Distributed Sleep Scheduling for Heterogeneous Wireless Networks
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Solution Overview
Problem
Existing energy management methods for wireless networks, particularly those with both battery-powered and mains-powered nodes, are inefficient due to synchronization requirements that increase idle time and energy waste, and fail to leverage the heterogeneity of nodes, leading to reduced network lifetime.
Innovation Solution
A distributed sleep management model and energy-efficient routing mechanism that allow battery-powered nodes to independently determine their active and sleep schedules, while mains-powered nodes remain active, and utilize metrics like battery-powered node count, minimum battery level, and overhearing count to optimize routing paths, reducing energy consumption and extending network lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized sleep control mechanism is used to synchronize nodes, then collision of data packets is reduced, but idle time increases resulting in additional energy waste
Solution Approach 1:
The network is segmented into two distinct node types with different operational modes: battery-powered nodes that implement independent sleep scheduling and mains-powered nodes that remain continuously active. This segmentation allows the system to avoid synchronized sleep cycles while still managing energy consumption effectively, as mains-powered nodes can immediately forward packets without waiting for synchronized wake-up periods.
Solution Approach 2:
Instead of having all nodes synchronize their sleep and wake cycles to reduce collisions, the patent inverts the approach by keeping mains-powered nodes continuously active and allowing battery-powered nodes to sleep independently. This inversion eliminates the need for synchronization-based collision avoidance while reducing idle listening time for battery-powered nodes.
2Ease of operation
If synchronization packet transmission and receiving is implemented, then network coordination is improved, but extra energy waste occurs
Solution Approach 1:
Battery-powered nodes independently determine their own sleep and wake schedules based on their battery status and network conditions, rather than relying on centralized synchronization commands. This self-service approach eliminates the need for energy-consuming synchronization packet exchanges while maintaining effective energy management.
Solution Approach 2:
Mains-powered nodes serve multiple functions: they act as always-active relay nodes for packet forwarding, eliminate the need for sleep synchronization in the network, and provide a stable backbone that allows battery-powered nodes to operate independently. This multi-functionality reduces overall network energy consumption without sacrificing coordination.
3Device complexity
If homogeneous network management methods are applied to heterogeneous networks, then implementation simplicity is maintained, but energy efficiency deteriorates
Solution Approach 1:
The patent applies different operational characteristics to different node types within the heterogeneous network: battery-powered nodes use independent sleep scheduling with metrics like battery-powered node count, minimum battery level, and overhearing count, while mains-powered nodes remain continuously active. This local differentiation optimizes energy efficiency for each node type based on its power source characteristics.
Solution Approach 2:
The system dynamically adjusts operational parameters based on network conditions and node characteristics. Battery-powered nodes modify their sleep and wake timing based on metrics such as the number of battery-powered nodes on routing paths, minimum battery levels, and overhearing counts. This parameter adaptation improves energy efficiency without requiring complex centralized control.
Data Source
Figure 1A~2A
Figure 2B
Figure 3A
AI summary
A wireless multi-hope network of nodes including data nodes and at least one sink node. The data nodes include battery-powered nodes (BPNs) having active and sleep periods and mains-powered nodes (MPNs) having only active periods, wherein each data node transmits the packets only within corresponding active periods. A BPN includes a transceiver for transmitting and receiving data packets and a processor for determining a schedule of active and sleep periods of the BPN independently from the active and sleep periods of other data nodes in the network and independently from commands transmitted by the sink node, and a battery for providing energy to the transceiver and the processor. The processor switches the transceiver ON and OFF according to the schedule.