Packet Scheduling Using Slack Time for Wireless Multimedia QoS
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Solution Overview
Problem
The integration of 3G cdma2000 1xEV-DO wireless networks with IP networks results in suboptimal resource allocation due to misalignment between Proportional Fairness and Weighted Fair Queuing scheduling algorithms, leading to excessive delays and unfair prioritization of packets, particularly affecting lower priority users.
Innovation Solution
Incorporating the concept of slack time into packet scheduling algorithms, such as Weighted Fair Queuing and Proportional Fairness, to reorder packets based on their remaining delivery time budget, ensuring timely delivery and optimizing resource allocation across hybrid wireline-wireless networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Proportional Fairness scheduling is used in wireless networks to maximize system throughput, then overall network capacity is improved, but packet delivery delay increases for time-sensitive applications
Solution Approach 1:
The patent applies preliminary action by calculating and tagging packets with slack time values before scheduling decisions are made. This allows the scheduler to proactively identify packets that are close to their deadline and prioritize them before delays occur, rather than reacting after delays have happened. The slack time calculation is performed in advance based on packet arrival time and deadline, enabling proactive scheduling adjustments.
Solution Approach 2:
The patent implements dynamics by making the scheduling algorithm adaptive based on real-time slack time conditions. The scheduler dynamically adjusts packet prioritization based on current slack time values, which change as packets approach their deadlines. This dynamic adjustment allows the system to balance throughput optimization with delay constraints, switching between different scheduling behaviors based on the urgency of pending packets.
2Speed
If Weighted Fair Queuing is used in IP networks to minimize average flow delay, then packet delivery speed is improved, but resource allocation fairness deteriorates for mixed traffic types
Solution Approach 1:
The patent applies local quality by treating different packets differently based on their individual slack time characteristics rather than applying a uniform scheduling policy to all packets. Packets with critical deadlines receive different (higher) priority treatment compared to packets with abundant slack time. This localized differentiation allows the system to optimize delivery speed for urgent packets while maintaining fair resource allocation for less urgent traffic.
Solution Approach 2:
The patent implements parameter changes by introducing slack time as a new scheduling parameter that modifies the traditional WFQ weight-based prioritization. Instead of solely relying on fixed weights for different traffic classes, the system dynamically adjusts scheduling decisions based on the slack time parameter, which reflects the remaining time budget for each packet. This parameter change enables the scheduler to adapt resource allocation fairness to the actual urgency of each packet.
3Ease of operation
If packets are scheduled based on fixed priority queues, then scheduling simplicity is improved, but delay optimization deteriorates for packets with varying deadline requirements
Solution Approach 1:
The patent applies self-service by having each packet carry its own slack time information (computed from its deadline and arrival time) that automatically guides its scheduling priority. The scheduler does not need complex external control or manual configuration for each packet type; instead, packets essentially schedule themselves based on their inherent deadline characteristics encoded in their slack time values. This maintains scheduling simplicity while achieving delay optimization.
Data Source
AI summary
Packet communication networks for transmission to wireless subscriber devices utilize both wireline and wireless packet routing components. The routing elements of these two different types often implement different packet scheduling algorithms, typically a form of Weighted Fair Queuing (WFQ) in the wireline portion of the network and Proportional Fairness (PF) queuing in the wireless domain. To improve resource allocation and thus end to end quality of service for time sensitive communications, such as integrated multimedia services, the present disclosure suggests adding the notion of slack time into either one or both of the packet scheduling algorithms. By modifying one or more of these algorithms, e.g. to reorder or shuffle packets based on slack times, global optimal resource allocations are possible, at least in certain cases.