Preemptive Cross-Layer Signaling for 5G Transport Optimization
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Solution Overview
Problem
In 5G networks, the increased buffer size and reordering timer at the NR-L2 layer, combined with the use of mmWave technology, lead to redundant data retransmissions due to the TCP congestion control mechanism's inability to adapt to dynamically changing radio conditions, resulting in performance issues such as poor throughput, latency, and power consumption.
Innovation Solution
Implementing preemptive cross-layer signaling between the NR L2 and NR L3 receivers to optimize the transport layer by requesting buffer status, inspecting data packets, enabling/disabling transport layer optimization, and managing retransmission timeouts and round trip times, thereby avoiding duplicate data packet transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the buffer size and reordering timer at NR-L2 layer are increased to handle mmWave radio conditions, then the ability to buffer data packets is improved, but redundant data retransmissions occur due to TCP congestion control mechanism inability to adapt
Solution Approach 1:
The patent applies preliminary action by having the NR-L2 layer proactively inform the TCP layer about buffered packet status before TCP retransmission timeout occurs. The NR-L2 layer sends signaling information to the TCP layer indicating which packets are already buffered, allowing the TCP layer to avoid initiating redundant retransmissions for packets that are already in the NR-L2 buffer.
Solution Approach 2:
The patent implements feedback by establishing a communication mechanism where the NR-L2 layer provides status information back to the TCP layer about buffered packets. This feedback loop allows the TCP congestion control mechanism to adapt to the actual buffer status, preventing it from unnecessarily retransmitting packets that are already buffered at the NR-L2 layer.
2Duration of action of stationary object
If the reordering timer value is increased to accommodate buffer size, then packet reordering capability is improved, but latency increases affecting ultra-low latency services
Solution Approach 1:
The patent applies dynamics by making the reordering timer value adaptable rather than fixed. The timer value is adjusted dynamically based on the actual buffer status and packet arrival patterns. When packets are already buffered, the effective reordering time is reduced, allowing the system to maintain ultra-low latency while still handling reordering when necessary.
Solution Approach 2:
The patent uses preliminary action by having the NR-L2 layer prepare and hold packets in the buffer before the reordering timer expires. This allows packets to be ready for immediate transmission once reordering is complete, reducing the actual latency impact of the reordering process while maintaining the necessary timer value for proper packet ordering.
3Reliability
If TCP congestion control mechanism is used to manage data transmission, then network congestion is controlled, but it cannot adapt to dynamically changing mmWave radio conditions
Solution Approach 1:
The patent introduces the NR-L2 layer as an intermediary between the TCP congestion control mechanism and the mmWave radio interface. The NR-L2 layer receives congestion control instructions from TCP, manages the actual buffer and packet transmission, and provides feedback about buffer status. This intermediary role allows the system to maintain TCP's reliable congestion control while adapting to rapid mmWave radio condition changes through the NR-L2 layer's direct control over packet buffering and transmission timing.
4Reliability
If NR-L2 layer recovers missing packets using ARQ, then packet loss is reduced, but TCP RTO triggers retransmission of already received packets
Solution Approach 1:
The patent implements feedback by having the NR-L2 layer continuously inform the TCP layer about which packets are already buffered and recovered. When the NR-L2 layer successfully recovers missing packets using ARQ, it sends this status information to the TCP layer, which then updates its retransmission decisions accordingly, avoiding unnecessary retransmissions of already recovered packets.
Solution Approach 2:
The patent applies preliminary action by having the NR-L2 layer recover and buffer packets using ARQ before the TCP retransmission timeout occurs. This preliminary recovery action ensures that packets are already available in the buffer when TCP checks for retransmission needs, preventing duplicate retransmissions and maintaining high throughput.
Data Source
AI summary
The embodiments herein achieve a method and a UE for enabling a transport layer optimization using a preemptive cross layer signaling. The method includes transmitting at least one information to the NR L2 receiver for the transport layer optimization for a data flow(s). The at least one information includes at least one of a configuration for requesting a buffer status of the NR L2 receiver, a policy to inspect data packets of the data flow(s), a configuration for enabling or disabling the transport layer optimization, a retransmission timeout (RTO) and a round trip time (RTT) of the data flow(s), an impending RTO value of the data flow(s) and a threshold value of a buffer size. Further, the method includes enabling the transport layer optimization based on the at least one information received from the NR L3 receiver to avoid receiving of duplicate data packets from a TCP sender.