# US 2021/0345211 A1 · Timing advance for rach-less backhaul handover > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0345211 A1 - Document ID: US20210345211A1 - Status: Published application - Kind: A1 - Application number: 17/281,150 - Filed: 2019-09-24 - Published: 2021-11-04 - Earliest claimed: 2018-10-05 - Assignees: Nokia Solutions and Networks Oy - Applicants: Nokia Solutions and Networks Oy - Inventors: Ilkka KESKITALO; Esa MALKAMAKI; Dawid KOZIOL; Juha Sakari KORHONEN - Web page: https://patentgrep.com/patent/US20210345211A1 ## CPC - H04W 36/12: Reselecting a serving backbone network switching or routing node - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W 24/02: Arrangements for optimising operational condition - H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports} - H04W 36/0058: {Transmission of hand-off measurement information, e.g. measurement reports} - H04W 36/00725: {Random access channel [RACH]-less handover} - H04W 56/0005: {synchronizing of arrival of multiple uplinks} - H04W 56/005: {compensating for timing error by adjustment in the receiver} - H04W 36/08: Reselecting an access point - H04W 84/047: {using dedicated repeater stations} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A technique of performing a handover procedure involves providing a proper timing adjustment indication for the UE performing RACH-less HO. Even though the discussion herein is on IAB scenarios and the idea takes an advantage of IAB nodes being in fixed locations (i.e., not moving in the network), it can be applied to UEs in general. The timing adjustment provided in performing a HO in an IAB network according to the improved techniques involves computing a timing advance (TA) to be used by an IAB node prior to executing HO to an alternative serving node. Such a use of a TA may enable a bypassing of a RACH procedure when accessing a cell. ## Claims ### Claim at position 1 1-56. (canceled) ### Claim 57 An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: measure a timing of a first signal received from a second node of a wireless network to produce a measurement result; generate a timing advance value based on the measurement result and an uplink reception reference time of the apparatus; send the timing advance value to the second node; and receive a second signal from the second node, wherein transmission of the second signal is at a time advanced by the timing advance value with respect to a downlink transmission reference time of the second node. ### Claim 58 (depends on 57) The apparatus as in claim 57, wherein the first signal includes a downlink broadcast signal. ### Claim 59 (depends on 58) The apparatus as in claim 58, wherein the downlink broadcast signal includes a synchronization signal block. ### Claim 60 (depends on 57) The apparatus as in claim 57, wherein the wireless network includes an integrated access and backhaul network. ### Claim 61 (depends on 60) The apparatus as in claim 60, wherein the apparatus includes a target integrated access and backhaul node of the integrated access and backhaul network, and the second node includes a migrating integrated access and backhaul node of the integrated access and backhaul network. ### Claim 62 (depends on 57) The apparatus as in claim 57, wherein the receiving the second signal from the second node is performed after a handover command message is received at the second node. ### Claim 63 (depends on 57) The apparatus as in claim 57, wherein the first signal includes a downlink transmission signal and the timing advance value for the apparatus comprises an uplink timing advance value for the apparatus. ### Claim 64 (depends on 57) The apparatus as in claims 57, wherein the at least one memory and the computer program code is further configured to, with the at least one processor, cause the apparatus at least to: store the timing advance value in a table of timing advance values. ### Claim 65 (depends on 57) The method as in claim 57, wherein the first signal and the second signal include channel state indication reference signals. ### Claim 66 An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: measure a timing of a first signal received from a second node of a wireless network to produce a measurement result; generate a timing advance value based on the measurement result and a downlink transmission reference time of the wireless network; and transmit a second signal to the second node at a time advanced by the timing advance value with respect to a reception reference time of the second node. ### Claim 67 (depends on 66) The apparatus as in claim 66, wherein the first signal includes a downlink broadcast signal. ### Claim 68 (depends on 67) The apparatus as in claim 67, wherein the downlink broadcast signal includes a synchronization signal block. ### Claim 69 (depends on 66) The apparatus as in claim 66, wherein the wireless network includes an integrated access and backhaul network. ### Claim 70 (depends on 69) The apparatus as in claim 69, wherein the apparatus includes a migrating integrated access and backhaul node of the integrated access and backhaul network, and the second node includes a target integrated access and backhaul node of the integrated access and backhaul network. ### Claim 71 (depends on 66) The apparatus as in claim 66, wherein the measuring is performed at a mobile termination part of the apparatus. ### Claim 72 (depends on 66) The apparatus as in claim 66, wherein the at least one memory and the computer program code is further configured to, with the at least one processor, cause the apparatus at least to: receive a handover command message from a third node, the handover command message indicating a handover to the second node, and wherein the transmitting the second signal is performed in response to receiving the handover command message. ### Claim 73 (depends on 72) The apparatus as in claim 72, wherein the handover command message is received in response to a signal strength of signals sent between the third node and the apparatus being less than a threshold signal strength. ### Claim 74 (depends on 66) The apparatus as in claim 66, wherein the at least one memory and the computer program code is further configured to, with the at least one processor, cause the apparatus at least to: store the timing advance value in a table of timing advance values. ### Claim 75 (depends on 66) The apparatus as in claim 66, wherein the first signal and the second signal include channel state indication reference signals. ### Claim 76 A method, comprising: measuring, by a first node of a wireless network, a timing of a first signal received from a second node of the wireless network to produce a measurement result; generating, by the first node, a timing advance value based on the measurement result and an uplink reception reference time of the first node; sending the timing advance value to the second node; and receiving, by the first node, a second signal from the second node, wherein transmission of the second signal is at a time advanced by the timing advance value with respect to a downlink transmission reference time of the second node.