Managing control plane latency for integrated access and backhaul
Systems and methods of reducing control plane latency in a 5G IAB network are described. SRs transmitted between nodes indicate that a control plane PDU is to be transmitted. The SRs use periodic resources or OCCs reserved for control plane signaling and are initiated by an RRC message or RACH from the UE. The SRs are initiated if the LCID field in the MAC subheader of the RRC message indicates the CCCH or the DCCH logical channel. If the PDU is available after the original resource, a resource is used that is provided via another grant, which is periodically provided or automatically initiated due to failure to transmit on the original grant. The SR or RRC message can also specify a delayed timeslot for the grant. For contention-based procedures the RACH preamble is randomly selected or selected from among a set of RACH preambles assigned for RRC procedures.
1. An apparatus of a first Integrated Access Backhaul (TAB) node in a 5th generation (5G) backhaul network, the apparatus comprising:
processing circuitry configured to:
determine that a first indication has been received from a downstream TAB node, the downstream IAB node having fewer hops to a user equipment (UE) than the first TAB node, the first indication indicating that uplink data is to be transmitted; and
in response to receiving the first indication, encode a second indication for transmission to a parent IAB node, the parent TAB node having more hops to the UE than the first IAB node,
wherein the second indication provides predictive information about data expected to arrive at the first IAB Node.
2. The apparatus of claim 1 , wherein the processing circuitry is further configured to:
decode, from the parent TAB node in response to transmission of the second indication to the parent IAB node, a grant of a parent resource for transmission of the uplink data from the first IAB node to the parent TAB node when the parent resource is a physical uplink shared channel (PUSCH) resource;
decode the uplink data from the downstream TAB node after transmission of the second indication to the parent IAB node; and
in response to reception of the uplink data, encode the uplink data for transmission to the parent IAB node.
3. The apparatus of claim 2 ,
wherein the parent resource is a non-contention based PUSCH resource.
4. The apparatus of claim 1 , wherein the processing circuitry is further configured to:
in response to reception of the first indication from the downstream IAB node, allocate a resource for transmission of the uplink data from the downstream IAB node to the first IAB node; and
encode, for transmission to the downstream IAB node, a grant of the resource prior to transmission of the uplink data to the parent IAB node.
5. The apparatus of claim 1 ,
wherein at least one of the first or second indications is included in a resource request message, and
wherein a logical channel identifier (LCID) field in a medium access control (MAC) subheader of the uplink data indicates a common control channel (CCCH) or dedicated control channel (DCCH) logical channel.
6. The apparatus of claim 5 , wherein the resource request message is a physical layer scheduling request or a buffer status report.
7. The apparatus of claim 1 , wherein:
at least one of the first or second indications is included in a resource request message, and
wherein the processing circuitry is further configured to communicate the indication using resources reserved for the at least one of the first or second indications.
8. The apparatus of claim 1 ,
wherein at least one of the first or second indications is included in a scheduling request (SR), and
wherein the processing circuitry is further configured to communicate the SR using an orthogonal cover code reserved for control plane SRs.
9. The apparatus of claim 1 , wherein:
at least one of the first or second indications is included in a scheduling request (SR) and the SR is initiated based on a radio resource control (RRC) Setup Request.
10. A first Integrated Access Backhaul (IAB) node in a 5th generation (5G) backhaul network, the first IAB node comprising:
a non-transitory computer-readable memory medium; and
processing circuitry configured to:
determine that a first indication has been received from a downstream TAB node, the downstream IAB node having fewer hops to a user equipment (UE) than the first TAB node, the first indication indicating that uplink data is to be transmitted; and
in response to receiving the first indication, encode a second indication for transmission to a parent IAB node, the parent TAB node having more hops to the UE than the first IAB node,
wherein the second indication provides predictive information about data expected to arrive at the first IAB Node, and
wherein the non-transitory computer-readable memory medium is configured to store the first indication.
11. The first TAB node of claim 10 , wherein the processing circuitry is further configured to:
decode, from the parent TAB node in response to transmission of the second indication to the parent IAB node, a grant of a parent resource for transmission of the uplink data from the first IAB node to the parent TAB node when the parent resource is a physical uplink shared channel (PUSCH) resource;
decode the uplink data from the downstream TAB node after transmission of the second indication to the parent IAB node; and
in response to reception of the uplink data, encode the uplink data for transmission to the parent IAB node.
12. The first IAB node of claim 11 ,
wherein the parent resource is a non-contention based PUSCH resource.
13. The first IAB node of claim 10 , wherein the processing circuitry is further configured to:
in response to reception of the first indication from the downstream IAB node, allocate a resource for transmission of the uplink data from the downstream IAB node to the first IAB node; and
encode, for transmission to the downstream IAB node, a grant of the resource prior to transmission of the uplink data to the parent IAB node.
14. The first IAB node of claim 10 ,
wherein at least one of the first or second indications is included in a resource request message, and
wherein a logical channel identifier (LCID) field in a medium access control (MAC) subheader of the uplink data indicates a common control channel (CCCH) or dedicated control channel (DCCH) logical channel.
15. The first IAB node of claim 14 , wherein the resource request message is a physical layer scheduling request or a buffer status report.
16. The first IAB node of claim 10 , wherein:
at least one of the first or second indications is included in a resource request message, and
wherein the processing circuitry is further configured to communicate the indication using resources reserved for the at least one of the first or second indications.
17. A method for operating a first Integrated Access Backhaul (IAB) node in a 5th generation (5G) backhaul network, the method comprising:
determining that a first indication has been received from a downstream IAB node, the downstream IAB node having fewer hops to a user equipment (UE) than the first IAB node, the first indication indicating that uplink data is to be transmitted;
in response to receiving the first indication, encoding a second indication for transmission to a parent IAB node, the parent IAB node having more hops to the UE than the first IAB node, wherein the second indication provides predictive information about data expected to arrive at the first IAB Node; and
storing the first indication in a non-transitory computer-readable memory medium.
18. The method of claim 17 , the method further comprising:
decoding, from the parent IAB node in response to transmission of the second indication to the parent IAB node, a grant of a parent resource for transmission of the uplink data from the first IAB node to the parent IAB node when the parent resource is a physical uplink shared channel (PUSCH) resource;
decoding the uplink data from the downstream IAB node after transmission of the second indication to the parent IAB node; and
in response to reception of the uplink data, encoding the uplink data for transmission to the parent IAB node.
19. The method of claim 18 ,
wherein the parent resource is a non-contention based PUSCH resource.
20. The method of claim 17 , the method further comprising:
in response to reception of the first indication from the downstream IAB node, allocating a resource for transmission of the uplink data from the downstream IAB node to the first IAB node; and
encoding, for transmission to the downstream IAB node, a grant of the resource prior to transmission of the uplink data to the parent IAB node.