Download 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, selforganization, 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
率
低
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
限
電源、記憶體、計算能力較
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