Beacon-enabled Mode Research Articles

A new highly efficient MAC protocol for WBAN: exceptional performance in the face of selfish behaviors

Over the last two decades, wireless body area networks (WBANs) have gained significant traction in healthcare applications. These networks facilitate connections among various sensors, which can be integrated into clothing, placed directly on the body, or implanted beneath the skin. While these sensors typically serve a single application, they generate traffic with diverse requirements. Managing this diversity necessitates tailored treatment to meet specific traffic needs while satisfying application requirements such as reliability and timeliness. In this paper, we propose a novel, flexible, and power-efficient medium access control (MAC) protocol designed to seamlessly complement existing solutions. Our protocol, available in two versions as an enhancement to the beacon-enabled mode of IEEE 802.15.4, aims to optimize quality of service (QoS) for periodic traffic applications within WBANs, irrespective of traffic and density conditions, without compromising energy efficiency. Our results demonstrate significant improvements compared to the standardized IEEE 802.15.4-MAC protocol across all test scenarios, even in the presence of selfish behaviors. These findings underscore the protocol’s efficacy in enhancing reliability and efficiency in wireless healthcare systems.

Artificial vision wireless PV system to efficiently track the MPP under partial shading

The solar photovoltaic industry is booming and the achievement of high efficiency in this kind of systems is crucial. Partial shading conditions complicate the search of the maximum power point (MPP) of the installations due to the existence of multiple peaks in the P-V curve. In addition, these photovoltaic (PV) systems require monitoring and control in real-time to guarantee the correct operation. Thus, this paper proposes a novel system to track the maximum power point through artificial vision, under partial shading conditions controlled and monitored by a wireless sensor network based on IEEE 802.15.4 technology. The infrastructure consists of a wireless distributed photovoltaic system (WDPS) where the power converter is connected to a sensor node that sends the information to the coordinator node. The coordinator node is connected to a webcam and a Raspberry Pi. This part of the system is called wireless webcam centralized control (WWCC) and is responsible for processing the sensors information and the images. Besides, the WWCC sends the control signal. The wireless communication is set in beacon-enabled mode allowing synchronization between the sensor nodes and the coordinator node. Moreover, the guaranteed time slot mechanism provides the correct transmission of data with low latency, ensuring the stability of the controller. Experimental tests have been carried out to validate the artificial vision wireless PV system. The results prove an appropriate operation, achieving an MPP tracking higher than 99%, even in partial shading conditions.

Rational Allocation of Guaranteed Time Slots to Support Real-Time Traffic in Wireless Body Area Networks

Background: The main requirement of Wireless Body Area Network (WBAN) is on-time delivery of vital signs that are sensed through the delay-sensitive biological sensors that are implanted in the body of the patient being monitored by the central gateway. The Medium Access Control (MAC) protocol standard IEEE 802.15.4 supports real-time data delivery through its unique feature called Guaranteed Time Slot (GTS) under its beacon-enabled mode. This protocol is considered suitable for the WBAN Scenario. However, as per the standard, IEEE 802.15.4 uses a simple and straightforward First Come First Served (FCFS) mechanism to distribute GTS slots among the contender nodes. This kind of blindfolded allocation of GTS slots results in poor utilization of bandwidth and also prevents the delay-sensitive sensor nodes from effectively utilizing the contention-free slots. Objective: The main objective of this work is to provide a solution for the unfair allocation of GTS slots in the beacon-enabled mode of the IEEE 802.15.4 standard in WBAN. Method: We propose a Rational Allocation of Guaranteed Time Slot (RAGTS) protocol that distributes the available GTS slots based on the delay-sensitivity of the contender nodes. Results: A series of simulation experiments has been performed to assess the performance of our proposed RAGTS protocol. The simulations capture the dynamic nature of the real-time deadlines associated with sensor traffic. Through simulations, we show that our proposed RAGTS protocol appears to be more stable in terms of various performance metrics than that of the FCFS nature of the GTS allocation technique. Conclusion: In this article, we introduced the RAGTS scheme that enhances the real-time traffic feature of the beacon-enabled mode of IEEE 802.15.4 MAC.

A Novel Energy-Safe Algorithm for Enhancing the Battery Life for IoT Sensors’ Applications

Energy safe is mandatory for all isolated IoT tools, such as in long way roads, mountains, or even in smart cities. If increasing the lifetime of these tools, the rentability of the global network loop becomes more efficient. Therefore, this paper presents a new approach for saving energy inside the source nodes by supervising the state of energy inside each source node and calculating the duty cycle factor. The relationship between these parameters is based on an optimization problem formulation. In this respect, the present paper is designed to propose a new approach that deals with increasing the lifetime of the wireless sensor network (WSN)-attached nodes, as fixed in the application. The newly devised design is based on implementing the IEEE 802.15.4 standard beacon-enabled mode, involving a cluster tree topology. Accordingly, every subgroup is allotted to apply a specifically different duty cycle, depending on the battery’s remaining energy level, which contributes to creating a wide range of functional modes. Hence, various thresholds are defined. Simulation results prove the efficiency of the proposed approach and show the energetic benefit. The proposed flowchart has minimized the consumed energy for the WSN, which improves the battery lifetime and enhances the IoT application’s robustness. Simulations and experiments have been carried out under different conditions and the results prove that the proposed method is a viable solution.

PERFORMANCE EVALUATION OF DATA TRANSPORT OVER DIFFERENT-NODE DENSITY OF ZIGBEE SENSOR NETWORK – AN OPNET SIMULATION STUDY

In this paper, we analyze the performance of different node density of Wireless Sensor Network (WSN) operating under the IEEE Standard 802.15.4 in the beacon-enabled mode. The motivation for evaluating the beacon-enabled mode is due to its flexibility for WSN applications as compared to the non-beacon enabled mode. The analysis is based on an accurate OPNET simulation model which supports slotted Carrier Sense Multiple Access Mechanism with Collision Avoidance (CSMA/CA) mechanism and Guaranteed Time Slot (GTS). The performance of the slotted CSMA/CA sensor network is evaluated and analyzed for different network settings to understand the impact of the protocol attributes, including super-frame order (SO), beacon order (BO), data packet size and maximum back-off number. Through the simulation results, high SO provides better network throughput, otherwise results in lower average latency. We also found that the MAC overheads on small MAC Service Data Unit (MSDU) are more significant than the overheads on large MSDU. And the back-off mechanism results in longer delays when the network traffic is heavy.

A robust guaranteed time slots allotment scheme for real-time and reliable communication in WBANs

The ever-increasing aging population and expenditure related to healthcare, consequently demand the requirement for a state-of-the-art healthcare system. Wireless body area networks (WBANs) are the potential contender for this requirement. The IEEE 802.15.4 standard is considered a suitable protocol for WBANs and its beacon-enabled mode supports real-time traffic through guaranteed time slots (GTS) feature. Nevertheless, it suffers from reliability and timeliness guarantees. To address this issue, this work advocates a robust guaranteed time slots allotment scheme (RGAS) that consists of two phases, viz.: 1) determination of the severity of sensor data using fuzzy inference system; 2) dynamic allocation of available GTS slots to the contending nodes. Through simulation results, we demonstrate that the proposed RGAS significantly outperforms the existing GTS mechanism specified in the IEEE 802.15.4 in terms of various performance metrics such as packets transmission, packet reception rate, packet loss rate, and effective utilisation of contention free period.

A robust guaranteed time slots allotment scheme for real-time and reliable communication in WBANs

The ever-increasing aging population and expenditure related to healthcare, consequently demand the requirement for a state-of-the-art healthcare system. Wireless body area networks (WBANs) are the potential contender for this requirement. The IEEE 802.15.4 standard is considered a suitable protocol for WBANs and its beacon-enabled mode supports real-time traffic through guaranteed time slots (GTS) feature. Nevertheless, it suffers from reliability and timeliness guarantees. To address this issue, this work advocates a robust guaranteed time slots allotment scheme (RGAS) that consists of two phases, viz.: 1) determination of the severity of sensor data using fuzzy inference system; 2) dynamic allocation of available GTS slots to the contending nodes. Through simulation results, we demonstrate that the proposed RGAS significantly outperforms the existing GTS mechanism specified in the IEEE 802.15.4 in terms of various performance metrics such as packets transmission, packet reception rate, packet loss rate, and effective utilisation of contention free period.

Multi-Sensor Based MK/HyperK/1/M Queuing Model for Heterogeneous Traffic

Integration of wireless sensor networks (WSNs) with Internet of Things (IoT) has given rise to applications such as Smart Home Networks, Vehicular Ad hoc Sensor Networks and Health and Wellness Wireless Sensor Networks among others. These applications tend to use multi-sensor nodes that have multiple sensors mounted on a single radio board and may require handling heterogeneous traffic. Modern WSNs are therefore no longer homogeneous in nature and have different quality of service (QoS) requirements. Modeling the performance of heterogeneous data is a challenging task owing to the complexity involved. In this paper we propose a MK/HyperK/1/M queuing model for multi-sensor nodes. Queues with Poisson arrivals and hyper-exponentially distributed service time and their applications have been widely discussed in literature however hardly any work can be found that uses them for modeling WSNs. In this paper we consider that the traffic from multi-sensor node is emanating from different sensor types within the node and is hence heterogeneous. The model captures the impact of varying arrival rates, mean packet lengths, buffer size and duty cycle on throughput. The model can be used with any duty cycle-based medium access control (MAC) protocols for WSNs. To test the model we apply it to IEEE 802.15.4 in beacon-enabled mode with star topology. Analytical results are corroborated by ns-2.35 simulations. Results indicate that the heterogeneity of traffic has a significant impact on the throughput and this may be useful in improving the QoS of applications.

On the issues of selective jamming in IEEE 802.15.4-based wireless body area networks

The beacon-enabled mode of IEEE 802.15.4 provides a Time Division Multiple Access (TDMA) method for low power devices by adopting Guaranteed Time Slots (GTS). GTS communication is a potential target for selective jammers where they perform GTS attacks. In GTS attacks, the adversary selectively picks one of the reserved device slots to corrupt its incoming communication. Considering countermeasures, most existing solutions rely on slot position randomization to distribute the harm of the attack over the other GTS slots. These solutions may be effective in the case of full-slot jamming. However, the introduced GTS attacks consider only TDMA property of GTS communication and ignore other important properties like the protocol behavior and the superframe structure effect on the traffic. Considering these properties while performing GTS attacks exempts the adversary from full-slot jamming and renders the existing solutions with no effect. In this paper, we introduce a new efficient version of GTS attacks that benefits from both the standard behavior and the superframe effect on the periodic traffic to conserve the adversary’s resources for the longest period. Additionally, we provide a solution specially developed to mitigate the harm from this detrimental attack. From extensive simulations conducted in this work, it follows that the attack is economic in terms of jamming duration and jamming packets ratio and the solution is efficient in terms of packet delivery ratio, energy consumption and delay overhead.

LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15.4 Cluster-Tree-Based IoT Applications

The IEEE 802.15.4 standard is one of the most widely used link layer technology for building Internet of Things (IoT). It specifies several physical layer options and MAC layer for meeting low-power and low-rate requirements of devices deployed in a network of IoT. The standard also specifies a synchronization scheme for devices connected in a star topology, operating in beacon-enabled (BE) mode using periodic beacons. The BE mode facilitates synchronization among devices for data transmission and is suitable for large networks to establish low duty-cycles. Absence of a such a scheme for a cluster-tree network has confined its application only to nonbeacon mode. The challenge here is to schedule beacon frame transmissions of multiple devices in a nonoverlapping manner to avoid beacon collisions. This paper tackles the problem of synchronization by proposing localized beacon synchronization (LBS) scheme, a distributed technique for beacon scheduling in cluster-tree network topologies. LBS uses 2-hop information and association order to compute beacon transmission offsets that better utilize the available time slots, incur fewer transmissions, and is highly scalable. Further, we analytically show that the schedulability of the proposed scheme is higher compared to other related schemes. In addition, we also address the important issue of resynchronization that has been ignored in all of the prior works. The proposed resynchronization mechanisms consider the interdependencies between synchronization and duty-cycling schemes and are shown to significantly lower the synchronization overhead when synchronization among devices is lost.

Single CCA for IEEE 802.15.4 networks: a cross layer energy model

For data frame transmissions in beacon-enabled mode, an IEEE 802.15.4 node performs two consecutive clear channel assessments (CCAs) to sense the channel after back off. Here, the authors study what would happen if the medium access control (MAC) layer performs only one CCA instead. Although it is apparent that the frame transmission cycle would be shortened with single CCA, it is not straightforward to assess the effect of single CCA on the overall transmission energy. A Markov chain-based MAC operation model is therefore constructed to analyse single-CCA-based MAC layer parameters. A combined physical (PHY) and MAC layer energy model is formulated next. It was found that the single CCA-based MAC outperforms its standard double CCA-based counterpart from the energy efficiency perspective.

A multimode and multithreshold approach for energy efficiency in Internet of things systems

The IEEE 802.15.4 is designed for wireless personal area networks. Indeed, wireless personal area network turns out to help greatly in maintaining a flexible mode of communication within limited area networks. It is in this context that our present study can be set, in which the beacon-enabled mode is enabled with cluster tree topology to reach the scope of a rather extended network, whereby the network turns out to be clustered into several subgroups. Every single subgroup is characterized by its specific duty cycle which is configured by its correspondent personal area network coordinator. Therefore, many modes are enabled in the same network. Based on a very special mathematical model developed by us for energy consumption, the personal area network coordinator detects the actual level of energy in the battery of node. Then, an interesting comparison is made with the multiple thresholds which are already set. After that, both beacon order and superframe order (the standard IEEE 802.15.4 parameters) are recomputed with reference to the remaining energy.

Study of Adjustment Delay Scheme on IEEE 802.15.4 Networks at Beacon Enabled Mode

In the contention mechanism used to slotted carrier sense multiple access with collision avoidance (CSMA/CA) on IEEE 802.15.4 standard. Device nodes will perform a backoff process as soon as the clear channel assessment (CCA) detects as busy condition. The challenge of CSMA/CA as following: first, when the device nodes detect the channel in busy condition, the device nodes have to increase the value of backoff exponent (BE) which cause range of blind backoff process also increase. Second, when the device nodes detect the channel in busy condition, the device nodes have to increase number of backoff stage which cause more energy consumptions for entering next backoff stage. This article proposes a scheme to improve IEEE 802.15.4 medium access control, called adjustment delay scheme (ADES). ADES not only reduce probability of collision but also reduce probability of going to next backoff stage. The validity of study is proven by simulation experiments. ADES performs better than IEEE 802.15.4 standard in term of the probability of successful packet transmission, network goodput, bandwidth utilization as well as energy consumption in the networks.

Behavioral Model of IEEE 802.15.4 Beacon-Enabled Mode Based on Colored Petri Net

The IEEE 802.15.4 standard is widely employed in power-constrained scenarios, such as Wireless Sensor Networks deployments. Therefore, modeling this standard is useful to predict network performance and fine-tune parameter settings. Previous work rely on determining all reachable network states, usually by a Markov chain, which is often complex and error prone. In contrast, we provide a novel behavioral approach to the IEEE 802.15.4 modeling, which covers the literature gap in assessing all metrics of interest, modeling asymmetric traffic condition and fully comprising the beacon-enabled mode. In addition, it is possible to test different values for the parameters of the standard, such as aMaxFrameRetries, macMaxCSMABackoffs, initialCW, and aUnitBackoffPeriod. The model was validated by NS2 simulations and by a testbed composed of telosB motes.

A Wireless Sensor System for Real-Time Monitoring and Fault Detection of Motor Arrays.

This paper presents a wireless fault detection system for industrial motors that combines vibration, motor current and temperature analysis, thus improving the detection of mechanical faults. The design also considers the time of detection and further possible actions, which are also important for the early detection of possible malfunctions, and thus for avoiding irreversible damage to the motor. The remote motor condition monitoring is implemented through a wireless sensor network (WSN) based on the IEEE 802.15.4 standard. The deployed network uses the beacon-enabled mode to synchronize several sensor nodes with the coordinator node, and the guaranteed time slot mechanism provides data monitoring with a predetermined latency. A graphic user interface offers remote access to motor conditions and real-time monitoring of several parameters. The developed wireless sensor node exhibits very low power consumption since it has been optimized both in terms of hardware and software. The result is a low cost, highly reliable and compact design, achieving a high degree of autonomy of more than two years with just one 3.3 V/2600 mAh battery. Laboratory and field tests confirm the feasibility of the wireless system.

Two-Hop Relay-Assisted Cooperative Communication in Wireless Body Area Networks

The pervasive use of wireless body area networks (BANs) has incurred potential inter-BAN interference, which can cause severe performance degradation. In this article, the coexistence of BANs is experimentally performed. A relay-assisted cooperative communications scheme is implemented in a real IEEE 802.15.4-based BAN system with a beacon-enabled mode and guaranteed time slot (GTS) scheduling. As far as we know, it is the first experimental work that enables real-time investigation of the effectiveness of cooperative communications in BANs for co-channel radio interference mitigation. First- and second-order statistics, including outage probability, level crossing rate (LCR), and average fade/nonfade duration, are calculated from the measured effective channel gains of the device-to-coordinator links across all superframes. Empirical results demonstrate significant advantages of using two-hop relay-assisted communications over traditional star topology BAN. Advantages include a maximum of a 10dB increase in channel gain threshold at an outage probability of 10%, which corresponds to a guideline for a 10% maximum packet error rate as specified in the IEEE BAN standard; a reduction in the level crossing rate by a factor of 5 at a channel gain threshold of − 100dB; and an average nonfade duration prolonged by a factor of 5 at the same threshold.

TDMA-Based IEEE 802.15.4 for Low-Latency Deterministic Control 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.

English

The personal area network (PAN) coordinator can assign a guaranteed time slot (GTS) to allocate a particular duration for requested devices in IEEE 802.15.4 beacon-enabled mode. The main challenge in the GTS mechanism is how to let the PAN coordinator allocate time slot duration for the devices which request a GTS. If the allocated devices use the GTS partially or the traffic pattern is not suitable, wasted bandwidth will increase, which degrades the performance of the network. In order to overcome the abovementioned problem, this paper proposes the Partitioned GTS Allocation Scheme (PEGAS) for IEEE 802.15.4 networks. PEGAS aims to decide the precise moment for the starting time, the end, and the length of the GTS allocation for requested devices taking into account the values of the superframe order, superframe duration, data packet length, and arrival data packet rate. Our simulation results showed that the proposed mechanism outperforms the IEEE 802.15.4 standard in terms of the total number of transmitted packets, throughput, energy efficiency, latency, bandwidth utilization, and contention access period (CAP) length ratio.

Power consumption analysis of priority-based service differentiation scheme for LR-WPANs

ABSTRACTIn this paper, we investigate the effect of service differentiation on the power consumption in contention period of IEEE 802.15.4 sensor networks. Power consumption is analysed for two different service differentiation schemes under non-saturation condition. The two service differentiation schemes are the differentiation by the backoff exponent (BED) and differentiation by the contention window (CWD), which provide multilevel differentiated services in beacon-enabled mode with slotted carrier sense multiple access/collision avoidance (CSMA/CA) algorithm. The analysis is based on the stationary probabilities of a discrete-time Markov chain, which is a model of CSMA/CA describing the state of a head packet of a device. Numerical results show that CWD uses the power more efficiently and performs better in terms of throughput, while BED more differentiates the service.

GreenNet: An Energy-Harvesting IP-Enabled Wireless Sensor Network

This paper presents G reen N et , an energy efficient and fully operational protocol stack for IP-enabled wireless sensor networks based on the IEEE 802.15.4 beacon-enabled mode. The stack runs on a hardware platform with photovoltaic cell energy harvesting developed by STMicroelectronics (STM) that can operate autonomously for long periods of time. G reen N et integrates several standard mechanisms and enhances existing protocols, which results in an operational platform with the performance beyond the current state of the art. In particular, it includes the IEEE 802.15.4 beacon-enabled medium access control (MAC) integrated with lightweight IP routing for achieving very low duty cycles. It offers an advanced discovery scheme that accelerates the process of joining the network and proposes an adaptation scheme for adjusting the duty cycle of harvested nodes to the available energy for increased performance. Finally, it supports security at two levels: a basic standard secure operation at the link layer and advanced scalable data payload security. This paper describes all techniques and mechanisms for saving energy and operating at very low duty cycles. It also provides an evaluation of the performance and energy consumption of G reen N et .