Dynamic Sequence Number Range Management in RLC Entities
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Solution Overview
Problem
The current Radio Link Control (RLC) protocol in LTE networks faces limitations due to the 10-bit sequence number (SN) range, leading to window stall phenomena, which restricts data throughput and is inadequate for higher peak rates and frequent Service Data Units over Signaling Radio Bearers, especially with the evolving LTE standards and Carrier Aggregation.
Innovation Solution
A method to dynamically manage the SN range by monitoring send state variables and transmitting control messages to adjust the SN range based on utilization, allowing for increased capacity during high data throughput needs and reducing it when not required, thereby minimizing protocol overhead and avoiding window stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the SN range is increased to support high data throughput and prevent window stalls, then the throughput capacity is improved, but the protocol overhead increases
Solution Approach 1:
The patent implements dynamic adjustment of the SN range size based on real-time monitoring of send state variables (VT(S) and VT(MS)). The transmitting node continuously monitors the difference between these variables and compares it against thresholds to determine when to increase or decrease the SN range, allowing the system to adapt to varying throughput demands and minimize overhead when high throughput is not required
Solution Approach 2:
The patent changes the SN range parameter (from 10 bits to 16 bits and vice versa) based on the utilization level detected through send state variable monitoring. When the difference between VT(MS) and VT(S) exceeds a threshold, indicating high throughput needs, the SN range is expanded to 16 bits to prevent window stalls. When utilization is low, the SN range is reduced to 10 bits to minimize protocol overhead
2Adaptability or versatility
If the SN range is dynamically adjusted, then the adaptability to varying throughput demands is improved, but the device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the transmitting node monitors send state variables (VT(S) and VT(MS)) and uses this information to trigger control messages that adjust the SN range. The receiving node also participates by sending feedback about its buffer status, enabling the transmitting node to make informed decisions about when to increase or decrease the SN range to prevent window stalls
Solution Approach 2:
The patent uses send state variables VT(S) and VT(MS) to predict when the SN range will be exhausted and takes preliminary action by transmitting control messages to adjust the SN range before the window stall actually occurs. This proactive approach prevents throughput degradation rather than reacting after the problem manifests
Data Source
Figure 1~2B
Figure 2C~3A
Figure 3B~4
AI summary
It is presented a method for managing a sequence number (SN) range for radio link control (RLC) entities in a radio access network (5) during an on-going connection. The method is performed in a transmitting node (4) of the radio access network and comprises the steps of: monitoring (60) send state variables for a transmission window; determining (61) to change the SN range based on the send state variables; and transmitting (62) a control message when the SN range is determined to change. It is also presented a transmitting node, a receiving node, a method performed in a receiving node, a computer program and a computer program product.