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An enhanced block acknowledgement (BlockACK) method for the aggregate MAC protocol data unit (A-MPDU) transmission is proposed. In the proposed method, the position information of each aggregated subframe is carried by the A-MPDU using the reserved bits and a novel position information control is used to acknowledge the A-MPDU. By utilising the enhanced BlockACK method, the aggregation level of the A-MPDU transmission will not be constrained by the effect of lost subframes. Theoretical analysis and simulation results demonstrate that the enhanced BlockACK method can achieve a more stable aggregation level and higher throughput than the conventional one.

The number of mobile devices increases exponentially and it becomes the trends and needs of human. Presently, the network infrastructures have the coverage issues in specific areas such as underground facilities. The cost of upgrade causes high budget and it is less profitable based on business and market point of view. Somehow, in coverage areas, the mobile devices still operate by the traditional Mobile Internet Protocol version 6 (MIPv6) for mobility management in inter network scenario. MIPv6 operation mechanisms frequently trigger the signaling overhead problem. Thus, these increase the end-to-end delay and lower the network throughput performance. Having known this issues, we consolidate MIPv6, HMIPv6, FMIPv6 and FHMIPv6 with Wireless Mesh Network (WMN) into one environment. The reason of constructing WMN is because WMN caters rural areas. We identify, analyze, and compare the performance of Host-Based mobility management protocols integrate with WMN in terms of latency, throughput and packet loss ratio. Finally, it is proven that the design and development of FHMIPv6 with WMN performs better as compared to the others Mobile Internet Protocols over the Internet using NS-2 Network Simulation software. Having implemented the FHMIPv6 with WMN, the MAP mechanism allow mobile node does not need to inform the highest hierarchical node upon the handover process. For fast handover mechanism, when the mobile node senses lower signal strength, mobile node advertises to the neighbour network for the need to attach to the new higher signal strength access point. Mobile node informs the new access point of the need to change to the new access point before the process of handover. Thus, this two mechanism can reduce the handover latency and increase the network throughput. In future, in intra network scenario also can implement FHMIPv6 to improve the network performance.

Connected vehicles allow to update the software (SW) running on their integrated electronic control units (ECUs) over-the-air. Such updates are complex procedures that involve several steps, such as the authentication with a remote device, the secure and reliable wireless transfer of the new binary, as well as its installation and verification on the target ECU. Each of these aspects affects the efficiency of the entire SW update process, and it is important to evaluate the impact of different solutions on the functionality of a vehicle and to compare their performance on real hardware. In this paper we present CESAR, a configurable testbed infrastructure that allows to evaluate the efficiency of an automotive SW update system in a highly automated way. CESAR allows to specify different update mechanisms, security configurations, wireless protocols used for the data transfer, and to carefully define the scenario of interest (i.e., pin down the number of wireless vehicle interfaces, the network topology, and the target ECU). Furthermore, CESAR can be used to measure the efficiency of a SW update on real hardware, and to derive insights about the weaknesses of a system under test or about the interaction of a specific SW with a given ECU.

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is the most popular channel access mechanism for Wireless Sensor Networks (WSNs). The random backoff and CCAs in CSMA/CA mechanism avoid the collisions. However, inefficient CCAs increase energy consumption. In order to reduce the energy consumption and enhance the reliability, a new channel access mechanism for IEEE 802.15.4e is proposed here. Besides, performance of the proposed MAC is analyzed in terms of reliability and throughput. Our models are compared with IEEE 802.15.4e MAC. It is found that the performance of the proposed MAC can outperform in terms of throughput, reliability, energy, transmission and channel access failure rate.

OF THE DISSERTATION RESOURCE MANAGEMENT AND OPTIMIZATION IN WIRELESS MESH NETWORKS by Xiaowen Zhang Florida International University, 2010 Miami, Florida Professor Hao Zhu, Major Professor A wireless mesh network is a mesh network implemented over a wireless network system such as wireless LANs. Wireless Mesh Networks(WMNs) are promising for numerous applications such as broadband home networking, enterprise networking, transportation systems, health and medical systems, security surveillance systems, etc. Therefore, it has received considerable attention from both industrial and academic researchers. This dissertation explores schemes for resource management and optimization in WMNs by means of network routing and network coding. In this dissertation, we propose three optimization schemes. (1) First, a triple-tier optimization scheme is proposed for load balancing objective. The first tier mechanism achieves long-term routing optimization, and the second tier mechanism, using the optimization results obtained from the first tier mechanism, performs the short-term adaptation to deal with the impact of dynamic channel conditions. A greedy sub-channel allocation algorithm is developed as the third tier optimization scheme to further reduce the congestion level in the network. We conduct thorough theoretical analysis to show the correctness of our design and give the properties of our scheme. (2) Then, a Relay-Aided Network Coding scheme called RANC is proposed to improve the performance gain of network coding by exploiting the physical layer multi-rate capability in WMNs. We conduct rigorous analysis to find the design principles and study the tradeoff in the performance gain of RANC.

OF THE DISSERTATION PERFORMANCE OPTIMIZATION OF NETWORK PROTOCOLS FOR IEEE 802.11S-BASED SMART GRID COMMUNICATIONS by Nico Saputro Florida International University, 2016 Miami, Florida Professor Kemal Akkaya, Major Professor The transformation of the legacy electric grid to Smart Grid (SG) poses numerous challenges in the design and development of an efficient SG communications network. While there has been an increasing interest in identifying the SG communications network and possible SG applications, specific research challenges at the network protocol have not been elaborated yet. This dissertation revisited each layer of a TCP/IP protocol stack which basically was designed for a wired network and optimized their performance in IEEE 802.11s-based Advanced Metering Infrastructure (AMI) communications network against the following challenges: security and privacy, AMI data explosion, periodic simultaneous data reporting scheduling, poor Transport Control Protocol (TCP) performance, Address Resolution Protocol (ARP) broadcast, and network interoperability. To address these challenges, layered and/or cross-layered protocol improvements were proposed for each layer of TCP/IP protocol stack. At the application layer, a tree-based periodic time schedule and a time division multiple access-based scheduling were proposed to reduce high contention when smart meters simultaneously send their reading. Homomorphic encryption performance was investigated to handle AMI data explosion while providing security and privacy. At the transport layer, a tree-based fixed Retransmission Timeout (RTO) setting and a path-error aware RTO that exploits rich

Vehicular Ad hoc Network (VANET) is developed to enhance the safety, comfort and efficiency of driving. The IEEE 802.11p/WAVE [1] is a standard intended to support wireless access in VANETs. The IEEE 1609.4 [2] is a MAC extension of IEEE 802.11p [1] to support multi-channel operations. In this paper, we propose an analytical model to evaluate the performance for safety and non-safety applications of IEEE 1609.4 under non-saturation condition. The 2-D Markov model is used to model two access categories in the IEEE 1609.4. The analytical model is validated by the extensive simulation, and it shows the effect of different parameters to the network performance.

Software defined Networks (SDN) is a paradigm that promises to facilitate the management of all types of networks, including the Wireless Mesh Networks (WMN). This integration enables an environment with enough resources and coverage to meet the demands of users, and thanks to a centralized network, resources can be managed in a better way. There are multiple simulators/emulators available, integrating SDN and WMN, but most of them do not have IEEE802.11s support. This paper proposes a framework that integrates NS-3, Open Vswitch, and Linux network namespaces, to create an environment that allows emulating IEEE802.11s SDN-WMN scenarios. The framework is used to evaluate the throughput and delay of a real-time streaming video application.

Over the past twenty years, wireless networks have been evolving to give continuity to the exponential demand for information that users require. This has allowed the development of multiple network infrastructures that offers new ways of establishing communication that improve the standard protocols. The Wireless Mesh Network (WMN) arise from this context of development and bring with it great advantages due to its mesh topology that results in an easy implementation, flexibility, self-forming, and adaptability in different scenarios. In this paper, we perform an analysis of Latency, Jitter, Throughput, and Bandwidth parameters, which provides enough information to establish a criterion over the performance of a WMN implemented in two different scenarios, with two different routing protocols, Hybrid Wireless Mesh Protocol (HWMP) of IEEE 802.11s standard and Better Approach to Mobile Ad Hoc Networking Advanced (BATMAN-Adv). As well as we evaluate performance of Video Streaming apps, Video Conferencing and VoIP calls within the network in order to evidence the efficiency of WMN.

The goal of this paper is two-fold. First, to expand an opportunistic network coding protocol for wireless networks, called PlayNCool, in order to incorporate new mechanisms to improve performance in the presence of packet losses. In particular, exploiting additional helper nodes to improve the quality of each link and even across neighbouring links and using simulations to show that an additional reduction of packet transmission in the order of 40% is possible. Second, to advocate for the use of network coding (NC) jointly with software defined networking (SDN) providing an implementation of the expanded PlayNCool protocol using SDN. This implementation uses an architecture developed with OpenFlow switches and a Pox controller to periodically gather statistics related to packet losses and the number of packets coded, recoded and decoded on a per link basis in order to adapt the configuration for the PlayNCool protocol optimally. The measurements carried out were validated with theoretical and simulated results.

After the occurrence of a disaster one of the main needs for the rescue teams and volunteer helpers is a functional communication infrastructure even during the first hours. The disaster recovery system (DRS) originally presented by us in a previous work [1] is based on an IEEE 802.11s wireless mesh network which is set up by non damaged legacy, mesh capable and battery powered devices still available in the disaster region. For lifetime enhancement, which is a key challenge for the proposed DRS based on battery powered devices, a distributed algorithm was proposed which enhances the lifetime of such a system by an approach which allows to shut down non necessary nodes and to keep them for a later usage while still keeping network connectivity. A simulation based proof of concept of this algorithm has been given in [1], however, employing a rather high level of abstraction. In this paper we evaluate the DRS network performance using a full implementation of the distributed algorithm within the simulation and which is based on alternating sleep and awake states for each individual node. Additionally, the algorithm is extended by a novel approach whereby the decision when a node changes its state from sleep to awake or vice-versa is based on the number of neighbors of the corresponding node, allowing for a much simpler implementation on the individual mesh nodes. The achievable lifetime enhancement first is evaluated through a Monte-Carlo simulation. Finally, the network performance achievable with the proposed lifetime enhancement algorithm for disaster recovery systems (LEA-DRS) is validated by a network simulation in ns-3 evaluating a Voice over IP connection between two nodes (e.g. between two rescuers).

With increase in size of wireless mesh networks so are problems on interference, load-imbalance, and congestion that lowers throughput significantly. Proposals to solve issues related to this problem include accurate accounting of the channel load so that traffic can be directed along calmer regions of the networks reaching destination in time. Load aware routing metrics have been proposed for this purpose and the interface buffer queue (IFQ) occupancy seemed to be the most preferred basis even until recently. Others used it in combination with the contention window (CW) levels. We perform an analysis of load-based routing metrics based on these parameters and perform extensive simulation experiments in order to find out which is the appropriate metric to use and under what conditions. Despite its popularity, we show that metrics based on the interface buffer queue occupancy and contention window level were not good bases for load accounting because these metrics do not vary with traffic load despite their ability to sense saturated regions. Routing simulations show that routing based on IFQ would behave similar to hop counts and no adaptation and performance improvement is achieved. Our study suggests that a careful consideration of these limitations is essential, and provides insights on the applicability of these metrics. As an alternative we present the channel load metric (CLM) that accurately accounts for channel load, contention, and interference. Simulations show, it improves routing performance better than hop count and other load aware routing metrics found in the literature.

IEEE standardized a highly efficient, low power, reliable, deterministic and time–frequency enabled medium access control protocol, IEEE 802.15.4e time slotted channel hopping (TSCH) as an amendment to the medium access control (MAC) protocol defined by the IEEE 802.15.4 standard. Once a communication schedule is built, the IEEE 802.15.4e TSCH is able to execute such a communication schedule. IEEE 802.15.4e TSCH standard lea ves out of scope defining how that communication schedule is built, updated and maintained. In order to fill this gap, we introduce such a scheduling algorithm, called as DIVA. DIVA is specifically designed for IEEE 8092.15.4e TSCH networks. It is a totally distributed scheduling algorithm for divergecast traffic where divergecast means that traffic flows in all directions in contrast to convergecast where traffic flows from leave nodes to root. In order to gain more comprehension about DIVA, we conducted extensive simulations. We also compared DIVA with Berkeley’s Aloha-based algorithm.

Seamless mobility in legacy multi-hop IEEE 802.11 Wi-Fi network is difficult to accomplish due to the lack of handoff mechanism. IEEE 802.11s MAC layer protocol adds the feature of mobile mesh networking to standard Wi-Fi by providing layer-2 routing and handoff mechanisms. With ubiquitous connectivity and seamless handoff, many applications requiring continuous data streaming like video, VOIP, file downloading, etc. become possible in Wi-Fi networks that requires mobility support like highways, railways and underground transportation. In this paper we study the handoff mechanism of IEEE 802.11s protocol extensively in a real mobile testbed. Our testbed comprises three mesh nodes, one of which is installed on a vehicle for finding the impact of vehicle speed on 802.11s handoff mechanism. We found that the vehicle speed does not drastically affect the performance metrics during handoff as previously understood. Moreover the results show frequent handoffs during mobility. This is called the ping pong effect, which indicates the absence of hysteresis mechanism in 802.11s protocol. For improving the performance during handoffs we therefore suggest the use of hysteresis mechanism along with the airtime link metric being used in the default routing protocol of 802.11s.

The adoption of IEEE 802.11 wireless networks has grown importantly in previous years. Recently, some vendors are developing smart access points for these networks, which are able to change their operation channel taking interference into consideration. Handoff management in wireless networks, i.e., transferring an active data session from one cell defined by an access point to another, is a critical function. In IEEE 802.11 networks, this function is performed in three phases: discovery, (re)-authentication and (re)-association. Each phase takes an execution time (delay) which interrupts mobile users' connection to the network, ultimately translating in service disruption. In this paper, we propose a probabilistic method to govern the handoff process that does not require modification of the traditional IEEE 802.11 standard and compare it with some traditional methods considering smarts access points. We show that it is possible to reduce the discovery delay by a maximum of 71% compared with standard handoff by reducing the set of channels to probe based on the usage probability of each particular channel.

Currently and due to its wide use, the wireless networks in conformance with IEEE 802.11 standard are generating channels saturation, that provokes interference between themselves. IEEE 802.11n is one of the standards that offers greater benefits to improve the wireless network performance. In this paper we analyze the performance of wireless network in conformance with IEEE 802.11n standard to evaluate its behavior in co-channel interference (CCI) scenarios. This evaluation will be taken in indoor environments under two test scenarios, with and without CCI, in terms of Quality of Service metrics: throughput, delay, jitter and packet loss. In first scenario, without CCI, we worked with orthogonal channels 1, 6 and 11, configured in three access points (AP), each one representing a different network in which the intrusive traffic injection technique is used to obtain the required metrics. The same procedure is repeated in second scenario, where CCI is recreated, we used channel 1 configured in three AP, each one representing a different network, this procedure is repeated for channels 6 and 11. The results show, by considering the normalized throughput as an efficiency measurement, that the wireless network in conformance with IEEE 802.11n standard reduces its performance by approximately 35% in CCI scenarios.

IEEE 802.11 DCF, which is the most famous MAC protocol, can not fully exploit the efficiency of channel bonding mechanism. The transmission in wider bandwidth not only leads to a higher carrier-sensing threshold but also causes the less signal power in each channel. Hence, Outside Warning Range Problem (OWRP) is conducted in the paper for IEEE 802.11ac WLANs. The paper analyzes the relationships among the transmission range, carrier-sensing range, and interference range in case that channel bonding mechanism is adopted and proposes a MAC protocol for IEEE 802.11ac WLANs to avoid collisions. Simulation results show that the proposed MAC protocol can increase network throughput.

An emerging trend in industry 4.0 is to use wireless communication infrastructure and mesh networks in applications requiring high reliability and safety. Although not a typical industrial production process, railway vehicular networks are also an industrial application which come with stringent reliability and safety requirements. Current research is focusing on using vehicular networks as an enabling technology to actively control the separation between two consecutive vehicles, enforcing a safe distance which is nevertheless much shorter than currently used to maintain vehicle separation. In this respect, we analyze a hopping strategy for Time-Slotted Channel-Hopping (TSCH), which was introduced in the IEEE 802.15.4e amendment with a view of improving the reliability of IEEE 802.15.4 networks. We define a probability framework to estimate the chance of successful hopping assuming two previously merged vehicles, and we design a zero-sum game and propose a payoff function to always place communicating nodes in a Nash equilibrium by choosing whether to hop or not, and therefore maximizing the communication throughput by mitigating jamming signals.

International audience; In this paper, a User-Based model is proposed to analyze and evaluate the performance of IEEE 802.11p MAC protocol for vehicular safety applications that can save lives and improve traffic flow. The proposed model provides a complete stability analysis compared to the Markovian models. Moreover, it provides a means for conducting further analysis on the design parameters of the protocol, leading to an optimization methodology which indicates how IEEE 802.11p should be configured for improved performance. The model is cross validated against simulations; the IEEE 802.11p can meet the needed latency and reliability requirements for the delivery of safety messages under the Finite user model, however, it fails to satisfy such requirements under the Infinite user model.

In this work, we mainly consider the synchronization problem of hybrid transmit-only nodes for slight modified IEEE 802.15.4 wireless sensor networks, which is called TRO 802.15.4. However, we should let the IEEE 802.15.4 networks to fit transmission cycle of transmit-only nodes in order to achieve the synchronization. The adaptive beacon interval shifting and resizing (ABISR) algorithm is then proposed to synchronize with transmit-only nodes in TRO 802.15.4.

Wireless Body Area Networks (WBANs) were designed to collect and transfer vital physiological parameters within a short distance of the human body by employing low-power, light-weight, small-sized and smart implantable or wearable sensor devices. Lately, WBANs are expected to support various types of applications with data rates from a few Kbps upto 10 Mbps and satisfy the heterogeneous requirements of both medical and consumer electronics applications. Hence, novel communication protocols that consider a unique set of constraints and demands of these networks need to be developed to provide optimum system efficiency and data transmission reliability. As the IEEE 802.15.6 Medium Access Control (MAC) protocol based on the latest WBANs standard, cannot maintain the balance between the strict energy limitation and Quality of Service (QoS) requirements of such networks, this paper focuses on developing MAC protocols to improve the performance of WBANs specifically in the saturation condition. Two IEEE802.15.6-based MAC protocols are proposed to enhance channel access for the highest user priority and the other user priorities in saturated networks. The simulation results show better network performance as well as lower energy consumption in the proposed MAC protocols compared to the IEEE 802.15.6 MAC protocol.

In this paper, a novel broadcast protocol is proposed for the receiver initiated transmission (RIT) media access control (MAC) protocol based wireless smart utility network (Wi-SUN) systems. The RIT protocol adopted by IEEE 802.15.4e achieves the low power consumption by switching the short wake-up state and the long sleep state, however, the protocol does not support broadcasting because terminals with the protocol are in the sleep state mostly. In the proposed protocol, terminals follow to adjusted periodical listening instructions that are unicasted, and the broadcasting frame transmitted at the periodical timing. Computer simulations are carried out to evaluate the required time for the layer 2 (L2) address resolution, as a typical case of the proposed broadcast protocol. The evaluation shows broadcasting is achieved by the proposed protocol and it is found that the average required time to finish the L2 address resolution is about 16s when a personal area network coordinator (PANC) performs broadcasting with repeat listen interval of 5.0s and the number of terminals is 100. Also, the evaluation results show that the proposed protocol has the flexibility that achieves broadcasting without setting parameters regardless of the number of terminals. By the proposed RIT based broadcast system, very low-power consumption internet protocol (IP) transmission in the Wi-SUN can be implemented within the permissible delay.

We present the results from a measurement-based performance evaluation of wireless networks based on IEEE 802.11n and IEEE 802.11ac standards in an indoor environment, with the aim to analyze their performance under high definition streaming video applications. We focus our study on analyzing the highest performance of these standards using off-the-shelf equipment, both with synthetic TCP and UDP traffic to measure the saturation throughput as well as high definition video streams. The measurements have been conducted in the student labs of our university and show good performance for streaming purposes in high definition and also ultra-high definition from a subjective video quality point of view. IEEE 802.11ac performance is very sensitive to the channel conditions. According to our experiments, these results heavily depend on the implementation of the IEEE 802.11ac standard of the commercial access points.

The IEEE 802.15.4 standard is the basis of many protocol suites such as ZigBee, WirelessHART and MiWi popular in Internet of Things systems, wireless sensor networks, and industrial wireless networks. In practice, due to its working bands are free to access, IEEE 802.15.4 based networks often suffer from interference which will deteriorate the network performance. In this paper, we model the interference as an on-off process and propose a new analytical model for IEEE 802.15.4 based networks which quantitatively characterizes how such interference affects the network throughput. We also conduct extensive simulations which demonstrate the accuracy of the model.

In this paper, we study the problem of jointly solving the contention and congestion distributed control problem in a bounded queue wireless ad-hoc network. The resulting flow rates satisfy fairness criteria according to a given Network Utility Maximization (NUM) function. In recent years a number of papers have presented solutions to this problem that are based on network utility maximization algorithms. However, this work typically necessitates either complex computations, heavy signaling/control overhead, and/or approximated sub-optimal results. In this paper, we combine a specific network utility maximization problem with a simple and efficient queue management mechanism that we believe is appropriate for wireless ad-hoc networks. We employ and adapt the IEEE 802.11 protocol to work with the utility maximization algorithm for contention optimization. Finally, we show via NS-3 simulations that the proposed Cross-Layer Design (CLD) significantly outperforms standard protocols such as TFRC.

The IEEE 802.11ad standard allows wireless devices to operate in the unlicensed spectrum band of 60 GHz. By utilizing the channel with 2.16 GHz width, the devices are able to transmit at multi-Gigabit data rates that potentially satisfy demanding requirements of quality of services. Additionally, the advent of off-the-shelf IEEE 802.11ad device motivates research efforts to exploit this 60 GHz opportunity for applications. Although much has been understood from the previous works, there is still a lack of insight into building IEEE 802.11ad networks, especially the ones with multi-Gigabit links. Address the issue, this work investigates the feasibility of multi-Gigabit IEEE 802.11ad networks, as well as, the factors that influence network performance in a typical office environment. By experimental study with off-the-shelf IEEE 802.11ad hardware, we can identify the conditions that the TCP and UDP throughput of IEEE 802.11ad link reach multi-Gigabit levels. Moreover, we show and discuss the negative effects of both co-channel and adjacent channel interference on the IEEE 802.11ad network's performance.

With an advancement towards the paradigm of Internet of Things (IoT), in which every device will be interconnected and communicating with each other, the field of wireless sensor networks has helped to resolve an ever-growing demand in meeting deadlines and reducing power consumption. Among several standards that provide support for IoT, the recently published IEEE 802.15.4e protocol is specifically designed to meet the QoS requirements of industrial applications. IEEE 802.15.4e provides five Medium-Access Control (MAC) behaviors, including three that target time-critical applications: Deterministic and Synchronous Multichannel Extension (DSME); Time Slotted Channel Hopping (TSCH) and Low Latency Deterministic Network (LLDN). However, the standard and the literature do not provide any worst-case bound analysis of these behaviors, thus it is not possible to effectively predict their timing performance in an application and accurately devise a network in accordance to such constraints. This paper fills this gap by contributing network models for the three time-critical MAC behaviors using Network Calculus. These models allow deriving the worst-case performance of the MAC behaviors in terms of delay and buffering requirements. We then complement these results by carrying out a thorough performance analysis of these MAC behaviors by observing the impact of different parameters.

Distributed Measurement Systems (DMSs) typically rely on real-time communication networks, since these latter allow to achieve timely and efficient data transfer among the distributed measurement nodes. The most suitable networks to this purpose are industrial communication systems such as fieldbuses and industrial Ethernet. In this scenario, wireless systems have recently started to be carefully evaluated, with a particular reference to the IEEE 802.11 Wireless LANs (WLAN). In this paper, we address the IEEE 802.11n version of the WLAN standard which, although widespread for general purpose applications, has not yet been adequately deployed for real-time communications. Specifically, we present the results of a performance analysis aimed at assessing the suitability of IEEE 802.11n for employment in DMSs. In detail, the proposed analysis starts with a measurement campaign carried out on commercial devices to determine the Packet Error Rate (PER) versus Signal-to-Noise (SNR) ratio behavior. Then we present the outcomes of a realistic simulation session executed on a network configuration typical of DMSs. The obtained results confirm that IEEE 802.11n may be a viable opportunity to implement DMSs and, moreover, they suggest some interesting future directions of research.

This paper proposes a multi-channel medium access control (MAC) protocol for hybrid VLC/Wifi networks. The proposed MAC protocol is based on an integration of two standards, IEEE 802.15.7 VLC and IEEE 802.11 Wifi CSMA/CA(s) (Carrier Sense Multiple Access/Collision Avoidance). We newly add on top of current MAC protocols a sub-layer that runs dynamic channel selection by taking intelligent control decisions, regarding channel aware and traffic aware. System performance metrics are analytically studied based on a combination of queuing and Markov chain theories. Numerical results quantitatively show how the proposed protocols significantly outperform the conventional ones.

This paper's objective is to present the performance comparison between Wi-Fi IEEE 802.11ac and Wi-Fi IEEE 802.11n by measuring the throughput and steaming rate of big data streaming. The performance test is divided into four scenarios, 1) data streaming to one device, 2) data streaming with different distances, 3) data streaming to multiple devices, and 4) live broadcast a big data streaming. The results of evaluations are as follow. In the first scenario, maximum transfer rate of IEEE 802.11ac is higher but the average transfer rate depends on the video type. In second scenario, maximum transfer rate to the first and second device of IEEE 802.11ac is significantly greater than IEEE 802.11n but IEEE 802.11ac cannot reach the third device which located on the different floor, while IEEE 802.11n can reach the third device with maximum transfer rate of 942.8 kbps. The throughput of IEEE 802.11ac is more stable than IEEE 802.11n by compare the data from the first and second device. In third scenario, the maximum transfer rate of IEEE 802.11ac is higher than IEEE 802.11n and throughput of IEEE 802.11ac is more stable than IEEE 802.11n. In fourth scenario, the maximum transfer rate and average transfer rate of IEEE 802.11ac is higher than IEEE 802.11n.

Over the time while IEEE 802.11 was developed, rate adaption algorithms had their own development stage. Most of rate adaption algorithms are not standardized and there are no rules on how one should operate. Therefore, this part of IEEE 802.11 is handled entirely by wireless vendors. Although, while IEEE 802.11 moved forward and introduced several performance increases with Quality of Service introduction, including IEEE 802.11ac wireless modulation and similar, rate control remained the same. Even now, IEEE 802.11ac re-uses the very first approach of rate control algorithm, because despite many attempts to improve the performance of rate control algorithms by introducing different methods to use statistical data for rate control knowledge, only few were successful in adding a difference in performance. This paper discusses hybrid rate control usage for IEEE 802.11. Most of the algorithms to this date are used on station device and on Access Point. In this paper we take a different approach and adapt a different rate control algorithm, which is based on the device operational mode, thus leveraging both the Received Signal Strength Indication (RSSI) based algorithm capabilities and the Packet Error Rate (PER) capabilities. The performance of named approach is tested in outdoor environment, on the infrastructural network topology.

We propose a sequential staging access scheme to minimize the occurrence of channel-access collisions in infrastructure IEEE 802.11 (WiFi) networks under emergency and crowded scenarios in this paper. The proposed scheme is based on separating the functions performed by station for channel access and dedicating states for contention and transmission separately rather than using a single shared state as done in IEEE 802.11. The result is an increase in access success ratio and avoidance of throughput collapse 802.11. The proposed scheme overcomes the throughput and utilization collapse of IEEE 802.11 under crowded scenarios and increases bandwidth utilization. This access is critical for crowded networks under emergency scenarios where many stations suddenly and intensively contend for network access. This scheme may also fits as a fallback mechanism of IEEE 802.11 networks to avoid throughput collapse under crowded scenarios and thus, to enable reliable communications in critical situations. Our simulation results show significant improvements on bandwidth utilization and throughput as compared to IEEE 802.11 under crowded conditions.

We provide an empirical evaluation of an IEEE 802.11ac Wireless Local Area Network (WLAN) cell with Multiple User Multiple Input Multiple Output (MU-MIMO) technology. We conducted our experiments on a testbed comprising consumer equipment under different office scenarios using 40MHz and 80MHz channels. This is the first performance study of MU-MIMO with 802.11ac in an operational scenario using a commercial access point. We find that, for clients that do not support MU-MIMO, operating in a cell that has MU-MIMO enabled may result in reduced performance.

This work explores the theoretical and practical performances of the two most recent IEEE standards, 802.11n and 802.11ac. Experiments were conducted to measure data rates to characterize performance effects of distance and interference between different channels. We conclude that the majority of test cases show 802.11ac achieved higher data rates than its predecessor, as expected. However, performance of 802.11ac decreased at a significantly faster rate with increasing distance from client to AP when compared to the decreasing performance experienced with 802.11n. Furthermore, 802.11n consistently achieved real data rates much closer to the theoretical data rate than did 802.11ac.

IEEE 802.11 based Wireless Local Area Networks (WLANs) are widely used because of its flexibility. IEEE 802.11n is the latest inclusion in IEEE 802.11 standard. High throughput can be gained by enhancing the performance medium access control (MAC) layer. In that case MAC layer Frame Aggregation Mechanism can be used. Two types of frame aggregation are introduced by this standard namely MAC Service Data Unit (MSDU) aggregation and MAC Proto-col Data Unit (MPDU) aggregation. In this paper we have implemented an aggregation scheme by combining these two types of mechanism an analyzed its performance by using NS-3 in multi-client mode. The simulation result outperformed in case of throughput.

In this paper, we design a Medium Access Control (MAC) protocol for Wireless Body Area Network (WBAN) to allocate slot to packets of each medical and non-medical node. Although a hybrid MAC protocol is defined in IEEE 802.15.6 as the international standard of WBAN, the detail specification depends on the implementation. It is important to consider the Quality of Service (QoS) requirements of each node and packet in WBAN, because different sensor nodes generate time varying packets which generate depending on human behavior. Besides, permissible delay time of each medical and non-medical node is different. To improve both priority control for QoS and dependability, we propose a MAC protocol with slot prediction algorithm. Simulation results show that our protocol outperforms IEEE 802.15.6 in terms of transmission success rate and worst delay time.

In 802.11 wireless network, a large number of multimedia applications are emerging. Accurate end-to-end bandwidth estimation techniques can help these applications adjust their behavior accordingly, such as stream’s bitrate adaptation, to improve quality of service. However, most current bandwidth estimation techniques are designed for wired networks that have high intrusiveness and consume long convergence time, which cannot be applied in resource-limited wireless network. In this article, we present a novel bandwidth estimation tool for IEEE 802.11 wireless network, which only needs to be deployed in one end of the end-to-end path and estimate available bandwidth based on round-trip-time measurements with low intrusiveness and short convergence time. We compare our tool with another state-of-the-art tool on an IEEE 802.11 wireless testbed, and the experimental results show that our tool has higher accuracy.

© 2016 IEEE. Wireless Mesh Network is an emerging technology with great potential to become a Self-Sustained Network. Unlike the traditional networks that dominate the current communication system and rely on a large and expensive setup of wired/wireless access points to provide connection between users, the Wireless Mesh Network is formed by the user devices (referred as Nodes) which connect to each other to form a network. However, due to the use of legacy/traditional network models for mesh networks, there exist various limitations towards its implementation. This paper presents a new approach towards the Wireless Mesh Network, incorporating a new routing scheme based on the Geo-Location of the devices. It puts forward the structure, working principle and its performance during the first implementation.

International audience; Low-Power Lossy Networks (LLNs) are at the core of many Internet of Things solutions. Significant standardization effort has been put in creating a protocol stack suited for LLNs. Among these standards, IEEE802.15.4-2011 and RPL allow LLN devices to form a multi-hop mesh network. Today, RPL creates a routing topology without a priori knowledge about the topology created at the MAC layer. This negatively impacts the number of redundant paths, their quality, and the overall performance of the routing protocol. In this article, we highlight the need for an intermediate layer between MAC and network layers to solve these problems. We describe the protocols to be used in future Internet of Things, emphasize their weaknesses when deployed together, and provide areas of improvement.

Machine-to-machine communication (M2M) technology enables large-scale device communication and networking, including home devices and appliances. A critical issue for home M2M networks is how to efficiently integrate existing home consumer devices and appliances into an IP-based wireless M2M network with least modifications. Due to its popularity and widespread use in closed spaces, Wi-Fi is a good alternative as a wireless technology to enable M2M networking for home devices. This paper addresses the energy-efficient integration of home appliances into a Wi-Fi- and IP-based home M2M network. Toward this goal, we first propose an integration architecture that requires least modifications to existing components. Then, we propose a novel long-term sleep scheduling algorithm to be applied with the existing 802.11 power save mode. The proposed scheme utilizes the multicast DNS protocol to maintain device and service availability when devices go into deep sleep mode. We prototyped our proposed architecture and algorithm to build a M2M network testbed of home appliances. We performed various experiments on this testbed to evaluate the operation and energy savings of our proposal. We also did simulation experiments for larger scale scenarios. As a result of our test-bed and simulation experiments, we observed significant energy savings compared to alternatives while also ensuring device and service availability. © The British Computer Society 2017. All rights reserved.

WOS: 000394680300033 The IEEE has established the standardization group 802.15.7r1 "Short Range Optical Wireless Communications", which is currently in the process of developing a standard for visible light communication (VLC). As with any other communication system, realistic channel models are of critical importance for VLC system design, performance evaluation, and testing. This article presents the reference channel models that were endorsed by the IEEE 802.15.7r1 Task Group for evaluation of VLC system proposals. These were developed for typical indoor environments, including home, office, and manufacturing cells. While highlighting the channel models, we further discuss physical layer techniques potentially considered for IEEE 802.15.7r1. Istanbul Development Agency (ISTKA) under the Innovative Istanbul Financial Support Program [TR10/15/YNK-72 OKATEM]; TUBITAK [113E307] This work is carried out as an activity of the "Optical Wireless Communication Technologies Excellence Centre" funded by the Istanbul Development Agency (ISTKA) under the Innovative Istanbul Financial Support Program 2015 (TR10/15/YNK-72 OKATEM). The statements made herein are solely the responsibility of the authors and do not reflect the views of ISTKA and/or the T.R. Ministry of Development. The works of Farshad Miramirkhani and Erdal Panayirci are supported by TUBITAK Research Grant No. 113E307.

Existing routing protocols for hybrid wireless mesh network neglect the negative impact on network lifetime and route stability caused by energy constraints and mobility of mesh clients. To solve this issue, a regional energy- and mobility-aware routing protocol is proposed in this article. Both energy and mobility features in hybrid wireless mesh network are considered in this routing protocol. On one hand, within the communication transmission range, the intensity and degree of dispersion in energy consumption can be perceived. The node whose neighbor area has sufficient energy can be selected for network services, which can balance energy and extend the network lifetime. On the other hand, the mobility of clients is considered to enhance the stability and reduce network overhead. Therefore, regional energy- and mobility-aware routing protocol can balance network energy consumption, prolong network lifetime, and improve route stability. Simulation results via NS2 show that regional energy- and mobility-aware routing protocol can achieve better performance significantly.

In this paper we consider a video surveillance application, using a camera mounted on a drone flying over the area to be monitored and sending the video to a control center (CC). In order to ensure connectivity between the drone and the CC some relays are deployed on the ground. The resulting network is composed of a static component (relays), and a moving component (the drone). All network devices are assumed to be equipped with IEEE 802.11s air interfaces. The goal of our work is to design and validate a routing protocol appropriate for this scenario. The IEEE 802.11s standard proposes Hybrid Wireless Mesh routing Protocol (HWMP) composed of a proactive tree-based routing and the reactive Radio Metric Ad-hoc On-Demand Distance Vector (RM-AODV) scheme to support mesh networks. To address the need for reliable connectivity, faster and resource-efficient path discovery, we envisage a mixed optimized scheme, called Optimized-Hybrid Wireless Mesh Protocol (O-HWMP), where both, RM-AODV and the proactive tree-based scheme, are used at the same time. In O-HWMP the output of the tree-based routing scheme provides input to the RM-AODV, in order to reduce flooding of control packets, and to minimize delays during path discovery. Through NS3-Evalvid simulations we demonstrate that, compared to RM-AODV scheme, our proposed protocol significantly improves network performance in terms of delays, packet success rate, overhead cost, and peak-signal-to-noise-ratio metric of the received video.

Recently, wireless sensor networks (WSNs) are emerging in various application fields thanks to their low cost and ease of deployment. In particular, the rapid increase of critical monitoring applications encourages the study and evaluation of wireless communication protocols that can fulfill the requirements of such applications. Among the WSN standards, the IEEE 802.15.4 is very promising, as it provides critical messages with the support for prioritized channel access through the Priority Channel Access mechanism. The paper assesses the behavior of an IEEE 802.15.4 wireless sensor network implementing the Priority Channel Access mechanism in a realistic monitoring scenario, focusing on the impact on critical message transmissions. The assessments are based on OMNeT++ simulations.