Energy Aware Routing for PicoRadio

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Energy Aware Routing for PicoRadio. Rahul C. Shah Berkeley Wireless Research Center. Wireless Sensor Networks. Dominant trend in wireless industry: More bits/sec/Hz Wireless sensor networks offer: More bits/$/nJ. PicoRadio System Design. Wireless Sensor Nodes – Constraints. - PowerPoint PPT Presentation

Text of Energy Aware Routing for PicoRadio

  • Energy Aware Routing for PicoRadioRahul C. Shah

    Berkeley Wireless Research Center

  • Wireless Sensor NetworksDominant trend in wireless industry:More bits/sec/HzWireless sensor networks offer:More bits/$/nJ

  • PicoRadio System Design

  • Wireless Sensor Nodes ConstraintsLow Data Rates
  • Energy Scavenging

  • Practical Means of Energy Scavenging

  • Protocol StackIssues at the network layer:AddressingAddressing will be class based:

    Symbolic addressing may be supportedRoutingShould route packets to the destinationGiven:Destination locationPosition of selfPosition of the neighbors

  • Distributed Positioning[Chris Savarese(UCB)]

  • Data Link Layer Functions Transfers data between network and physical layers;Maintains neighborhood info Power control, error control and access controlComputes location


  • Mostly-Sleepy MAC Layer ProtocolsReceiving a bit is computationally more expensive than transmitting one (receiver has to discriminate and synchronize)Most MAC protocols assume that the receiver is always on and listening!Activity in sensor networks is low and randomCareful scheduling of activity pays off big time, but has to be performed in distributed fashion

  • A Reactive PicoMACTruly Reactive MessagingPower Down the Whole Data RadioReduce Monitoring Energy Consumption by 103 TimesWakeup Radio will Power Up Data Radio for Data ReceptionMulti-Channel Access SchemeTo Reduce Collision RateTo Reduce Signaling Overhead (Shrink Address Space)

  • Multi-Channel Access SchemeChannel AssignmentUsing Distributed Graph Coloring (combined with discovery) Receiver-based Channel Assignment: Channel code used as address[Chunlong Guo(UCB)]

  • Reactive Radio IssuesBroadcast and data communication modes must co-exist simultaneously Sleeping nodes have to wake-up to broadcast signals, and not to any signal leaking from surrounding communicating nodes Broadcast signals should not disrupt data transmission

  • PicoRadio Routing Protocol

  • PicoNetwork SpecificationsDensity of nodes 1 node every 1 to 20 sq. m. Radio range 3 to 10 mAverage bit rate per node ~ 100-500 bpsPeak bit rate per node ~ 10 kbpsVery low mobility of nodesLoose QoS requirements:Sensor data is redundant, so reliability is not required Most data is delay insensitive

  • Routing Protocol CharacteristicsEnsure network survivabilityLow energy (communication and computation)Tolerant and robust to topology changesScalable with the number of nodesLight weight

  • Network SurvivabilityNetwork survivability is application-dependent coverage may also be an issue

  • Proactive vs. Reactive RoutingProactive routing maintains routes to every other node in the networkRegular routing updates impose large overhead

    Suitable for high traffic networks

    Reactive routing maintains routes to only those nodes which are neededCost of finding routes is expensive since flooding is involvedGood for low/medium traffic networks

  • Traditional Reactive ProtocolsFinds the best route and then always uses that!But that is NOT the best solution!Energy depletion in certain nodesCreation of hotspots in the networkSourceDest

  • Directed DiffusionDestinationSourceSetting up gradientsDestination initiatedMultiple paths are kept aliveC. Intanagonwiwat, R. Govindan and D. Estrin, Directed Diffusion: A scalable and robust communication paradigm for sensor networks, IEEE/ACM Mobicom, 2000

  • Energy Aware RoutingDestination initiated routingDo a directional flooding to determine various routes (based on location)Collect energy metrics along the wayEvery route has a probability of being chosenProbability 1/energy costThe choice of path is made locally at every node for every packet

  • Setup PhaseControllerSensorDirectional flooding

  • Data Communication PhaseEach node makes a local decision

  • Whats The Advantage?Spread traffic over different paths; keep paths alive without redundancyMitigates the problem of hot-spots in the networkHas built in tolerance to nodes moving out of range or dyingContinuously check different paths

  • Energy CostThe metric can also include:Information about the data buffered for a neighbor Regeneration rate of energy at a nodeCorrelation of data

  • Simulation SetupSimulations done in Opnet76 nodes in a typical office setup47 light sensors18 temperature sensors7 controllers4 mobile nodesLight sensors send data every 10 seconds, while the temperature data is sent every 30 secondsComparison with directed diffusion routing

  • Simulation ModelOffice layoutNodelayoutNetworkmodel

  • Simulation MeasurementsEnergy used is measured:For reception: 30 nJ/bitFor transmission: 20 nJ/bit + 1 pJ/bit/m3Packet sizes are ~ 256 bits1 hour simulation time

    Energy (mJ)Avg.Std. Dev.MaxMinDiffusion14.9912.2857.440.87Energy Aware Routing11.769.6741.110.98

  • Energy Usage ComparisonDiffusion RoutingEnergy Aware RoutingPeak energy usage was ~50 mJ for 1 hour simulation

  • Normalized Energy ComparisonDiffusion RoutingEnergy Aware RoutingEnergy of each node is normalized with respect to the average energy

  • Bit Rate ComparisonDiffusion RoutingEnergy Aware RoutingPeak bit rate was 250 bits/sec.Average bit rate was 110 bits/sec.

  • Network LifetimeNodes have fixed initial energy 150 mJMeasure the network lifetime until the first node dies outDiffusion: 150 minutesEnergy Aware Routing: 216 minutes

    44% increase in network lifetime

  • Funneling AlgorithmInterest FloodingData Communication[w/ Dragan Petrovi (UCB)]

    Border Nodes



    Border Node



  • PicoRadio Implementations

  • PicoNode IsensordigitalpowerradioOff-the-shelf fully programmable communication/computation node

  • PN3 Architecture - RxTwo ChannelChannel Spacing ~ 50MHz10kbps/channelIssues include noise suppression and isolation between RF filtersPrototype Target: 3mA @ 1V

  • PN3 Architecture - TxUse simple modulation scheme (OOK)Allows efficient non-linear PATarget output power: 0dBmPrototype Target: 4mA @ 1V

  • PN3 Cycled Receiver