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AssigneeInterDigital Patent Holdings, Inc.
InventorsPeter S. Wang, Guodong Zhang, Jin Wang, Mohammed Sammour, Shankar Somasundaram, Stephen E. Terry, Ulises Olvera-Hernandez
Estimating the term…
A method and an apparatus for performing a handover in an evolved universal terrestrial radio access network (E-UTRAN) are disclosed. A wireless transmit/receive unit (WTRU) sends a measurement report to a source evolved Node B (eNB), and receives a handover command from the source eNB. The WTRU initiates reception and processing of a primary broadcast channel (P-BCH) at the target cell after receiving the handover command. The WTRU then sends a random access preamble to the target eNB, receives a random access response from the target eNB, and sends a handover complete message to the target eNB. The reception and processing of the P-BCH may be initiated immediately after receiving the handover command or after sending the handover complete message. The WTRU may apply default configuration or source cell configuration in the target cell until a target cell SFN and/or P-BCH information are acquired.
A method implemented in a wireless transmit/receive unit (WTRU) for performing a handover from a source cell to a target cell, the method comprising:
A wireless transmit/receive unit (WTRU) comprising:
A method implemented in a wireless transmit/receive unit (WTRU) for performing a handover from a source cell to a target cell, the method comprising:
A wireless transmit/receive unit (WTRU) comprising:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
This application is related to wireless communications.
A handover is a process of transferring an ongoing call or data session from one cell to another. Conventionally, a wireless transmit/receive unit (WTRU) assisted network controlled handover is implemented such that a WTRU measures a signal strength of neighboring cells and a serving cell and sends a measurement report to the network. The network then determines whether to perform the handover to another cell, (i.e., a target cell).
FIG. 1 is a signaling diagram of a handover process 100 in the third generation partnership project (3GPP) long term evolution (LTE) network (intra-mobility management entity (MME)/serving gateway handover procedure). The source evolved Node-B (eNB) configures the WTRU measurement procedures according to the area restriction information (step 102). The WTRU sends a measurement report in accordance with the rules set by system information, specification, etc. (step 104). The source eNB makes a handover decision based on the measurement report (step 106). The source eNB issues a handover request message to a target eNB passing necessary information to prepare the handover at the target eNB (step 108). Admission control may be performed by the target eNB (step 110). Once the target eNB decides to admit the WTRU, the target eNB prepares handover with L1/L2 and sends a handover request acknowledgement message to the source eNB (step 112). The handover request acknowledgement message includes a transparent container to be sent to the WTRU as a radio resource control (RRC) message. The source eNB sends a handover command to the WTRU (step 114).
A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein;
FIG. 1 is a signaling diagram of a handover process in the 3GPP LTE network;
FIG. 2 is a signaling diagram of an example process in accordance with the second embodiment;
When referred to hereafter, the terminology “WTRU” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “eNB” includes but is not limited to a base station, a Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.
In accordance with a first embodiment, a new handover command format is defined. The new handover command format reduces the handover interruption time, which is defined as the difference between the time a WTRU receives the handover command and the time the WTRU resumes its uplink and downlink data transmission and reception in the target cell.
In order for the WTRU to perform normal operation (such as data transmission, reception and DRX) in the target cell, the WTRU needs to know cell-specific system information carried on a P-BCH and a D-BCH. However, reading P-BCH (with a transmission time interval (TTI) of 40 ms repeated 4 times) and D-BCH (with scheduling units of 160 and 320 ms) will increase the handover interruption time dramatically. In accordance with the first embodiment, the cell specific system information carried on the P-BCH and the D-BCH in the target cell is included in the handover command. This information may be provided by the target eNB to the source eNB in the handover request acknowledgement message, (e.g., included in the transparent container of the handover request acknowledgement).
Using monitoring of external events, e.g. the presence of a signal: where the received signal is a wanted signal
Orthogonal multiplex systems, e.g. using WALSH codes: cell search, i.e. determining cell identity [cell-ID]
Transmission or use of information for re-establishing the radio link: of neighbour cell information
Transmission or use of information for re-establishing the radio link: of control information between different access points
About 2 years 8 months of term left · ends 26 Jun 2029 (estimated)
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