Split RLC Protocol Stack for Multi-Carrier SMART Networks
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Solution Overview
Problem
Carrier aggregation in wireless systems is limited in Seamless Macro-cell Anchored Radio Transmission (SMART) networks due to non-colocated carriers and high latency between nodes, preventing concurrent transmission over multiple carriers for individual radio bearers.
Innovation Solution
A split Radio Link Control (RLC) protocol stack is implemented, with an upper RLC layer handling packet data transmission across multiple carriers and multiple lower RLC layers operating on geographically separated network nodes, enabling efficient packet data transmission and retransmission while accommodating higher backhaul latencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is implemented with co-located carriers and tight coordination, then concurrent transmission over multiple carriers is achieved, but device complexity and network coordination requirements increase significantly
Solution Approach 1:
The RLC layer is segmented into upper and lower RLC entities, with the upper RLC entity handling multiple carriers and lower RLC entities handling individual carriers. This segmentation allows each entity to operate independently with simpler coordination requirements while maintaining the functionality of concurrent multi-carrier transmission.
Solution Approach 2:
The upper RLC entity acts as an intermediary between the network layer and multiple lower RLC entities. It receives data from upper layers, segments it into PDUs, and distributes them to appropriate lower RLC entities for transmission over different carriers, thereby simplifying the coordination architecture.
2Adaptability or versatility
If carriers are non-colocated in SMART networks, then network flexibility and deployment ease improve, but concurrent transmission over multiple carriers for individual radio bearers cannot be implemented
Solution Approach 1:
The RLC layer is divided into upper and lower entities that can be distributed across geographically separated network nodes. The upper RLC entity maintains the radio bearer context while lower RLC entities handle carrier-specific transmission, enabling concurrent transmission over non-colocated carriers in SMART networks.
Solution Approach 2:
The upper RLC entity is designed to handle multiple carriers universally, providing a common interface for data distribution across different carriers and network nodes. This multi-functional design allows the same entity to support both co-located and non-colocated carrier scenarios.
3Reliability
If tight coordination among carriers is maintained, then carrier aggregation performance is optimized, but latency increases in geographically separated network nodes
Solution Approach 1:
The RLC functionality is segmented such that the upper RLC entity performs segmentation and distribution of data packets, while lower RLC entities handle local transmission and retransmission. This segmentation reduces the need for constant coordination between geographically separated nodes, thereby reducing backhaul latency while maintaining reliability through the distributed retransmission capability.
Data Source
AI summary
Various methods and apparatuses are provided to address the need for improved multi-carrier communication. In one apparatus, a radio access network (RAN) (402) includes multiple network nodes (403, 406) operative to transmit, via multiple carriers (411-412), packet data to a user element (UE) (401) using a protocol stack. The protocol stack includes a radio link control (RLC) layer split into an upper RLC processing layer and multiple lower RLC processing layers. Each lower RLC processing layer is associated with one carrier of the multiple carriers and each lower RLC processing layer supports packet data transmission via its associated carrier. The upper RLC processing layer supports packet data transmission via the multiple carriers.