# US 2022/0046574 A1 · Time adjustment during handover

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- Number: US 2022/0046574 A1
- Document ID: US20220046574A1
- Status: Published application
- Kind: A1
- Application number: 17/443,932
- Filed: 2021-07-28
- Published: 2022-02-10
- Earliest claimed: 2020-08-06
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Emad N. Farag; Hongbo Si; Nishith D. Tripathi; Kyeongin Jeong
- Web page: https://patentgrep.com/patent/US20220046574A1

## CPC

- H04W 56/0045: {compensating for timing error by altering transmission time}
- H04L 27/2607: {Cyclic extensions}
- H04L 27/2675: {Pilot or known symbols}
- H04W 74/0841: {with collision treatment}
- H04W 36/0072: {of resource information of target access point}
- H04W 84/06: Airborne or Satellite Networks (space-based or airborne stations H04B7/185)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Methods and apparatuses for time adjustment during handover in non-terrestrial networks. A method of operating a user equipment (UE) includes receiving configuration information for a first and a second RS and receiving the first RS from a first base station (BS) and the second RS from a second BS. The method also includes measuring a time of arrival of the second RS relative to a time of arrival of the first RS, determining a differential propagation delay between the first RS and the second RS based on the times of arrival. The method further includes determining a transmission time for an uplink (UL) UE-dedicated channel to the second BS based on the differential propagation delay and transmitting the UL UE-dedicated channel to the second BS based on the determined time.

## Claims

### Claim 1

A user equipment (UE), comprising:
a transceiver configured to:
receive configuration information for a first and a second reference signal (RS), and
receive the first RS from a first base station (BS) and the second RS from a second BS; and
a processor operably connected to the transceiver, the processor configured to:
measure a time of arrival of the second RS relative to a time of arrival of the first RS,
determine a differential propagation delay between the first RS and the second RS based on the times of arrival, and
determine a transmission time for an uplink (UL) UE-dedicated channel to the second BS based on the differential propagation delay,
wherein the transceiver is further configured to transmit the UL UE-dedicated channel to the second BS based on the determined transmission time.

### Claim 2 (depends on 1)

The UE of claim 1, wherein:
a difference between a reference time of the first BS (TRefA) and a reference time of the second BS (TRefB) (ΔRefAB=TRefA−TRefB) is indicated to the UE, and
the determination of the differential propagation delay and the determination of the UL transmission time is further based on ΔRefAB.

### Claim 3 (depends on 2)

The UE of claim 2, wherein ΔRefAB is updated by L2 or L1 control signaling.

### Claim 4 (depends on 1)

The UE of claim 1, wherein the transceiver is further configured to:
transmit, to the second BS, a physical random access channel (PRACH) associated with a random access channel (RACH) procedure, and
transmit the UL UE-dedicated channel to the second BS using the determined transmission time before receiving a timing advance (TA) command associated with the PRACH transmission.

### Claim 5 (depends on 4)

The UE of claim 4, wherein the RACH procedure is terminated based on an indication of successful reception of the UL UE-dedicated channel.

### Claim 6 (depends on 1)

The UE of claim 1, wherein:
the transceiver is further configured to use a guard band for the UL UE-dedicated channel transmission, and
the guard band is around the UL UE-dedicated channel transmission and based on a timing error of the determined transmission time.

### Claim 7 (depends on 1)

The UE of claim 1, wherein:
the transceiver is further configured to use a guard period for the UL UE-dedicated channel transmission, and
the guard period is around the UL UE-dedicated channel transmission and based on a timing error of the determined transmission time.

### Claim 8

A base station (BS), comprising:
a transceiver configured to transmit a reference signal (RS); and
a processor operably connected to the transceiver, the processor configured to identify an indication from a neighboring BS about a user equipment (UE) that would start communicating with the BS before completion of a random access procedure,
wherein the transceiver is further configured to:
transmit a downlink (DL) UE-dedicated channel to the UE; and
receive an uplink (UL) UE-dedicated channel from the UE.

### Claim 9 (depends on 8)

The BS of claim 8, wherein the base station is configured to transmit information to a neighboring BS on a reference time of the BS.

### Claim 10 (depends on 8)

The BS of claim 8, wherein the transceiver is further configured to:
receive physical random access channel (PRACH) associated with a random access channel (RACH) procedure
receive the UL UE-dedicated channel from the UE before transmitting a timing advance (TA) command associated with the PRACH transmission from the UE.

### Claim 11 (depends on 10)

The BS of claim 10, wherein the RACH procedure is terminated based on successful reception of the UL UE-dedicated channel and indication of the successful reception to the UE.

### Claim 12 (depends on 8)

The BS of claim 8, wherein:
a guard band is around the UL UE-dedicated channel transmission, and
the guard band is based on a timing error of a determined transmission time.

### Claim 13 (depends on 8)

The BS of claim 8, wherein:
a guard period is around the UL UE-dedicated channel transmission, and
the guard period is based on a timing error of a determined transmission time.

### Claim 14

A method of operating a user equipment (UE), the method comprising:
receiving configuration information for a first and a second reference signal (RS);
receiving the first RS from a first base station (BS) and the second RS from a second BS;
measuring a time of arrival of the second RS relative to a time of arrival of the first RS;
determining a differential propagation delay between the first RS and the second RS based on the times of arrival;
determining a transmission time for an uplink (UL) UE-dedicated channel to the second BS based on the differential propagation delay; and
transmitting the UL UE-dedicated channel to the second BS based on the determined transmission time.

### Claim 15 (depends on 14)

The method of claim 14, wherein:
a difference between a reference time of the first BS (TRefA) and a reference time of the second BS (TRefB) (ΔRefAB=TRefA−TRefB) is indicated to the UE, and
the determination of the differential propagation delay and the determination of the UL transmission time is further based on ΔRefAB.

### Claim 16 (depends on 14)

The method of claim 14, wherein ΔRefAB is updated by L2 or L1 control signaling.

### Claim 17 (depends on 14)

The method of claim 14, further comprising transmitting, to the second BS, a physical random access channel (PRACH) associated with a random access channel (RACH) procedure,
wherein transmitting the UL UE-dedicated channel further comprises transmitting the UL UE-dedicated channel to the second BS using the determined transmission time before receiving a timing advance (TA) command associated with the PRACH transmission.

### Claim 18 (depends on 17)

The method of claim 17, wherein the RACH procedure is terminated based on an indication of successful reception of the UL UE-dedicated channel.

### Claim 19 (depends on 14)

The method UE of claim 14, wherein:
transmitting the UL UE-dedicated channel further comprises using a guard band for the UL UE-dedicated channel transmission, and
the guard band is based on a timing error of the determined transmission time.

### Claim 20 (depends on 14)

The method of claim 14, wherein:
transmitting the UL UE-dedicated channel further comprises using a guard period for the UL UE-dedicated channel transmission, and
the guard period is based on a timing error of the determined transmission time.