In this chapter, we address the simulation results comparing the performance of our solution against a shortest path mechanism, a simple multicast mechanism and a simple aggregation mechanism. We evaluate the relation between perfor-mance and the overlap of objective functions. We also increase the objective function in the size and numbers.
4.1 simulation environment
We setup 60 nodes randomly deployed in 500 × 500 unit2 in the simulations.
The transmission radius of each node is 50 units. In shortest path mechanism, the transmission number for a pair of a destination and a source is the least hop-count between the destination and the source. We sum up all the cost of the pairs in the network as total transmission numbers. In multicast mechanism, for each requested source and its subscriber, we construct a multicast tree based on a minimum spanning tree. The total transmission numbers is the total cost of the multicast trees. In aggregation mechanism, for each destination and its requiring source, we construct an aggregation tree based on a minimum spanning tree. As well as multicast mechanism, the total transmission numbers is the total cost of the aggregation trees in the network.
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4.2 Overlap of Objective Function
First, we evaluate the overlap of objective functions. Fig. 4.1 shows the simu-lation results. In the figure, there are 3 objective functions in the network. Each of them requiring 6 source for their inputs. Since the more overlap of the objective functions have the more opportunities to share the sensing data, the transmission number decreases while we increase the overlap ratio. The SPT mechanism is case that transmits data packets individually without any aggregation data or multicast relay techniques. Therefore, we normalize the transmission numbers to the value of SPT. The aggregation mechanism brings just a little outperformance since there is precedence of operation in the objective functions. That means, it can not ag-gregation data at some agag-gregation node in its agag-gregation tree so the mechanism just reduce the transmission numbers slightly.
0
sources overlap per objective function(%) SPT
Muticast Aggregation MMA
(a) Avg. Transmission Number
0
Avg. Normalized Transmission Numbers
sources overlap per objective function(%) SPT
Muticast Aggregation MMA
(b) Normalized to SPT
Figure 4.1: Overlap of Objective Functions
4.3 Increase Objective Function
In the section, we increase the objective function in numbers and size of inputs.
Fig. 4.2 and Fig. 4.3 show the simulation results. The results are similar in both figures. Our solution takes the more efficient than multicast mechanism. However,
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the simple aggregation mechanism suffers from the many-to-many communica-tion with objective funccommunica-tions. In some cases, SPT even surpasses the aggregacommunica-tion mechanism.
requesting sources per objective function SPT
Muticast Aggregation MMA
(a) Avg. Transmission Number
0
Avg. Normalized Transmission Numbers
requesting sources per objective function SPT
Muticast Aggregation MMA
(b) Normalized to SPT
Figure 4.2: Increase the size of each objective function
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requesting sources per objective function SPT
Muticast Aggregation MMA
(a) Avg. Transmission Number
0
Avg. Normalized Transmission Numbers
Number of Objective Function SPT
Muticast Aggregation MMA
(b) Normalized to SPT
Figure 4.3: Increase the number of objective functions
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Chapter 5 Conclusions
This paper addressed the problem of many-to-many communications in a wire-less sensor network. We propose a mobile agent model for distributed multi-source and multi-destination data transmission which takes a logical view to pro-vide a routing schema to satisfy the objective requirements in the many-to-many communication. We decompose the objective requirements into several single ag-gregation operations in the network. Thus, it is easy to share the joint agag-gregation requirements. The simulation results reveal the outperformance of the model in the many-to-many communication. Moreover, Mobile agent model can be easily adapted to many-to-one or one-to-many communication schema since it concerns about not only the aggregation but also the multicast techniques.
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