# US 2019/0357167 A1 · Method and apparatus for maintaining uplink synchronization and reducing battery power consumption > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0357167 A1 - Document ID: US20190357167A1 - Status: Published application - Kind: A1 - Application number: 16/530,178 - Filed: 2019-08-02 - Published: 2019-11-21 - Earliest claimed: 2006-03-24 - Assignees: InterDigital Technology Corporation - Applicants: InterDigital Technology Corporation - Inventors: Jin Wang; John S. Chen; Mohammed Sammour; Stephen E. Terry; Arty Chandra; Guodong Zhang - Web page: https://patentgrep.com/patent/US20190357167A1 ## CPC - H04W 56/0045: {compensating for timing error by altering transmission time} - H04J 11/0069: {Cell search, i.e. determining cell identity [cell-ID] (design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655)} - H04W 52/0216: {using a pre-established activity schedule, e.g. traffic indication frame} - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - H04W 92/10: between terminal device and access point, i.e. wireless air interface - Y02D 30/70: in wireless communication networks - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A Node-B sends a polling message to a wireless transmit/receive unit (WTRU). The WTRU sends an uplink synchronization burst in response to the polling message without contention. The Node-B estimates an uplink timing shift based on the synchronization burst and sends an uplink timing adjustment command to the WTRU. The WTRU then adjusts uplink timing based on the uplink timing adjustment command. Alternatively, the Node-B may send a scheduling message for uplink synchronization to the WTRU. The WTRU may send a synchronization burst based on the scheduling message. Alternatively, the WTRU may perform contention-based uplink synchronization after receiving a synchronization request from the Node-B. The WTRU may enter an idle state instead of performing a handover to a new cell when the WTRU moves to the new cell. A discontinuous reception (DRX) interval for the WTRU may be set based on activity of the WTRU. ## Claims ### Claim at position 1 1-6. (canceled) ### Claim 7 A method performed by a wireless transmit/receive unit (WTRU), the method comprising: receiving discontinuous reception (DRX) control information from a wireless network, the DRX control information indicating a time interval that the WTRU should monitor a downlink control channel; receiving a control message on the downlink control channel while monitoring the downlink control channel according to the DRX control information, wherein the control message is associated with an identifier of the WTRU, the control message indicating that the WTRU should transmit a random access preamble to the wireless network; transmitting the random access preamble to the wireless network in response to receiving the control message; and receiving a timing adjustment command from the wireless network. ### Claim 8 (depends on 7) The method of claim 7, further comprising adjusting uplink timing according to the timing adjustment command. ### Claim 9 (depends on 8) The method of claim 8, further comprising sending a hybrid automatic repeat request (H-ARQ) feedback to the wireless network after adjusting uplink timing according to the timing adjustment command. ### Claim 10 (depends on 7) The method of claim 7, wherein the identifier includes a sequence number that uniquely identifies the WTRU. ### Claim 11 (depends on 7) The method of claim 7, wherein the control message indicates a resource to be used by the WTRU for transmitting the random access preamble. ### Claim 12 (depends on 11) The method of claim 11, wherein the resource includes a subframe to be used by the WTRU to transmit the random access preamble. ### Claim 13 (depends on 7) The method of claim 7, further comprising entering a DRX mode while the WTRU is in an active state. ### Claim 14 (depends on 7) The method of claim 7, wherein the random access preamble is sent using a contention-based mechanism. ### Claim 15 A wireless transmit/receive unit (WTRU) comprising: a transceiver, and a processor coupled to the transceiver, the processor configured to: receive discontinuous reception (DRX) control information from a wireless network, the DRX control information indicating a time interval that the WTRU should monitor a downlink control channel; receive a control message on the downlink control channel while monitoring the downlink control channel according to the DRX control information, wherein the control message is associated with an identifier of the WTRU, the control message indicating that the WTRU should transmit a random access preamble to the wireless network; transmit the random access preamble to the wireless network in response to receiving the control message; and receive a timing adjustment command from the wireless network. ### Claim 16 (depends on 15) The WTRU of claim 15, wherein the processor is further configured to adjust uplink timing according to the timing adjustment command. ### Claim 17 (depends on 16) The WTRU of claim 16, wherein the processor is further configured to send a hybrid automatic repeat request (H-ARQ) feedback to the wireless network after adjusting uplink timing according to the timing adjustment command. ### Claim 18 (depends on 15) The WTRU of claim 15, wherein the identifier includes a sequence number that uniquely identifies the WTRU. ### Claim 19 (depends on 15) The WTRU of claim 15, wherein the control message indicates a resource to be used by the WTRU for transmitting the random access preamble. ### Claim 20 (depends on 19) The WTRU of claim 19, wherein the resource includes a subframe to be used by the WTRU to transmit the random access preamble. ### Claim 21 (depends on 15) The WTRU of claim 15, wherein the processor is further configured to enter a DRX mode while the WTRU is in an active state. ### Claim 22 (depends on 15) The WTRU of claim 15, wherein the random access preamble is sent using a contention-based mechanism. ### Claim 23 A wireless transmit/receive unit (WTRU) comprising: a transceiver, and a processor coupled to the transceiver, the processor configured to: receive discontinuous reception (DRX) control information from a wireless network, the DRX control information indicating a time interval that the WTRU should monitor a downlink control channel; receive a control message on the downlink control channel while monitoring the downlink control channel according to the DRX control information, wherein the control message is associated with an identifier of the WTRU, the control message indicates that the WTRU should transmit a random access preamble to the wireless network, and the control message is indicative of a time and resource for the WTRU to transmit the random access preamble; transmit the random access preamble to the wireless network in response to receiving the control message; and receive a timing adjustment command from the wireless network. ### Claim 24 (depends on 23) The WTRU of claim 23, wherein the processor is further configured to adjust uplink timing according to the timing adjustment command. ### Claim 25 (depends on 23) The WTRU of claim 23, wherein the processor is further configured to send a hybrid automatic repeat request (H-ARQ) feedback to the wireless network after adjusting uplink timing according to the timing adjustment command. ### Claim 26 (depends on 23) The WTRU of claim 23, wherein the time for the WTRU to transmit the random access preamble indicated by the control message comprises one or more subframes.