Emergency Packets Research Articles

Preset delay broadcast: a protocol for fast information dissemination in vehicular ad hoc networks (VANETs)

Vehicular ad hoc networks (VANETs) have been proposed in order to assist the driver on the road. There are multiple applications where VANETs are needed, for example, proposing routes to reach a given destination, cooperating for traffic management, or preventing the driver of dangers on the road. In this paper, we focus on message broadcast for driver safety. Such broadcasting must be fast and reliable such that all the vehicles in a certain area receive the message as fast as possible. There are several proposals in the literature of broadcast protocols for critical messages in VANETs. In order to get a wide view of the different techniques to broadcast a message, we evaluate a set of protocols representing one or more broadcast techniques. Moreover, we propose PDB, a preset delay broadcast protocol with a fixed delay for vehicles attempting to retransmit a warning message, which provides a fast and reliable dissemination. We show that by adequately setting the waiting time for the relay candidates, we can significantly reduce the delay to cover a given area, while at the same time preserving a good reliability. Moreover, we model different techniques to broadcast an emergency packet in a VANET such as count-based, geographical, distance-based, and opportunistic, and thus we implement a subset of state-of-the-art protocols that implement one or more of those techniques. Finally, our research shows that stopping beacon transmissions when a warning message is detected does not provide a significant performance improvement. Nonetheless, by allowing a continuous channel access, we prove that the performance of any protocol might be greatly increased.

An On-Demand Emergency Packet Transmission Scheme for Wireless Body Area Networks.

The rapid developments of sensor devices that can actively monitor human activities have given rise to a new field called wireless body area network (BAN). A BAN can manage devices in, on and around the human body. Major requirements of such a network are energy efficiency, long lifetime, low delay, security, etc. Traffic in a BAN can be scheduled (normal) or event-driven (emergency). Traditional media access control (MAC) protocols use duty cycling to improve performance. A sleep-wake up cycle is employed to save energy. However, this mechanism lacks features to handle emergency traffic in a prompt and immediate manner. To deliver an emergency packet, a node has to wait until the receiver is awake. It also suffers from overheads, such as idle listening, overhearing and control packet handshakes. An external radio-triggered wake up mechanism is proposed to handle prompt communication. It can reduce the overheads and improve the performance through an on-demand scheme. In this work, we present a simple-to-implement on-demand packet transmission scheme by taking into considerations the requirements of a BAN. The major concern is handling the event-based emergency traffic. The performance analysis of the proposed scheme is presented. The results showed significant improvements in the overall performance of a BAN compared to state-of-the-art protocols in terms of energy consumption, delay and lifetime.

An Emergency Adaptive Communication Protocol for Driver Health Monitoring in WSN Based Vehicular Environments

Driver health and activity monitoring is one of the principal design issues for the safety provision in vehicular environments. Recently, the wireless sensor network technology is widely used to address the concerns in such applications. However, only few conventional protocols have dealt with reliable and prompt delivery of emergency packets considering the vehicular specifications. In this paper, we propose an emergency adaptive communication protocol, which treats the data packet in a discriminatory manner by investigating whether it is emergency or not. Hence, the proposed protocol defines an emergency factor for each data packet and exploits it for both route establishment and channel access procedures. In route establishment, the proposed protocol chooses a route with low delay and high reliability among the candidates by periodic calculation of emergency factor. Then, it dynamically adjusts back-off parameters before participating in the channel contention among the neighbors. In addition, an emergency aware queue management scheme and packet drop policy are proposed to improve the reliability of emergency data traffic during transmission. Our simulation results show that the proposed protocol provides a better performance compared with the existing protocol in terms of packet delivery ratio, end-to-end packet delay, and number of dropped packets.

Disaster Preparedness and Awareness of Patients on Hemodialysis after Hurricane Sandy.

Patients with ESRD on dialysis live in a complex sociomedical situation and are dependent on technology and infrastructure, such as transportation, electricity, and water, to sustain their lives. Interruptions of this infrastructure by natural disasters can result in devastating outcomes. Between November of 2013 and April of 2014, a cross-sectional survey was conducted of patients who received maintenance hemodialysis before and after the landfall of Hurricane Sandy on October 29, 2012 in lower Manhattan, New York. The primary outcome was the number of missed dialysis sessions after the storm. Dialysis-specific and general disaster preparedness were assessed using checklists prepared by the National Kidney Foundation and US Homeland Security, respectively. In total, 598 patients were approached, and 357 (59.7%) patients completed the survey. Participants were 60.2% men and 30.0% black, with a median age of 60 years old; 94 (26.3%) participants missed dialysis (median of two sessions [quartile 1 to quartile 3 =1-3]), and 236 (66.1%) participants received dialysis at nonregular dialysis unit(s): 209 (58.5%) at affiliated dialysis unit(s) and 27 (7.6%) at emergency rooms. The percentages of participants who carried their insurance information and detailed medication list were 75.9% and 44.3%, respectively. Enhancement of the dialysis emergency packet after the hurricane was associated with a significantly higher cache of medical records at home at follow-up survey (P<0.001, Fisher's exact test). Multivariate Poisson regression analysis showed that dialysis-specific preparedness (incidence rate ratio, 0.91; 95% confidence interval, 0.87 to 0.98), other racial ethnicity (incidence rate ratio, 0.34; 95% confidence interval, 0.20 to 0.57), dialysis treatment in affiliated units (incidence rate ratio, 0.69; 95% confidence interval, 0.51 to 0.94), and older age (incidence rate ratio, 0.98; 95% confidence interval, 0.97 to 0.99) were associated with a significantly lower incidence rate ratio of missed dialysis. There is still room to improve the preparedness for natural disasters of patients with ESRD. Provider- or facility-oriented enhancement of awareness of the disease and preparedness should be a priority.

A novel energy efficient MAC protocol for Wireless Body Area Network

Wireless Body Area Network (WBAN) is the most promising technology in e-health applications. Energy efficiency stands out as the paramount issue for WBAN. In this paper, an energy efficient MAC protocol named Quasi-Sleep-Preempt-Supported (QS-PS) is proposed. The protocol is mainly TDMA-based: nodes transmit packets in the allocated slots, while entering the Q-Sleep mode in other slots. Moreover, for a node with emergency packet, it can broadcast a special designed Awakening Message to wake up the whole network and preempts the right to use the current slot to transmit that emergency packet, thus decreasing delay. Compared with relevant protocols, QS-PS can achieve high energy efficiency and decrease the delay of both normal packets and emergency packets.

A hybrid MAC protocol for emergency response wireless sensor networks

We introduce ER-MAC, a novel hybrid MAC protocol for emergency response wireless sensor networks. It tackles the most important emergency response requirements, such as autonomous switching from energy-efficient normal monitoring to emergency monitoring to cope with heavy traffic, robust adaptation to changes in the topology, packet prioritisation and fairness support. ER-MAC is designed as a hybrid of the TDMA and CSMA approaches, giving it the flexibility to adapt to traffic and topology changes. It adopts a TDMA approach to schedule collision-free slots. Nodes wake up for their scheduled slots, but otherwise switch into power-saving sleep mode. When an emergency occurs, nodes that participate in the emergency monitoring change their MAC behaviour by allowing contention in TDMA slots to achieve high delivery ratio and low latency. In its operation, ER-MAC prioritises high priority packets and sacrifices the delivery ratio and latency of the low priority ones. ER-MAC also guarantees fairness over the packets’ sources and offers a synchronised and loose slot structure to allow nodes to join or leave the network. Simulations in ns-2 show the superiority of ER-MAC over Z-MAC, a state-of-the art hybrid MAC protocol, with higher delivery ratio, lower latency, and lower energy consumption. When a cluster of nodes in the network detects fire, nodes with ER-MAC deliver twice as many high priority emergency packets and four times faster than Z-MAC. This is achieved by ER-MAC with only one fifth as much energy as Z-MAC.

A New Emergency Handling Mechanism based on IEEE 802.15.4 for Health Monitoring Applications

The recent advances in wireless communication systems and semiconductor technologies are paving the way for new applications over wireless sensor networks. Health-monitoring application (HMA) is one such emerging technology that is focused on sensing and reporting human vital signs through the communication network comprising sensor devices in the vicinity of the human body. The sensed vital signs can be divided into two categories based on the importance and the frequency of occurrence: occasional emergency signs and regular normal signs. The occasional emergency signs are critical, so they have to be delivered by the specified deadlines, whereas the regular normal signs are non-critical and are only required to be delivered with best effort. Handling the occasional emergency sign is one of the most important attributes in HMA because a human life may depend on correct handling of the situation. That is why the underlying network protocol suite for HMA should ensure that the emergency signs will be reported in a timelymanner. However, HMA based on IEEE 802.15.4 might not be able to do so owing to the lack of an appropriate emergency-handling mechanism. Hence, in this paper, we propose a new emergency-handling mechanism to reduce the emergency reporting delay in IEEE 802.15.4 through the modified superframe structure. A fraction of an inactive period is modified into three new periods called the emergency reporting period, emergency beacon period, and emergency transmission period, which are used opportunistically only for immediate emergency reporting and reliable data transmission. Extensive simulation is performed to evaluate the performance of the proposed scheme. The results reveal that the proposed scheme achieves improved latency and higher emergency packets delivery ratio compared with the conventional IEEE 802.15.4 MAC.

An emergency packet forwarding scheme for V2V communication networks.

This paper proposes an effective warning message forwarding scheme for cooperative collision avoidance. In an emergency situation, an emergency-detecting vehicle warns the neighbor vehicles via an emergency warning message. Since the transmission range is limited, the warning message is broadcast in a multihop manner. Broadcast packets lead two challenges to forward the warning message in the vehicular network: redundancy of warning messages and competition with nonemergency transmissions. In this paper, we study and address the two major challenges to achieve low latency in delivery of the warning message. To reduce the intervehicle latency and end-to-end latency, which cause chain collisions, we propose a two-way intelligent broadcasting method with an adaptable distance-dependent backoff algorithm. Considering locations of vehicles, the proposed algorithm controls the broadcast of a warning message to reduce redundant EWM messages and adaptively chooses the contention window to compete with nonemergency transmission. Via simulations, we show that our proposed algorithm reduces the probability of rear-end crashes by 70% compared to previous algorithms by reducing the intervehicle delay. We also show that the end-to-end propagation delay of the warning message is reduced by 55%.

An evolutionary computation approach for optimizing connectivity in disaster response scenarios

This article presents an evolutionary computation approach for increasing connectivity in disaster scenarios. Connectivity is considered to be of critical importance in disaster scenarios due to constrained and mobile conditions. We propose the deployment of a number of auxiliary static nodes whose purpose is to increase the reachability of broadcast emergency packets among the nodes which are participating in the disaster scenario. These nodes represent people and vehicles acting in rescue operations. The main goal is to find the optimum positions for the auxiliary nodes, reinforcing the communications in points where certain lack of connectivity is found. These points will depend on the movements of the rescue teams, which are influenced by tactical reasons. Due to the complexity of the problem and the number of parameters to be considered, a genetic algorithm combined with the network simulator NS-2 is proposed to find the optimum positions of the auxiliary nodes. Specifically, NS-2 is used to model the communication layers and provide the fitness function guiding the genetic search. The proposed approach has been tested using the disaster mobility model included in the motion generator BonnMotion. The simulation results obtained demonstrate the feasibility of the proposed approach and illustrate its applicability in other scenarios where lack of connectivity is evident.

McMAC: towards a MAC protocol with multi-constrained QoS provisioning for diverse traffic in Wireless Body Area Networks.

The emergence of heterogeneous applications with diverse requirements for resource-constrained Wireless Body Area Networks (WBANs) poses significant challenges for provisioning Quality of Service (QoS) with multi-constraints (delay and reliability) while preserving energy efficiency. To address such challenges, this paper proposes McMAC, a MAC protocol with multi-constrained QoS provisioning for diverse traffic classes in WBANs. McMAC classifies traffic based on their multi-constrained QoS demands and introduces a novel superframe structure based on the “transmit-whenever-appropriate” principle, which allows diverse periods for diverse traffic classes according to their respective QoS requirements. Furthermore, a novel emergency packet handling mechanism is proposed to ensure packet delivery with the least possible delay and the highest reliability. McMAC is also modeled analytically, and extensive simulations were performed to evaluate its performance. The results reveal that McMAC achieves the desired delay and reliability guarantee according to the requirements of a particular traffic class while achieving energy efficiency.

A Distributed MAC Scheme for Emergency Message Dissemination in Vehicular Ad Hoc Networks

The successful dissemination of emergency messages in vehicular ad hoc networks can make a difference between life and death. To achieve the life-saving goals, emergency message dissemination needs timely and lossless medium access in vehicular ad hoc networks. Although there are existing medium access control (MAC) protocols that support priority medium access in the literature, these protocols focus on providing statistical priority for unicast flows instead of strict priority for individual packets. This paper proposes a new MAC scheme to address this issue. With its novel pulse-based control mechanism, the proposed MAC scheme realizes strict packet-level priority scheduling for emergency packets in a fully distributed way. With the same mechanism, the proposed scheme supports multiple levels of strict priority for emergency packets. The comprehensive simulation results in this paper show the effectiveness of the proposed MAC scheme in serving emergency messages in vehicular ad hoc networks.

Proposal of an Assured Corridor Mechanism for Urgent Information Transmission in Wireless Sensor Networks

Wireless sensor networks are expected to play an essential role as a social infrastructure to realize our safe and secure living environment. In such a network, critical information must be transmitted faster and more reliably than other information. We propose a distributed transmission mechanism which enables emergency packets to be carried with high reliability and low latency along a preferential path, which is called an corridor. In this self-organizing assured corridor mechanism (ACM), which works above the network layer and does not depend on any specific routing or MAC protocol, a corridor is gradually established as the first packet containing urgent information propagates to the base station. The nodes surrounding the corridor suppress the transmission of non-urgent information and nodes in the corridor are kept awake to forward emergency packets. ACM avoids packet loss and possible delay caused by collisions in the wireless transmission and normal sleep scheduling. An acknowledgment and retransmission scheme is incorporated into ACM in order to improve reliability of transmission of urgent information. Simulation experiments showed that, when only one node transmitted urgent information, the retransmission contributed to establish a corridor quickly and that ACM improved the delivery ratio and the delay of the urgent information transmission once a corridor is established. It was proved that ACM was effective to improve the reliability and the latency of urgent information as well in the cases where multiple nodes sent urgent information at once.

Design and analysis of multi-level active queue management mechanisms for emergency traffic

Multiple average-multiple threshold (MAMT) active queue management (AQM) is proposed as a solution for providing available and dependable service to traffic from emergency users after disasters. MAMT is a simple but effective approach that can be applied at strategic network locations, where heavy congestion is anticipated. It can provide low loss to emergency packets while dropping non-emergency packets only as much as necessary. Fluid flow analysis and simulation is conducted to provide guidelines for proper MAMT design, especially regarding the queue size and averaging parameters that are most important. This work considers non-responsive traffic exclusively, since non-responsive traffic types are currently getting the most attention from emergency management organizations. Plus, very little work has been performed regarding AQM and non-responsive traffic. It demonstrates queue oscillation problems that previously may have been attributed to the interactions between TCP and AQM, but which are actually inherent to AQM and can be greatly reduced with proper parameter settings. MAMT is shown to perform well over a range of loads and can effectively protect emergency traffic from surges in non-emergency traffic.