Sleep Mode Control for Real-Time Services in Wireless Systems
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Solution Overview
Problem
Existing sleep mode control methods in broadband wireless access systems trade off power conservation with quality of service (QoS) deterioration, particularly affecting real-time services with arbitrary sleep interval selection and lack of synchronization with packet transmission.
Innovation Solution
The solution involves negotiating and synchronizing sleep modes with real-time services by setting maximum latency as a mandatory QoS parameter, ensuring sleep intervals do not exceed the negotiated latency value and synchronizing sleep cycles with packet transmission to align with listening intervals, thereby preventing excessive buffering and maintaining acceptable QoS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sleep mode control is implemented with arbitrary sleep interval selection, then power consumption is reduced, but quality of service deteriorates due to excessive buffering delays
Solution Approach 1:
The patent changes the sleep interval parameter from arbitrary selection to being constrained by the negotiated maximum latency value. By setting the sleep interval to be less than or equal to the maximum latency, the system ensures that packets are not buffered excessively long, thereby maintaining QoS while still achieving power savings through sleep mode operation.
Solution Approach 2:
The patent implements a feedback mechanism where the mobile station and base station negotiate and synchronize sleep modes with real-time services based on QoS requirements. The mobile station monitors frame latency and synchronizes packet transmission with listening intervals, creating a closed-loop system that adjusts sleep intervals to maintain acceptable QoS while reducing power consumption.
2Loss of energy
If sleep intervals are extended to reduce power consumption, then energy efficiency improves, but buffering delays increase causing QoS deterioration
Solution Approach 1:
The patent establishes a direct relationship between sleep interval duration and maximum latency parameter. By constraining the sleep interval to be less than or equal to the negotiated maximum latency value, the system prevents excessive buffering delays while still achieving energy efficiency through extended sleep periods when QoS allows.
Solution Approach 2:
The patent makes the sleep interval dynamic rather than fixed, allowing it to be adjusted based on real-time service requirements and negotiated QoS parameters. The sleep interval adapts to the specific needs of different services, extending when QoS permits and reducing when latency constraints require faster packet transmission.
3Reliability
If sleep mode is synchronized with packet transmission, then quality of service is maintained, but device complexity increases due to additional synchronization mechanisms
Solution Approach 1:
The patent applies preliminary action by negotiating and establishing synchronization parameters before actual sleep mode operation begins. The mobile station and base station pre-agree on maximum latency values and listening interval timings, so that during sleep mode operation, the mobile station can simply follow the pre-established schedule without complex real-time decision-making, reducing operational complexity.
Solution Approach 2:
The patent makes the synchronization mechanism universal by using the same listening interval timing for both sleep mode operation and packet transmission coordination. The base station's listening interval schedule serves multiple purposes: it determines when the mobile station should wake for sleep mode and also synchronizes packet transmission timing, eliminating the need for separate synchronization mechanisms.
Data Source
AI summary
Consideration of Quality of Service is taken into account during the establishment of a sleep cycle in a mobile station providing real-time services. Upon the mobile station's identification of a need for a real-time service to enter into sleep mode, a request conveying that need is sent to the base station. The base station replies with a start frame number and other sleep parameters. Thereafter the mobile station enters sleep mode comprising sleep intervals interleaved with listening intervals. To prevent transmission packets from being buffered at the mobile station for an excessive period of time due to attempts to transmit packets to the base station during a sleep interval, the length of the sleep interval is set so as not to exceed the maximum latency value reflecting the QoS of the real-time service negotiated during establishment of the real-time services.