It's been a while since I last wrote about IAB on this blog
here. At that time 3GPP Release-16 was being discussed. Since then things have moved on. While Release-16 is being prepared for final release soon, Release-17 study and work items have just been agreed
upon.
IAB is included as part of Rel-16 but there isn't a comprehensive document or presentation easily available to details all that it will contain. Similarly the enhancements for Release-17 are available only superficially. Qualcomm is well known for making some really excellent presentations available on 5G. One of their presentations from January (
here) has some details on IAB (pg. 32 - 35). There was also an excellent presentation by Navid Abedini, Qualcomm from IEEE Sarnoff Symposium, 2019 which is embedded at the end.
In a 3GPP RAN#84 discussion document RP-191181, Samsung has provided a comprehensive summary of what is being done as part of Rel-16 and what did not make in that:
- Rel-16 IAB aims at basic operations
- Architecture and protocol design
- IAB integration procedure
- Routing, BAP and BH configuration
- CP and UP data transmission via IAB
- Topology support:
- Spanning Tree (ST) and Directed acyclic graph (DAG)
- Intra-Donor adaptation is prioritized
- The following cannot be supported in Rel-16
- Mobile IAB
- Topology support: Mesh
- Some functionalities in Rel-16 may not be completed due to time constrains e.g.
- Topology adaptation between IAB donors
- Mechanisms for efficient control signaling transmission
Ericsson also provides a good summary in RP-190971 regarding Release 16 IAB and Rel-17 enhancements:
- IAB Rel-16 provide basic support for multi-hop and multi-path relaying.
- The solution supports
- QoS prioritization of traffic on the backhaul link
- Flexible resource usage between access and backhaul
- Topology adaptivity in case link failure
- In Rel-17 it would be possible to further evolve the IAB solution targeting increased efficiency and support for new use cases
Meanwhile in the recently concluded RAN#86, AT&T provided a good detailed summary on what enhancements are required for IAB as part of Rel-17 in RP-192709
- Duplexing enhancements
- Multiplexing beyond TDM (FDM/SDM/multi-panel Tx/Rx) including multi-parent scenarios, case 6/7 timing alignment, power control/CLI optimizations
- Topology enhancements
- Mobile IAB: CP/UP split + Group mobility
- Inter-CU topology adaptation
- Mesh-connectivity between IAB nodes for local control/user plane routing
- User plane enhancements
- Multi-hop scheduling enhancement – exchange of benefit metric between IAB nodes to enable radio-aware multi-hop scheduling to improve throughput performance
- Network Coding
- Study benefits compared to duplication over redundant backhaul routes
We will have to wait and see what makes it into the enhancements and what don't. Meanwhile here is a video from Navid Abedini, Qualcomm from IEEE Sarnoff Symposium, 2019
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