Systems and methods for multi-hop configurations in iab networks for reduced latency
Multi-hop configurations in integrated Access and Backhaul (IAB) networks are provided for reduced latency. For modifications to a backhaul adaptation protocol (BAP) header supports faster data radio bearer (DRB) transmissions. Or, for both signaling radio bearer (SRB) and DRB flows, configuration forwarding may be used to reduce configuration latency wherein a single RRCReconfiguration message is forwarded to intermediate nodes that process the configuration and respond back independently. Alternatively, for both SRB and DRB flows, configuration multi-casting may be used for simultaneous IAB node and backup configurations. Methods are provided for fast activation of backup links in IAB nodes.
1 . A method for backhaul radio link control (RLC) channel establishment using a backhaul adaptation protocol (BAP) in a wireless network, the method comprising:
generating, at a donor Integrated Access and Backhaul (IAB) node, a BAP protocol data unit (PDU) comprising a BAP header including a first field comprising a destination field, a second field comprising a path field, and a third field comprising a bit configured to indicate whether the destination field comprises a unicast address or a multicast address;
generating, at the donor IAB node, a multicast radio resource control (RRC) reconfiguration message comprising the BAP PDU;
in response to sending the multicast RRC reconfiguration message, processing, at the donor IAB node, a separate unicast RRC reconfiguration complete message received from each of a plurality of IAB nodes using the BAP;
in response to processing the separate unicast RRC reconfiguration complete message received from each of the plurality of IAB nodes, sending a unicast RRC reconfiguration message to a user equipment (UE) in communication with one of the plurality of IAB nodes;
processing an RRC reconfiguration complete message from the UE; and
in response to the RRC reconfiguration complete message from the UE, sending, from the IAB donor node, a PDU session setup complete message to a core network.
2 . The method of claim 1 , further comprising setting the bit to indicate to the plurality of IAB nodes to treat an address in the destination field as the multicast address for a path identifier in the path field of the BAP header.
3 . The method of claim 2 , further comprising:
grouping the plurality of IAB nodes into a subnet corresponding to a subnet prefix; and
including the subnet prefix in the destination field of the BAP header.
4 . The method of claim 1 , further comprising:
generating the BAP PDU in response to a PDU session setup request from the core network.
5 . The method of claim 4 , wherein the plurality of IAB nodes comprises a first IAB node for a priority link in a first backhaul path between the UE and the core network and a second IAB node for a backup link in a second backhaul path between the UE and the core network.
6 . A method for backhaul radio link control (RLC) channel establishment using radio resource configuration (RRC) reconfiguration with multicasting, the method comprising:
configuring an Integrated Access and Backhaul (IAB) donor node and one or more child IAB nodes as a subnet;
generating, at the IAB donor node, a multicast reconfiguration message to send to the one or more child IAB nodes of the subnet, the multicast reconfiguration message comprising an information element (IE) for the subnet including configuration settings for the backhaul RLC channel establishment, the IE identifying the subnet to indicate to the IAB donor node and the one or more child IAB nodes with Internet Protocol (IP) addresses associated with the subnet to apply the configuration settings;
in response to sending the multicast reconfiguration message, processing a separate unicast reconfiguration complete message received from each of the one or more child IAB nodes of the subnet;
in response to IAB node failure at an end node of the one or more child IAB nodes, receiving, from the end node of the one or more child IAB nodes, a unicast reconfiguration complete message, wherein the unicast reconfiguration complete message comprises an identifier (ID) corresponding to the end node; and
resending the reconfiguration message to the end node.
7 . The method of claim 6 , wherein the configuration settings are for a one-to-one (1-1) or a many-to-one (many-1) mapping configuration of the RLC for the IAB.
8 . An apparatus comprising:
one or more processors; and
one or more non-transitory computer-readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform backhaul radio link control (RLC) channel establishment using a backhaul adaptation protocol (BAP) in a wireless network, the one or more processors configured to:
generate, at a donor Integrated Access and Backhaul (IAB) node, a BAP protocol data unit (PDU) comprising a BAP header including a first field comprising a destination field, a second field comprising a path field, and a third field comprising a bit configured to indicate whether the destination field comprises a unicast address or a multicast address;
generate, at the donor IAB node, a multicast radio resource control (RRC) reconfiguration message comprising the BAP PDU; and
in response to sending the multicast RRC reconfiguration message, process, at the donor IAB node, a separate unicast RRC reconfiguration complete message received from each of a plurality of IAB nodes using the BAP;
in response to processing the separate unicast RRC reconfiguration complete message received from each of the plurality of IAB nodes, send a unicast RRC reconfiguration message to a user equipment (UE) in communication with one of the plurality of IAB nodes;
process an RRC reconfiguration complete message from the UE; and
in response to the RRC reconfiguration complete message from the UE, send, from the IAB donor node, a PDU session setup complete message to a core network.
9 . The apparatus of claim 8 , wherein the one or more processors are further configured to set the bit to indicate to the plurality of IAB nodes to treat an address in the destination field as the multicast address for a path identifier in the path field of the BAP header.
10 . The apparatus of claim 9 , wherein the one or more processors are further configured to:
group the plurality of IAB nodes into a subnet corresponding to a subnet prefix; and
include the subnet prefix in the destination field of the BAP header.
11 . The apparatus of claim 8 , wherein the one or more processors are further configured to:
generate the BAP PDU in response to a PDU session setup request from the core network.
12 . The apparatus of claim 11 , wherein the plurality of IAB nodes comprises a first IAB node for a priority link in a first backhaul path between the UE and the core network and a second IAB node for a backup link in a second backhaul path between the UE and the core network.