Fair Congestion Detection in WCDMA Transport Networks
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Solution Overview
Problem
In WCDMA radio access networks, HSPA's increased air interface capacity leads to congestion issues due to inefficient bandwidth reservation, as the transport network capacity often lags behind, causing unfair bandwidth distribution among data packet flows, which existing TCP and RLC protocols fail to address effectively.
Innovation Solution
Implementing a flow control mechanism in RNC and Node B to detect and manage congestion by monitoring packet loss and delay, communicating congestion information among affected flows, and adjusting bit rates to ensure fair sharing of transport network resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If HSPA is introduced to improve air interface bit rate, then communication speed is improved, but transport network congestion increases and bandwidth distribution becomes unfair
Solution Approach 1:
The patent implements feedback mechanisms where Node Bs monitor transport network conditions and send congestion indication information back to RNCs and UEs. This feedback loop enables dynamic adjustment of transmission parameters based on actual network conditions, resolving the contradiction between high speed and efficient capacity utilization.
Solution Approach 2:
The patent introduces dynamic flow control mechanisms that allow bit rate adjustment on a per-flow basis. The system transitions from static bandwidth allocation to dynamic allocation where flows can adjust their transmission rates in real-time based on congestion conditions, enabling both high speed and fair resource sharing.
2Device complexity
If existing TCP and RLC protocols are used for data transmission, then protocol simplicity is maintained, but congestion detection and fair bandwidth distribution fail
Solution Approach 1:
The patent segments the congestion control function from the existing TCP/RLC protocols by introducing a separate flow control mechanism at the Node B level. This segmentation allows congestion detection and fair bandwidth distribution to be implemented as an additional layer without fundamentally redesigning the existing protocol stack.
Solution Approach 2:
The patent introduces flow control entities at Node Bs as intermediary components between the transport network and radio access network. These intermediaries perform congestion detection and bit rate adjustment, bridging the gap between simple protocols and the need for sophisticated congestion management.
3Productivity
If transport network capacity is increased to match HSPA capabilities, then network throughput is improved, but network infrastructure cost increases
Solution Approach 1:
The patent implements preliminary flow control and congestion prevention mechanisms that allow the transport network to operate efficiently without requiring immediate infrastructure expansion. By proactively managing congestion through flow control entities and congestion indication protocols, the system maximizes existing infrastructure capacity before additional investment is needed.
Data Source
AI summary
Congestion is detected in a radio access transport network including one or more radio network controllers each coupled to one or more radio base stations. Multiple data packet flows are each associated with a mobile radio terminal communication, and each flow is controlled in the radio access transport network by a corresponding flow control entity. They are monitored for congestion in the transport network. If a congestion area in the transport network is detected for one of the monitored data packet flows, then a determination is made whether other monitored data packet flows share the detected congestion area. Congestion notification information is communicated to the flow control entities corresponding to the other monitored data packet flows that share the detected congestion area. Based on the congestion notification information, the informed flow control entities may take a flow control action, e.g., to enable fair sharing of communications resources in the transport network.