Relay Node Congestion Handling in Multi-Hop RAN Backhaul
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Solution Overview
Problem
In Radio Access Networks (RAN), multi-hop backhaul architectures face congestion issues due to reduced link capacities, leading to packet dropping and inefficiencies in data transmission, as intermediate nodes experience buffer overflow conditions without effective flow control mechanisms.
Innovation Solution
The implementation of a congestion handling mechanism where relay nodes detect downlink or uplink congestion and generate indications to donor or serving nodes, allowing these nodes to limit data transmission rates or alter prioritization for affected UE bearers or backhaul RLC channels, using end-to-end or hop-by-hop communication protocols to manage buffer limitations and prevent packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-hop backhaul is enabled via intermediate nodes, then network coverage and connectivity are improved, but congestion and packet dropping occur at intermediate nodes
Solution Approach 1:
The patent implements a feedback mechanism where the relay node monitors its buffer status and sends buffer status reports to the donor node. When the buffer becomes full or approaches full capacity, the relay node notifies the donor node, which then adjusts or stops data transmission to prevent buffer overflow and packet dropping. This closed-loop feedback system resolves the contradiction by enabling the network to adapt transmission rates based on actual buffer conditions at intermediate nodes.
Solution Approach 2:
The relay node autonomously monitors its own buffer status and generates buffer status reports when needed, without requiring external intervention. The node independently detects congestion conditions and initiates communication with the donor node to adjust data flow, enabling self-service congestion management that maintains reliable packet delivery while preserving multi-hop backhaul functionality.
2Productivity
If data transmission rate is increased to improve productivity, then network throughput is improved, but buffer overflow and packet dropping occur at relay nodes
Solution Approach 1:
The patent implements dynamic data rate adjustment where the donor node modifies the data transmission rate to the relay node based on real-time buffer status reports. When the relay node's buffer is nearly full, the donor node reduces or stops data injection. When buffer space is available, normal transmission resumes. This dynamic adaptation resolves the contradiction by allowing high throughput when conditions permit while preventing buffer overflow when the relay node is congested.
Solution Approach 2:
The relay node proactively sends buffer status reports before buffer overflow occurs, enabling the donor node to take preliminary anti-action by reducing or stopping data transmission in advance. This preventive approach avoids buffer overflow and packet dropping while maintaining high productivity during normal operating conditions, resolving the contradiction between throughput and reliability.
3Reliability
If flow control mechanism is implemented to prevent buffer overflow, then packet delivery reliability is improved, but data transmission efficiency decreases
Solution Approach 1:
The patent implements an efficient feedback mechanism where the relay node sends buffer status reports to the donor node, which then adjusts data transmission accordingly. This targeted feedback approach maintains high data transmission efficiency by only intervening when necessary (when buffer status indicates potential overflow), rather than continuously throttling transmission. The system achieves both reliability and efficiency by using intelligent feedback to enable the donor node to maintain high throughput during normal conditions while preventing buffer overflow when needed.
Data Source
AI summary
Provided herein is an apparatus and a method for congestion handling in RAN. The disclosure provides an apparatus for a relay node in a RAN including the relay node and a donor node providing an interface to a core network and a backhaul link to the relay node. The apparatus includes a RF interface to receive and transmit downlink data for one or more UEs or UE bearers; and a processing circuitry coupled with the RF interface. The processing circuitry is to determine a downlink congestion occurs at the relay node; and generate a downlink congestion indication to identify a UE or a UE bearer or a backhaul RLC channel affected by the downlink congestion. The RF interface is to transmit the downlink congestion indication to the donor node. In addition to the downlink congestion handling, the relay node can also be to handle uplink congestion in a similar way.