Due to their popularity, large coverage areas, and diversity of radio technologies, Low Power Wide Area Networks (LPWAN) will experience high levels of cross-technology interference. In this work, we investigate the impact of LoRa interference on IEEE 802.15.4 (Wi-SUN) networks. Using hardware experiments, we characterize the interaction between these two very different radio technologies. In particular, we observe that the IEEE 802.15.4 Clear Channel Assessment (CCA) mechanism does not reliably detect interfering LoRa transmissions. We therefore propose an enhanced CCA mechanism based on a Multi-Layer Perceptron classifier and show that it significantly reduces the number of unsuccessful transmissions, while remaining compatible with the IEEE 802.15.4 standard.

We present some preliminary results on LoRaWAN and IEEE 802.15.4-SUN interference in urban environments. The results are based on a simple simulation that is parameterized using PHY layer measurements of controlled interference scenarios.

The rapid growth of new radio technologies for Smart City/Building/Home applications means that models of cross-technology interference are needed to inform the development of higher layer protocols and applications. We systematically investigate interference interactions between LoRa and IEEE 802.15.4g networks. Our results show that LoRa can obtain high packet reception rates, even in presence of strong IEEE 802.15.4g interference. IEEE 802.15.4g is also shown to have some resilience to LoRa interference. Both effects are highly dependent on the LoRa radio's spreading factor and bandwidth configuration, as well as on the channelization. The results are shown to arise from the interaction between the two radios' modulation schemes. The data have implications for the design and analysis of protocols for both radio technologies.

Task Graph (ATaG) is a sensor network application development paradigm where the application is visually described by a graph where the nodes correspond to application-level tasks and edges correspond to data flows. We extend ATaG with the option to add non-functional requirements: constraints on end-to-end delay and packet delivery rate. Setting up these constraints at the design phase naturally leads to enabling run-time assurance at the deployment phase, when the conditions of the constraints are used as network's performance goals. We provide both run-time middleware that checks the conditions of these constraints and a central management unit that dynamically adapts the system by doing task reallocation and putting task copies on redundant nodes. Through extensive simulations we show that the system is efficient enough to enable adaptations within tens of seconds even in large networks.

Body area sensor networks (BASNs) are powered by batteries and hence energy is a scarce resource. Thus communication protocols in BASN need to be energy efficient. This paper addresses this problem by proposing a Minimum Energy Packet Forwarding Protocol (MEPF). First, we analyze the tradeoff of energy consumption between lower transmission power and packet retransmission. Then we propose the transmission power control part of MEPF. It transmits a packet using the minimum transmission power that can guarantee a high packet reception rate. Unlike the previous work, we not only need to adjust the power of the forward transmission but also the ACKs, which further reduces the consumption. MEPF outstands from the earlier works by also retransmitting lost packets when a link is good enough. The quality of the link is dynamically judged by a machine learning algorithm which also considers the limited buffer space in a sensor node. By MEPF, the energy consumption to forward a packet is minimized without sacrificing the packet reception ratio. Experimental results show quantitatively that MEPF save significant amounts of energy.

With the evolution of wireless sensor network, body area sensor networks are expected to realize many realtime monitoring applications. Localization is one of the most important amongst all contexts. In indoor environments signal strength-based localization algorithms usually fail to achieve good accuracy due to deficient antenna coverage and multi- path interference. We propose spatial diversification method, which solves this problem by combining multiple receivers in a body area sensor network to estimate the location with a higher accuracy. This method mitigates the errors caused by antenna orientations and beam forming properties. With a range free localization algorithm that we developed, we show with experimental results that with spatial diversity the localization accuracy is improved compared to using single receiver alone.

A personal network (PN) is a network of personal devices regardless of their geographical locations. A PN may consist of several ad-hoc sub-networks, each of which is referred to as a cluster. Different clusters are connected to each other through their gateways and using interconnecting structures, e.g., the Internet. Inside each cluster, there might be several nodes that are able to act as gateway. Gateway nodes may support different access technologies, such as WiFi, Ethernet, WiMax, etc. It also may happen that a single gateway, which supports several access technologies, is able to connect to different access networks. To benefit from the availability of different gateways and access networks with different characteristics for a PN user, an efficient methodology for gateway and access network selection is needed. In this work, we are motivated to design a generic architectural framework for selecting the best gateway(s) and access network(s) in a PN. Issues, such as characteristics of the gateway nodes and access networks, QoS requirements of the applications, mobility of gateway nodes, dynamism of the PN topology, etc., have been considered in designing the proposed framework. The main advantages of this framework is leveraging the benefits of different alternative solutions, in terms of overhead, efficiency, complexity, and user satisfaction.

Accurate and fast wireless link quality assessment (LQA) for wireless channels would bring huge benefits for mobile multi-hop and multi-rate wireless ad hoc and sensor networks in the form of improved end-to-end performance. In this paper, we propose a novel LQA method based on cross-layer information. The method is implemented in a real test-bed, which is based on IEEE 802.11b/g, and achieved a significant LQA improvement up to 50% in mobile scenarios without introducing overhead. The effectiveness of accurate and fast LQA is demonstrated by feeding it into the routing layer to enable the route decisions to adapt faster during changing situations, especially in mobile scenarios. The experiment results show that the proposed LQA method can lead to faster and smarter routing decisions and higher end-to-end throughput compared to traditional methods, which only use hello packets to determine the link quality in mobile scenario.

Today, many wireless devices are mobile and battery powered, which means that the service duration is highly dependent on energy consumptions and battery capacities. Based on the fact that battery capacity is still limited, energy saving is an important issue in wireless communication. Many methods have been proposed to save energy in wireless communication, such as power-aware routing and sleep mode. However, another important approach, transmission power adaptation, is not yet well discussed. In this paper, we propose a mechanism that selects the appropriate transmission power level to transmit packets instead of using a fixed default power level for all packets, which is common in IEEE 802.11. Lower transmission power levels may result in more retransmissions, but still consumes less energy. In total, energy can be saved and interference can be reduced by selecting a good transmission power level. We propose a two phase power saving mechanism and implemented it in a real test-bed. To evaluate the performance of our mechanism, we used an indoor environment to carry out measurements. The measurement results indicate that a significant amount of energy can be saved for the transmitter in most scenarios compared to using a fixed transmission power level for all packets.

With the advent of miniaturization and higher computing capabilities of wireless devices, there is an exponential rise in the number of devices such as personal digital assistants, etc. Application development for these devices is the main focus for many device manufacturers and software developers. The applications developed need to be tested and tried before releasing it to the market. There are cross-compilers to produce the binary files of the software applications that can run on these devices. However, it is rather difficult for developers to test it on the actual devices every time a change is made in the program. Further, a wireless network infrastructure should also be in place for testing. To expedite application development FEW-PNets - a Framework for Emulation of Wireless Personal Networks is proposed. It is a networked application to emulate a Personal Network (PN) owned by a person. It supports emulation of the most functions of PNs. We explain our model by emulating simple PN devices. In this article we elucidate the concepts, advantages, application domains and limitations of FEW-PNets.

With more and more consumer devices becoming capable of wireless communication, the need for good quality ad hoc networking becomes more imminent. Self-configuring and self-adapting multi-hop networking will provide an excellent solution for wireless personal area networks (WPAN) as well as wireless home networks. In such networks, scalability is rarely believed to be a real issue. Instead, the issues are related to the end-to-end quality due to wireless links with constantly and rapidly changing quality. Hence, the network layer not only needs to adapt accurately but also in time. This paper looks into the design of accurate and fast wireless link quality assessment (LQA) options. We investigate the possibility to use cross layer information to improve this process which can be used by the routing layer to adapt faster and more accurately to changing situations. Experiments are done and the result shows the importance of adapting the new LQA options.

A personal network is an overlay network which builds on different wireless networking technologies. This overlay network is responsible of glueing the different wireless networking technologies. In this paper, we consider the cooperation of two key technologies to realize a personal network, namely, Wireless Personal Area Network and Universal Mobile Telecommunications System (UMTS). The co-operation poses a new set of problems as these technologies were not designed to intework with each other. In this paper, we describe each of these problems and their solutions.

Personal networks (PN) is a new concept related to pervasive computing with a strong user-focus view. The key to a successful PN realization is a general network architecture that is capable of bridging different current and future technologies and offers a homogeneous and clear view to the end-user. In this paper, we focus on forming a PN by connecting remote personal devices using infrastructure-based IP networks, including 3G networks and WLAN hotspots. One way is to upgrade the current access networks with new functionality to support PNs. Since many devices in PNs are mobile and battery powered, this may help them to achieve a faster service and to save energy. However, to deploy such functionality is not easy and may hamper the adoption of PNs altogether. Therefore, in this paper we study three possible inter-cluster communication architectures that can use current IP networks. To discern the above proposal we also give a detailed picture of PN network architecture supported by infrastructure. We believe that this detailed discussion will help the success of PNs

In this paper, we introduce a highly efficient flooding protocol for MANETs using only one-hop hello messages. By simulation, we show that the protocol has a performance close to flooding protocols that use two-hop hello messages. Further, the protocol performs very good even when the node mobility increases. The only "cost" this protocol must pay is an increased end-to-end delay. However, with some clever cross-layer optimization, this delay can be reduced to become comparable with other flooding protocols. Further, the overhead generated for flooding a packet by this protocol is lower than other protocols, if one-hop hello messages are already provided.

The wide deployment of IP technologies has driven the development of IP-based solutions for wireless networks, like the IP-based radio access networks (RAN). Such wireless networks have different characteristics than traditional IP networks, imposing very strict requirements on quality of service (QoS) solutions. Current QoS solutions are not able to satisfy these requirements. This paper describes the prototype implementation of a QoS-framework, called resource management in differentiated services (RMD), which aims to correct this situation. RMD is a framework offering scalable fine-grained QoS guarantees in differentiated services (DiffServ) networks. It extends the DiffServ architecture with new admission control and resource reservation concepts in a scalable way.