Time Alignment for Inter-Cell Mobility

A method performed by a wireless device for timing advance (TA) management between the wireless device and at least one target candidate cell for layer one (L1)/layer two (L2) inter-cell mobility, wherein the wireless device is operating in a serving cell different from the target candidate cell, the method comprising:

• receiving an uplink configuration for a target candidate cell;
• transmitting an uplink message to the target candidate cell based on the uplink configuration;
• and
• receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from the serving cell.

A wireless device operable to perform timing advance (TA) management between the wireless device and at least one target candidate cell for layer one (L1)/layer two (L2) inter-cell mobility when the wireless device is operating in a serving cell different from the target candidate cell, the wireless receiver comprising processing circuitry operable to:

• receive an uplink configuration for a target candidate cell;
• transmit an uplink message to the target candidate cell based on the uplink configuration;
• and
• receive a TA value associated with the target candidate cell, wherein the TA value is received in a message from the serving cell.

A method performed by a network node operating as a candidate distributed unit (DU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1)/layer two (L2) inter-cell mobility of the candidate DU, the method comprising:

• receiving, from a serving central unit (CU), a message requesting TA establishment for the wireless device and at least one target candidate cell;
• transmitting, to the serving CU, an uplink configuration for a target candidate cell and the wireless device;
• receiving, from the wireless device, an uplink message based on the uplink configuration;
• and
• transmitting, to the wireless device via the serving CU, a TA value associated with the target candidate cell and calculated based on the received uplink message.

A network node capable of operating as a candidate distributed unit (DU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1)/layer two (L2) inter-cell mobility of the candidate DU, the network node comprising processing circuitry operable to:

• receive, from a serving central unit (CU), a message requesting TA establishment for the wireless device and at least one target candidate cell;
• transmit, to the serving CU, an uplink configuration for a target candidate cell and the wireless device;
• receive, from the wireless device, an uplink message based on the uplink configuration;
• and
• transmit, to the wireless device via the serving CU, a TA value associated with the target candidate cell and calculated based on the received uplink message.

A method performed by a network node operating as a serving central unit (CU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1)/layer two (L2) inter-cell mobility, the method comprising:

• transmitting a request to a candidate distributed unit (DU) requesting TA establishment for the wireless device and at least one target candidate cell;
• receiving from the candidate DU an uplink configuration for a target candidate cell and the wireless device;
• transmitting an uplink message to a serving DU to be transmitted to the wireless device, wherein the uplink message comprises the uplink configuration;
• receiving from the candidate DU a TA value associated to the target candidate cell;
• and
• transmitting to the wireless device via the serving DU the TA value.

A network node capable of operating as a serving central unit (CU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1)/layer two (L2) inter-cell mobility, the network node comprising processing circuitry operable to:

• transmit a request to a candidate distributed unit (DU) requesting TA establishment for the wireless device and at least one target candidate cell;
• receive from the candidate DU an uplink configuration for a target candidate cell and the wireless device;
• transmit an uplink message to a serving DU to be transmitted to the wireless device, wherein the uplink message comprises the uplink configuration;
• receive from the candidate DU a TA value associated to the target candidate cell;
• and
• transmit to the wireless device via the serving DU the TA value.