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Wireless Sensor networks

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					                                       University of Tehran
                            Dept. Electrical and Computer Engineering


                 Wireless Sensor networks
                     survey and research challenges
                                         Presented by
                            Hosein Sabaghian-Bidgoli
                                      hsabaghianb@gmail.com
                                          January 11, 2009




Wireless Ad hoc Network (Fall 2008)                             WSN survey and research challenges
      Outlines
          Main references
          Introduction
               Definition
               Communication Architecture
               Protocol stack
               WSN Characteristics
               WSN Design factors
          WSANs
          WSN Structures
          WSN Constraints
          WSN Applications
          WSN types
          .




Wireless Ad hoc Network (Fall 2008)          2   WSN survey and research challenges
      Outlines (cont.)
          Task classification
             Internal sensor system
                  –   Standard
                  –   Storage
                  –   Testbed
                  –   Diagnostic and debugging support
             Network services
                  –   Localization
                  –   Synchronization
                  –   Coverage
                  –   Compression and aggregation
                  –   Security
             Communication protocol
                  –   Transport
                  –   Network
                  –   Data link
                  –   Physical
                  –   Cross-layer
          Conclusion

Wireless Ad hoc Network (Fall 2008)              3       WSN survey and research challenges
      Main references
      1.   Ian F. Akyildiz, Weilian Su, Yogesh Sankarasubramaniam, and Erdal
           Cayirci, A Survey on Sensor Networks, IEEE Communications
           Magazine, August 2002
      2.   Ian F. Akyildiz, Ismail H. Kasimoglu, Wireless sensor and actor
           networks research challenges, Elsevier Ad Hoc Networks 2 (2004)
           351–367
      3.   Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal, Wireless sensor
           network survey, Elsevier Computer Networks 52 (2008) 2292–2330




Wireless Ad hoc Network (Fall 2008)        4            WSN survey and research challenges
                                                                       [1]
Wireless Ad hoc Network (Fall 2008)   5   WSN survey and research challenges
                                                                      [2]

Wireless Ad hoc Network (Fall 2008)   6   WSN survey and research challenges
                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   7   WSN survey and research challenges
      Introduction
      WSN Definition
      A sensor network is composed of a large
      number of sensor nodes that are densely
      deployed inside or very close to the
      phenomenon
             random deployment
             self-organizing capabilities


                                                                         [1]


Wireless Ad hoc Network (Fall 2008)   8      WSN survey and research challenges
      Introduction
      WSN communication Architecture




                                                                      [1]


Wireless Ad hoc Network (Fall 2008)   9   WSN survey and research challenges
      Introduction
      Components of Sensor Node




                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   10   WSN survey and research challenges
      Introduction
      Protocol Stack

       Protocols                 should be
             Power aware
             Location aware
             Application aware




                                                                          [1]

Wireless Ad hoc Network (Fall 2008)      11   WSN survey and research challenges
      Introduction
      WSN Characteristics
          Major differences between sensor and ad-hoc
           network
               Number of nodes is higher
               Densely deployment
               Sensor nodes are prone to failure.
               Frequent topology changes
               Broadcast communication paradigm
               Limited processing and power capabilities.
               Possible absence of unique global ID
                                                                            [1]


Wireless Ad hoc Network (Fall 2008)   12        WSN survey and research challenges
      Introduction
      WSN Design Factors

       FaultTolerance
       Scalability
       Production Costs
       Hardware Constraints
       Sensor Network Topology
       Environment
       Transmission Media
       Power Consumption                                              [1]


Wireless Ad hoc Network (Fall 2008)   13   WSN survey and research challenges
      WSN Design Factors
      Fault Tolerance
       Each   Nodes are prone to unexpected
        failure (more than other network)
       Fault tolerance is the ability to sustain
        sensor network functionalities without
        any interruption due to sensor node
        failures.

                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   14   WSN survey and research challenges
      WSN Design Factors
      Scalability
       Size:Number of node (100 ~1000)
       Density : μ(R)=(N R2)/A
       Protocol should
             be able to scale to such high degree
             take advantage of the high density of such
              networks


                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   15   WSN survey and research challenges
      WSN Design Factors
      Production Costs
       The cost of a single node must be low
        given the amount of functionalities
       Much less than $1




                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   16   WSN survey and research challenges
      WSN Design Factors
      Hardware Constraints
       All       these units combined together must
             Extremely low power
             Extremely small volume




                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   17   WSN survey and research challenges
      WSN Design Factors
      Topology
       Must    be maintained specially in very
           high densities
             Pre-deployment and deployment phase
             Post-deployment phase
             Re-deployment of additional nodes phase



                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   18   WSN survey and research challenges
      WSN Design Factors
      Environment
          May be inaccessible
             either because of hostile environment
             or because they are embedded in a structure
          Impact of environment condition
               Temperature
               Humidity
               Movement
               Underwater
               Underground
                                                                         [1]


Wireless Ad hoc Network (Fall 2008)   19     WSN survey and research challenges
      WSN Design Factors
      Transmission Media

       RF
       Infrared
       Optical
       Acoustic                [3]



                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   21   WSN survey and research challenges
      WSN Design Factors
      Power Consumption

       Power              conservation
             Sensing
             Communication
             Data processing




                                                                       [1]


Wireless Ad hoc Network (Fall 2008)   22   WSN survey and research challenges
      wireless sensor and actor
      networks (WSANs)
          WSAN Capabilities
               Observing the physical world
               Processing the data
               Making decisions
               Performing appropriate actions
          WSAN applications:
               battlefield surveillance
               microclimate control in buildings
               nuclear, biological and chemical attack detection
               Home automation
               environmental monitoring

                                                                                   [2]

Wireless Ad hoc Network (Fall 2008)       24           WSN survey and research challenges
      WSANs unique characteristics
       Real-time requirement
       Coordination:
             Sensor-Actor Coordination
             Actor-Actor Coordination




                                                                       [2]

Wireless Ad hoc Network (Fall 2008)   25   WSN survey and research challenges
      WSN structure
      A   WSN typically has little or no
        infrastructure
       There are two types of WSNs
             Structured model
             Unstructured model




                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   26   WSN survey and research challenges
      Unstructured model
       Densely  deployed (many node)
       Randomly Deployed
       Can have uncovered regions
       Left unattended to perform the task
       Maintenance is difficult
             managing connectivity
             detecting failures
                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   27   WSN survey and research challenges
      Structured model
       Deployed in a pre-planned manner
       Fewer nodes
       Lower network maintenance
       Lower cost
       No uncovered regions




                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   28   WSN survey and research challenges
      WSN constraints
          Resource constraints
               limited energy
               short communication range
               low bandwidth
               limited processing
               limited storage
          Design constraints
             application dependent
             environment dependent
                  – size of the network / number of node
                  – deployment scheme
                  – network topology (obstacle)
                                                                                   [3]

Wireless Ad hoc Network (Fall 2008)       29           WSN survey and research challenges
      Available sensors in the market
          Generic nodes (take measurements)
             Light, Temperature, Humidity, barometric
              pressure, velocity, Acceleration, Acoustics,
              magnetic field
          Gateway (bridge) node
             gather data from generic sensors and relay them
              to the base station
             higher processing capability
             higher battery power
             higher transmission (radio) range
                                                                           [3]

Wireless Ad hoc Network (Fall 2008)   30       WSN survey and research challenges
      Types of sensor network
           Depending on the environment
            1. terrestrial WSN
                  – Ad Hoc (unstructured)
                  – Preplanned (structured)
            2. underground WSN
                  – Preplanned
                  – more expensive equipment, deployment, maintenance
            3. underwater WSN
                  – fewer sensor nodes( sparse deployment)
                  – more expensive than terrestrial
                  – acoustic wave communication
                           Limited bandwidth
                           long propagation delay
                           signal fading




Wireless Ad hoc Network (Fall 2008)              31     WSN survey and research challenges
      Types of sensor network (cont.)
           Depending on the environment
            4. multi-media WSN
                  – sensor nodes equipped with cameras and microphones
                  – pre-planned to guarantee coverage
                  – High bandwidth/low energy, QoS, filtering, data processing
                    and compressing techniques

            5. mobile WSN
                  – ability to reposition and organize itself in the network
                  – Start with Initial deployment and spread out to gather
                    information
                  – deployment, localization, self-organization, navigation and
                    control, coverage, energy, maintenance, data process



Wireless Ad hoc Network (Fall 2008)          32            WSN survey and research challenges
      WSN applications
                                                                       [3]




Wireless Ad hoc Network (Fall 2008)   33   WSN survey and research challenges
      WSN applications (Open research issues)
          application-specific characteristics and requirements of
               environmental monitoring
               health monitoring
               industrial monitoring
               Military tracking
          Coupled with today’s technology
          Lead to different hardware platforms and software
           development
          more experimental work is necessary to make these
           applications more reliable and robust in the real world
          Applying sensor technology to industrial applications
           will improve business


Wireless Ad hoc Network (Fall 2008)        34   WSN survey and research challenges
      Tasks Classification
          Systems
             Each sensor node is an individual system
             Development of new platforms, operating
              systems, and storage schemes

          Communication protocols
             Between sensors
             In different layer(app, trspt, net, DLink, phy)

          services
             which are developed
                  – to enhance the application
                  – to improve system performance
                  – and network efficiency


                                                                                            [3]

Wireless Ad hoc Network (Fall 2008)           35                WSN survey and research challenges
      Internal sensor system
          sensor platform
               radio components
               processors
               Storage
               sensors (multiple)
          OS
             OS must support these sensor platforms
      researches:
       Designing platforms that support
             automatic management
             optimizing network longevity,
             distributed programming
                                                                               [3]

Wireless Ad hoc Network (Fall 2008)     36         WSN survey and research challenges
      Platform Sample 1
      (Bluetooth-based sensor networks)

          WSN typically uses single freq (Share channel)
          BTnodes use spread-spectrum transmission
          A special version of TinyOS is used
          Two radio communication
             Master (up to 7 connection)
             Slave
          Note:
               Bluetooth is connection oriented
               New node enables its slave radio
               Topology: connected tree
               high throughput, high energy consumption
                                                                                 [3]

Wireless Ad hoc Network (Fall 2008)     37           WSN survey and research challenges
      Platform Sample 2:VigilNet
      (Detection-and-classification system)

          detection and classification
             vehicles
             persons
             persons carrying ferrous objects
          200 sensor nodes with
             Magnetometer
             motion sensor,
             and a microphone
          deployed in a preplanned manner
          four tiers hierarchical architecture
               sensor-level,
               node-level,
               group-level,
               and base-level                                                [3]

Wireless Ad hoc Network (Fall 2008)     38        WSN survey and research challenges
      Internal sensor system
      Standards

          IEEE 802.15.4:
             standard for low rate wireless personal area
              networks (LR-WPAN)
             low cost deployment
             low complexity
             low power consumption
             topology :star and peer-to-peer
             physical layer: 868/915 MHz ~2.4 GHz
             MAC layer: CSMA-CA mechanism
                                                                          [3]

Wireless Ad hoc Network (Fall 2008)   39      WSN survey and research challenges
      Internal sensor system
      Standards
          ZigBee
             higher layer communication protocols built on the
              IEEE 802.15.4 standards for LR-PANs.
             simple, low cost, and low power
             embedded applications
             can form mesh networks connecting hundreds to
              thousands of devices together.
             types of ZigBee devices:
                  – ZigBee coordinator: stores information, bridge
                  – ZigBee router: link groups of devices
                  – ZigBee end device: sensors, actuators communicate only
                    to routers
                                                                                 [3]

Wireless Ad hoc Network (Fall 2008)      40          WSN survey and research challenges
      Internal sensor system
      Standards
          IEEE 802.15.3:
             physical and MAC layer standard high data rate
              WPAN.
             support real-time multi-media streaming
             data rates (11 Mbps to 55 Mbps)
             time division multiple access (TDMA) =>QoS
             synchronous and asynchronous data transfer
             wireless speakers, portable video, wireless
              connectivity for gaming, cordless phones, printers,
              and televisions

                                                                           [3]

Wireless Ad hoc Network (Fall 2008)   41       WSN survey and research challenges
      Internal sensor system
      Standards
          WirelessHART (released in September 2007)
             Process measurement and control applications
             based on IEEE 802.15.4
             supports channel hopping, and time-synchronized
              messaging
             Security with encryption, verification,
              authentication and key management
             support mesh, star, and combined network
              topologies
             manages the routing and network traffic

                                                                        [3]

Wireless Ad hoc Network (Fall 2008)   42    WSN survey and research challenges
      Internal sensor system
      Standards
          ISA100.11a
             defines the specifications for the OSI layer, security,
              and system management
             low energy consumption, scalability, infrastructure,
              robustness
             interoperability with other wireless devices
             use only 2.4 GHz radio and channel hopping to
              minimize interference
             provides simple, flexible, and scaleable security
              functionality.

                                                                            [3]

Wireless Ad hoc Network (Fall 2008)   43        WSN survey and research challenges
      Internal sensor system
      Standards
          6LoWPAN
             IPv6-based Low power Wireless Personal Area Networks
             over an IEEE 802.15.4 based network.
             Low power device can communicate directly with IP devices
              using IPbased protocols
          Wibree
             designed for low power consumption, short-range
              communication, and low cost devices
             is designed to work with Bluetooth
             operates on 2.4 GHz
             data rate of 1 Mbps
             linking distance is 5–10 m.
             was released publicly in October 2006.

                                                                               [3]

Wireless Ad hoc Network (Fall 2008)    44          WSN survey and research challenges
      Internal sensor system
      Storage
          problems
             storage space is limited
             Communication is expensive
          Solutions
             Aggregation and compression
             query-and-collect (selective gathering)
             a storage model to satisfy storage constraints and query requirements
          GEM: Graph Embedding
             provides an infrastructure for routing and data-centric storage
                  1. choosing a labeled guest graph
                  2. embed the guest graph onto the actual sensor topology
             Each node has a label encoded with its position
             each data item has a name that can be mapped to a label
          TSAR: Two-tier sensor storage architecture
          Multi-resolution storage: provides storage and long-term querying of the
           data for data-intensive applications

                                                                                                  [3]

Wireless Ad hoc Network (Fall 2008)                 45                WSN survey and research challenges
      Internal sensor system
      Testbeds
          Provides researchers a way to test their protocols, algorithms,
           network issues and applications in real world setting
          Controlled environment to deploy, configure, run, and monitoring of
           sensor remotely
          Some testbeds:
             ORBIT: Open access research testbed for next generation
              wireless networks
                  – 64 nodes, 1 GHZ
             MoteLab: web-based WSN testbed
               – central server handles scheduling, reprogramming and data
                 logging of the nodes
             Emulab: remotely accessible mobile and wireless sensor (such
                as a robot)                                                        [3]

Wireless Ad hoc Network (Fall 2008)      46            WSN survey and research challenges
      Internal sensor system
      Diagnostics and debugging support
          Measure and monitor the sensor node performance of the
           overall network
          to guarantee the success of the sensor network in the real
           environment
          Sympathy:
             is a diagnosis tool for detecting and debugging failures in sensor
              networks
             designed for data-collection applications
             detects failures in a system by selecting metrics such as
                  – Connectivity
                  – data flow
                  – node’s neighbor
             can identify three types of failures: self, path and sink
          Analysis of data packet delivery:
             packet delivery performance at the physical and MAC layers
                                                                                         [3]

Wireless Ad hoc Network (Fall 2008)          47              WSN survey and research challenges
      Internal sensor system
      Open research issues
          optimization of (HW, SW, HW/SW) to make a WSN
           efficient
          more practical platform solution for problems in new
           applications
          data structure
             Performance
             energy-efficient storage
          Performance
             communication throughput when network size increases
             Scalability issues can degrade system performance
             Optimizing protocols at different layers
          services to handle node before and after failures
                                                                              [3]

Wireless Ad hoc Network (Fall 2008)      48       WSN survey and research challenges
      Network services
       Localization
       Synchronization
       Coverage
       Compression and aggregation
       Security




                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   49   WSN survey and research challenges
      Network services
      Localization
          Problem:
             determining the node’s location (position)
          Solutions:
             global positioning system (GPS)
                  – Simple
                  – Expensive
                  – outdoor
             beacon (or anchor) nodes
                  – does not scale well in large networks
                  – problems may arise due to environmental conditions
             proximity-based
                  – Make use of neighbor nodes to determine their position
                  – then act as beacons for other nodes

                                                                                       [3]

Wireless Ad hoc Network (Fall 2008)         50             WSN survey and research challenges
      Network services
      Localization
       Other            solutions:
             Moore’s algorithm:
                  – distributed algorithm for location estimation
                    without the use of GPS or fixed beacon
                    (anchor) nodes
                  – algorithm has three phases:
                           cluster localization phase
                           cluster optimization phase
                           cluster transformation phase

                                                                                       [3]

Wireless Ad hoc Network (Fall 2008)           51           WSN survey and research challenges
      Network services
      Localization
       Other            solutions:
             RIPS: Radio Interferometric Positioning
              System
                  – Two radio transmitters create an interference
                    signal at slightly different frequencies
                  – At least two receivers are needed to measure
                    relative phase of two signal
                  – The relative phase offset is a function of the
                    relative positions
                                                                              [3]

Wireless Ad hoc Network (Fall 2008)   52          WSN survey and research challenges
      Network services
      Localization
          Other solutions:
             Secure localization:
                  – goal is to prevent malicious beacon nodes from providing
                    false location to sensors
                  – Sensors must only accept information from authenticated
                    beacon nodes
                  – Sensors should be able to request location information at
                    anytime
                  – Upon a location request, information exchange must take
                    place immediately and not at a later time.
                  – SeRloc, Beacon Suite, DRBTS, SPINE, ROPE
                                                                                   [3]

Wireless Ad hoc Network (Fall 2008)       53           WSN survey and research challenges
      Network services
      Localization
       Other            solutions:
             MAL: Mobile-assisted localization
                  – Mobile node collects distance information
                    between itself and static sensor nodes for node
                    localization
                  – given a graph with measured distance edges




                                                                             [3]

Wireless Ad hoc Network (Fall 2008)   54         WSN survey and research challenges
      Network services
      Synchronization

       Time            synchronization is important for
               routing
               power conservation
               Lifetime
               Cooperation
               Scheduling


                                                                         [3]

Wireless Ad hoc Network (Fall 2008)   55     WSN survey and research challenges
      Network services
      Synchronization

       Uncertainty-driven approach
       Lucarelli’s algorithm
       Reachback firefly algorithm (RFA)
       Timing-sync protocol for sensor network
        (TPSN)
       CSMNS
       Time synchronization (TSync)
       Global synchronization
                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   56   WSN survey and research challenges
      Network services
      Synchronization
          Synchronization protocol classification:
             application-dependent features approaches
                  – single-hop vs. multi-hop networks
                  – stationary vs. mobile networks
                  – MAC layer-based vs. standard-based
             synchronization issues
                  –   adjusting their local clocks to a common time scale
                  –   master–slave synchronization
                  –   peer-to-peer synchronization
                  –   clock correction
                  –   untethered clocks
                  –   internal synchronization,
                  –   external synchronization,
                  –   Probabilistic synchronization,
                  –   deterministic synchronization,
                  –   sender to receiver synchronization,
                  –   and receiver-to-receiver synchronization.
                                                                                               [3]

Wireless Ad hoc Network (Fall 2008)               57               WSN survey and research challenges
      Network services
      Coverage

       Isimportant in evaluating effectiveness
       Degree of coverage is application
        dependent
       Impacts on energy conservation
       Techniques:
             selecting minimal set of active nodes to be
              awake to maintain coverage
             sensor deployment strategies
                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   58   WSN survey and research challenges
      Network services
      Compression and aggregation
          Both of them
             reduce communication cost
             increase reliability of data transfer
          Data-compression
             compressing data before transmission to base
             Decompression occurs at the base station
             no information should be lost
          data aggregation
             data is collected from multiple sensors
             combined together to transmit to base station
             Is used in cluster base architectures

                                                                                  [3]

Wireless Ad hoc Network (Fall 2008)       59          WSN survey and research challenges
      Network services
      Security

       Constraints                   in incorporating security into
           a WSN
               limitations in storage
               limitations in communication
               limitations in computation
               limitations in processing capabilities


                                                                                 [3]

Wireless Ad hoc Network (Fall 2008)          60      WSN survey and research challenges
      Network services
      Open research issues
          localization
               efficient algorithms
               minimum energy
               minimum cost
               minimum localization errors
          Coverage: optimizing for better energy conservation
          time synchronization: minimizing uncertainty errors over long periods of
           time and dealing with precision
          compression and aggregation: Development of various scheme
             event-based data collection
             continuous data collection
          Secure monitoring: protocols have to monitor, detect, and respond to
           attacks
             It has done for network and data-link layer (can be improved)
             Should be done for different layers of the protocol stack
             Cross-layer secure monitoring is another research area

                                                                                           [3]

Wireless Ad hoc Network (Fall 2008)            61              WSN survey and research challenges
      Communication protocol
       Transport  layer
       Network layer
       Data-link layer
       Physical layer




                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   62   WSN survey and research challenges
      Communication protocol
      Transport layer

          Packet loss
             may be due to
                  –   bad radio communication,
                  –   congestion,
                  –   packet collision,
                  –   memory full,
                  –   node failures
             Detection and recovering
                  – Improve throughput
                  – Energy expenditure

                                                                             [3]

Wireless Ad hoc Network (Fall 2008)        63    WSN survey and research challenges
      Communication protocol
      Transport layer

       Congestion                    control/packet recovery
             hop-by-hop
                  – intermediate cache
                  – more energy efficient (shorter retransmission)
                  – higher reliability
             end-to-end
                  – source caches the packet
                  – Variable reliability

                                                                                [3]

Wireless Ad hoc Network (Fall 2008)         64      WSN survey and research challenges
      Communication protocol
      Transport layer

       Sensor transmission control protocol (STCP)
       Price-oriented reliable transport protocol
        (PORT)
       GARUDA
       Delay sensitive transport (DST)
       Pump slowly, fetch quickly (PSFQ)
       Event-to-sink reliable transport (ESRT)
       Congestion detection and avoidance (CODA):
                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   65   WSN survey and research challenges
      Communication protocol
      Transport layer (Open research issues)
       cross-layer                   optimization
             selecting better paths for retransmission
             getting error reports from the link layer
       Fairness
             assign packets with priority
             frequently-changing topology
       Congestion  control with active queue
           management
                                                                                 [3]

Wireless Ad hoc Network (Fall 2008)         66       WSN survey and research challenges
      Communication protocol
      Network layer

       Important:
             energy efficiency
             traffic flows
       Routing               protocols
             location-based: considers node location to
              route data
             cluster-based: employs cluster heads to do
              data aggregation and relay to base station
                                                                           [3]

Wireless Ad hoc Network (Fall 2008)       68   WSN survey and research challenges
      Communication protocol
      Network layer (Open research issues)

          Future research issues should address
             Security
                  – Experimental studies regarding security applied to
                    different routing protocols in WSNs should be examined
             QoS
                  – guarantees end-to-end delay and energy efficient routing
             node mobility
                  – handle frequent topology changes and reliable delivery



                                                                                   [3]

Wireless Ad hoc Network (Fall 2008)       69           WSN survey and research challenges
      Communication protocol
      Data-link layer (Open research issues)
          system performance optimization
          Cross-layer optimization
             Cross-layer interaction can
                  – reduce packet overhead on each layer
                  – reduce energy consumption
             Interaction with the MAC layer provide
                  – congestion control information
                  – enhance route selection
             Comparing performance of existing protocols of static
              network in a mobile network
             improve communication reliability and energy efficiency


                                                                                       [3]

Wireless Ad hoc Network (Fall 2008)          71            WSN survey and research challenges
      Communication protocol
      Physical layer

       Bandwidth choices
       Radio architecture
       Modulation schemes




                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   73   WSN survey and research challenges
      Communication protocol
      Physical layer (Open research issues)
          Minimizing the energy consumption
             Optimizing of circuitry energy
                  – reduction of wakeup and startup times
             Optimizing of transmission energy
                  – Modulation schemes
          Future work
             new innovations in low power radio design with emerging
              technologies
             exploring ultra-wideband techniques as an alternative for
              communication
             creating simple modulation schemes to reduce
              synchronization and transmission power
             building more energy-efficient protocols and algorithms

                                                                                        [3]

Wireless Ad hoc Network (Fall 2008)         74              WSN survey and research challenges
      Communication protocol
      Cross-layer interactions (Open research issues)

       Collaboration   between all the layers to
           achieve higher
             energy saving
             network performance
             network lifetime




                                                                       [3]

Wireless Ad hoc Network (Fall 2008)   76   WSN survey and research challenges
      Conclusion
          Large number of application is exist regarding to
           WSN
          Large number of work has done on WSN
          There are still many open issue research in WSN
          Open research area:
               Application-specific characteristic
               Power efficient algorithm
               Cross-layer optimization
               more experimental work to reach more reliability
               Improvement of existing protocol
               Security
               Error reduction in localization

                                                                                   [3]

Wireless Ad hoc Network (Fall 2008)       78           WSN survey and research challenges
      Main references
      1.   Ian F. Akyildiz, Weilian Su, Yogesh Sankarasubramaniam, and Erdal
           Cayirci, A Survey on Sensor Networks, IEEE Communications
           Magazine, August 2002
      2.   Ian F. Akyildiz, Ismail H. Kasimoglu, Wireless sensor and actor
           networks research challenges, Elsevier Ad Hoc Networks 2 (2004)
           351–367
      3.   Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal, Wireless sensor
           network survey, Elsevier Computer Networks 52 (2008) 2292–2330




Wireless Ad hoc Network (Fall 2008)       79            WSN survey and research challenges

				
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