PDCP-RLC Credit Feedback for Bursty Wireless Traffic
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems face challenges in managing packet flows to prevent packet drops when dealing with bursty traffic, particularly between the packet data convergence protocol (PDCP) and radio link control (RLC) sublayers.
Innovation Solution
Implementing a flow management process where the RLC sublayer tracks and decrements credits as packets are received, and proactively sends new credits to the PDCP sublayer when the tally of unredeemed credits falls below a threshold, allowing for a buffer to accommodate bursty traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RLC sublayer continuously allocates credits to the PDCP sublayer, then the PDCP sublayer has sufficient buffer capacity, but packet drops increase due to excessive credit allocation
Solution Approach 1:
The RLC sublayer implements a feedback mechanism by tracking redeemed credits and dynamically adjusting credit allocation based on actual packet reception. The system monitors the difference between allocated and redeemed credits, and only allocates additional credits when the unredeemed credit balance falls below a threshold, preventing both packet drops and excessive allocation.
Solution Approach 2:
The system performs preliminary tracking of credit redemption status before allocating new credits. By monitoring the unredeemed credit balance in advance and only triggering new credit allocation when the threshold is breached, the system prevents packet drops while avoiding excessive credit allocation that would cause packet loss.
2Adaptability or versatility
If the PDCP sublayer maintains a large credit buffer, then bursty traffic can be accommodated, but the system complexity increases
Solution Approach 1:
The system dynamically adjusts the credit buffer parameter based on actual traffic conditions. Instead of maintaining a large fixed buffer, the system changes the effective buffer size by allocating credits only when needed, based on the threshold of unredeemed credits. This allows adaptation to bursty traffic while keeping the management logic simple.
Solution Approach 2:
The credit allocation system transitions from a static large buffer approach to a dynamic credit-based mechanism. The RLC sublayer dynamically tracks redeemed credits and adjusts credit allocation in real-time based on the threshold condition, enabling the system to adapt to varying traffic patterns without increasing operational complexity.
3Productivity
If the RLC sublayer sends credits proactively, then bursty traffic is prepared for, but unnecessary credits are sent reducing efficiency
Solution Approach 1:
The RLC sublayer uses feedback from tracking redeemed credits to determine when proactive credit sending is necessary. By monitoring the unredeemed credit balance and only triggering new credit allocation when the threshold is breached, the system sends credits proactively only when needed, avoiding unnecessary transmissions while preparing for bursty traffic.
Data Source
AI summary
Flow control assistance for bursty traffic in a wireless communication system contemplates a radio link control (RLC) sublayer that may control credits issued to a packet data convergence protocol (PDCP) sublayer to control how many packets the PDCP sublayer may send to the RLC sublayer. As the PDCP sublayer sends packets to the RLC sublayer, the PDCP sublayer tracks (and decrements) an internal count of available (unredeemed) credits. Concurrently, the RLC sublayer tracks (and decrements) issued credits as packets are received (effectively redeemed) at the RLC sublayer from the PDCP sublayer. When the tally of unredeemed credits falls below a threshold, the RLC sublayer issues new credits, which the PDCP sublayer adds to its internal tally. Further, the RLC sublayer may have an inactivity timer which causes some credits (up to a calculated maximum) to be sent to the PDCP sublayer even if the threshold has not been passed.