In this paper, the applicability of the network coding technique in 6LoWPAN-based sensor multihop networks is examined. The 6LoWPAN is one of the standards proposed for the Internet of Things architecture. Thus, we can expect the significant growth of traffic in such networks, which can lead to overload and decrease in the sensor network lifetime. The authors propose the inter-session network coding mechanism that can be implemented in resource-limited sensor motes. The solution reduces the overall traffic in the network, and in consequence, the energy consumption is decreased. Used procedures take into account deep header compressions of the native 6LoWPAN packets and the hop-by-hop changes of the header structure. Applied simplifications reduce signaling traffic that is typically occurring in network coding deployments, keeping the solution usefulness for the wireless sensor networks with limited resources. The authors validate the proposed procedures in terms of end-to-end packet delay, packet loss ratio, traffic in the air, total energy consumption, and network lifetime. The solution has been tested in a real wireless sensor network. The results confirm the efficiency of the proposed technique, mostly in delay-tolerant sensor networks.
Abstract-Cognitive Radio (CR) was designed to support flexible spectrum usage by adding spectrum sensing facilities and decision making logic to the radio devices. Cognitive Radio Network (CRN) is an extension of the CR concept to enable holistic end-to-end optimization of the network operation and services. We discuss CRN management issues in the context of military and tactical operation environments, where the key feature is the temporal nature of the network installations. Our special interest is in the wireless ad hoc network solutions. The network lifetime may extend from just hours to several days. The limited lifetime of the networks makes it both possible and necessary to define the management functionalities with respect to different mission phases. Traditional FCAPS (Fault, Configuration, Administration, Performance, and Security) functions and their required actions are therefore detailed to some level at each operational phase (before, during and after mission). We will emerge the idea that, as the cognitive and autonomous technologies will be developed to operate communication networks and become trustworthy enough to be applied also in tactical context, they will most likely first be applied in the during mission phase. Of course, this phase is also the most critical in the sense that it is here that lives are at stake. To answer this critical issue, the policy management must be seen as an equally critical functionality. It is necessary to develop the interconnection between mission goals and defined policies so that the Cognitive Network Engine (CNE) determining the operational parameters of the network, in all situations provides a reliable and failsafe communication solution to be utilized. 1
In the absence of real-life implementations, this paper attempts to conceptually capture potential benefits and improvements that Cognitive Radio Networks (CRN) could introduce to a military environment. Functional business capability areas, as well as a system model, are used to frame analysis. Military CRNs improve reliability and availability of information flows. These may lead to improved information sharing and situation awareness and eventually to wider adoption of mission command and self-synchronization. However, fundamental capacity benefits of the CRNs remain a research topic. The requirement of computer-aided planning, preparation and simulation environment in support of deployed CRNs could also serve as a research and development platform for a Cognitive Radio System development activity as a collaborative international effort.
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