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Next-generation IEEE 802.11ax Wireless Local Area Networks (WLANs) will make extensive use of multi-user communications in both Downlink (DL) and Uplink (UL) directions to achieve high and efficient spectrum utilization in scenarios with many user stations per access point. It will become possible with the support of Multiuser (MU) Multiple Input, Multiple output (MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) transmissions. In this paper, we first overview the novel characteristics introduced by IEEE 802.11ax to implement AP-initiated OFDMA and multiuser MIMO (MU-MIMO) transmissions in both DL and UL directions. Namely, we describe the changes made at the Physical (PHY) layer and at the Medium Access Control (MAC) layer to support OFDMA, the use of trigger frames to schedule uplink multi-user transmissions, and the new multiuser RTS/CTS mechanism to protect large multi-user transmissions from collisions. Then, in order to study the achievable throughput of an IEEE 802.11ax WLAN, we use both mathematical analysis and simulations to numerically quantify the gains of MU transmissions and the impact of IEEE 802.11ax overheads on the WLAN saturation throughput. Results show the advantages of using MU transmissions in scenarios with many user stations. Additionally, we provide novel insights on the conditions in which IEEE 802.11ax WLANs are able to maximize their performance, such as the need to provide strict prioritization to AP-initiated MU transmissions to avoid collisions with transmissions from user stations.

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.

In this book chapter, a flexible and contention-free point-to-point direct communication (PDC) approach is proposed to achieve direct transmission between SSs within IEEE 802.16 PMP networks. With the considerations of both relative locations and channel conditions among the BS and SSs, a two-tiered admission control scheme is proposed to determine the establishment of direct link between the SSs in the PDC approach. While adapting the PDC approach, the

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.

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.

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.

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.

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.

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

This article gives an overview of the IEEE 802.15.10 standard specifying a layer 2 routing (L2R) protocol enabling communication over multiple hops in IEEE 802.15.4 networks. IEEE 802.15.4 is expected to be a predominant technology as we move toward an increasingly interconnected society. IEEE 802.15.10 allows increasing the range of an IEEE 802.15.4 network while maintaining low-power transmission. This new standard is suitable for applications such as smart metering, intelligent transportation systems, and automation, where a varying number of devices are deployed in an area ranging from a few square meters to entire cities or countries.

The IEEE 802.16e standard, known as mobile Worldwide Interoperability for Microwave Access (WiMAX) becomes the most demanding broadband wireless access (BWA) technology recently. Its main advantage is rapid delivery of services in remote areas due to the cost efficiency factor. The base station (BS) supports data rate up to 70 Mbps, mobile stations with 5–15 km length of coverage, and for the fixed stations the wireless access range up to 50 km. To resolve the bandwidth contention issue and guarantee seamless packet transmission from the subscriber stations (SS) to the BS, the uplink (UL) traffic scheduling must be efficient and reliable. This paper studies the work on the UL scheduling algorithm, namely minimum rest time (MRT). The MRT goal is to strengthen the packet transferring time between the SS and the BS by refining the pre-stipulated expired time and the deadline time of the earliest expiry first (EEF) and earliest deadline first (EDF) hybrid algorithms. These legacy algorithms are inadequate to support the multi-class traffic systems due to the shortage of quality of service (QoS) parameters featuring. Moreover, the algorithms are highly static. Using the Omnet++ with the relevant performance metrics the obtained results confirmed the MRT outperforms effectively from the legacy algorithms.

In IEEE 802.11 networks, many access points (APs) are required to cover a large area due to the limited coverage range of APs, and frequent handoffs may occur while a station (STA) is moving in an area covered by several APs. However, traditional handoff mechanisms employed at STAs introduce a few hundred milliseconds delay, which is far longer than what can be tolerated by some multimedia streams such as voice over Internet protocol (VoIP), it is a challenging issue for supporting seamless handoff service in IEEE 802.11 networks. In this paper, we propose a pre-scan based fast handoff scheme within an IEEE 802.11 enterprise wireless local area network (EWLAN) environment. The proposed scheme can help STA obtain the best alternative AP in advance after the pre-scan process, and when the handoff is actually triggered, STA can perform the authentication and reassociation process toward the alternative AP directly. Furthermore, we adopt Kalman filter to minimize the fluctuation of received signal strength (RSS), thus reducing the unnecessary pre-scan process and handoffs. We performed simulations to evaluate performance, and the simulation results show that the proposed scheme can effectively reduce the handoff delay.

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.

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.

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.

IEEE 802.15.4 targets low data rate communication with limited power devices and cheap wireless networking solutions. In recent years both industry and academia are attracted to IEEE 802.15.4 because of its applicability in wireless sensor networks and wireless body area networks. An important feature of IEEE 802.15.4 is its very low duty cycle operation for conserving energy consumption of sensor device. Super-frame structure of IEEE 802.15.4 defines the duty cycle of nodes. The super-frame structure is based on two parameters: beacon order (BO) and super-frame order (SO). The performance of an IEEE 802.15.4 network depends on the values of BO and SO. These values depict the energy consumption, throughput, node discovery and latency of communication. IEEE 802.15.4 uses fixed BO and SO values which can be carefully chosen to meet the network requirements. In this paper, an extensive survey of dynamic super-frame adjustment algorithms is presented. The survey focuses on beacon-enabled star topology of IEEE 802.15.4 and studies the impact of aforementioned algorithms for various applications. Also, the survey categorizes common IEEE 802.15.4 applications based on their requirements for super-frame adjustment. A brief simulation analysis is included in this survey to highlight the impact of BO and SO on the network performance.

IEEE 802.16, also known as Worldwide Interoperability for Microwave Access, is a standardization effort carried out by the IEEE to provide last-mile broadband access to end users. The IEEE 802.16 standard supports two medium access control modes--a mandatory point to multipoint mode and an optional mesh mode. In this paper, we propose an asymmetric interference aware routing algorithm and a new multipointer approach in implementing scheduling algorithms for IEEE 802.16 mesh networks. We modify three different centralized scheduling algorithms, fixed scheduling, ordered scheduling and per-slot scheduling using multipointer approach to allow for spatial reuse in IEEE 802.16 mesh networks. Simulation results reveal that fixed scheduling with SR provides the best performance.

This paper concentrates on the IEEE 802.11p MAC sublayer to analyze its performance in the presence of hidden terminals. An analytical model for the throughput of the IEEE 802.11p in the presence of hidden terminal is presented in this paper. A 3-D Markov chain is created to model the backoff procedure for each access category. The different contention windows and arbitration interframe space are considered for each access category. The model also takes into consideration control packets and data packets separately. The probabilities of frame blocking, successful transmission, collisions and hidden terminals have been derived and used to calculate the throughput. The simulation results are presented to validate the analytical results of the proposed model. The results of the proposed model are compared with the existing model IEEE 802.11 EDCA (Kosek-Szott et al. in Comput Netw 55(3):622---635, 2011). The results of the proposed model outperform the existing model.

Energy efficiency has become a regular hot topic in the research on wireless communications networks. However, existing proposals leave room for improvement when multi-hop wireless broadband networks are used to provide on-demand connectivity under low traffic load conditions. For this kind of networks, the capability of bringing the network up and down on demand wirelessly would help significantly to design energy-efficient, compact and low-cost network nodes. This paper presents a new approach for multi-hop energy-efficient networks based on a dual network architecture called dualWireless. Each node belongs to two parallel wireless multi-hop networks, an on-demand IEEE 802.11n network for data communications and a permanent IEEE 802.15-4 network for control purposes. The paper explains the proposal, the development of prototypes and the empirical validation with a testbed. In addition, a power consumption analytical model is used to measure the energy savings achieved by dualWireless and for comparison with other authors proposals. The dualWireless approach is shown to be more energy efficient than other alternatives as long as the occupation time of the network is under 40%, which is the case for many particular applications.

In this paper, we propose a technique for making IEEE 802.15.4 standard suitable for low-latency deterministic networks for wireless control applications where the cyclic update time of sensor’s information is not more than 10 ms. The IEEE 802.15.4 has shown good characteristics for deterministic networks in beacon-enabled mode, but with minimum cyclic update time for personal area network devices not less than 15.36 ms. Moreover, it is unsuitable for hard real-time systems when used in nonbeacon-enabled mode due to the random nature of channel access protocol. The proposed technique employs time-division multiple access (TDMA)-based protocol that works on slightly modified IEEE 802.15.4 in star topology. Each end device in the network transmits its data frame after certain time delay in response to periodic requests from the coordinator. This time delay is optimized for better channel bandwidth utilization and reliable data exchange. While this TDMA-based protocol eliminates the risk of frame collisions to a great extent, medium-access control sublayer modifications reduce the nondeterminism of the network and increase the bandwidth efficiency. A mathematical model is proposed to design and develop a practical communication network with commercial off-the-shelf radios that can predict worst case arrival time of data frames. Experiments were conducted to evaluate the model for the proposed protocol.

The IEEE 802.11 standard has contributed to increasing ubiquitous connectivity. Its success is motivated, among other factors, by its inexpensive costs and the easiness of its deployment, turning WiFi into the most widespread wireless access technology. However, most users are not aware of the constant evolution in the IEEE 802.11 family. In this article we focus on some of the IEEE 802.11 amendments included in the latest version of the standard, which address interesting challenges in the context of WLANs, such as minimization of the interruption when changing the point of attachment to the network. However, these amendments have not had much commercial impact, and have gone somehow unnoticed by the majority of users and even part of the research community. We analyze their motivation, the functionality they provide, and their existing practical applications, if any. We also evaluate the possible factors that influence their adoption. If most of the commercial hardware does not implement these amendments, their impact on real WLAN deployment and experimental research will be limited.

IEEE 802.15.4m TVWS Multi-Channel Tree PAN (TMCTP) standard that uses the vacant TV frequency of a region is the key to provide a flexible, scalable and cost-effective AMI smart grid networks. However, the performance of the IEEE 802.15.4m based AMI network can suffer from network interruption, varying transmission reliability and energy consumption problems due to the excessive number of channels and periodic channel scanning. To resolve these issues, we presented an enhanced IEEE 802.15.4m TMCTP called TVWS Orphan channel scanning with Multi-Channel Tree PAN Routing (TOMTPR). The proposed TOMTPR framework includes pilot-channel based Multi-Channel beaconing and interleaving-based TVWS orphan channel scanning. Furthermore, a capacity-aware routing tree is constructed during the neighbor discovery procedure. The proposed protocol suite is designed to provide compatibility with the IEEE 802.15.4 family standards with lower architecture complexity. The simulation results in presence of realistic AMI traffic and AMI network model show that TOMTPR can not only satisfy delay requirements of the AMI traffic, but also outperforms IEEE 802.15.4m TMCTP with IEEE 802.15.5 layer 2 mesh routing in terms of topology construction delay, end-to-end transmission reliability, and energy efficiency.

Summary Wireless body sensor networks are offered to meet the requirements of a diverse set of applications such as health-related and well-being applications. For instance, they are deployed to measure, fetch and collect human body vital signs. Such information could be further used for diagnosis and monitoring of medical conditions. IEEE 802.15.4 is arguably considered as a well-designed standard protocol to address the need for low-rate, low-power and low-cost wireless body sensor networks. Apart from the vast deployment of this technology, there are still some challenges and issues related to the performance of the medium access control (MAC) protocol of this standard that are required to be addressed. This paper comprises two main parts. In the first part, the survey has provided a thorough assessment of IEEE 802.15.4 MAC protocol performance where its functionality is evaluated considering a range of effective system parameters, that is, some of the MAC and application parameters and the impact of mutual interference. The second part of this paper is about conducting a simulation study to determine the influence of varying values of the system parameters on IEEE 802.15.4 performance gains. More specifically, we explore the dependability level of IEEE 802.5.4 performance gains on a candidate set of system parameters. Finally, this paper highlights the tangible needs to conduct more investigations on particular aspect(s) of IEEE 802.15.4 MAC protocol. Copyright © 2015 John Wiley & Sons, Ltd.

IEEE 802.15.4 enabled wireless sensor networks are often impacted by the coexistence of different sources of external interference sharing the ISM band. Such external interference may significantly deteriorate achievable wireless sensor network throughputs due to uncontrollable collisions of interference transmissions with IEEE 802.15.4 packets. Forward error correction may be considered as a mechanism to alleviate the resiliency of IEEE 802.15.4 packets against partial collisions due to interference. In this paper, theoretical analysis of network throughput of IEEE 802.15.4 enabled wireless sensor networks under external interference with deployment of FEC will be presented. The throughput performance of IEEE 802.15.4 network under FEC deployment is governed by the percentage of collided bits within IEEE 802.15.4 coded payloads that the FEC code can withstand. The analysis in this paper considers convolutional codes as FEC candidate codes for IEEE 802.15.4 networks and proceeds to theoretically derive collision percentage thresholds that convolutional codes may tolerate under Viterbi decoding. Numerical results indicate that an optimal FEC coding rate exists for a given IEEE 802.15.4 and external interference configuration. The optimal coding rate introduces enough resiliency for the IEEE 802.15.4 transmissions to withstand external interference. Any additional redundancy bits for more robust codes would render unneeded protection that unnecessarily reduces the goodput of IEEE 802.15.4 networks.

This paper proposes a solution for reducing handoff latency due to security procedures. This solution is in the spirit of current research aiming to set the standard for future generation wireless services with a focus on the IEEE 802.16m standard. The aim of this paper is to present a solution which incorporates a ticket-based mechanism and a modified key derivation algorithm to reduce the problem of handoff latency.

Recently, the IEEE 802.15.6 Task Group introduced a new wireless communication standard that provides a suitable framework specifically to support the requirements of wireless body area networks (WBANs). The standardization dictates the physical (PHY) layer and medium access control (MAC) layer protocols for WBAN-based communications. Unlike the pre-existing wireless communication standards, IEEE 802.15.6 standardization supports short-range, extremely low power wireless communication with high quality of service and support for high data rates upto 10 Mbps in the vicinity of living tissues. In this work, we construct a discrete-time Markov chain (DTMC) that efficiently depicts the states of an IEEE 802.15.6 CSMA/CA-based WBAN. Following this, we put forward a thorough analysis of the standard in terms of reliability, throughput, average delay, and power consumption. The work concerns non-ideal channel characteristics and a saturated network traffic regime. The major shortcoming of the existing literature on Markov chain-based analysis of IEEE 802.15.6 is that the authors did not take into consideration the time spent by a node awaiting the acknowledgement frame after transmission of a packet, until time-out occurs. Also, most of the work assume that ideal channel characteristics persist for the network which is hardly the case in practice. This work remains distinctive as we take into account the waiting time of a node after it transmits a packet while constructing the DTMC. Based on the DTMC, we perform a user priority (UP)-wise analysis, and justify the importance of the standard from a medical perspective.

IEEE 802.11ah Task Group has been developing an amendment to the 802.11 standard to define sub-1-GHz license-exempt operation to support sensors and Internet of Things applications. This article presents an overview of major physical layer and MAC layer features of 802.11ah.

IEEE 802.11 is one of the most popular wireless technologies in recent days. Due to easiness of adaption and relatively low cost the demand for IEEE 802.11 devices is increasing exponentially. IEEE works in two bands 2.4 GHz and 5 GHz, these bands are known as ISM band. The unlicensed bands are managed by authority which set simple rules to follow when using unlicensed bands, the rules includes requirements as maximum power, out-of-band emissions control as well as interference mitigation. However these rules became outdated as IEEE 802.11 technology is emerging and evolving in hours the rules aren’t well suited for current capabilities of IEEE 802.11 devices. In this article we present game theory based algorithm for IEEE 802.11 wireless devices, we will show that by using game theory it’s possible to achieve better usage of unlicensed spectrum as well as partially decline CSMA/CA. Finally by using this approach we might relax the currently applied maximum power rules for ISM bands, which enable IEEE 802.11 to work on longer distance and have better propagation characteristics. Santrauka Lengvai pritaikoma ir panaudojama įvairiuose sprendimuose IEEE 802.11 technologija tapo viena populiariausių bevielių technologijų. IEEE 802.11 įrenginiai veikia nelicencijuotais 5 GHz ir 2,4 GHz dažniais – pramonės, mokslo ir medicinos dažnių ruože (angl. Industrial, scientific and medical (ISM) radio bands). Šiam dažnių ruožui taikomos supaprastintos taisyklės, nurodančios, kad įrenginiai, veikiantys ISM dažniais, turi atitikti tik maksimalią signalo perdavimo galią ir interferencijos triukšmus bei neviršyti triukšmo normos už dažnių ruožo ribų. Tobulėjant IEEE 802.11 protokolo įrangai, šios taisyklės tapo nelanksčios ir neatitinka dabartinių įrenginių galimybių. Straipsnyje pristatomas naujas IEEE 802.11 įrenginių kanalo prieigos metodas, pagrįstas žaidimų teorija. Parodoma, kad taikant šį metodą galima pagerinti spektro panaudojimo efektyvumą bei kartu iš dalies atsisakyti dabar egzistuojančio CSMA/CA mechanizmo IEEE 802.11 įrenginiuose. Taikant efektyvesnį kanalo prieigos metodą atsiranda galimybė laikytis lankstesnių siųstuvo galių taisyklių ir taip padidinti skvarbą uždarose patalpose bei įrangos veikimo nuotolį. Raktiniai žodžiai:IEEE 802.11, WiFi, interferencija, kognityvusis radijas, žaidimų teorija.

The wireless communication has shown its improvement in sensor skills which motivates the wireless sensor networking. IEEE 802.15.4 was created with having few tremendous advantages like low-power ,very low cost and low energy consumption in wireless consumption From the last few years it has been used in man applications including hospitals, hotels, home, industrial controlling networks and the environmental monitoring. It is the basic standard which specifies the MAC layer and Physical layer for low rate wireless PAN at 2.4GHz ISM band. IEEE802.15.4 is susceptible to interference from the other wireless technologies such as IEEE802.15.1 and IEEE80.11. Here we have given a overview of the IEEE 802.15.4 and IEEE 802.11 and analyse the performance of IEEE 802.15.4 and IEEE 802.11. The parameters on which the simulation is done are packet loss, packet received, End-to-End delay, Energy consumption, bandwidth used and packet delivery ratio by using NS2 simulator software. The final simulation results evaluated by taking 30 and 50 nodes for both 802.11 and 802.15.4 based networks.

IEEE 802.11 wireless local area networks (WLAN) have been widely deployed, and many applications are implemented on WLAN. As one of the interesting wireless services, wireless voice over internet protocol (VoIP) can provide low-cost real-time voice service to mobile users. But the IEEE 802.11 wireless network cannot satisfy the QoS of VoIP. The delay during handoff process can last up to 1 second. Applications with delay restraint like VoIP will drop the call when the delay is more than 50 ms. Therefore this paper analyzed the delay made by the handoff process, and proposed a pre-scanning fast handoff scheme. This fast handoff scheme is based on selective scanning and caching. It can predict the next AP for STAs and use pre-scanning before the handoff is triggered. Simulations on OPNET show this proposed scheme can reduce the average handoff delay to 23.45 ms and avoid some unnecessary handoffs. The pre-scanning fast handoff scheme is feasible and economical according to its performance in the handoff process.

In the next generation networks (4G) for Wireless Metropolitan area technology, the Mobile Wi-max (Wireless Interoperability Wireless Access) is one of the outstanding technologies that have promised to offer broadband wireless access (BWA) over long distance. The Mobile WiMAX was successfully adopted by ITU (International Telecommunication Union) as one of the IMT2000 (International mobile Telecommunications) technologies in November-2007. Mobile WiMAX, based on the IEEE 802.16e standard (release 1), supports a several types of handovers and allows fully mobility of users. Today the IEEE 802.16 Working Group (WG) has formed the IEEE 802.16m (release 2) and IEEE 802.16j. The IEEE 802.16j will provide relay functionality and IEEE 802.16m (Advance Air Interface) will provide high data rates and additional functionalities to meet the requirements for IMT-Advanced defined by ITU-R (ITU-Radio communication Sector) for 4G system. Another technology considered by IMT-Advanced for the 4G Radio Access Technology is LTE-Advanced. This paper provides vast overview of IEEE 802.16e and its comparison with other wireless technologies.

In 2013, global mobile data traffic grew 81% and it is projected to increase 11-fold between 2013 and 2018. Further, it is predicted that by 2018, over two-thirds of the world's mobile traffic will be video and more than half of all traffic from wireless connected devices will be offloaded to Wi-Fi networks and femto-cells [1]. Consequently, wireless LANs need major upgrades to improve both throughput and efficiency. IEEE 802.11ac is an amendment to the 802.11 standard that was just ratified by IEEE 802.11. Promising up to gigabit data rates, many Wi-Fi products are being built based on this specification. In addition to technologies that improve throughput, IEEE 802.11ax is investigating and evaluating advanced wireless technologies that enable more efficient utilization of the existing spectrum.

A new key management and security scheme is proposed to integrate Layer Two (L2) and Layer Three (L3) keys for secure and fast Mobile IPv6 handover over IEEE 802.11 Wireless Local Area Network (WLAN). Unlike the original IEEE 802.11-based Mobile IPv6 Fast Handover (FMIPv6) that requires time-consuming IEEE 802.1x-based Extensible Authentication Protocol (EAP) authentication on each L3 handover, the newly proposed key management and security scheme requires only one 802.1x-EAP regardless of how many L3 handovers occur. Therefore, the proposed scheme reduces the handover latency that results from a lengthy 802.1x-based EAP. The proposed key management and security scheme is extensively analyzed in terms of security and performance, and the proposed security scheme is shown to be more secure than those that were previously proposed.

IEEE 802.11 Community wireless hotspots are widely used to provide ubiquitous Internet connections to the end-users in public areas such as airports and restaurants. The recent analysis of the traffic pattern in a wireless hotspot shows more APs are deployed in a public area than required, though the users visit only a few APs. As a consequence, severe load imbalance is observed in a hotspot local area network (LAN), that results in performance degradation in terms of quality of service (QoS) for the network and quality of experience (QoE) for the end-users. This paper proposes a set of bandwidth management policies to achieve this goal, and the effectiveness of these policies is analyzed theoretically. According to the theoretical foundation, a context aware handover management scheme for proper load distribution in a public IEEE 802.11 network, supporting the class-aware bandwidth management policies, is designed in this paper. The performance of the proposed scheme is evaluated using an IEEE 802.11g+e wireless LAN testbed, and compared with other schemes proposed in the literature.

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.

Rapid development of wireless network impacts the development of IEEE 802.11x standard technology. However, the existing standard technologies still can not solve the problem of capacity, coverage, and power consumption. Due to these limitations, IEEE 802.11ah standard was made. IEEE 802.11ah is a standard of Wi-Fi technology that supports wireless networking scenarios, such as ability to arrange the large number of devices, a wide range of coverage, and power consumption mechanism on a limited energy condition. Wireless network is a best-effort network in delivering package. But VoIP service on the wireless network has lower QoS value, compared to the network using cables. This paper addresses the performance analysis of 802.11ah standard against VoIP services, especially at the MAC layer. To analyze the influence of node density and performance of RAW mechanism on VoIP service, a simulation is conducted through two scenarios, which are changing the number of nodes and RAW station. The simulation is performed using network simulator NS3 version 3.23. Analysis results show with the increasing number of nodes, the value of throughput and delay increase by 60.09% and 93.43%. Then, with the increasing number of RAW station, throughput and delay value have increased by 81.54% and 43.45%. The increase stops in a constant value when the number of RAW station has exceeded the number of nodes in the network.

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.