Compared to other schemes designed for the mobile ad hoc networks explained in Section 28.3, SMAC is designed particularly for use in wireless sensor networks. It attempts to combine the advantages of TDMA scheduling for power saving by periodically requiring sensing nodes to go to sleep. The sleeping patterns are coordinated in order to minimize the latency, as discussed before. Nevertheless, a solution with a fixed duty cycle does not give the optimal performance.
Authors claim that this scheme forms a flat topology and intercluster problems are absent; however, this may not be true in cases in which the application requires real clusters to be formed, at least temporarily. In such a case, the communication patterns will depend on the cluster formation and that these real clusters and the virtual clusters formed will coincide is not guaranteed. The adaptability of this scheme to such a situation should be investigated.
A significant portion of nodes will belong to two or more virtual clusters under this scheme. The energy consumption of such nodes would be higher compared to nodes within a single virtual cluster. Hence, the portion of such nodes and its effect on performance should be analyzed under real application scenarios. Also, the performance of this MAC scheme should be studied along with different routing schemes in order to assess its performance of intercluster communication, especially for multihop unicast and multicast messages. Data routing across virtual clusters needs to be studied further for its latency and throughput.
In WSN applications, it is possible for certain nodes to be exhausted with power and new nodes to be added. Performance of SMAC during times when a significant portion of nodes is discarded or added, or in cases with a higher portion of mobile nodes, should be studied. Another instance to be observed is what happens if the coordinated sleep schedules of two neighboring clusters are completely opposite. In such cases, it is not clear whether the bordering nodes could adopt both schedules.
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