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In Wireless Sensor Networks, the traffic is light under idle or light load. When an event is detected the network becomes active and the data flow traffic becomes heavy, which leads to congestion. Congestion plays an vital role in reducing the performance of the network. Hence it necessitates to develop an effective congestion control technique. This paper focus on congestion detection and control...
With the increase of network bandwidth, more and more new applications such as audio, video and online games have become the main body in network traffic. Based on real time considerations, these new applications mostly use UDP as transport layer protocol, which directly increase UDP traffic. However, traditional studies believe that TCP dominates the Internet traffic and previous traffic measurements...
Wi-Fi enabled hand-held devices quickly occupied the consumer market as a result of the remarkable customer acceptance of IEEE 802.11 standard. But the widely used contention based medium access mechanism is unable to meet the increasing traffic demand of today's home users. Especially, delay sensitive multimedia contents suffer heavily from quality degradation under high traffic load. However, the...
Motivated by the fact that when selfish users choose their policies independently without any coordination mechanism, Nash equilibria could result in a network collapse, we develop in this paper a hierarchical distributed learning framework for decision-making in heterogeneous cognitive networks. We introduce the Nash-Stackelberg fuzzy Q-learning, with the network as leader that aims at maximizing...
Several underwater network characteristics, including long propagation delays and a bandwidth dependent on distance, provide unique challenges to protocol designers. In this paper we present STUMP-WR, a distributed routing and channel scheduling protocol, designed for heavily loaded underwater networks. STUMP-WR selects and schedules links using a distributed algorithm to overlap communications by...
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...
We propose an analytical model to assess the throughput and call blocking rate of Opportunistic Spectrum Orthogonal Frequency Division Multiple Access network constituted of multiple classes of Secondary Users (SUs) and temporarily active Primary Users (PUs) of different priorities. In the case of PUs we consider low activity wideband and high activity narrowband users. While in the case of SUs we...
This article presents a new MAC layer protocol for IEEE 802.11 EDCA-based ad-hoc networks with hidden nodes. The key idea of the proposed solution is based on an intelligent two-step reservation procedure which is combined with the advantages of EDCA service differentiation. The new protocol achieves significant performance improvement for high priority traffic (e.g., Voice) in terms of fairness,...
Wireless Mesh Networks (WMNs) have been widely deployed as a new communication paradigm that can provide innovative services for a community (neighborhood, campus, etc.). WMNs are capable to provide both delay-sensitive services such as Voice over Internet Protocol (VoIP) and delay-insensitive services such as peer-to-peer file sharing. Network routing protocols in WMNs often employ the minimum-hops...
In this paper, we investigate the machine learning based strategies for dynamic channel selection in Cognitive Access Points (CogAPs) of WLANs. We employ Multi-layer Feedforward Neural Network (MFNN) models that utilize historical traffic information from network environment for learning the influence of spatio-temporal-spectral factors on the network and then predicting future traffic loads on each...
In this paper, we study the problem of transmission power control and its effects on the link-scheduling performance when a set of end-to-end flows established in the network are given. This problem is approached by means of the stability region of the link-scheduling policy. The stability region is defined for link-scheduling policies as the set of input-packet rates under which the queues in the...
This paper presents a history based statistical channel access mechanism for enabling traffic prioritization in wireless sensor networks. Prioritized access is realized such that low priority non-real-time sensors can access channel bandwidth that is unused by high priority real-time traffic. The key idea is for the low priority sensor nodes to first observe and statistically model the channel usage...
This paper proposes an intelligent rate controller for the Internet traffic. Called the IntelRate (Intelligent Rate), it is a router-based controller and uses the fuzzy logic control approach to adjust the source sending rate based on the instantaneous queue size of the router. Unlike other explicit congestion control protocols, the IntelRate controller need not evaluate the link states (such as bottleneck...
In this paper, we propose a distributed adaptive interference coordination algorithm for a practical orthogonal frequency division multiple access (OFDMA)-based mobile cellular systems. The designed algorithm can achieve an efficient frequency reuse for any user distribution and traffic load. Since no a priori frequency planning is required, the minimal coordination between base stations is also achieved...
In multihop wireless networks, end-to-end throughput is often hard to predict and is even harder to optimize due to the effect of interference. To date there is no precise result other than asymptotic bounds for this question: if there is no routing information given, what is the maximum throughput of a network using uncoordinated transmission such as IEEE 802.11 MAC? This paper attempts to address...
Energy consumption is a concern with mobile de-vices nowadays. Network interfaces are among the most power hungry components in these devices. In this paper, we describe the design and implementation of a client-centric protocol for energy efficiency. Inspired by earlier work, our protocol works by exploiting the TCP flow-control mechanism to shape incoming traffic into bursts in order to utilize...
IEEE 802.16d standard defines WiMAX Mesh mode, which uses Centralized Scheduling (CS), Distributed Scheduling (DS), and co-existence of CS/DS data subframes to allocate resources for data transmissions. The CS and CS/DS schemes are suitable for Internet traffic, but the lack of spatial reuse in over-pessimistic use of CS causes scalability problems and bandwidth limitations. In this paper a Hybrid...
Heterogeneous wireless network (HWN) technology has emerged as an important option for the next generation mobile network, where mobile client (MC) are capable of simultaneously connecting to multiple access networks for better quality of services (QoS) at a lower cost. Different from a conventional HWN that uses a single connection and performs vertical handover, we observe the performance of MCs...
The estimation of Retransmission Timeout (RTO) in Transmission Control Protocol (TCP) affects the throughput of the transmission link. If the RTO is just a little larger than the Round Trip Time (RTT), retransmissions will occur too often, and this increases congestion in the transmission link. If the RTO is much larger than the RTT, the response to retransmit when a packet is lost will be too slow,...
In cognitive radio networks, secondary users can be coordinated to perform cooperative spectrum sensing to achieve higher detection accuracy. However, when the number of cooperative users increases, more overhead traffic of decision transmission introduced to network and throughput of cognitive radio network decreases. Furthermore, the performance of cooperative spectrum sensing is limited by the...
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