METHOD AND APPARATUS FOR TRANSMITTING SIGNAL, AND COMMUNICATION SYSTEM

1 . An apparatus for transmitting and receiving signals, applicable to a mobile integrated access and backhaul (IAB) node, the apparatus comprising:

first processor circuitry controlling the IAB node so that the IAB node executes the following:

configuring a first logical mobile IAB distributed unit (IAB-DU) and a second logical mobile IAB distributed unit (IAB-DU) in the node respectively with uplink backhaul mapping configuration by different IAB-donor central units; and

transmitting signals by a mobile termination of the node (IAB-MT) according to the uplink backhaul mapping configuration.

2 . The apparatus according to claim 1 , wherein,

the mobile termination of the node (IAB-MT) has one common BAP (backhaul adaptation protocol) entity to support two logical mobile IAB-DUs.

3 . The apparatus according to claim 1 , wherein the first processor circuitry controls the node to execute the following operation:

separately configuring the uplink backhaul mapping configuration for the first logical mobile IAB-DU and for the second logical mobile IAB-DU via corresponding F1AP (F1 application protocol) signaling.

4 . The apparatus according to claim 3 , wherein,

the uplink backhaul mapping configuration comprises Uplink Traffic to Routing ID Mapping Configuration and Uplink Traffic to BH (backhaul) RLC (radio link control) Channel Mapping Configuration.

5 . The apparatus according to claim 1 , wherein,

the first logical mobile IAB distributed unit has F1AP association with a first IAB-donor central unit, and

the second logical mobile IAB distributed unit has F1AP association with a second IAB-donor central unit.

6 . The apparatus according to claim 5 , wherein,

the first IAB-donor central unit is a source IAB-donor central unit of the mobile IAB node during a distributed unit migration procedure, and

the second IAB-donor central unit is a target IAB-donor central unit of the mobile IAB node during the distributed unit migration procedure.

7 . The apparatus according to claim 6 , wherein,

a terminal device connected to the mobile IAB node is handed over from a cell of the first logical mobile IAB-DU to a cell of the second logical mobile IAB-DU.

8 . The apparatus according to claim 3 , wherein,

the BAP layer maintains variables for the second logical mobile IAB-DU,

the variables comprising:

a second uplink traffic to routing ID mapping configuration and/or a second uplink traffic to BH RLC channel mapping configuration.

9 . The apparatus according to claim 7 , wherein,

at the node, for a backhaul adaptation protocol service data unit (BAP SDU) needing to be transmitted in an upstream direction received from an upper layer, the BAP entity performs mapping to a BAP address and a BAP path identity based on the following configuration variables:

a first uplink traffic to routing ID mapping configuration, the configuration being obtained from F1AP signaling to the node, the F1AP signaling comprising no signaling to the second logical mobile IAB-DU; and

a second uplink traffic to routing ID mapping configuration, the configuration being obtained from F1AP signaling to the second logical mobile IAB-DU.

10 . The apparatus according to claim 9 , wherein,

at the node, for the BAP SDU needing to be transmitted in an upstream direction received from the upper layer, the BAP entity further performs the following operation:

for a BAP SDU encapsulating an F1-U packet, if the BAP SDU is from the second logical mobile IAB-DU, selecting a corresponding egress in the configuration of mapping from the second uplink traffic to the routing identity based on a traffic type specifier to which a destination IP address and a tunnel endpoint identity (TEID) corresponds.

11 . An apparatus for transmitting and receiving signals, applicable to a mobile integrated access and backhaul (IAB) node, the apparatus comprising:

second processor circuitry controlling the IAB node to execute the following:

using a default BAP (backhaul adaptation protocol) configuration by a mobile termination (MT) in the node for a first logical mobile IAB distributed unit (IAB-DU) and a second logical mobile IAB distributed unit (IAB-DU) in the node; and

transmitting signals by the mobile termination (MT) in the node based on the default BAP configuration.

12 . The apparatus according to claim 11 , wherein,

the default BAP configuration comprises a default uplink BAP routing identity and a default uplink BH (backhaul) RLC (radio link control) channel.

13 . The apparatus according to claim 12 , wherein,

at the node, for a BAP SDU (backhaul adaptation protocol service data unit) received from an upper layer needing to be transmitted in an upstream direction, a BAP entity performs the following operation:

if an Uplink Traffic to Routing ID Mapping Configuration has not been configured or reconfigured by a F1AP (application protocol) on the logical mobile IAB-DU from which the BAP SDU comes after the RRC (radio resource control) layer configures the default uplink BAP routing identity, selecting a BAP address and a BAP path identity configured by the default uplink BAP routing identity for a non-F1-U packet.

14 . The apparatus according to claim 12 , wherein,

at the node, for a BAP SDU received from an upper layer needing to be transmitted in an upstream direction, after an egress link has been selected, the BAP entity further performs the following operation:

if an Uplink Traffic to BH RLC Channel Mapping Configuration has not been configured or reconfigured by the F1AP on the logical mobile IAB-DU from which the BAP SDU comes after the RRC layer configures the default uplink BH RLC channel, selecting an egress BH RLC channel corresponding to the default uplink BH RLC channel for a non-F1-U packet.

15 . An apparatus for transmitting and receiving signals, applicable to a mobile integrated access and backhaul (IAB) node, the apparatus comprising:

third processor circuitry controlling the IAB node to execute the following:

for data in a downstream direction arriving at the node, determining by the node based on an IP address that the data in the downstream direction are transferred to a first logical mobile IAB distributed unit (IAB-DU) or a second logical mobile IAB distributed unit (IAB-DU) of the node.

16 . The apparatus according to claim 15 , wherein,

the node determines based on a target IP address that the data in the downstream direction are transferred to the first distributed unit (IAB-DU) or the second distributed unit (IAB-DU) of the node.

17 . The apparatus according to claim 16 , wherein the third processor circuitry controls the node to execute the following:

when the node requests an IP address from a donor central unit (donor CU) via RRC (radio resource control), a purpose of usage of the IP address is included, the purpose of usage being used to indicate that the IP address is used by the second distributed unit (IAB-DU).

18 . The apparatus according to claim 17 , wherein,

if an RRC message received by the node contains an assigned IP address and a corresponding purpose of usage is indicated as being used by the second distributed unit (IAB-DU), the node saves the IP address as an IP address of the second IAB-DU.

19 . The apparatus according to claim 16 , wherein,

when a BAP (backhaul adaptation protocol) data protocol data unit (PDU) is received from a lower layer, a reception portion of a BAP entity performs the following:

if a destination field of the BAP data PDU matches with a BAP address configured by an IAB donor providing an egress BH RLC channel, removing a BAP header of the BAP data PDU and submitting the BAP SDU to an upper layer; and

deciding by the upper layer based on the target IP address of the BAP SDU to transfer the BAP SDU to the first distributed unit (IAB-DU) or the second distributed unit (IAB-DU).

20 . The apparatus according to claim 15 , wherein,

the node determines based on a source IP address to transfer the data in the downstream direction to the first distributed unit (IAB-DU) or the second distributed unit (IAB-DU) of the node.