Time-Scalable Priority-Based Scheduler for CDMA Capacity
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Solution Overview
Problem
In CDMA communication systems, long scheduling durations lead to inefficient capacity utilization, as mobile stations with small data buffers are unable to transmit at high rates for extended periods, increasing the probability of data-limited disable transmissions and resulting in large average packet delays.
Innovation Solution
A time-scalable priority-based scheduler that dynamically adjusts scheduling durations based on buffer depth and available power, allowing mobile stations to transmit data at variable rates for scheduled durations, maximizing system capacity utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If long scheduling durations are used in CDMA communication systems, then system stability and resource allocation efficiency are improved, but mobile stations with small data buffers cannot transmit at high rates, leading to increased data-limited disable transmissions and larger average packet delays
Solution Approach 1:
The patent implements dynamic scheduling durations that adapt to mobile station conditions. The base station determines scheduling duration based on buffer depth, channel quality, and service type, allowing short durations for small buffers and long durations for large buffers. This dynamic adjustment resolves the contradiction by making the scheduling system flexible rather than fixed, enabling high rates when needed while maintaining stability when appropriate.
Solution Approach 2:
The patent changes the scheduling duration parameter based on system state. Different parameters (buffer depth, C/I ratio, service type) trigger different scheduling duration values. This parameter adaptation allows the system to optimize between stability and delay by selecting appropriate scheduling durations for different operational contexts, directly addressing the contradiction.
2Productivity
If long scheduling durations are assigned, then capacity utilization improves through reduced scheduling overhead, but mobile stations with insufficient data experience data-limited disable transmissions, reducing effective capacity utilization
Solution Approach 1:
The scheduling duration is dynamically adjusted based on the mobile station's data buffer status. When buffer depth is low, shorter scheduling durations are assigned to prevent data-limited disable transmissions. When buffer depth is high, longer scheduling durations are assigned to improve capacity utilization. This dynamic adaptation resolves the contradiction by matching scheduling duration to actual data availability.
Solution Approach 2:
The base station receives feedback about mobile station buffer status and channel conditions, then adjusts scheduling duration accordingly. This feedback mechanism enables the system to avoid assigning long scheduling durations to stations with small buffers, preventing data-limited disable transmissions while maintaining high capacity utilization for stations with sufficient data.
3Productivity
If high data rates are transmitted, then system throughput is improved, but power consumption increases and may exceed mobile station power availability
Solution Approach 1:
The patent adjusts the data rate parameter based on available power. The base station considers mobile station power status when determining the scheduled data rate, selecting rates that achieve high throughput when power is available while reducing rates when power is constrained. This parameter adaptation resolves the contradiction between throughput and power consumption.
Solution Approach 2:
The system dynamically adjusts transmission parameters including data rate and scheduling duration based on power availability. When power is abundant, higher rates and longer durations are used to maximize throughput. When power is limited, the system reduces rates and adjusts durations to maintain sustainable operation, resolving the throughput-power contradiction.
Data Source
AI summary
A system and method for a time-scalable priority-based scheduler. A flexible scheduling algorithm utilizing variable scheduling durations enables better system capacity utilization. A rate request is transmitted if data arrives in a buffer, data in the buffer exceeds a buffer depth, and sufficient power exists to transmit at the rate requested. A rate assignment responsive to the rate request indicates a scheduled duration and a scheduled rate applicable for the scheduled duration. The scheduled duration is less than or equal to a scheduling period. The scheduling period is an interval of time and after which a scheduler makes a scheduling decision. The scheduling period is variable and the scheduled duration is variable.