hybrid indirect transmissions (hit) for data gathering in wireless micro sensor networks with...
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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
H
BS
INTRODUCTION
• Current remote sensing routing protocols increase efficiency• data fusion• power management systems• clustering• chaining
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BS
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
HH
BS
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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A B
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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)
H
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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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ij
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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
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