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Energy-Efficient Broadcast and Multicast Trees for Reliable Wireless Communication
Suman Banerjee, Archan Misra, Jihwang Yeo and Ashok Agrawala
IEEE Wireless Communications and Networking Conference
(WCNC) 2003
Speaker: Ju-Mei Li
Outline
Introduction Calculating Energy Costs Retransmission-Aware Minimum
Energy Trees Performance Comparisons Conclusions
Introduction
In wireless environments Individual links often have high error
rates Currently minimum-energy tree
formation algorithms Assign costs to links based on the
energy spent in a signal transmission Do not consider the link error rates
Introduction
Wieseltheir et al [10] Have constant approximation ratios to th
e optimal solution for error-free wireless links
Three broadcast tree formation algorithms
Broadcast Incremental Power (BIP) Broadcast Least-Unicast-cost (BLU) Broadcast Link-based MST (BLiMST)
Introduction: BIP
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Introduction: BLU and BLiMST
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BLU BLiMST
Assumption
Error rate pi,j for any link (i, j): 30~40% No mobility Packet will be retransmission until all children rec
eive it ACK
Chooses minimum power to reach each child which does not receive broadcast packet
NAK: just one NAK will be received by sender Use a transmission power to reach all children on the tree
Calculating Energy Costs
Packet error rate, S[i].error = p = 1 – (1 - pb)s
S[i].not_rcv_prob = S[i].not_rcv_prob * (S[i].error)tx
pb is the bit error rate and
s is the packet size
Nerfcpb
rconstant.P
Calculating Energy Costs: ComputeTxCost(x, S)
x
i1
i2
i3
i1
The set within the transmission power and is sorted by decreasing order of distance
from x
For i1
Px,i1: transmission a packet from x to i1
Ex,i1: single transmission power
Use Px,i1 i1.error, i2.error and i3.error
Use i1.error tx (number of reliable transmissions of i1)
Use tx, Ex,i1 and i1.not_rcv_prob cost of i1
Update i2.not_rcv_prob and i3.not_rcv_prob
For i2
Px,i2: transmission a packet from x to i1
Ex,i2: single transmission power
Use Px,i2 i1.error, i2.error and i3.error
Use i2.error tx (number of reliable transmissions of i2)
Use tx, Ex,i2 and i2.not_rcv_prob cost of i2
Update i3.not_rcv_prob
i2
i3
For i3
Px,i3: transmission a packet from x to i1
Ex,i3: single transmission power
Use Px,i3 i1.error, i2.error and i3.error
Use i3.error tx (number of reliable transmissions of i3)
Use tx, Ex,i3 and i3.not_rcv_prob cost of i3
Retransmission-Aware Minimum Energy Trees
RBIP RBLU RBLiMST Sweep algorithm Multicast trees
Retransmission-Aware Minimum Energy Trees: RBIP
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Update cost and parent of node 5 and
node 6
Update Cost and parent of node 3 and
node 4
Retransmission-Aware Minimum Energy Trees: RBIP
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Like the BLU, but the cost of link (i, j) Ei,j (reliable) = Ei,j * (1/1 – pi, j)
Retransmission-Aware Minimum Energy Trees: RBLiMST
Like extension of BLiMST algorithm
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Retransmission-Aware Minimum Energy Trees
Sweep algorithm in a post order traversal of the tree Δy = ComputeTxCost(y, Cy – {x}) – ComputeTx
Cost(y, Cy)
Δz = ComputeTxCost(z, Cz {x}) – ComputeTxCost(z, Cz)
x
y
z
Cy
Cy
Cz
Cz
Cz
Retransmission-Aware Minimum Energy Trees
Multicast trees Compute the broadcast tree without
using sweep algorithm Delete nodes which do not lead to
any multicast group numbers (in a single post-order traversal)
Sweep algorithm are performed on the remaining tree (in post-order)
Performance Comparisons
100 nodes Network environment
Random Grid: 100*100 square gird
100 runs for each result
Performance Comparisons: ACK
Performance Comparisons: ACK
Performance Comparisons: ACK
Performance Comparisons: NAK
Performance Comparisons: NAK
Performance Comparisons: NAK
Conclusions
for multi-hop wireless environments Present energy-efficient reliable
broadcast and multicast schemes ACK NAK
End