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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

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.

Increasing safety and automation in transportation systems has led to the proliferation of radar and IEEE 802.11pbased dedicated short-range communication (DSRC) in vehicles. However, current implementations of vehicular radar devices are expensive, use a substantial amount of bandwidth, and are susceptible to multiple security risks. In this paper, we use the IEEE 802.11 orthogonal frequency-division multiplexing communications waveform, as found in IEEE 802.11a/g/p, to perform radar functions. In this paper, we present an approach that determines the mean-normalized channel energy from frequencydomain channel estimates and models it as a direct sinusoidal function of target range, enabling closest target range estimation. In addition, we propose an alternative to vehicular forward collision detection by extending IEEE 802.11 DSRC and WiFi technology to radar, extending the foundation ofjoint communications and radar frameworks. Furthermore, we perform an experimental demonstration near DSRC spectrum using IEEE 802.11 standard compliant software defined radios with potentially minimal modification through algorithm processing on frequency-domain channel estimates. The results of this paper show that our solution delivers sufficient accuracy and reliability for vehicular RADAR if we use the largest bandwidth available to IEEE 802.11p (20 MHz). This indicates significant potential for industrial devices with joint vehicular communications and radar capabilities.

The IEEE 802.15.4 standard is the most widely used for the realization of Wireless Sensor Networks (WSN) and Internet of Things (IoT) applications. The effects of various disturbances on IEEE 802.15.4 wireless transmissions in the 2.4 GHz band have been studied previously for background noise, multipath fading, wideband and narrowband interference caused by WiFi and Bluetooth networks. The influence of co-channel interference, which originates from collisions between IEEE 802.15.4 devices which perform simultaneous radio transmission, has not been investigated previously. The IEEE 802.15.4 standard uses the Carrier Sense Medium Access with Collision Avoidance (CSMA/CA) channel access mechanism to prevent collisions between devices, but this mechanism does not provide protection from a hidden node problem, which is the primary source of co-channel interference. Hidden node collision in the CSMA/CA channel access mechanism occurs because of the time-spatial relation between nodes located inside the radio range of the recipient device. In our paper, we determined the spatial probability for k -tuple of mutually hidden nodes using the Monte Carlo simulation method. Furthermore, we analyzed the influence of co-channel interference on the error probability of IEEE 802.15.4 communication, and derived accurate analytical models by considering the non-ideal features of the used spreading sequences. The accuracy of the derived mathematical models was tested by numerical Monte Carlo simulation of the IEEE 802.15.4 communication and in a real-world experiment using IEEE 802.15.4 compliant wireless transceivers for creating co-channel interference. The presented simulation and real world experiment results show consistency with the proposed analytical error probability models.

The IEEE 802.11ad amendment to the 802.11 standard ratified in 2012 created the first multi- Gb/s Wi-Fi technology by using the large swath of unlicensed spectrum at the mm-Wave band. While enabling multi-Gb/s wireless local communications was a significant achievement, throughput and reliability requirements of new applications, such as augmented reality (AR)/virtual reality (VR) and wireless backhauling, exceed what 802.11ad can offer. For this reason, building upon IEEE 802.11ad, the IEEE 802.11 Task Group ay has recently defined new PHY and MAC specifications that enable 100 Gb/s communications through a number of technical advancements. In this article, we identify and describe the main design elements of IEEE 802.11ay, including MIMO, channel bonding, improved channel access, and enhanced beamforming training. For each of these elements, we discuss how their design is impacted by mm-Wave radio propagation characteristics and present enabling mechanisms defined in IEEE 802.11ay.

In IEEE 802.11 based wireless networks interference increases as more access points are added. A metric helping to quantize this interference seems to be of high interest. In this paper we study the relationship between the $$\textit{improved\,attacking\,case}$$ metric, which captures interference, and throughput for IEEE 802.11 based network using directional antenna. The $${y}^{1/3} = a + b\ {(\text {ln}\ x)}^{3}$$ model was found to best represent the relationship between the interference metric and the network throughput. We use this model to predict the performance of similar networks and decide the best configuration a network operator could use for planning his network.

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.

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.

Understanding the main short-range wireless technologies operating in unlicensed bands is an important step before deploying Internet of Things (IoT) applications. In this study, we have selected IEEE 802.11ah, Bluetooth Low Energy and IEEE 802.15.4 for performance comparison in terms of delay, service ratio, traffic loss, activity factor and battery lifetime in a home automation scenario. Also, a low overhead protocol stack suitable for IoT applications is considered. The analysis takes into account heterogeneous devices and different traffic loads. The results show advantages and disadvantages with respect to the different performance indicators with generally satisfactory behavior for the three technologies. Among them, BLE is recognized as the most suitable candidate technology for the home automation domain.

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

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

Several analytical models for the channel bonding feature of IEEE 802.11ac have previously been presented for performance estimation, but their accuracy has been limited by the assumptions that there are no collisions or all nodes are in saturated state. Therefore, in this letter, we develop an analytical model for the throughput performance of channel bonding in IEEE 802.11ac, considering the presence of collisions under both saturated and non-saturated traffic loads, and our numerical results were validated by a simulation study.

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.

In this Letter, we experimentally demonstrate a full-duplex transmission system of IEEE 802.11ac-compliant multiple-input multiple-output (MIMO) signals over a 2-km 7-core fiber for in-building wireless local-area network (WLAN) distributed antenna systems. For full-duplex 3 i?½ 3 MIMO demonstration, the crosstalk impacts of both fiber-transmission-only and optic-wireless transmission situation are evaluated. The results indicate that the impact of crosstalk on radio-over-fiber (ROF) link performance is not significant and the quality of the cascaded multi-core fiber and wireless channel is mainly determined by the wireless part. To further improve the system capacity, polarization multiplexing (PolMux) technology is employed to achieve a full-duplex 6 i?½ 6 MIMO over a single 7-core fiber. Although employing the PolMux method will slightly decrease the EVM and condition number performance as opposed to a non-PolMux MCF system, it is still a competitive solution in large optical connection demand scenarios that require a low cost.

With the ever-increasing range of video and audio applications in portable handheld devices, demand for high throughput in Wi-Fi networks is escalating. In this paper we introduce several novel features defined in next generation WLAN, termed as IEEE 802.11ax standard, and compare between the maximum throughputs received in IEEE 802.11ax and IEEE 802.11ac in a scenario where the AP continuously transmits to one station in the Single User mode. The comparison is done as a function of the modulation/coding schemes in use. In IEEE 802.11ax we consider two levels of frame aggregation. IEEE 802.11ax outperforms IEEE 802.11ac by about 29% and 48% in reliable and unreliable channels respectively.

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

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

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

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.

To cope with the increasing demand of multimedia applications, new IEEE 802.11 wireless local area networks devices have been defined such as IEEE 802.11aa and IEEE 802.11ac. The former proposes new intra-access categories (AC) differentiation based on stream classification service (SCS) scheme. The latter standard allows simultaneous downlink transmissions thanks to downlink multi-user MIMO technology and sharing transmission opportunity (TXOP) period scheme. In this paper, we focus on the basis of this technique and the behavior of the access point (AP) to manage the multi-user access. Then, we propose a hybrid access mechanism entitled multi-user multi-cast access mechanism (MUMAM) that supports downlink multi-user transmissions while considering intra-AC differentiation. MUMAN considers SCS scheme to prioritize between multicast and unicast flows of an AC and follows transmissions based on IEEE 802.11ac TXOP sharing technique. Extensive simulation and analysis show that MUMAM has a significant positive impact on delay and throughput performance of different AC(s).

The IEEE 802.11s wireless mesh networking standard supports power save mode where a mesh station can switch from the awake state to the doze state when there is no data to transmit. In the standard, the doze state is peer specific and has two different modes of operations—light sleep mode and deep sleep mode. This paper analytically evaluates the performance of a mesh basic service set under the operation of different power save modes, with the help of a queuing petri net modeling. The analytical model gives several insights of the power save mode operations, which are further validated using simulation results as well as results from a practical mesh networking testbed. Our analysis reveals that there exists interesting performance tradeoffs among light sleep mode and deep sleep mode, that can be explored to design an efficient power profile for mesh networks.

We have developed an analytical model for a non-saturated IEEE 802.15.6 wireless body area network (WBAN) operating under an error-prone channel. The most suitable vehicle for improving network performance was found to be the choice of access phase lengths based on traffic loads for different user priorities (UPs). It was also found that the deployment of exclusive access phase (EAP) is not necessary in a typical WBAN; in fact, short exclusive and random access phases (EAP and RAP, respectively) lead to inefficient use of available bandwidth. We have also found that four user priorities (out of the eight available) typically suffice to achieve even the most stringent requirements for WBAN 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.

Vehicular communication for accident avoidance is an important application defined in the IEEE 802.11p. One of the challenges of vehicular communications in the current IEEE 802.11p standard is the complex and rapidly changing channel conditions. In this study, the author focusses on the vehicle-to-vehicle channels under the IEEE 802.11p standard and point out that there exist two different kinds of fading. Then, a new dedicated short range communication (DSRC) system with two improved methods is proposed for the weak performance of anti-fading of current system in IEEE 802.11p environments. The author adopts matrix spectral transformation method to replace least squares algorithm in spectral temporal averaging (STA) scheme proposed by Fernandez to further mitigate the negative effects of DSRC system caused by fast time-varying fading. Meanwhile, the author also proposes a spectral keying method to further enhance its ability of anti-frequency-selective fading. The final simulation results show that compared with STA and other methods, the improved scheme shows better performance on mean square error, bit error rate and packet error rate, which is promising for practical applications.

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.

The IEEE 802.11e enhanced distributed channel access (EDCA) protocol follows class-based service differentiation for providing differentiated quality-of-service (QoS). However, its collision avoidance mechanism using backoff algorithm can be inefficient for providing improved performance with respect to throughput and channel access delay, especially in a high network configuration (i.e. number of stations) with imperfect wireless channel. The existing and emerging works have devoted considerable attention on tuning the backoff parameters for achieving optimal throughput only. The prior works do not consider the channel access delay and throughput metrics altogether for performance improvement. Additionally, in most of the cases, the optimal configuration of backoff parameters are performed by a centralized controller. In this paper, we propose a delay-aware distributed dynamic adaptation of contention window scheme, namely D2D , for the cumulative improvement of both the throughput and the channel access delay at runtime. The D2D scheme requires two ad-hoc, distributed, and easy-to-obtain estimates— delay deviation ratio and channel busyness ratio —of the present delay level and channel congestion status of the network, respectively. A key advantage of the D2D scheme is that it is compliant with the IEEE 802.11 standard, and, thus, can be seamlessly integrable with the existing wireless card. We show the integrated model of the medium access control protocol, namely D2D Channel Access ( D2DCA ), for the IEEE 802.11e networks. We further propose a two-dimensional Markov chain model of the D2DCA protocol for analyzing its theoretical performance in saturated networks with imperfect wireless channel. Theoretical comparison with the benchmark protocols establishes the effectiveness of the D2DCA protocol.

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.

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.