Accidents are becoming more common with the number of roads and automobiles. This risk doubles in bad weather due to fog and poor visibility. It is vital to rapidly warn drivers of approaching cars and the operation center (OC) if an accident happens, especially in adverse weather. This paper proposes an accident alert light and sound (AALS) system for accident detection and alarms in all types of automobiles. Rather than equipping each car with a separate system, the purpose of this research is to develop smart roads (SRs). This research is based on infrared, smoke, and other sensors which are integrated as a single unit and installed on roads. These sensors are used in the construction of SRs to detect accidents and sent their information immediately to approaching vehicles and OC.

In VANET, each vehicle near an event location actively collects and disseminates critical event information to adjacent vehicles. Most of the existing message trustworthiness schemes are not suitable for VANET. In this paper, we propose an efficient message trustworthiness scheme to disseminate trustworthy event messages in a timely manner in VANET. We compare our scheme with the Waze in a qualitative way and explain the main advantages of our scheme compared to the Waze.

Vehicular ad hoc networks (VANETs) have been studied intensively due to their wide variety of applications and services, such as passenger safety, enhanced traffic efficiency, and infotainment. With the evolution of technology and sudden growth in the number of smart vehicles, traditional VANETs face several technical challenges in deployment and management due to less flexibility, scalability, poor connectivity, and inadequate intelligence. Cloud computing is considered a way to satisfy these requirements in VANETs. However, next‐generation VANETs will have special requirements of autonomous vehicles with high mobility, low latency, real‐time applications, and connectivity, which may not be resolved by conventional cloud computing. Hence, merging of fog computing with the conventional cloud for VANETs is discussed as a potential solution for several issues in current and future VANETs. In addition, fog computing can be enhanced by integrating Software‐Defined Network (SDN), which provides flexibility, programmability, and global knowledge of the network. We present two example scenarios for timely dissemination of safety messages in future VANETs based on fog and a combination of fog and SDN. We also explained the issues that need to be resolved for the deployment of three different cloud‐based approaches.

One of the challenging issues in wireless network is rogue access point (RAP) detection and mitigation. The authors propose a new access point (AP) selection mechanism to keep wireless users from RAPs. A centralised server called AP registration centre (APRC) maintains a list of authorised APs, and a wireless user can check if a specific AP is legitimate by querying APRC about its legitimacy in a secure way using the concept of voting and signal strength‐based authentication. The authors compare their scheme with a timing‐based scheme and the experiment results show that our scheme detects RAPs accurately with lower false positives and false negatives.

A preplanned path-protection scheme with sufficient spare bandwidth is appropriate for real-time fault restoration in multiprotocol label switching (MPLS) networks. In this case, however, it is important to reduce the amount of spare bandwidth to prevent degradation of network efficiency. A distributed label switched path (D-LSP) scheme is proposed to reduce the amount of spare bandwidth required for protecting against network faults in MPLS networks. The main idea of the proposed D-LSP scheme is to partition traffic into multiple LSPs, each of which is established on a distinct link-disjoint route between each pair of end nodes. The D-LSP scheme is evaluated in terms of the reduction ratio of total network cost in comparison with the conventional LSP scheme. Traffic partitioning in the D-LSP scheme can decrease the statistical multiplexing gain (SMG) obtained by aggregating IP packet flows into an LSP. The tradeoff between spare bandwidth reduction and degradation of SMG due to traffic partitioning is also investigated. The numerical results show that the proposed D-LSP scheme yields the network cost-reduction ratio (NCRR) of at least 29%, 27%, and 15% for the networks where average node degrees are 4.6, 4.4, and 3.2, respectively. The D-LSP scheme shows the similar performance of NCRR in both Markovian traffic and self-similar traffic environments.

Spare bandwidth is required for recovering the network service from network faults. However, it degrades the efficiency of network utilization. Spare bandwidth demand can be reduced significantly by letting spare bandwidth be shared among several network services. Spare bandwidth reserved on a network element can be shared by a set of network services for a network fault if they are not simultaneously affected by the network fault. A new, and more practical spare bandwidth sharing scheme, which is based on the network reliability, is proposed in this paper. In the proposed scheme, multiple link failures are allowed with a given link failure rate, and a reasonable restoration level of near 100%; while in the conventional scheme, only a single link failure, and 100% restoration level are considered. To develop the spare bandwidth sharing scheme, we first investigate the framework for evaluating the reliability of path-based network services, and then we explain the proposed spare bandwidth sharing scheme with decision parameters such as lifetime of the path, restoration level, and the maximum number of working paths which can be protected by a backup link. Simulation results show that the proposed spare bandwidth sharing scheme requires a smaller amount of spare bandwidth than the conventional scheme.

The paper is concerned with estimating the available bandwidth of a network path. We first develop a theory to estimate the available bandwidth of a queueing system. In order to estimate the available bandwidth, we propose a probing method, called a minimal backlogging method, and a statistic based on the service rate of minimally backlogging probing traffic. We show that the available bandwidth of a queueing system can be estimated by the statistic if probing packets are sent to the queueing system by the minimal backlogging method. For a network path consisting of multiple hops, we extend the approach for a single server by introducing a simplified path model. Since the proposed mechanism can estimate the available bandwidth quickly and track it adaptively, a reasonable range of available bandwidth for a short time interval can be obtained using the mean and variance of the estimated available bandwidth. The performance of the proposed available bandwidth estimation mechanism is evaluated by simulation in a multiple hop network topology.

Rapid growth of Internet traffic causes a new challenge in the design of high-speed switches. One of main design issues for high-speed switches is a scalability problem. This paper proposes a scalable crossbar matrix (SCM) switch architecture, which consists of multiple crossbar switch units (XSU) with virtual output queues (VOQs) at the inputs and single-cell scheduling decomposition buffers (SDBs) at the outputs. We propose a distributed scheduling algorithm for the proposed scalable crossbar switch architecture, which consists of a credit based SLIP (C-SLIP) scheduling for crossbar switch units and backlog weighted round robin (BWRR) scheduling for switching fabric output ports. In this paper, we show that large-scale switch fabric can be built up by small-size crossbar switch units with improved delay performance and enough arbitration time margins. The simulation results show that the proposed switch architecture and distributed scheduling algorithm can provide 100% throughput under i.i.d. uniform traffic with a single iteration arbitration in a time slot.

This paper presents a comparative evaluation of a modified version (A-protocol) of the distributed-queueing request update multiple access (DQRUMA)/multi-code code division multiple access (MC-CDMA) protocol and an enhanced version (P-protocol) of the DQRUMA/MC-CDMA protocol with a lattice pool for request accesses (LPRA) scheme in a packet-based voice traffic environment. The analytical results agree with the simulation ones and show that the P-protocol outperforms the A-protocol in terms of the packet loss rate for voice traffic.

Conventional input switches usually employ a single crossbar switch fabric to transfer cells from input buffers to output ports. This type of switch suffers from input and output cell contention problems which cause lower performance than for output buffer switches. However, dividing one crossbar fabric into several smaller crossbar fabrics, we can decrease the input and output contention probabilities. Based on this principle, we propose a new decomposed crossbar switch architecture. Since a decrease in input and output contention probabilities causes an increase in the grant probability for the cells at input buffers, the proposed decomposed crossbar switches yield better performance than conventional input switches. We derive the grant probability for a simple arbitration algorithm and evaluate the performance of the proposed switch architecture in terms of the average cell latency through simulation.

Real-time traffic requires strict delay constraints in terms of maximum cell transfer delay (CTD) and cell delay variation (CDV). In order to support the required quality of service (QoS) of each connection in ATM networks, it is important to estimate the current status of networks by using local information such as cell delay and delay variation in switches. We develop a framework for obtaining delay distribution in a single switch module by monitoring the internal buffer. We also propose a new delay estimation mechanism utilizing a fast convolution approximation scheme in order to reduce the number of operations and the required amount of the data for estimating end-to-end delay. The feasibility of the proposed delay estimation mechanism is verified by simulation for various types of CBR and VBR traffic loads.