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The adoption of wireless communications and, in particular, Wi-Fi, at the lowest level of the factory automation hierarchy has not increased as fast as expected so far, mainly because of serious issues concerning determinism. Actually, besides the random access scheme, disturbance and interference prevent reliable communication over the air and, as a matter of fact, make wireless networks unable to support distributed real-time control applications properly. Several papers recently appeared in the literature suggest that diversity could be leveraged to overcome this limitation effectively. In this paper a reference architecture is introduced, which describes how seamless link-level redundancy can be applied to Wi-Fi. The framework is general enough to serve as a basis for future protocol enhancements, and also includes two optimizations aimed at improving the quality of wireless communication by avoiding unnecessary replicated transmissions. Some relevant solutions have been analyzed by means of a thorough simulation campaign, in order to highlight their benefits when compared to conventional Wi-Fi. Results show that both packet losses and network latencies improve noticeably., preprint, 13 pages (Winner of the "2017 Best Paper Award for the IEEE Transactions on Industrial Informatics")

Full-duplex (FD) technology is under consideration for adoption in various legacy communications standards. The IEEE 802.11ax working group has been considering a simultaneous transmit and receive (STR) mode for the next-generation wireless local area networks (WLANs). Enabling STR mode (FD communication mode) in 802.11 networks creates bidirectional FD (BFD) and unidirectional FD (UFD) links. The key challenge is to integrate STR mode with minimal protocol modifications, while accounting for the coexistence of FD and legacy half-duplex (HD) stations (STAs) and backward compatibility. This paper proposes a simple and practical approach to enable STR mode in 802.11 networks while explicitly accounting for the peculiarities of BFD and UFD links along with the coexistence of FD and HD STAs. Key aspects of the proposed solution include FD capability discovery, handshake mechanism for channel access, node selection for UFD, adaptive acknowledgment timeout, and contention unfairness mitigation. A comprehensive analytical model has been developed to evaluate the gain of STR. Performance evaluation demonstrates the effectiveness of the proposed solution in realizing the gains of FD technology for next-generation WLANs.

A new generation of Wireless Local Area Networks (WLANs) will make its appearance in the market in the forthcoming years based on the amendments to the IEEE 802.11 standards that have recently been approved or are under development. Examples of the most expected ones are IEEE 802.11aa (Robust Audio Video Transport Streaming), IEEE 802.11ac (Very-high throughput at < 6 GHz), IEEE 802.11af (TV White Spaces) and IEEE 802.11ah (Machine-to-Machine communications) specifications. The aim of this survey is to provide a comprehensive overview of these novel technical features and the related open technical challenges that will drive the future WLAN evolution. In contrast to other IEEE 802.11 surveys, this is a use case oriented study. Specifically, we first describe the three key scenarios in which next-generation WLANs will have to operate. We then review the most relevant amendments for each of these use cases focusing on the additional functionalities and the new technologies they include, such as multi-user MIMO techniques, groupcast communications, dynamic channel bonding, spectrum databases and channel sensing, enhanced power saving mechanisms and efficient small data transmissions. We also discuss the related work to highlight the key issues that must still be addressed. Finally, we review emerging trends that can influence the design of future WLANs, with special focus on software-defined MACs and the internet-working with cellular systems.

Wireless Sensor Network (WSN) consists of many tiny, autonomous sensor nodes capable of sensing, computation and communication. The main objective of IEEE 802.15.4 based WSN standard is to provide low cost, low power and short range communication. Providing QoS in WSN is a challenging task due to its severe resource constraints in terms of energy, network bandwidth, memory, and CPU. In this chapter, Quality of Service (QoS) performance evaluation has been carried out for IEEE 802.15.4 networks based WSN star and mesh topology using routing protocols like AODV, DSR and DYMO in QualNet 4.5 simulator. Performance evaluations metrics like Packet Delivery Ratio (PDR), throughput, average end to end delay, energy per goodput bit, network lifetime of battery model and total energy consumption which includes transmission, reception, idle and sleep mode were considered for both the topology. From the simulation studies and analysis, it can be seen that on an average DSR and DYMO performs better than AODV for different traffic load rates.

Wireless networked control systems (WNCSs) with control loops closed over a wireless network are prevailing these days. However, due to uncertainties such as random accessing delays and possible packet drops, the stability analysis for a WNCS is a challenging task. Most previous studies on the communication network analysis either relied on Monte Carlo simulation or followed the multistate Markov chain framework. In this paper, our main contribution is to propose a formal method-based stability analysis in which the communication system is modeled as a probabilistic timed automaton. The underlying communication protocol is analyzed through probabilistic model checking. In particular, the stability condition of the WNCS is expressed in the probabilistic temporal logic formula as the quality of service requirement, which can be checked, and the satisfaction of the specification is equivalent to the stability guarantee of the WNCS. We then study the impact of different media access control (MAC) parameters on the satisfaction of the specification. Furthermore, if the specification is not satisfied initially, we propose a systematic way to tune the MAC parameters or redesign the controller so that the specification can be met. This paper presents an attempt and a new angle to the communication and control system codesign problem.

The biggest challenge in adopting industrial wireless sensor networks (IWSNs) for factory automation applications is to provide low latency and highly reliable communication in harsh factory environments. IEEE 802.15.4e low latency deterministic network (LLDN) mode attempts to address this requirement at the medium access control (MAC) layer. However, the measures offered by this mode are inadequate considering realistic factory environments, suffering from noise, interference, multipath fading, and resulting in frequent packet losses. Cooperative diversity using relay nodes and incorporation of forward error correction (FEC) techniques are the two conventional ways to enhance communication reliability. However, the challenge lies in the placement of relay nodes considering a realistic three-dimensional (3-D) factory space and satisfying various physical, performance, and energy-related constraints. Moreover, the versatile and dynamic behavior of factory environment demand that the solutions offered to enhance communication reliability must be generic and adaptive, thereby eliminating the need for unnecessary redesigns. This paper proposes a twofold solution to enhance the communication reliability offered by 802.15.4e LLDN. First, an efficient and pragmatic relay-placement strategy based on rainbow product ranking algorithm for a 3-D factory space. Second, an adaptive transmission scheme (ATS) inspired from reinforcement learning (RL) technique called Q-learning is proposed, which incorporates cooperative diversity and Reed Solomon (RS) block codes. The effectiveness of the proposed solution is established and demonstrated using a real-world case study.

Various measurements and studies have shown that some licensed frequency bands are underutilized at certain times and in certain locations. In particular, TV bands have been shown to have unused spectrum. Such observations have triggered strong interest in white space dynamic spectrum access among researchers, wireless equipment manufacturers, and standards development organizations. The IEEE Standards Committee on Dynamic Spectrum Access Networks has created the White Space Radio Working Group in June 2011 to develop the IEEE 1900.7 standard for white space dynamic spectrum access radio systems. The draft of this standard is now finalized and ready for review by a broad audience during the sponsor ballot procedure. This paper gives an overview of key concepts and technologies of the draft standard P1900.7, including its use cases and requirements, its physical layer and MAC sub-layer.

Sharing spectrum resources in unlicensed bands grants vehicular applications inexpensive and ubiquitous access to wireless services. However, wireless technology coexistence concerns are gaining increased attention. In response, coexistence test methods are now being reported in the literature, and novel solutions are considered in the American National Standards Institute C63.27 Standard for Evaluation of Wireless Coexistence. Furthermore, the IEEE 802 standards committee formed a new study group, named wireless automotive coexistence, operating under the umbrella of 802.19 working group to highlight the increasing concerns of wireless coexistence in the automotive domain. The radiated open environment coexistence test (ROECT) method offers high flexibility to test wireless devices for coexistence. Radio signal propagation during testing is over the air, reducing access to the signal path. Consequently, monitoring instantaneous device performance is a challenge yet to be addressed. This paper introduces a novel method for estimating the channel utilization of multiple, concurrent wireless transmitters sharing the 2.4-GHz ISM band in the context of ROECT. Passively received power measurements were collected during testing, and then a Gaussian mixture model was used to build a classifier for labeling observed power samples relative to their source. Case studies utilizing IEEE 802.11n as an interfering system with an under test system based on either IEEE 802.11n or ZigBee are detailed. Findings demonstrate the mutual effect of spectrum sharing on both interfering and under test systems in terms of per-second channel utilization and frame collision. Experimental results show an overall accuracy exceeding 98%.

We present in this paper a mechanism to provide intelligent QoS to IEEE 802.11e compliant devices. Our mechanism combines two schemes previously proposed in the literature, while at the same time offers considerable improvements on traffic management for the enhanced distributed channel access (EDCA) mode for IEEE 802.11e. We evaluate our mechanism, called ACI-EDCA, by simulations with the NS-2 simulator. We test the performance of our proposal with four classes of traffic: Voice over IP (VoIP), Video on Demand (VoD), best-effort, and background traffic. This work extends previous findings mainly focused on the analysis of throughput and medium access collisions. Since the IEEE 802.11e is considered of critical importance for delay sensitive applications, we compare the performance of the end-to-end delay and traffic variance over the fluctuation on the transmission time as key indicators of the QoS that the network may provide. Through extensive simulations with the NS-2 simulator, we show how our ACI-EDCA algorithm outperforms the other two mechanisms we consider.

Wireless body area network (WBAN) is a communication technology, which aims providing both medical and consumer electronics services through sensor devices in, on, or around a human body. Due to the absence of the IEEE 802.15.6-based RF modules, the IEEE 802.15.4, a typical low-power communication technology of which requirements are similar, is considered to implement WBANs. In the case where a lot of WBANs coexist, meanwhile, collisions and signal attenuations may lead to their communication performance degradation. However, the IEEE 802.15.4 does not provide any solutions to solve coexistence problems, and thus, coexistence mitigation schemes for the IEEE 802.15.4-based WBANs are necessary. In this paper, we perform preliminary experiments to identify aspects of coexistence problem among the coexisting IEEE 802.15.4-based WBANs. Based on the results of preliminary experiments, we also propose a hybrid channel access scheme to mitigate coexistence problems in WBANs. The proposed scheme can be classified into two phases. In the first phase, the proposed scheme provides probabilistic collision avoidance on the contention-free period. When the pre-defined requirements of reliability cannot be satisfied with performing the first phase, the proposed scheme performs the second phase, which helps to mitigate collision or interference through changing channel access method. To evaluate the performance of the proposed scheme, we implement our scheme and perform experiments by comparing with an IEEE 802.15.4-based WBAN.

The IEEE 802.15.4-2015 standard provides a link-layer mechanism, based on time synchronized channel hopping (TSCH), to enable deterministic low-power wireless mesh networking. The emerging IPv6 over IEEE 802.15.4e TSCH (6TiSCH) working group aims at harmonizing an IP-enabled protocol stack with the IEEE 802.15.4e link layer. In 802.15.4-TSCH medium access control, nodes follow a communication schedule; however, the standard does not specify any scheduling policy. Therefore, a number of recent studies have investigated scheduling mechanisms for 6TiSCH wireless networks. This paper introduces DeAMON , which is decentralized adaptive multi-hop scheduling protocol for 6TiSCH wireless networks. The key features of DeAMON include traffic-awareness, sequential scheduling, parallel transmissions, robust over-provisioning, and adaptability to topology changes. Moreover, DeAMON incurs minimal signaling overhead. Performance evaluation demonstrates that DeAMON outperforms state-of-the-art distributed scheduling protocols in terms of reliability, latency, and resource utilization.

High throughput wireless standards based on IEEE 802.11n and IEEE 802.11ac have been developed and released within the last few years as new amendments over the commercially popular IEEE 802.11. IEEE 802.11n and IEEE 802.11ac support a large pool of parameter set such as increased number of spatial streams via multiple input multiple output (MIMO) communications, channel bonding, guard intervals, different modulation and coding schemes, several levels of frame aggregation, block acknowledgement etc. As a consequence, they boost up physical data rate in the order of Gigabits per second. However, all these enhancements have their internal trade-offs with the channel quality, as explored in the existing literature. For example, higher channel bonding levels result in poor performance under high bit error rate. In a free wireless environment, multiple heterogeneous stations share the wireless channel which is again a time-varying system. Consequently, none of these link level parameters provide an optimal performance for all channel quality instances. Therefore, to practically meet the theoretical high throughput, each wireless device should adapt its physical data transmission rate dynamically by an appropriate tuning of different link parameters. Otherwise, high transmission failure may arise. In this paper, we design an adaptive automated on-line learning mechanism, called “Smart Link Adaptation” (SmartLA), for dynamic selection of link parameters, motivated by “State-Action-Reward-State-Action” (SARSA) model, a variant of reinforcement learning. SmartLA can make a wireless station quite intelligent to cope up with various network conditions by exploiting the best suited data rate observed so far for various channel conditions from the past experience as well as by exploring different possible set of parameters. We analyze the performance of SmartLA in both from simulation analysis and over a 26 nodes IEEE 802.11ac testbed (6 access points and 20 client devices). We observe that the proposed link adaptation mechanism performs significantly better compared to other competing mechanisms mentioned in the literature.

The internet of Thing (IoT)technology has much development in this era. It has various wireless media transmission systems such as ESP and XBEE. Some IoT device can monitor website or application. On the other hand, Augmented Reality (AR) is a technology that used more on the entertainment sector. Here, we try to use AR to monitor the xbee based IoT device. As a result, there is the different result between Zigbee Protocol and IEEE 802.14.5 real time monitoring system. The optimum estimation of realtime time tolerance of those monitoring systems is >1500 ms (IEEE 804.14.5) and > 50 ms (Zigbee protocol).

IEEE 802.11ad specifies a hybrid medium access control (MAC) protocol consisting of contention as well as noncontention-based channel access mechanisms. Further, it also employs directional antennas to compensate for the high freespace path loss observed in 60GHz frequency band. Therefore, it significantly differs from other IEEE 802.11(b/g/n/ac) MAC protocols and thus requires new methods to analyze its performance. In this paper, we propose a new analytical model for performance analysis of IEEE 802.11ad employing a threedimensional Markov chain considering all the features of IEEE 802.11ad medium access mechanisms including the presence of non-contention access and the different number of sectors due to the use of directional antennas. We show that the number of sectors has a high impact on the network throughput. We also show that the MAC packet delay is significantly affected by the duration of the contention period. Our results indicate that a suitable choice of the number of sectors and contention period can illustriously improve the channel utilization and MAC delay performance.

Reliable and QoS-aware multimedia delivery is one of the most important requirements to satisfy end user needs. IEEE 802.11 networks have become one of the most popular Internet access methods owing to their low-cost and fast connection speed. Multicasting is a transmission technique that can significantly increase network efficiency through the simultaneous delivery of the same multimedia content to multiple multicast group members. IEEE 802.11 describes several multicast protocols targeted to increase the robustness of audio and video delivery. Some researchers have investigated the performance of such multicast protocols in terms of their achievable throughput. However, for a better understanding of the suitability of the protocols for a QoS-aware multimedia transmission, an in-depth analysis of the achievable delay is needed. This study provides a detailed delay analysis and describes analytical models for estimating the average achievable delay of IEEE 802.11 multicast protocols co-existing with legacy stations. The proposed analytical models are compared against simulation results under various conditions and parameter configurations. The simulation results validate the accuracy of the proposed models.

As the widely adopted IEEE 802.15.4 standard exhibited severe drawbacks when used in multi-hop WSN environment, the IEEE Standards Association Board has released a revised version, IEEE 802.15.4e, which includes Time-Slotted Channel Hopping (TSCH) mechanism as the MAC amendment to IEEE 802.15.4. The key feature of IEEE 802.15.4e TSCH mechanism is to allow the sensors to plan the time-slot schedule for efficient data transmission. However, the standard does not specify how to plan a time-slot schedule so that data collected by the sensors can be received by the base station as soon as possible without being delayed by transmission conflicts. In this paper, we propose a constant-time, distributed time-slot scheduling algorithm to address this problem. Existing works on IEEE 802.15.4e TSCH scheduling depend on one or a few nodes to collect traffic-flow information from their descendants and plan a centralized time-slot schedule for the whole network. In contrast, our algorithm allows every sensor node to compute its time-slot schedule in a simple, truly distributed manner. Simulation results show that our algorithm significantly outperforms a state-of-the-art protocol in terms of the packet transmission delay and yields a smaller duty cycle. HighlightsThe current state of the art of IEEE 802.15.4e standard is reviewed.The minimum TSCH schedule for conflict-free data gathering process in an IEEE 802.15.4e WSN is shown to be NP-hard.A constant-time, distributed scheduling algorithm to address the minimum IEEE 802.15.4e TSCH scheduling problem is proposed.

In a wireless body area network (WBAN), high data reliability and long operating time are important requirements. The retransmission process of the default Automatic Repeat reQuest (ARQ) mechanism in IEEE 802.15.4 is a suitable method to ensure the data reliability of WBAN communications, where frame loss can occur frequently. However, retransmitting the entire DATA frame is energy inefficient due to the fact that the most of payload data within lost frames are only partially corrupted. Therefore, this paper proposes the automatic segment repeat request scheme for the IEEE 802.15.4-based WBANs. The proposed scheme partitions the data payload into segments when the channel condition is bad, and retransmits only the corrupted segment(s). This reduces the size of the retransmitted frames, which improves frame reception rate and decreases the amount of transmitted traffic, and thus energy consumption. Our experiments using a real IEEE 802.15.4-based WBAN test bed show that the proposed method provides higher transmission reliability and lower power consumption than the default IEEE 802.15.4 ARQ mechanism.

Seamless redundancy can be profitably exploited to improve predictability of wireless networks in general and, in particular, IEEE 802.11. According to this approach, packets are transmitted by senders on two (or more) channels at the same time and duplicate copies are discarded by receivers. As long as the behavior of physical channels is uncorrelated, communication quality improves noticeably, in terms of both transmission latencies and percentage of dropped frames. In this paper, communication over redundant links has been analyzed by means of a thorough experimental campaign, based on measurements carried out on real devices. Results confirm that, under typical operating conditions, the assumption of independence among channels in properly designed systems is verified reasonably well. Indeed, in our experiments, measured link quality indices did not differ more than 10% from what we expected from theory. This grants for redundant solutions tangible advantages over conventional Wi-Fi networks., preprint, 10 pages

Just like Ethernet before, IEEE 802.11 is now transcending the borders of its usage from the office environment toward real-time communication on the factory floor. However, similar to Ethernet, the availability of synchronized clocks to coordinate and control communication and distributed real-time services is not a built-in feature in WLAN. Over the years, this has led to the design and use of a wide variety of customized protocols with varying complexity and precision, both for wired and wireless networks, in accordance with the increasingly demanding requirements from real-time applications. This survey looks into the details of synchronization over IEEE 802.11 with a particular focus on the infrastructure mode which is most relevant for industrial use cases. It highlights the different parameters which affect the performance of clock synchronization over WLAN and compares the performance of existing synchronization methods to analyze their shortcomings. Finally, it identifies new trends and directions for future research as well as features for wireless clock synchronization which will be required by the applications in the near future.

In this paper we provide a model for analyzing the saturation throughput of the ieee 802.15.4 mac protocol, which is the de-facto standard for wireless sensor networks, ensuring fair access to the channel. To this end, we introduce the concept of a natural layer, which reflects the time that a sensor node typically has to wait prior to sending a packet. The model is simple and provides new insight how the throughput depends on the protocol parameters and the number of nodes in the network. Validation experiments with simulations demonstrate that the model is highly accurate for a wide range of parameter settings of the mac protocol, and applicable to both large and small networks. As a byproduct, we discuss fundamental differences in the protocol stack and corresponding throughput models of the popular 802.11 standard.

The degradation of end-to-end quality of service (QoS) on mobile users is becoming a common issue for IEEE 802.11 infrastructure-based networks in crowded areas. This research tackles the issue by employing an SDN framework on an integrated wireless/wired environment. Thereby, we present the development and implementation of a system that performs user management by analyzing the network load from the OpenFlow statistics, as well as the wireless information collected from the associated users. In order to analyse the behaviour of the proposed user migration algorithm, we evaluate the system under scenarios with different traffic load and user session duration. From the experiments, we observed that in several cases wireless users get a considerable QoS improvement at the application layer (up to 30% improvement in throughput and up to 20% in delay in our simulations) once the system is activated. Based on the results, we present an analysis on how and when user migration in multi-access point IEEE 802.11 networks can be most effective.

The DCF (Distributed Coordination Function) is the basic MAC (Medium Access Control) protocol of IEEE 802.11 wireless LANs and compatible with various IEEE 802.11 PHY extensions. The performance of the DCF degrades exponentially as the number of nodes participating in the DCF transmission procedure increases. To deal with this problem, we propose a simple, however efficient modification of the DCF by which the performance of the DCF is greatly enhanced.

Despite the success of IEEE 1687, it has one significant shortcoming: it's difficult to use on devices without an 1149.1 test access port controller. IEEE P1687.1 addresses this problem.

A load balancing mechanism can adjust the load distribution among access points (APs) and improve resource utilization for dense wireless local area networks (WLANs). In this paper, we propose a semi-matching-based load balancing scheme for the IEEE 802.11 dense WLANs. The proposed scheme runs in a centralized controller. The controller judges whether the load is unevenly distributed according to the collected channel busy time ratio information of the entire network, and triggers the load balancing mechanism accordingly. In order to realize load balancing among APs and maximize the overall network throughput, we model the station to AP association problem as a weighted bipartite graph matching problem and find the optimal semi-matching using the Kuhn-Munkres (K-M) algorithm. Simulation results show that the proposed scheme achieves performance improvement comparing with traditional schemes.

This paper presents an updated survey on research related to ultra wideband (UWB) communications, particularly that of impulse radio (IR) technology. In addition to the research, we survey UWB physical layer specifications of the two existing standards-the IEEE 802.15.6-2012 and the IEEE 802.15.4-2015-as well as the leading global UWB spectrum regulatory limitations which have been updated recently. The latter standard including the UWB specifications was first published in 2007 and the latest revision dates to 2015. The focus in this paper is the period from 2007 to 2015. Our purpose is to provide an in-depth survey with a clearly specified topic together with the standard specifications and the related regulatory restrictions. Additionally, the last part of this paper discusses the possibilities of increasing the current IR-UWB data rates to meet increasing future demands.

This paper investigates optical camera communication (OCC) technologies, targeting new spectrum, multiple-input-multiple-output diversity, transmission access, and novel architectures with augmented reality user experience for the extended 5G wireless network. It provides the current OCC research status and trend pertaining to these technologies, especially an inside view on the revision of IEEE 802.15.7-2011 known as the IEEE 802.15.7m (TG7m) Optical Wireless Communication Task Group. Such standardization activities have a major impact on the development of OCC technologies. In addition, it provides a detailed review of the related literature. Herein, OCC technologies are classified into five categories to elucidate their operations and technical characteristics. Furthermore, a concise performance analysis, numerical simulations, and some comparison of the results obtained for associated systems are presented, and the future directions of research and development are discussed.

In this paper, we propose a sounding control scheme for IEEE 802.11ac multiuser multiple-input multiple-output (MU-MIMO). The proposed scheme comprehensively considers the long-term characteristics of a network environment, including the downlink traffic loads and channel coherence times of wireless links, and jointly determines the sounding node set and sounding interval to maximize the long-term expected MU-MIMO throughput gain in consideration of sounding overhead. To this end, we analytically formulate an MU-MIMO throughput gain maximization problem, considering the network environment and sounding overhead. We conduct MIMO channel measurement in practical wireless local area network (WLAN) environments and evaluate the performance of the proposed scheme by employing the real channel data traces. Simulation results verify that the proposed scheme adaptively determines the sounding node set and sounding interval, according to the network environment, and outperforms the existing scheme, which considers the channel coherence times only.

208 p. In the design of IEEE 802.16 multi-hop wireless networks, accurate estimation of end-to-end capacities plays a critical role in Quality of Service (QoS) provision-ing. Capacity information has been applied to various network control functions such as admission control, routing, and packet scheduling for assuring service guarantees. In IEEE 802.16 multi-hop relay networks, optimal relay selection, in relation to end-to-end capacity, forms an essential function in achieving good network performance in capacity-constrained networks. In this thesis, research issues relating to end-to-end capacity estimation and optimal relay selection are studied in details for improved network performance in IEEE 802.16 multi-hop wireless networks. DOCTOR OF PHILOSOPHY (EEE)

Wireless vehicular communications are gaining momentum, mainly to improve road safety through the use of cooperative systems. Such visionary cooperative applications are based on recently established families of standards, notably the IEEE Wireless Access for Vehicular Environment (WAVE) and the ETSI ITS G5. Despite some relevant differences, both family of standards share the same physical and MAC layers, described in the IEEE 802.11:2012 - amendment 6, also know as IEEE 802.11p. Due to the characteristics of the wireless communications in vehicular environment, e.g., high-speed mobility causing unpredictable time-varying changes in connectivity, IP protocols are not suitable for safety communications as they require channel scanning, authentication and association under strict time limits. Safety vehicular communications rely, instead on non-IP protocols, either the WAVE Short Message Protocol (WSMP) or the FAST Network and Transport Protocol (FNTP). In this paper, we explore some of the challenges of implementing such protocols, and designed an architecture for a stack capable of handling both standards. The proposed architecture, including the communication and transport layers of the stack, was implemented in a custom ETSI ITS G5 compliant platform (IT2S), and its performance was assessed using a prototype.

Wireless local area networks (WLANs) are widely deployed for internet-centric data applications. It is predicted that by 2018, about two-thirds of the world's internet traffic will be video, and mo...

In this paper, we propose an adaptive medium access control (MAC) solution for a fully connected mobile ad hoc network (MANET), supporting homogeneous best-effort data traffic. The MAC scheme achieves consistently high network performance by adapting to the ever-varying network traffic load. Based on the detection of a current network load condition, nodes can make a switching decision between IEEE 802.11 distributed coordination function (DCF) and dynamic time-division multiple access (D-TDMA), when the network traffic load reaches a threshold, referred to as MAC switching point. The adaptive MAC solution determines the MAC switching point to maximize network performance. Approximate and closed-form performance analytical models for both MAC protocols are established, which facilitate the computation of MAC switching point in a tractable way. Extensive analytical and simulation results demonstrate that the adaptive MAC solution provides consistently maximal network performance in the presence of traffic load dynamics.

Wireless networks are today employed as complementary access technology, implemented on the last hop towards the Internet end-user. The shared media that wireless deployments provide and which is relevant to interconnect multiple users has a limited technical design, as only one device can be served per unit of time, design aspect that limits the potential applicability of wireless in dense environments. This paper proposes and evaluates a novel MAC-layer mechanism that extends current wireless networks with the possibility to perform downstream transmission to multiple devices within a single transmission time-frame, resulting in improved fairness for all devices. The mechanism, which is software-defined, is backward-compatible with current wireless standards and does not require any hardware changes. The solution has been validated in a realistic testbed, and the paper provides details concerning the computational aspects of our solution; a description of the implementation; and results extracted under different realistic scenarios in terms of throughput, packet loss, as well as jitter.

IEEE 802.11-based wireless networks are becoming more popular, and a lot of research is done to enhance the performance of the distributed control function (DCF) found in the IEEE 802.11 standard. Many researchers utilized jamming to further enhance the performance of the contention resolution in DCF. However, jamming-based protocols follow elimination schemes based on the use of jam signals which add to the complexity of wireless devices, add new types of errors like falsely detecting noise as a jam, and are not compatible with the IEEE 802.11 standard. In this paper we propose a self-elimination MAC protocol, called SEMP, for wireless networks to achieve a high performance like that of jamming-based protocols but without the use of jamming signals. SEMP requires no changes to the IEEE 802.11 physical layer, is fully compatible with the IEEE 802.11 wireless devices, and is designed to work without any prior knowledge of the number of nodes. Through extensive simulation, we evaluate SEMP and compare it to the IEEE 802.11 DCF and CONTI (a jamming-based protocol that was shown to highly improve the performance of the IEEE 802.11 wireless networks). Simulation results demonstrate that SEMP outperforms the IEEE 802.11 DCF in terms of the throughput, delay, fairness, and jitter. In addition, results show that SEMP provides throughput and delay gains over CONTI, and that both schemes have comparable fairness and jitter measures. Hence, results reveal that SEMP actually does achieve a high performance like CONTI even though no jamming is used.

Today, most of us take access to Wi-Fi (IEEE Std. 802.11n) for granted. That is what makes our daily lives go-around at home, in the office, or on the road with access to information across the Internet. Compared to the "tethered" Internet access of a few years ago, we became so much more mobile and productive having "cut the cord." But one aspect of our technology usage that is still tied to cords is the need for power, even when you have battery operated devices. Think about all of the devices in our lives that require batteries to be recharged: wireless phones, laptops, electric vehicles, medical devices, all the fun wearables, and so much more. What if you didn't need to plug in a device to recharge its battery? Or what if your device didn't even need a battery for its power supply? There are a number of standards currently available and in development that support that capability through wireless power transfer (WPT) that can allow us to "cut the cord" to traditional power sources.

Recently, as IoT (Internet of Things) becomes more important, low cost implementation of sensor nodes also becomes critical issues for two well-known standards, IEEE 802.15.4 and IEEE 802.15.6 which stands for WPAN (Wireless Personal Area Network) and WBAN (Wireless Body Area Network), respectively. This paper presents the area-optimized AES-CCM (Advanced Encryption Standard - Counter with CBC-MAC) hardware security engine which can support both IEEE 802.15.4 and IEEE 802.15.6 standards. First, for the low cost design, we propose the 8-bit AES encryption core with the S-box that consists of fully combinational logic based on composite field arithmetic. We also exploit the toggle method to reduce the complexity of design further by reusing the AES core for performing two operation mode of AES-CCM. The implementation results show that the total gate count of proposed AES-CCM security engine can be reduced by up to 42.5% compared to the conventional design.