SIV Protocol Scheduling for WLAN Power Reduction
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Solution Overview
Problem
Current wireless local area networks (WLANs) face significant power consumption issues due to the broadcast-based wireless MAC protocol, which requires stations to continuously monitor the channel, preventing them from sleeping and leading to battery drain, especially in mobile devices, and existing power-saving techniques do not fully address the problem, particularly with the increasing demand for Quality of Service (QoS) applications.
Innovation Solution
A power-saving system utilizing a Schedule Information Vector (SIV) protocol with an optimal scheduler and transmission time calculation algorithm, prioritizing data transmissions to minimize channel contention and maximize sleep time, by scheduling wake-up times for stations based on calculated transmission times and using a priority queue to arrange transmissions from stations with shorter to longer times, thereby reducing overall power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stations continuously monitor the channel in broadcast-based WLAN MAC protocol, then channel access reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic channel monitoring instead of continuous monitoring by introducing beacon intervals and wake-up schedules. Stations wake up at scheduled times to receive beacons and data, then sleep for the remaining interval. This periodic action maintains channel access reliability through regular monitoring while dramatically reducing power consumption during sleep periods.
Solution Approach 2:
The access point calculates transmission times for downlink data to multiple stations and schedules wake-up times in advance based on these calculations. By performing preliminary scheduling of wake-up times and beacon transmissions, the system ensures stations are awake exactly when needed to receive their data, maintaining reliability while minimizing unnecessary wake-ups that would increase power consumption.
2Loss of time
If stations wake up frequently to check for data, then data transmission timeliness is improved, but power consumption increases
Solution Approach 1:
The access point performs preliminary calculation of transmission times for downlink data to each station and schedules wake-up times in advance. This preliminary scheduling ensures stations wake up exactly when their data will be transmitted, eliminating delays while avoiding premature wake-ups that would waste power. The SIV protocol encodes these pre-calculated wake-up times efficiently.
Solution Approach 2:
The patent uses the Schedule Information Vector (SIV) protocol to efficiently copy and transmit wake-up time information to multiple stations in a compact format. The SIV encodes wake-up times as offsets from the current beacon time, allowing stations to receive their scheduled wake-up times with minimal overhead, thus maintaining timeliness while reducing the power cost of communication.
3Productivity
If multiple stations transmit simultaneously without scheduling, then channel utilization is improved, but channel contention increases
Solution Approach 1:
The access point calculates transmission times for downlink data to multiple stations and schedules their wake-up times in advance to avoid simultaneous transmissions. By preliminarily organizing the transmission schedule, the system ensures stations wake up at staggered times, eliminating channel contention while maintaining high channel utilization through coordinated access.
Solution Approach 2:
The patent segments the channel access time by assigning different wake-up times to different stations based on their data transmission requirements. This temporal segmentation divides the channel access into non-overlapping intervals for different stations, eliminating simultaneous transmissions and associated contention while ensuring each station gets adequate channel access.
4Productivity
If the access point transmits data to all stations simultaneously, then transmission efficiency is improved, but transmission complexity increases
Solution Approach 1:
The access point performs preliminary calculation of transmission times for downlink data to each station and schedules wake-up times in advance. This preliminary scheduling simplifies the actual transmission process by pre-determining the sequence and timing of transmissions, reducing real-time decision complexity while maintaining efficient channel utilization through coordinated multi-station transmission.
Data Source
AI summary
A new system and method is described, utilizing a scheduler based on a transmission time calculation and prioritizing algorithm. The system utilizes a Schedule Information Vector (SIV) protocol for saving power in wireless local area networks. The system comprises an access point having a priority queue, one or more stations, an SIV frame comprising an association ID for identifying one of the stations and a scheduled wake-up time for the identified station. An algorithm is employed for calculating the transmission time of downlink data for the stations. The access point originates and transmits to the one or more stations the SIV frame of the scheduled wake-up times. The current data to be transmitted to each station is accessed by the algorithm to determine the total transmission time to each station. A priority queue in the access point is ordered from the shortest to the longest transmission, assigning the highest priority to the shortest power save transmission to minimize the total power consumption of the network.