Methods for random access channel (RACH) configuration for relay node
Techniques are provided for implementing backhaul communications for an integrated access and backhaul node (IAB) operating in a wireless network. For example, an IAB node determines a first random access channel (RACH) configuration for a child node in the wireless network that is served by the IAB node. The IAB transmits a RACH configuration request message including the first RACH configuration to a parent IAB node, and receives, from the parent IAB node, a second RACH configuration complete message that includes a second RACH configuration that is based on the first RACH configuration for the child node. The IAB then performs backhaul communication with the parent IAB node using the second RACH configuration.
1. A method of operating an integrated access and backhaul (IAB) node in a wireless network, comprising:
determining, at the IAB node, a first random access channel (RACH) configuration for a child node served by the IAB node;
transmitting, by the IAB node, a RACH configuration request message including the first RACH configuration to a parent IAB node;
receiving, from the parent IAB node, a second RACH configuration complete message that includes a second RACH configuration that is based on the first RACH configuration for the child node; and
performing a backhaul communication with the parent IAB node using the second RACH configuration.
2. The method of claim 1 , wherein the first RACH configuration is used for backhaul communication with the child node served by the IAB node, wherein the child node is a second IAB node.
3. The method of claim 1 , wherein the first RACH configuration provides a base RACH configuration, and wherein the second RACH configuration includes one or more RACH extensions defined relative to the base RACH configuration.
4. The method of claim 3 , wherein the one or more RACH extensions include one or more of:
a scaling factor for a periodicity of the base RACH configuration;
a frame offset with respect to a frame index of the base RACH configuration;
a subframe offset with respect to a subframe index of the base RACH configuration; or
a slot offset with respect to a slot index of the base RACH configuration.
5. The method of claim 1 , wherein the child node is a user equipment (UE), the method further comprising performing an access communication with the UE using the first RACH configuration.
6. A method of operating an integrated access and backhaul (IAB) node in a wireless network, comprising:
receiving, at the IAB node, a first broadcast message from a parent IAB node that includes a first random access channel (RACH) configuration to be used for backhaul communication between the IAB node and the parent IAB node;
determining, by the IAB node, a second RACH configuration based on the first RACH configuration;
transmitting, by the IAB node, a second broadcast message that includes the second RACH configuration to a child IAB node that is served by the IAB node;
performing a backhaul communication with the parent IAB node using the first RACH configuration;
performing a backhaul communication with the child IAB node using the second RACH configuration; and
performing an access link communication with the child IAB node using the second RACH configuration.
7. The method of claim 6 , wherein the first RACH configuration provides a base RACH configuration, and wherein the second RACH configuration includes one or more RACH extensions defined relative to the base RACH configuration.
8. The method of claim 7 , wherein the one or more RACH extensions include one or more of:
a scaling factor for a periodicity of the base RACH configuration;
a frame offset with respect to a frame index of the base RACH configuration;
a subframe offset with respect to a subframe index of the base RACH configuration; or
a slot offset with respect to a slot index of the base RACH configuration.
9. The method of claim 6 , further comprising:
determining a third RACH configuration for a user equipment (UE) served by the IAB node; and
performing access communications with the UE using the third RACH configuration.
10. The method of claim 6 , wherein at least one of the first broadcast message or the second broadcast message is a system information block (SIB) message.
11. The method of claim 6 , wherein the parent IAB node is an upstream IAB node of the IAB node.
12. The method of claim 6 , further comprising transmitting the second broadcast message that includes the second RACH configuration to the child IAB node via system information block type 1 (SIB 1 ).
13. The method of claim 6 , wherein determining the second RACH configuration based on the first RACH configuration further comprises:
determining a half-duplex constraint of the first RACH configuration; and
determining the second RACH configuration based on the half-duplex constraint.
14. The method of claim 6 , further comprising receiving the first broadcast message from the parent IAB node via system information.
15. An integrated access and backhaul (IAB) apparatus, comprising:
radio front end circuitry configured to perform wireless communication over a wireless network; and
processor circuitry, coupled to the radio front end circuitry, configured to:
determine a first random access channel (RACH) configuration for a child node served by the IAB apparatus;
transmit, using the radio front end circuitry, a RACH configuration request message including the first RACH configuration to a parent IAB node;
receive, from the parent IAB node, a second RACH configuration complete message that includes a second RACH configuration that is based on the first RACH configuration for the child node; and
perform, using the radio front end circuitry, a backhaul communication with the parent IAB node using the second RACH configuration.
16. The IAB apparatus of claim 15 , wherein the first RACH configuration is used for backhaul communication with the child node served by the IAB apparatus, wherein the child node is a second IAB node.
17. The IAB apparatus of claim 15 , wherein first RACH configuration provides a base RACH configuration, and wherein the second RACH configuration includes one or more RACH extensions defined relative to the base RACH configuration.
18. The IAB apparatus of claim 17 , wherein the one or more RACH extensions include one or more of:
a scaling factor for a periodicity of the base RACH configuration;
a frame offset with respect to a frame index of the base RACH configuration;
a subframe offset with respect to a subframe index of the base RACH configuration; or
a slot offset with respect to a slot index of the base RACH configuration.
19. The IAB apparatus of claim 15 , wherein the child node is a user equipment (UE), and wherein the processor circuitry is further configured to perform access communication with the UE using the first RACH configuration.