Routing for Wireless Sensor Network

							Routing for Wireless Sensor
Network
          行動通訊系統專題報告




 教授:林振緯
 班級: 研一
 報告人:郭彥蔚,黃皓祺

                              1
Abstract
   Wireless Sensor Network(WSN)是目前研究領
    域的重要課題，這裡面包含了許多相關的研
    究方向。
    – Physical layer protocols and related issues
    – Routing protocols and data communications
    – System Reliability and Fault Tolerance
    – Target Detection, Classification and Tracking with
      Sensor Networks
    – Data Fusion and Data Management
    – TCP over Wireless Networks
    – Other
   傳統ad hoc路由協定為何不適用於WSN
   WSN路由協定所要解決的問題及方法
                                                           2
Agenda
 What’s Wireless Sensor Network
 WSN vs MANET
 Wireless Sensor Network Architecture
 Communication and Data Delivery Model
 Routing Protocol
 Conclusion
 Q&A



                                          3
Glossary
 WSN – Wireless Sensor Network
 MANET – Mobile Ad-hoc Network
 MEMS – Micro Electro Mechanical
  Systems




                                    4
What’s Wireless Sensor Network
 Introduction
 Features of sensor networks
 Wireless Sensor Networks Application




                                         5
Introduction
 The development of low-cost, low-power,
  multifunctional sensor networks is due to
  advancement in wireless communications
  and electronics
 The tiny sensor nodes consist of sensing,
  data processing, and communicating
  components


                                              6
Introduction (cont.)
 A sensor network is composed of a large
  number of sensor nodes that are densely
  deployed either inside the phenomenon or
  very close to it
 The position of sensor nodes need not be
  engineered or predetermined



                                             7
Features of sensor networks
 Sensors can be random deployment in
  inaccessible terrains; sensor network
  protocols and algorithms must possess
  self-organizing capabilities
 Sensor networks require the cooperative
  effort of sensor nodes



                                            8
Features of sensor networks (cont.)
   Instead of sending the raw data to the
    nodes responsible for the fusion, sensor
    nodes use their processing abilities to
    locally carry out simple computations and
    transmit only the required and partially
    processed data



                                                9
Wireless Sensor Networks
Application
 A wide range of application areas of sensor
  networks are health, military, and home
 In military, the rapid deployment, self-
  organization, and fault tolerance
  characteristics of sensor networks make
  them a very promising sensing techniques
  for military command, control,
  communication, computing, intelligence,
  surveillance, reconnaissance, and
  targeting systems
                                                10
Wireless Sensor Networks
Application (cont.)
 In health, sensor nodes can also be
  deployed to monitor patients and assist
  disabled patients
 Commercial applications: managing
  inventory, monitoring product quality, and
  monitoring disaster areas



                                               11
WSN vs MANET

    The differences between sensor networks
     and ad hoc networks are：
     – The number of sensor nodes are several orders
       of magnitude higher
     – Sensor nodes are densely deployed
     – Sensor nodes are prone to failures
     – The topology of a sensor network changes
       very frequently

                                                       12
WSN vs MANET (cont.)
   Sensor nodes mainly use a broadcast
    communication paradigm whereas most ad hoc
    networks are based on point-to-point
    communications
   Sensor nodes are limited in power, computational
    capacities, and memory
   Sensor nodes may not have global identification
    (ID) because of the large amount of overhead and
    large number sensors

                                                       13
WSN vs MANET (cont.)
             WSN            MANET

節點數量   通常裝置的數量龐大      網路內的裝置數量有限

節點密度   密集             鬆散

節 點 故 障 很高            低
率
網路拓樸   變動頻率很高         變動頻率高但較WSN低

通訊方式   廣播             點對點

裝置硬體   電源、記憶體、計算能力有   電源、記憶體、計算能力較
       限              好
識別方式   沒有特定的識別碼       有特定的識別碼
                                     14
Wireless Sensor Network
Architecture
 Hardware
 Software
 Wireless Sensor Network Design Factors




                                           15
Hardware Architecture




                        16
Hardware Architecture (cont.)
   Sensing Unit
    – The analog signals produced by the sensors based on
      the observed phenomenon are converted to digital
      signals by the ADC, and then fed into the processing
      unit
   Processing Unit
    – Sensor nodes use their processing abilities to locally
      carry out simple computations and transmit only the
      required and partially processed data

                                                               17
Hardware Architecture (cont.)
 Transceiver    Unit
  – A transceiver connects the node to the
    network
 Power   Unit
  – Power unit may be supported by power
    scavenging units such solar cells



                                             18
Software
   Tiny OS
    – 無線感測網路(Sensor Network)上的每個點
      都是一個小型電腦，都具備有通訊網路的
      功能，其上面的作業系統稱為 Tiny OS，顧
      名思義是個極小的嵌入式作業系統。




                                    19
Wireless Sensor Network Design
Factors
   Fault Tolerance
    – the ability to sustain sensor network
      functionalities without any interruption due to
      sensor node failures
   Scalability
    – The number of sensor nodes deployed in
      studying a phenomenon may be on the order
      of hundreds or thousands Sensor Costs

                                                        20
Wireless Sensor Network Design
Factors (cont.)
   Production costs
    – The cost of a sensor node should be much less
      than US$1 in order for the sensor network to
      be feasible
   Hardware Constraints
    – A sensor node is made up of 4 basic
      components a sensing unit, a processing unit,
      a transceiver unit, and a power unit
    – Use MEMS technique

                                                      21
Wireless Sensor Network Design
Factors (cont.)
   Sensor Network Topology
    – Planning and Deployment Phase
           感測器的部署可以事先精心規劃，再依據所規劃的藍圖佈署感
            測器。
    – Post-Deployment Phase
           在感測器部署完成後，就已經形成一個完整的無線網路架構，
            但是感測器的位置容易受到環境因素，造成網路拓樸的改變；
            這時候，系統就必須對拓樸的改變做出即時反應，並迅速對殘
            缺的網路拓樸做出修正。
    – Redeployment of Additional Phase
           在經過一段時間後，許多感測器可能由於電力嚴重不足或是損
            壞的緣故，造成整個感測網路中，可以偵測環境以及傳輸資料
            的節點個數不足。必須依靠外力(人員、機械等)在這個網路中
            新增一些額外的感測器，以彌補感測器數量不足的問題。

                                           22
Wireless Sensor Network Design
Factors (cont.)
   Environment
    – Sensors can be random deployment in
      inaccessible terrains; sensor network protocols
      and algorithms must possess self-organizing
      capabilities
 Transmission Media
 Power Consumption



                                                        23
Communication and Data Delivery
Model




                              24
Communication and Data Delivery
Model (Cont.)
    Communication Model
     – Application
     – Infrastructure
    Data Delivery Model
     – Application Layer
           Continuous
           Even-Driven
           Observer-Initiated
           Hybrid
     – Physical Layer
           Flooding, unicast, multicast

                                           25
Communication Model

    Application
     – 應用通訊主要是將所偵測到的資料及數
       據傳送回基地台,因此通訊模式大多是點對
       點(end-to-end)的型態
     – 此架構對資料的蒐集又可分為
           Cooperative
             – Data fusion or Data Aggregation
           Non-Cooperative


                                                 26
Communication Model (cont.)




                              27
Communication Model (cont.)

    Infrastructure
     – 基礎建置通訊主要運用在感測器網路需
       要configure、maintain、optimize網路時
     – 此架構依照任務需求,以不同的演算法進行
       調整




                                         28
Data Delivery Model

    Continuous
     – 資料以固定間隔持續的送至基地台
    Even-Driven
     – 事件發生時,資料才送回基地台
    Observer-Initiated
     – 由觀測者送出指令或需求時,資料才送回基地台
    Hybrid
     – 上述三種型態都有的混合型


                               29
Data Delivery Model (cont.)
    Flooding
     – 來源端傳送資料給所有的鄰居,一直到資料
       抵達目的端




                              30
Data Delivery Model (cont.)

    Unicast
     – 資料傳送至單一節點,可能為路由路徑的下
       一節點或基地台
    Multicast
     – 鄰近的感測器依需求建立群組,資料傳送可
       直接傳送給群組的各個成員



                              31
Routing Protocol

    The networking layer of sensor networks is
     usually designed according to the following
     principles:
     – Power efficiency
     – Sensor networks are mostly data centric
     – Data aggregation is useful only when it does not
       hinder the collaborative effort of the sensor nodes
     – An ideal sensor network has attribute-base addressing
       and location awareness

                                                               32
Power efficiency

    An energy-efficient route is selected by
     one of the following approaches:
     –   Maxmum PA route
     –   Minimum Energy (ME) route
     –   Minimum Hop (MH) route
     –   Maximum minimum PA node route



                                                33
Maximum PA route




                   34
Minimum Energy (ME) route




                            35
Minimum Hop (MH) route




                         36
Maximum Minimum PA node route




                            37
Routing Protocol (cont.)

    Network Layer
     –   SMECN
     –   Flooding
     –   Gossiping
     –   SPIN
     –   SAR
     –   LEACH
     –   Directed Diffusion

                              38
Routing Protocol (cont.)




                           39
Routing Protocol (cont.)

    Transport Layer
     – Protocol are still unexplored
     – They may be purely UDP-type protocols,
       because each sensor node has limited memory
       and power
    Application Layer
     – SMP
     – TADAP
     – SQDDP
                                                     40
Conclusion

 Many researchers are currently engaged in
  developing the technologies needed for
  different layers of the sensor networks
  protocol stack
 A list of current sensor network research
  projects shown in reference Table 3.



                                              41
Reference




            42
Reference
   Ian F. Akyildiz, Weilian Su, Yogesh Sankarasubramaniam, and
    Erdal Cayirci @ GaTech A Survey on Sensor Networks
    IEEE Communications Magazine, 2002
   S. Tilak, N. Abu-Ghazaleh, and W. Heinzelman @ Binghamton &
    Rochester
    A Taxonomy of Wireless Micro-Sensor Network Models.
    ACM Mobile Computing and Communications Review (MC2R),
    Volume 6, Number 2, April 2002
   Holger Karl and Andreas Willig
    A Short Survey of Wireless Sensor Networks.
    TKN Technical Report TKN-03-018, October 2003
   Deborah Estrin, Ramesh Govindan, John Heidemann and Satish
    Kumar @ USC/ISI
    Next Century Challenges: Scalable Coordination in Sensor
    Networks. In Proc. of the fifth Annual ACM International
    Conference on Mobile Computing and Networking, 1999, Seattle,
    Washington, USA


                                                                    43