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Energy Efficient Routing Algorithms for Application to Agro-Food Wireless Sensor Networks Francesco Chiti*, Andrea De Cristofaro*, Romano Fantacci *, Daniele Tarchi*, Giovanni Collodi§, Gianni Giorgetti*, Antonio Manes▲ *Dipartimento di Elettronica e Telecomunicazioni, ▲Dipartimento di Energetica, §Consorzio MIDRA Università di Firenze -Via di S. Marta, 3 - 50139 Firenze, Italy [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] COST 289 7th MCM - München March, 7-8 2005 1/24 Contents 1. WSN features 2. Routing protocols 3. Proposed approach 4. Performance analysis 5. Conclusions COST 289 7th MCM - München March, 7-8 2005 2/24 Research involvements “GoodFood” EU Integrated Project • Development of novel solutions for the safety and quality assurance, along the food chain within the agro-food industry. • Work Package 7 aims at investigating integrated solutions according to the AmI concepts, allowing full interconnection and communication of multi-sensing systems. “NEWCOM” EU NoE Project A is addressed to “Ad Hoc and Sensor networks” with regards to: Cross-layer design of sensor networks; Simulation models and architectures for cross-layered sensor networks. COST 289 7th MCM - München March, 7-8 2005 3/24 1. WSN features Definition Wireless Sensor Network (WSN) is composed of a large number of sensor nodes (N) that are densely deployed either inside the investigated phenomenon or very close to it. N N IPvx Task Mng Satellite N N Gateway N N 2G/3G/ 4G N N N Gateway N N N N N COST 289 7th MCM - München March, 7-8 2005 4/24 1. WSN features WSN Applications • Military, Environmental, Health, Home, Space Exploration, Chemical Processing, Disaster Relief Sensor types • Seismic, Low sampling rate magnetic, Thermal, Visual, Infrared, Acoustic, Radar Sensor tasks • Temperature, Humidity, Lightning Condition, Pressure, Soil Makeup, Noise Levels • Vehicular, Movement, Presence or Absence of certain types of objects, Mechanical stress levels on attached Objects, current characteristics (Speed, Direction, Size) of an object COST 289 7th MCM - München March, 7-8 2005 5/24 1. WSN features WSN implementation (HW & SW) Functional blocks Network Nodes Location Finding Sensor ADC Mobilizer Processor Memory Transceiver Gateway Power Unit COST 289 7th MCM - München March, 7-8 2005 6/24 1. WSN features Multi-Hop WSN Theorem (Stojmenovic, Xu Lin) Let be the source and the gateway at distance d and the needed transmitted power satisfies: ud ad c This is minimized if: 1 c d 1 a 1 2 Otherwise, the overall requested energy can be minimized by choosing equally spaced n-1 relay nodes such that n is the integer closer to: 1 a 1 d c COST 289 7th MCM - München March, 7-8 2005 7/24 1. WSN features Multi-Hop WSN Communication paradigm Source relay relay Gateway COST 289 7th MCM - München March, 7-8 2005 8/24 1. WSN features Multi-Hop WSN Flexibility: Adaptability Re-configurability Robustness Scalability Power saving Untethered 3 1 Dummy node 2 6 No nw planning • • • 0 Energy-awareness • • WSN GATEWAY 4 Sensor Node 5 Random deployment Self-organization Re-configuration Cooperative approach • • Distributed procedures Data processing COST 289 7th MCM - München March, 7-8 2005 9/24 2. Routing protocols Protocol design Ad Hoc protocol are often unsuitable because: • Number of sensor nodes can be several order of magnitude higher • Sensor nodes are densely deployed and are prone to failures • The topology of a sensor network changes very frequently due to node mobility and node failure • Sensor nodes are power, computational capacities and memory limited • May not have global ID like IP address • Need tight integration with sensing tasks Specific cross-layer protocols design with an across layers information passing and functionalities adaptation to channel and load variations COST 289 7th MCM - München March, 7-8 2005 10/24 2. Routing protocols Network layer This layer is in charge of discovering the best path between a couple of nodes (Sender and Destination), relaying on the following characteristics: • Sensor networks are mostly data centric • An ideal sensor network has attribute based addressing and location awareness • Data aggregation may be joined with a collaborative effort • Power efficiency is always a key factor Application Transport Network LLC MAC Physical COST 289 7th MCM - München March, 7-8 2005 11/24 2. Routing protocols Network layer Metrics considered to develop energy efficient routing algorithms: • Power Available (PA) at each node • Energy () needed to send a packet over a link Resorting to these, there 4 possible approaches to choose the proper path: Maximum PA Route (PAs summation) Minimum Energy Route ( summation) Minimum Hop Route (number of hops) Maximum Minimum PA Route (minimum of maximum PA) COST 289 7th MCM - München March, 7-8 2005 12/24 2. Routing protocols Network layer Flooding Each node forwards the packets to all the neighbor nodes within its transmission range PROs CONs Simple implementation No table updating No neighbor nodes discovering Scalability Implosion and goodput decreasing Duplicate packets No available resource knowledge COST 289 7th MCM - München March, 7-8 2005 13/24 2. Routing protocols Network layer Gossiping Each node sends a packet only to one neighbor node chosen according to a suited criterion (random or metric based) PROs CONs Scalability Long convergence transient time Adaptability Possible presence of loops Modularity Graceful performance degradation Packet loss if TTL expires Signaling overhead No implosion COST 289 7th MCM - München March, 7-8 2005 14/24 3. Proposed approach Network layer Dynamic table driven and link state Each idle node periodically broadcasts an HELLO message with fields: • SOURCEID: unique hardware identifier; • NUMHOPS: number of hops to reach the sink; • COORDINATES: location with respect to the gateway; • AVAILABLE ENERGY: i.e., the energy that is still available to transmit and process the packets. COST 289 7th MCM - München March, 7-8 2005 15/24 3. Proposed approach Network layer an HELLO reception makes the routing table to be updated and, hence, to select the best next hop by means of the following procedure: i. entries with minimum NUMHOPS to the sink are chosen; ii. among the remaining nodes those with higher AVAILABLE ENERGY are the candidates; iii. finally, the node minimizing the Euclidean distance to the gateway is selected; COST 289 7th MCM - München March, 7-8 2005 16/24 3. Proposed approach Protocol behavior Dynamic Gossiping Packet Optimum next hop selection HELLOforwarding broadcasting COST 289 7th MCM - München March, 7-8 2005 17/24 4. Performance analysis Application scenario Field-trial of the University of Florence’s Montepaldi farm for the Wine Chain monitoring (wine production and ageing chain steps) Sensed parameters: air, ground, plants (leaf temperature, stem growth, xylem flux and pathogenic diseases), fermentation and ageing issues 1 2 2 1 1 3 2 3 1 2 3 3 COST 289 7th MCM - München March, 7-8 2005 18/24 4. Performance analysis Simulation results Reference metrics: power consumption or, equivalently node lifetime especially for the most solicited nodes (connectivity); end-to-end throughput or delivering efficiency; end-to-end packet delivering delay. Compared approaches: basic flooding routing scheme; a static gossiping: proactive link state evaluation; proposed dynamic gossiping. Utilization of Network Protocol Simulator (NePSing): a C++ framework for modeling time-discrete, asynchronous systems [“the NePSing Project,” 2004. [Online]. Available: http://nepsing.sourceforge.net] COST 289 7th MCM - München March, 7-8 2005 19/24 4. Performance analysis Power consumption 6X6 9X4 12000 12000 8000 4000 8000 Flooding Random G Proposed G UE UE Flooding Random G Proposed G 4000 0 0 1 2 3 4 5 6 7 8 9 10 1 2 3 4 time [slot] 5 6 7 8 9 10 time [slot] remarkable gain of the dynamic gossiping vs flooding scheme; same behavior of the static and the dynamic gossiping; Increasing signaling overhead (slightly worse performance) especially in an asymmetric network topology, i.e., in a rectangular-wise grid if compared with a square-wise. COST 289 7th MCM - München March, 7-8 2005 20/24 4. Performance analysis Delivering efficiency 6X6 9X4 1 Flooding Random G Proposed G 0,5 Delivery efficiency Delivery efficiency 1 0 Flooding Random G Proposed G 0,5 0 0 1 2 3 4 5 6 7 8 9 10 11 time [slot] 0 1 2 3 4 5 6 7 8 9 10 11 time [slot] increasing end-to-end packet delivering of dynamic vs static gossiping; worse delivering efficiency (throughput). COST 289 7th MCM - München March, 7-8 2005 21/24 4. Performance analysis Network connectivity Static gossiping Dynamic gossiping Topology Node 1 Node 2 Node 3 Topology Node 1 Node 2 Node 3 6×6 105 35 105 6×6 82 76 85 9×4 42 21 182 9×4 86 70 89 50% reduction of power consumption for the most solicited nodes (1,2,3); lesser spatial variance of energy wasting; lesser dependency with the topology. COST 289 7th MCM - München March, 7-8 2005 22/24 5. Conlusions Pervasive use of AmI concepts in agriculture, relying on highlyintegrated WSNs to create a sensitive and responsive environment; Proposal of an energy efficient dynamic routing protocol; Performance analysis: • signaling overhead, delay and throughput; • Power consumption; • Network life-time (connectivity). Further developments: • On-board implementation and testing; • Cross-layer integration with energy efficient Link Layer schemes (e.g., SMAC); • Management of differentiated services. Francesco Chiti, Andrea De Cristofaro, Romano Fantacci, Daniele Tarchi, Giovanni Collodi, Gianni Giorgetti and Antonio Manes, “Energy Efficient Routing Algorithms for Application to Agro-Food Wireless Sensor Networks” in Proc. of IEEE ICC 2005. COST 289 7th MCM - München March, 7-8 2005 23/24 Energy Efficient Routing Algorithms for Application to Agro-Food Wireless Sensor Networks Francesco Chiti*, Andrea De Cristofaro*, Romano Fantacci *, Daniele Tarchi*, Giovanni Collodi§, Gianni Giorgetti*, Antonio Manes▲ *Dipartimento di Elettronica e Telecomunicazioni, ▲Dipartimento di Energetica, §Consorzio MIDRA Università di Firenze -Via di S. Marta, 3 - 50139 Firenze, Italy [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] COST 289 7th MCM - München March, 7-8 2005 24/24 2. Routing protocols Network layer Quality of Service oriented routing protocols • Routes based on QoS requirements without periodic table updating (no need for routing tables ) • Flexibile, robust and modular • One-to-one, many-to-one, one-to-many, and many-tomany communications Types of Streams Type 1: Time critical and loss sensitive Type 2: time critical but not loss sensitive data Type 3: loss sensitive data that is not time critical Type 4: neither time critical nor loss sensitive COST 289 7th MCM - München March, 7-8 2005 25/24