Hybrid Indirect Transmissions (HIT) for Data Gathering in Wireless Micro Sensor Networks with Biomedical Applications

Jack Culpepper(NASA), Lan Dung, Melody Moh

CCW 2003 , IEEE

Speaker : Chi-Chih Wu

Outline

• INTRODUCTION• BASIC MODELS• PROTOCOL DESCRIPTION• PERFORMANCE EVALUATION• CONCLUSION

INTRODUCTION

• Micro sensors• The consumers of power

• Data processing• Communications

• Major consumer of power• Communications

• Most energy expensive applications• Remote sensing

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INTRODUCTION

• Current remote sensing routing protocols increase efficiency• data fusion• power management systems• clustering• chaining

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INTRODUCTION

• W. Heinzelman et al , “Energy-Efficient Communication Protocol for Wireless Microsensor Networks” (LEACH)• Each node has a probability p of

becoming a cluster-head• the protocol guarantees that every

node will be cluster-head only once in 1/p rounds

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INTRODUCTION

• Stephanie Lindsey and Cauligi S. Raghavendra , “PEGASIS:Power Efficient Gathering in Sensor Information Systems”• Chains of nodes are computed using a gr

eedy algorithm• Chain leaders are elected to fuse data an

d transmit the result to BS

INTRODUCTION

• Features of HIT• Utilizing one or more clusters to reduce the

number of transmissions to the remote base station

• Parallel, multi-hop indirect transmissions even in the presence of multiple, adjacent clusters

• Goals• Minimize energy consumption• Minimize network delay

BASIC MODELS

• Data Delivery Model• Radio Model• Analysis of Direct versus Indirect

Transmissions• Parallel Transmissions• Analysis of TDMA versus CSMA

Data Delivery Model

• Sensor networks can be classified in terms of the data delivery required• Continuous (HIT based)• Event-driven• Observer-initiated• Hybrid

Radio Model

• A radio transceiver dissipates• Eelec = 50 nJ/bit

Analysis of Direct versus Indirect Transmissions

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• Energy Saving

Parallel Transmissions

• Parallel indirect transmissions• Use intelligent scheduling algorithm

(TDMA)• Achieves lower delay than LEACH

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Analysis of TDMA versus CSMA• CSMA wastes energe versus TDMA

• Collisions• Overhearing• Control packet overhead• Idle listening

• Advantages of TDMA• No collisions• Little overhead• High energy efficient

• Disadvantages of TDMA• Time synchronization• It is difficult to change the TDMA schedule

PROTOCOL DESCRIPTION

• HIT is consisting of two periods• Cluster setup• Long steady state

PROTOCOL DESCRIPTION

• HIT makes the following assumptions• Nodes are distributed randomly• Nodes are able to communicate by CSMA• the result of n fusions will be independent of

n, and be no more than a constant multiple of s

• Nodes are able to estimate distances• Each sensor node has a unique node ID

PROTOCOL DESCRIPTION

• HIT protocol consists of the following phases• Cluster-Head Election• Cluster-Head Advertisement• Cluster Setup• Route Setup• Blocking Set Computation• MAC Schedule Creation• Data Transmission

Cluster-Head Election

• Election Scheme I(a)• single cluster• nodes take as cluster-head turn in order of node

ID• Election Scheme I(b)

• single cluster• nodes take turn as cluster-head, some nodes m

ay not ever be cluster-head (lower levels of connectivity or energy)

Cluster-Head Election

• Election Scheme II(a)• multiple clusters• nodes are elected randomly (LEACH)

• Election Scheme II(b):• multiple clusters• nodes are elected randomly, some nodes may n

ot ever be cluster-head (lower levels of connectivity or energy)

Cluster-Head Advertisement(CSMA/CD)• <MsgType=Advertise, source-id = H>• Cluster-heads broadcast their status at the

fixed power with the message• Non-cluster-heads then compute the distance t

o the clusterhead and save the value as D(H, j)

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D(H,j)H-id

Cluster Setup

• one or more clusters will be formed, and the upstream and downstream relationship will be created.• <MsgType = Member, source-id = j, D(H, j)>• each node has only one upstream neighbor• d(u, H) < d(i, H) , d(i, u) < d(i, H)

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Cluster Setup

D(H,j)id

D(j,uj)

d(u, H) < d(i, H) , d(i, u) < d(i, H)

Route Setup

• all nodes broadcast its upstream neighbor’s information• <MsgType = MyUpstream,

source-id = j, upstream-id = uj, d(j,uj) >• it adds i to its list of downstream neighbors for j, D

OWN(j)

Source-idUpstream-idD(j,uj)

Blocking Set Computation

• each node computes the blocking set for its downstream neighbors• we say node i blocks node j if and only if d(i, ui) > d

(i, uj)• i blocks j does not necessarily imply that j blocks I• <MsgType = Blockdown, node-id, blocklist>• each downstream neighbor of j blocks all other do

wnstream neighbors of j

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MAC Schedule Setup

MAC Schedule Setup

Data Transmission

• <MsgType=Data, source-id, destination-id, payload>

• This phase does not require the use of a CDMA code

PERFORMANCE EVALUATION• All nodes were bestowed with 20 J of initial energy,• round was fixed at 10,000.• The data rate of the wireless net-work is 1 Mbit/s,• the coordinates for the base station are (l/2,-200),• The average size of a sensor data item, a 50-bit pac

ket• For LEACH and HITm, we specified that 1% of the n

odes would be elected cluster-heads

PERFORMANCE EVALUATION

PERFORMANCE EVALUATION

PERFORMANCE EVALUATION

PERFORMANCE EVALUATION

PERFORMANCE EVALUATION

PERFORMANCE EVALUATION

CONCLUSION

• We introduce a hybrid clustering and indirect transmission scheme for micro sensor networks

• The novel feature of parallel indirect transmissions and the complete protocol including phases of clustering, routing, and scheduling

• Performance evaluations showed that HIT provides energy savings over LEACH, PEGASIS, and Direct

• HIT also greatly reduces the delay

THANK YOU