LEACH module

林政龍

Outline

IntroductionLEACH (Low-Energy Adaptive Clustering

Hierarchy)InstallationLEACH module

WSN (wireless sensor network)

Sensor node 的能力 Sensing Process communication

Sensor node 的特色 量多 (hundreds or thousands of sensor nodes), 體積小 ,

夠便宜 電池供電

衍生問題 很難各別去置換 sensor 或是它的電池 power conservation is a critical design issue for routing

protocol.

能量消耗模組

Problem of energy consumption

Sensor node

Base station

Problem of energy consumption (cont.)

Sensor node

Base station

LEACH (Low-Energy Adaptive Clustering Hierarchy)

Employs randomized rotation of the cluster-heads to evenly distribute the energy load among the sensor nodes in the network

LEACH 的圖解100 m

叢集區

觀測區域

Base Station

Sensor (Non Cluster Head)

Sensor (Cluster Head)

Initial Data

Aggregated Data

~100m

LEACH (cont.)

The operation is divided into rounds.Each of these rounds consists of 2 phases:

a set-up phase and a steady-state phase.During the set-up phase cluster-heads are

determined and the clusters are organized.During the steady-state phase data trans-f

erence to the base station occurs.

LEACH (cont.)

Cluster-head election process : (the same as LEACH) A sensor determines whether to become a cluster head by generating a random number and compare this value with a threshold

A node becomes a cluster head if the random number is less than a threshold

iix (0 1)ix

( )T iP,the desired percentage to become a cluster-head;

r,the current round

the set of nodes that have not being selected as a cluster-head in the last 1/P rounds.

ix ( )T i

LEACH (cont.)

形成 cluster 後， cluster-head 會排定 TDMA schedule 給屬於相同 cluster 的 non-cluster 傳輸的時槽 (time slot) ，已決定每個 non-cluster 傳輸時間

等待 cluster-head 收集完 non-cluster 的資料後，便將資料傳給 BS

ㄧ開始 cluster-head 發送 adv. 給所有的 sensor nodes 與 sensor nodes 加入某個 cluster 是利用CSMA 機制，之後 non-cluster 傳輸資料給 cluster 或是 cluster 收集完資料，再將資料傳送給 BS ，都是利用 CDMA 的機制去傳輸資料

LEACH 的 flow chart

Installation

http://www.internetworkflow.com/downloads/ns2leach/

LEACH module

Mobile node

cmu-trace.cc

mac-sensor-timer.ccmac-sensor.cc

wireless-phy.cc

Resource-Adaptive node

ns-ranode.tcl

resource.cc

rcagent.cc

rca-all.cc

energy.cc

LEACH 程式結構

Wireless.tcl

Leach.tcl

uamps.tcl

ns-leach.tcl

ns-bsapp.tclns-resource-manager.tcl

extras.tclns-energy-resource.tcl

stats.tclns-neighbor-resource.tcl

ns-ranode.tcl

Leach 主程式

執行 base station 的功能

統計產生檔案Resource Adaptive Node

設定參數

執行

Reference

http://nslab.ee.ntu.edu.tw/NetworkSeminar/slides/EDACH.ppt

http://www.internetworkflow.com/resources/ns2leach.pdf

http://www.internetworkflow.com/downloads/ns2leach/

Final project

ACT : Adaptive Colored Threshold100 m

叢集區

觀測區域

Base Station

Sensor (Non Cluster Head)

Sensor (Cluster Head)

Initial Data

Aggregated Data

~100m

100 m

叢集區

觀測區域

Base Station

Sensor (Non Cluster Head)

Sensor (Cluster Head)

Initial Data

Aggregated Data

~100m

ACT scheme

提出了 temporal suppression 與 spatial suppression 兩種抑制傳輸，目的是為了達到energy efficient ，但省 energy 卻會造成傳回給 BS 的資料有精確性的問題，所以又提出 α 值來使誤差降至最低

Temporal 與 Spatial 圖解 (sensor node端 )

α 的選定

為了使誤差降至最低，因此，提出了下列公式，來選定 α 為最小誤差值

SV 為 sensor node 的前一輪的感測值dj 為 cluster-head 目前的感測值di 為 sensor node 目前的感測值

流程圖

Temporal 與 Spatial (BS 端 ) (1)

若 sensor node 並未達到 suppression 的條件，會將完整的感測值傳回給 BS ，因此，BS 可以得到正確的感測資料，便不需要執行估計的程序，反之，若 BS 未得到 sensor node 的感測值，就必須根據下列公式來估計其 sensor node 的感測值 :

Temporal 與 Spatial (BS 端 ) (2)

SV 為 temporal 的估計值，將直接採用 sensor node 最後傳給 BS 的感測值當估計值

為 spatial 的估計值，利用線性方程式 求得

斜率 m 與截距 b 後，再使用兩點內插法或外插法來求得估計值

Simulation

環境 NS2 field of 100 * 100 base station (50 , 170) initial battery capacity of 2 J

oules

metrics

Result (heat source module)

Result (heat oscillation module)

Result (wave front module)

Conclusion

proposed the Adaptive Color Threshold (ACT) scheme to provide priority treatments to enhance the efficiency of redundancy suppression

利用 α 、 temporal 及 spatial 的機制來提升sensor node 被抑制感測值的精確度

Thank you

Introduction TEEN

TEEN : Threshold sensitive Energy Efficient sensor Network protocol Good for time-critical applications This sensor network model likes LEACH uses a

hierarchical clustering scheme Cluster headers broadcast:

Hard Threshold

• This is a threshold value for the sensed attribute Soft Threshold

• This is a small change in the value of the sensed attribute which triggers the node to switch on its transmitter and transmit

hierarchical clustering scheme

TEEN 的運作示意圖

LEACH and TEEN

LEACH Abstract: Reelect Cluster head (CH) each round

Advantage: Load balance Disadvantage: Data Redundancy

TEEN Abstract: Hard and soft threshold

Advantage: Reduce similar data to transmit at each node Disadvantage:

• Thresholds are fixed

• 無法得知 node 存亡• 沒有考慮環境的變化，資料重要性相同