Post on 29-Mar-2015
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Mohamed Hauter
CMPE 259 – Sensor Networks
UCSC
Energy Management
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Outline
*Introduction
*Objectives
*Proposals and approaches
*Related Work
*Simulations and Results
*Strengths and weaknesses
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Paper 1:An Energy-Efficient Dynamic Power
Management in Wireless Sensor Networks
* An energy-efficient sensor network
*Minimal number of sensor nodes in active mode
*Increase the lifetime of the sensor network
*Prevent connection degradation
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Dynamic Power Management (Cont.)
*Terminology:
*DPM: Dynamic Power Management
*OGDC: Optimal Geographical Density Control
*ACPI: Advanced Configuration and Power Interface
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Dynamic Power Management (Cont.)
*Approach:
*Tackle energy efficiency on all levels of the entire network
*Dynamic power management = shutting down nodes when not needed and wake them up when necessary
*Consideration of the state of components ( microprocessor, A/D converter, memory, transceiver, etc.) when making a decision to turn off a node
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Dynamic Power Management (Cont.)
*Approach (continue):
*Density control while maintaining:a. Coverage
b. Connectivity
*Localized density control algorithm
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Dynamic Power Management (Cont.)*Approach (continue):
*Consideration of battery status and energy wasted in the process of node-awakening
*Incorporate OGDC in the control logic
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Dynamic Power Management (Cont.)
Related Work
*Verity of DPM techniques
*Dynamic Voltage Scaling
*Dynamic Voltage and Frequency Scaling
*Sentry based power management (application driven)
*Software and operating system power management
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Dynamic Power Management (Cont.)
Related Work (continues)
*Weaknesses of traditional predictive techniques:
*Cannot provide an accurate tradeoff between energy saving and performance degradation
*Does not deal with systems in which requests can be queued
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Dynamic Power Management (Cont.)
*Power aware sensor node model:
*Node components: processor, memory, AD converter, and transceiver (radio)
*Components of each node can be in different states: active, idle, or sleep
*Different combinations of component power modes
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Dynamic Power Management (Cont.)
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Dynamic Power Management (Cont.)
*Sleep-state transition policy:
*P = Power Consumption
*t = Time of event
*s = sleep state
*Tau = transition mode
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Dynamic Power Management (Cont.)
*System Parameters:
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Dynamic Power Management (Cont.)
Simulations*50x50 meters area of coverage
*100 nodes
*Uniformly and randomly distributed
*Nodes are capable of directly communicating with the host
*Each node’s initial energy is 100 joules
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Dynamic Power Management (Cont.)
Results
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Dynamic Power Management (Cont.)
Strengths: * An energy-efficient sensor network * Minimal number of sensor nodes in active mode * Increase the lifetime of the sensor network * Prevent connection degradation
Weaknesses: *Analysis did not take latency into account * Events missed during deepest-sleep state * OGDC requires knowledge of node’s location (extra processing and memory overhead)
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Paper 2:Wireless Sensor Networks with Energy
Harvesting Technologies
* Utilize natural sources of energy (solar, motion, vibration, etc.) to recharge nodes’ batteries
*Employ energy-saving mechanisms
*Determine the sleep and wake up probabilities of nodes using a bargaining game
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Wireless Sensor Networks with Energy Harvesting Technologies
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Wireless Sensor Networks with Energy Harvesting Technologies
Energy Harvesting Technologies
1. Solar 2. Thermoelectric
3. Vibration Based
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Wireless Sensor Networks with Energy Harvesting Technologies
Buffers
Two types of buffers:
1.Local buffer: gathers data collected locally (through sensors).
2. External buffer: gathers data from other nodes to be relayed.
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Wireless Sensor Networks with Energy Harvesting Technologies
Energy-Efficient Routing Protocol
To find the optimal path to deliver data packets while considering:
1. Energy level2. Path length3. Path reliability
Avoid:1. Idle listening2. Overhearing3. Packet collisions
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Wireless Sensor Networks with Energy Harvesting Technologies
Energy-Efficient Routing Protocol (cont.)
• Using Explicit Signaling:• A node notifying the access point that it is going
into power-saving (PS) mode
• Dual Channel MAC Protocols (Avoid Collisions):• Signaling channel• Data transmission channel
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Wireless Sensor Networks with Energy Harvesting Technologies
Energy-Efficient Packet Scheduling
• Lazy packet-scheduling scheme• Determine beginning and duration of transmission• Transmit at a low data rate• Save energy• Packet delay and reduced throughput
• Tradeoffs!
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Wireless Sensor Networks with Energy Harvesting Technologies
Issues
• QoS vs. Energy Constrains
• Energy harvesting limitations
• Integration of energy harvesting techniques across layers
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Wireless Sensor Networks with Energy Harvesting Technologies
Optimal sleep and wakeup strategy
• Radio modes:• Active – 25mW• Listen – 14mW• Sleep – 0.01mW
• Channel and queue-aware strategy• Radio - Listen when queue is empty• Sensor – sleep when channel quality is bad
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Wireless Sensor Networks with Energy Harvesting Technologies
Bargaining Game
• Players: • Player 1: node• Player 2: data receiving entity
• Strategy:• Player 1: select wakeup probability when in sleep
mode• Player 2: select wakeup probability when in listen
mode• Payoff:
• Player 1: packet blocking probability• Player 2: packet dropping probability
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Wireless Sensor Networks with Energy Harvesting Technologies
Bargaining Game
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Wireless Sensor Networks with Energy Harvesting Technologies
Bargaining Game
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Wireless Sensor Networks with Energy Harvesting Technologies
Bargaining Game
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Wireless Sensor Networks with Energy Harvesting Technologies
Strengths: 1. Energy efficient 2. Incorporates the states of different components of the network
Weaknesses: 1. battery energy level is not taken into consideration when making a sleep/wakeup decisions 2. Data transmission delay – low data transmission rates 3. The assumption of one-hop routing model in which all nodes can reach the sink is not practical
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* Paper 3:A Low Energy and Adaptive Architecture for
Efficient Routing and Robust Mobility Management
in Wireless Sensor Networks
*Prolong the lifetime of the network
*Minimizing the data processing and communication costs
*Employ multi-hop communications effectively
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
Related Work
*LEACH: dividing the sensor network into cluster heads (CH) which can communicate with sinks and amongst themselves. Cluster Heads are constantly changing (random selection) to prevent draining its energy.
*SOP: a tree of cluster heads is built using fixed nodes.
*EDETA: builds a hierarchal tree among cluster heads to avoid direct communication with sink.
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
How is HARP different? .
*HARP can save more energy by forming intra-cluster hierarchal architectures in conjunction with inter-cluster trees.
* Leverage node mobility to enhance network performance in terms of coverage, lifetime, energy efficiency, and latency.
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
*Two hierarchal tree structure:1. Between CHs and the sinks
2. Within the cluster
*HARP has a local reconfiguration scheme in case of a failure
*Supports more than one sink - scalability
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
HARP messages
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
HARP phases
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
LEACH clustering
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
HARP clustering
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
Failure Recovery Mechanisms
*Causes of failure:
*Battery depletion, node malfunction, multipath fading, low link quality, or node mobility.
*Mechanisms;1. The recovery slot
2. The substitute node
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
s-HARP
*Unlike the LEACH approach, HARP ensures that nodes all die at the same time
*Solves the problem of the extra energy waste of CHs
*CHs are randomly selected, unless new node has less energy than existing CH.
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
Results
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
Results – wasted energy
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
Results – total energy consumption
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Hierarchical Adaptive and Reliable Routing Protocol (HARP)
s-HARP
*Strengths:
*Very high level of energy efficiency
*Scalable design
*Efficient Local recovery capability
*Optimizes routing of both upstream and downstream traffic flows
*Weakness:
*Increased complexity in terms of resource scheduling and network topology management
*Increased memory overhead
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*Questions ?