects of the LTE system have been changed, it is necessary to reconsider the handover process and related operations within the LTE system. [0003] In LTE_ACTIVE mode, user equipment (U...

AI Technical Summary

Problems solved by technology

[0009] The intra-LTE handover procedure 100 described above does not provide details of the handover command (e.g., configuration of UE 152 based on target eNode-B requirements) and details of UE operation after the UE receives the handover command (e.g., source eNode-B 154 and Data transmission between UEs 152, Radio Link Control (RLC) and Hybrid Automatic Repeat Request (HARQ) resets, and Packet Data Convergence Protocol (PDCP) sequence number (SN) gap identification implemented by UEs 152)

Furthermore, the above-mentioned intra-LTE handover procedure 100 also does not provide details of UE timing adjustment for synchronous and asynchronous eNode-Bs and details of efficient target eNode-B resource scheduling for UE transmissions

Images