Energy-Efficient Broadcast and Multicast Trees for Reliable Wireless Communication

1. 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

2. Outline • Introduction • Calculating Energy Costs • Retransmission-Aware Minimum Energy Trees • Performance Comparisons • Conclusions

3. 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

4. Introduction • Wieseltheir et al [10] • Have constant approximation ratios to the 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)

5. Introduction: BIP 2 4 10 8 9 1 6 7 5 3

6. Introduction: BLU and BLiMST 2 2 4 4 10 10 8 8 9 9 1 1 6 6 7 7 5 5 3 3 BLU BLiMST

7. Assumption • Error ratepi,jfor any link (i, j): 30~40% • No mobility • Packet will be retransmission until all children receive 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

8. 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

9. Calculating Energy Costs: ComputeTxCost(x, S) 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 • 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 i1 i1 i3 i3 x i2 i2

10. Retransmission-Aware Minimum Energy Trees • RBIP • RBLU • RBLiMST • Sweep algorithm • Multicast trees

11. Retransmission-Aware Minimum Energy Trees: RBIP Update cost and parent of node 5 and node 6 5 5 3 3 2 2 6 6 1 7 7 4 4 Update Cost and parent of node 3 and node 4

12. Retransmission-Aware Minimum Energy Trees: RBIP • Like the BLU, but the cost of link (i, j) • Ei,j (reliable) = Ei,j * (1/1 – pi, j) 5 3 2 6 1 7 4

13. Retransmission-Aware Minimum Energy Trees: RBLiMST • Like extension of BLiMST algorithm 5 3 2 6 1 7 4

14. Retransmission-Aware Minimum Energy Trees • Sweep algorithm in a post order traversal of the tree • Δy = ComputeTxCost(y, Cy – {x}) – ComputeTxCost(y, Cy) • Δz = ComputeTxCost(z, Cz {x}) – ComputeTxCost(z, Cz) Cy Cz x z Cz y Cy Cz

15. 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)

16. Performance Comparisons • 100 nodes • Network environment • Random • Grid: 100*100 square gird • 100 runs for each result

17. Performance Comparisons: ACK

18. Performance Comparisons: ACK

19. Performance Comparisons: ACK

20. Performance Comparisons: NAK

21. Performance Comparisons: NAK

22. Performance Comparisons: NAK

23. Conclusions • for multi-hop wireless environments • Present energy-efficient reliable broadcast and multicast schemes • ACK • NAK

24. End