# US 2015/0105084 A1 · Method and apparatus for handover in heterogeneous cellular networks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0105084 A1 - Document ID: US20150105084A1 - Status: Published application - Kind: A1 - Application number: 14/052,324 - Filed: 2013-10-11 - Published: 2015-04-16 - Earliest claimed: 2013-10-11 - Assignees: BlackBerry Limited - Applicants: BlackBerry Limited - Inventors: Chandra Sekhar Bontu; Zhijun Cai; Yi Song - Web page: https://patentgrep.com/patent/US20150105084A1 ## CPC - H04W 36/0072: {of resource information of target access point} - H04W 36/249: {according to timing information} - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04W 36/0088: {Scheduling hand-off measurements} - H04W 36/08: Reselecting an access point - H04W 56/003: {Arrangements to increase tolerance to errors in transmission or reception timing} - H04W 72/0446: Resources in time domain, e.g. slots or frames - H04W 76/19: Connection re-establishment - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method at a user equipment for handover from a serving cell to a target cell, the method sending a measurement report to the serving cell; and transmitting a reconfiguration complete message to the target cell; wherein the measurement report includes downlink timing measurements for the target cell. Further, a method at a source network element for handover of a user equipment from the source network element to a target network element, the method receiving a measurement report from the user equipment; sending a handover request to the target network element; receiving a handover request acknowledgement from the target network element, the handover request acknowledgement including a reconfiguration message and at least one downlink subframe in which an uplink grant is expected at the target network element for the user equipment; and forwarding the reconfiguration message and at least one downlink subframe to the user equipment. ## Claims ### Claim 1 A method at a user equipment for handover from a serving cell to a target cell, the method comprising: sending a measurement report to the serving cell; and transmitting a reconfiguration complete message to the target cell; wherein the measurement report includes downlink timing measurements for the target cell. ### Claim 2 (depends on 1) The method of claim 1, further comprising, prior to the transmitting, receiving a reconfiguration message from the serving cell, the reconfiguration message including an uplink grant or at least one downlink subframe to receive the uplink grant from the target cell. ### Claim 3 (depends on 2) The method of claim 2, wherein the reconfiguration message includes a timing advance value for the target cell. ### Claim 4 (depends on 1) The method of claim 1, wherein the transmitting comprising adjusting uplink transmit timing at the user equipment based on downlink reception timing differences between the serving cell and the target cell. ### Claim 5 (depends on 2) The method of claim 2, wherein at least one downlink subframe is a downlink control channel subframe indicating the uplink grant at the target cell. ### Claim 6 (depends on 1) The method of claim 1, further comprising receiving a response from the target cell based on the transmitting the reconfiguration complete message. ### Claim 7 (depends on 6) The method of claim 6, wherein if no response is received, retransmitting the reconfiguration complete message at a higher power. ### Claim 8 (depends on 7) The method of claim 7, wherein if a maximum number of retransmissions is reached, performing random access procedure for uplink synchronization with the target cell. ### Claim 9 (depends on 1) The method of claim 1, wherein the uplink grant contains a subframe number. ### Claim 10 A method at a source network element for handover of a user equipment from the source network element to a target network element, the method comprising: receiving a measurement report from the user equipment; sending a handover request to the target network element, the handover request including a request for an uplink grant at the target network element for the user equipment to send a reconfiguration complete message; receiving a handover request acknowledgement including a reconfiguration message and the uplink grant; and forwarding the reconfiguration message and uplink grant to the user equipment. ### Claim 11 (depends on 10) The method of claim 10, wherein the measurement report includes downlink timing measurements for the target cell. ### Claim 12 (depends on 10) The method of claim 10, wherein the reconfiguration message includes a timing advance value for the target cell. ### Claim 13 A source network element for handover of a user equipment from the source network element to a target network element, the source user equipment comprising a processor configured to: receive a measurement report from the user equipment; send a handover request to the target network element; receive a handover request acknowledgement from the target network element, the handover request acknowledgement including a reconfiguration message and at least one downlink subframe in which an uplink grant is expected at the target network element for the user equipment; and forward the reconfiguration message and at least one downlink subframe to the user equipment. ### Claim 14 (depends on 13) The source network element of claim 13, wherein the measurement report includes downlink timing measurements for the target cell. ### Claim 15 (depends on 13) The source network element of claim 13, wherein the reconfiguration message includes a timing advance value for the target cell. ### Claim 16 (depends on 13) The source network element of claim 13, wherein the source network element in configured to receive a range of downlink subframes, and forward by providing the user equipment with a subset of downlink subframes within the range of downlink subframes. ### Claim 17 (depends on 16) The source network element of claim 16, wherein the source network element chooses the subset of downlink subframes within the range of downlink subframes. ### Claim 18 (depends on 17) The source network element of claim 17, wherein the source network element is further configured to send a confirmation message to the target network element with the subset of downlink subframes. ### Claim 19 (depends on 18) The source network element of claim 18, wherein the source network element is configured to send the confirmation just prior to the forwarding the reconfiguration message. ### Claim 20 (depends on 13) The source network element of claim 13, wherein the at least one downlink subframe for the uplink grant is a downlink control channel subframe indicating the uplink grant at the target cell.