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Supporting QoS for safety-critical applications for intelligent transportation systems accentuates the analytical modeling of delays in vehicular networks. Such analysis is, however, challenging due to the dynamics of such a network. We make progress by deriving lower- and upper-bounds for information dissemination delays in multi-hop vehicular networks using two different routing schemes. In particular,...
We present an empirical model of the upstream end-to-end Voice-over-IP (VoIP) delay over a mobile, multi-hop wireless network towards a single gateway. First, we define the “VoIP regime” as the regime of network operation in which a fraction 1 - ϵ of the packets are received by the gateway within the maximum tolerable VoIP networking delay yvoip, and such that e is less than a maximum tolerable outage...
There has been much research focusing on the routing problem in delay tolerant networks (DTNs). Much of the work has mainly focused on coding schemes for message distribution, while other work has been done on the probabilistic forwarding. Coding schemes achieve higher delivery rate via redundancy before forwarding, while probabilistic forwarding efficiently limits the abuse of the store and forward...
In this paper, we address the relation between message delivery delay and reliability for the communication between a vehicle and a road side unit (RSU). We focus on sparse or low density vehicular ad hoc networks (VANETs), where timely message delivery and reliable transmission are of significant importance. We present an exact message delivery delay distribution for a two-lane road, where vehicles...
Opportunistic scheduling has been recognized as an effective method that significantly outperforms fixed TDMA scheduling in both channel capacity and communication reliability. Nevertheless the superior system performance comes at a price of high computational complexity, large signaling overhead, and unfairness among users. In this paper, we find that in relay-assisted next-generation wireless networks,...
We analyze the asymptotic performance of rate adaptation for Transmit Antenna Selection (TAS) and Maximum Eigenmode Beamforming (MEB) schemes in Multiple-Input Multiple-Output (MIMO) systems under imperfect channel state information (CSI) and feedback delay. The rate is adapted according to a target outage probability. We derive lower and upper bounds to this rate. We also asymptotically characterize...
Minimizing the sensing activity during the pre-attack phase while meeting the performance requirements is critical for reducing the operational costs of chemical sensor networks. In this paper, we present a formal problem formulation for this optimization problem, and propose a decentralized, dynamic sensor activation protocol for meeting this goal. We analyze the behavior of the activation protocol...
Different applications in the network have different sensitivity for the certain QoS parameters. The existing mechanisms cannot modify the packet loss policy exactly according to the needs of QoS parameters. Therefore, the network will not maximize its overall efficiency. This paper proposes a novel cognitive approach for QoS. It classifies the applications by various combinations of the QoS parameters...
In this paper, we derive the probability density function and cumulative distribution function of packet transmission time in a spectrum sharing system. In combination with the time-out characteristics of packets, we further study the outage probability and average transmission time under peak power interference constraint over Nakagami-m fading channel. Especially, we employ the M/G/1 queuing model...
In this paper, an enhanced access protocol minimizing message delivering latency is proposed. It is basically based on modified version of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol in which one sensor at a time is allowed to deviate from standard rules behaving like a cheater and keeping the Contention Window (CW) fixed and equal to the minimum value. The proposed scheme...
In a cognitive radio (CR) network, secondary users (SUs) are allowed to opportunistically access a licensed spectrum that is not currently being occupied by primary users. This paper is concerned with the problem of how to quickly and accurately locate an unoccupied channel or determine that there is no unoccupied channel, from multiple (yet finite) candidate channels for a SU with a single detector...
In this paper, a random on-off accumulative transmission (R-OOAT) scheme is proposed to achieve collision-tolerant (CT) media access control (MAC) for asynchronous wireless sensor networks. Unlike conventional MAC schemes that discard packages with collisions at receivers, the CT-MAC extracts the salient information from the colliding signals by using the R-OOAT scheme in the physical layer. Nodes...
Since IEEE 802.11p has been adopted as Vehicular Ad hoc Networks (VANET) main technology, the research and development of vehicular safety applications has gained momentum. Because broadcasting is the predominant traffic type in VANETs, their safety applications will face a challenge in managing the channel capacity to insure good performance in terms of throughput, delay, fairness and broadcast coverage...
Energy efficiency is one of the crucial design criteria for wireless sensor networks. Idle listening constitutes a major part of energy waste, and thus solutions such as duty cycling and the use of wake-up radios have been proposed to reduce idle listening and save energy. Compared to duty cycling, wake-up radios save more energy by reducing unnecessary wake-ups and collisions. In this paper, we investigate...
We propose the dynamic BS-selection schemes for distributed wireless MIMO links, which aim at minimizing the average base-station (BS) usage while satisfying the specified statistical delay quality-of-service (QoS) constraint characterized by the delay-bound violation probability. In particular, the distributed transmission system consists of a number of location-independent BS's, a central server,...
Qualitative Discrete Event Simulation (QDES) is an event scheduling approach that uses the Qualitative Event Graphs (QEGs) and the Event Graphs (EGs) as a general framework to discrete event simulation modeling. In QDES, the uncertainty in event execution times is represented in a closed time interval in ℜ. When two or more event execution times overlap, it results in multiple event execution sequences...
As the maximum flow could be the indicator of congestion possibility, the theoretical study of major airport was how to determinate the maximum flow when the parameter changed. Then, a discrete time loss queuing algorithm of airport was proposed, which calculated maximum flow with deducting probability transfer matrix of flight arrival rate and airport service rate. Compared to the existing general...
Spectrum sensing algorithms are developed for cognitive radios to support real-time traffic. Multiple bands are sensed in parallel to reduce sensing delay, while meeting a minimum rate requirement with a prescribed outage probability. Interference constraints are also imposed to protect primary user (PU) transmissions. Both fixed sample size (FSS) and sequential sensing algorithms are developed. In...
The paper analysed MAC protocol based on multiple-channel RMA by dividing transmission time of information packet into 1 & a. The paper adopts a joint-control strategy that detect with probability p1 in time 1, detect with probability p2 in time a. On this basis the paper brought forward a new RMA and wireless sensor networks MAC protocol. The paper resolves the throughput of the system, of the...
In the few last years, there is an increasing need of QoS guarantees for multimedia and real time applications in mobile ad hoc networks. While several QoS routing protocols were proposed, adaptive routing has not be enough exploited. We propose in this paper a new delay oriented adaptive routing protocol for mobile ad hoc networks. We integrate a mean delay estimation model at each node in our protocol...
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