Logical Channel Token Bucket Prioritization for Wireless Traffic Shaping
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Solution Overview
Problem
In wireless systems, high-priority transmissions can negatively impact cell capacity and quality of service for lower priority flows by consuming more network resources than expected, particularly in uplink traffic where the network cannot guarantee adherence to Maximum Data Burst Volume (MDBV) requirements.
Innovation Solution
A wireless transmit/receive unit (WTRU) associates logical channels with both long-term and short-term token buckets, ensuring that transmitted data does not exceed the minimum value between these buckets, and decrements both buckets by the size of MAC service data units served, to manage resource allocation and enforce MDBV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-priority devices transmit more data than expected, then the quality of service for high-priority flows is improved, but the cell capacity and quality of service for lower priority flows deteriorate
Solution Approach 1:
The network pre-configures Maximum Data Burst Volume (MDBV) limits for each logical channel during connection setup. These limits are established in advance to prevent high-priority devices from transmitting excessive data that would starve lower-priority flows, thereby resolving the contradiction between ensuring high-priority QoS and maintaining overall cell capacity
Solution Approach 2:
The system implements feedback mechanisms where the network monitors actual data transmissions from high-priority devices and adjusts scheduling decisions accordingly. When a high-priority device approaches its MDBV limit, the network reduces its allocated resources, preventing it from consuming excessive cell capacity and thereby protecting lower-priority flows while still maintaining acceptable high-priority service quality
2Loss of time
If logical channel prioritization serves high-priority data first, then the delay requirement for high-priority transmissions is satisfied, but the network resources available for lower priority transmissions are reduced
Solution Approach 1:
The system dynamically changes the MDBV parameter based on network conditions and device behavior. When high-priority devices exhibit excessive transmission patterns, the network adjusts their MDBV limits downward, which automatically modulates the amount of resources they can consume while still meeting their delay requirements, thereby preserving resources for lower-priority flows
3Quantity of substance
If the network admits more data flows, then the cell capacity utilization is improved, but the quality of service for individual flows deteriorates due to resource starvation
Solution Approach 1:
The network performs preliminary admission control by evaluating the MDBV configurations of incoming flows against available cell capacity. By pre-calculating whether admitting new flows with their specified MDBV limits would cause resource starvation for existing flows, the network can safely increase capacity utilization while maintaining quality of service guarantees for all admitted flows
Data Source
AI summary
A method performed by a WTRU may comprise associating a logical channel with a plurality of token buckets, including at least a long term token bucket and a short term token bucket. The method may further comprise transmitting logical channel data on the associated logical channel, in a TTI. The transmitted logical channel data of the TTI may be no larger than a value corresponding to a minimum of the long term token bucket and the short term token bucket. The long term token bucket may be initialized to a value which is greater than an initialized value of the short term token bucket. When the WTRU transmits logical channel data in a TTI, the WTRU may decrement the long term token bucket and the short term token bucket by a total size of one or more MAC SDUs served on the associated logical channel.