The Experiment Results

Field experiments are conducted in order to evaluate the performance of the proposed ECMR proto-col. The ODMRP algorithm [5] is also implemented for comparison purpose. The network topology utilized in the experiments is illustrated as in Fig. 10.2. The source node S intends to deliver data packets to its corresponding receivers R₁, R₂, and R₃ via the intermediate nodes I₁ and I₂. Two metrics are employed for performance comparison: the energy consumption for relaying data packets and the packet delivery ratio.

Fig. 10.3(a) shows the performance comparison between the ECMR and the ODMRP algorithms by observing the energy consumption versus the round index. It is noted that the round index rep-resents each periodically refreshed round conducted by the route updating process. The energy con-sumption for relaying data packets is calculated by multiplying the total data packets delivered be-tween every two rounds with the energy consumption for each packet transmission. It is noted that the transmitter bit rate equals 11 Mbps; while the transmitting power is 15 dBm. The data rate is fixed to 6 packets per round with each packet size of 1024 bytes. The parameters utilized within the ECMR protocol are listed as follows: FLDT = 6 sec, CDT = 0.5 sec, CT_I= 1.5 ms, and CT_R= 30 ms.

Since the ODMRP protocol is designed based on the shortest path construction, node R₁ will randomly select either I₁or I₂as its upstream node. Moreover, I₂is consistently chosen since it is the

only node on the shortest path to both R₂and R₃. Consequently, the number of required intermediate nodes by adopting the ODMRP algorithm will alternate between one and two, which results in the fluctuation on the energy consumption versus the round index (i.e. the green bars as shown in Fig.

10.3(a)). On the other hand, the number of intermediate nodes will always be one after the second round by exploiting the proposed ECMR protocol. Considering the worst case, node R₁ will select I₁ as the upstream node to S in the first round. In the remaining rounds, node R₁will always select I₂ as the upstream node to S since the N WGHT parameter from node I₂is greater than that from node I₁. It can be seen from the experimental results (in Fig. 10.3(a)) that the energy consumption by using the ECMR protocol is comparably less than that from the ODMRP algorithm. It is also noticed that as the available number of intermediate nodes is increased, the benefits of adopting the ECMR algorithm will become more observable.

Fig. 10.3(b) shows performance comparison considering the packet delivery ratio versus the in-terdeparture time (with packet size of 1024 bytes). It is noted that the packet inin-terdeparture time represents the time interval for delivering two consecutive data packets. It can be seen that both the ECMR and the ODMRP protocols can provide high packet delivery ratio (with almost 100%) under different packet interdeparture time. The slightly low delivery ratio resulted from the ECMR algorithm is attributed to its less number of duplicated data packets that are transmitted.

1 2 3 4 5 6 7 0

50 100 150 200 250 300 350 400 450

Round Index

Energy Consumption of Relaying Data Packets (uJ)

ODMRP ECMR

(a)

100 150 200 250

0.94 0.95 0.96 0.97 0.98 0.99 1

Delivery Ratio

Packet Interdeparture Time (ms)

ODMRP ECMR

(b)

Figure 10.3: (a) Energy Consumption for Relaying Data Packets vs. Round Index, (b) Packet Delivery Ratio vs. Packet Inter-Departure Time.

Chapter 11

Conclusion

An Energy-Conserving Multicast Routing (ECMR) protocol for the wireless multihop networks is proposed in this paper. Both the proposed ECMR protocol and the existing mesh-based ODMRP algorithm are implemented on an ARM-based embedded platform for performance evaluation. The experimental results show that the ECMR protocol can provide high packet delivery ratio under dif-ferent packet inter-departure time; while comparably less energy is consumed.

Bibliography

[1] E.M. Royer and C.E. Perkins, ”Multicast Operation of the Ad-Hoc On-Demand Distance Vec-tor Routing Protocol,” Proc. of the Fifth Annual ACM/IEEE International Conference on Mobile Computing and Networking, pp. 207-218, Aug. 1999.

[2] C.W. Wu and Y.C. Tay, ”AMRIS: A Multicast Protocol for Ad Hoc Wireless Networks,” Proc. of IEEE Military Communications Conference, Vol. 1, pp. 25-29, Oct. -Nov. 1999.

[3] J. Xie, R.R. Talpade, A. Mcauley, and M. Liu, ”AMRoute: Ad Hoc Multicast Routing Protocol,”

ACM/Kluwer Journal of Mobile Networks and Applications, Vol. 7, Iss. 6, pp. 429-439, Dec. 2002.

[4] S.K.S. Gupta and P.K. Srimani, ”An Adaptive Protocol for Reliable Multicast in Mobile Multi-Hop Radio Networks,” Proc. of the Second IEEE Workshop on Mobile Computing Systems and Applications, pp. 111-122, Feb. 1999.

[5] S.J. Lee, M. Gerla, and C.C. Chiang, ”On-Demand Multicast Routing Protocol,” Proc. of IEEE Wireless Communications and Networking, Vol. 3, pp. 1298-1302, Sept. 1999.

[6] S.J. Lee, W. Su, and M. Gerla, ”On-Demand Multicast Routing Protocol in Multihop Wireless Mobile Networks,” ACM/Kluwer of Mobile Networks and Applications, Vol. 7, pp. 441-453, Dec.

2002.

[7] J.J. Garcia-Luna-Aceves and E.L. Madruga, ”The Core-Assisted Mesh Protocol,” IEEE Journal on Selected Areas in Communications, Vol. 17, Iss. 8, pp. 1380-1394, Aug. 1999.

[8] P. Sinha, R. Sivakumar, and V. Bharghavan, ”MCEDAR: Multicast Core-Extraction Distributed Ad Hoc Routing,” IEEE Wireless Communications and Networking Conference, Vol. 3, pp. 1313-1317, Sept. 1999.

[9] P.M. Ruiz and A.F. Gomez-Skarmeta, ”Approximating Optimal Multicast Trees in Wireless Mul-tihop Networks,” Proc. of IEEE Computers and Communications (ISCC), pp. 686-691, Jun. 2005.

[10] Wookey and Tak-Shing, ”Porting the Linux Kernel to a New ARM Platform,” Wireless Solutions Journal, Vol. 4, pp. 52-59, 2002.

[11] K. Wehrle, F. P¨ahlke, Hartmut, D. M¨uller, and M. Bechler, ”The Linux Networking Architecture:

Design and Implementation of Network Protocols in the Linux Kernel,” Prentice Hall, Aug. 2004.

[12] ”PCM-7230 User’s Manual,” Advantech Co., Ltd., 2003.