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A multichannel scheduling based on an extension of modified largest weighted delay first (M-LWDF) scheduling is proposed for heterogeneous traffic. We consider the downlink of an orthogonal frequency division multiplexing (OFDM) system where the wireless channel and queue state information are taken into account to schedule delay-sensitive and ratesensitive traffic. We propose a logarithmic notion...
We analyze TCP-controlled bulk file transfers in a single station WLAN with nonzero propagation delay between the file server and the WLAN. Our approach is to model the flow of packets as a closed queueing network (BCMP network) with 3 service centres, one each for the Access Point and the STA, and the third for the propagation delay. The service rates of the first two are obtained by analyzing the...
We study the performance of cognitive (secondary) users in a cognitive radio network which uses a channel whenever the primary users are not using the channel. The usage of the channel by the primary users is modelled by an ON-OFF renewal process. The cognitive users may be transmitting data using TCP connections and voice traffic. The voice traffic is given priority over the data traffic. We theoretically...
To reduce the channel access latency in WiMedia networks, we propose a distributed and dynamic adaptation scheme (DDAS) where the optimal transmission probability contention window size is derived after getting traffic information by means of distributed beaconing procedures. Simulation results demonstrate that DDAS can reduce the channel access latency significantly, especially when the number of...
The purpose of our study is to guarantee the required throughput of high-priority (UDP) flows and to achieve the stable throughput for each flow in a wireless LAN in which both high-priority and low-priority (TCP) flows exist. The authors previously proposed a QoS control scheme called Receiving Opportunity Control in MAC Frame (ROC), in which an Access Point (AP) intentionally does not return an...
This paper proposes a new scheduling algorithm for IEEE 802.16-2005 Broadband Wireless Metropolitan Area Networks in TDD mode. The proposed algorithm focuses on solving the problem of handling high priority traffic in congested networks while minimizing starvation conditions for other served classes. In this work, a detailed simulation study is carried out for the proposed scheduling algorithm as...
LTE (Long Term Evolution) supports QoS (Quality of Service) with several service classes. For each class of traffic, a big difference exists on BER (Bit Error Rate) requirement. This leads to a considerable difference in transmission power for various classes of traffic. In this paper, a novel scheduler is designed and proposed for LTE which supports CoS (Class of Service) with the consideration of...
Cell outage management is a self-healing functionality in future mobile cellular networks, aiming to automatically detect cell or site level outages (cell outage detection) as well as to mitigate as much as possible the caused degradation of coverage, capacity and/or service quality (cell outage compensation). Cell outage compensation has a variety of control parameters (and combination thereof) at...
In a wireless domain where a mobile user accesses heterogeneous wireless technologies with multiple interfaces, a multi-path scheduling algorithm can benefit mobile users' experience by aggregating different network bandwidth together. However, existing literature actually shows that for TCP flows, it may not be the case. To better exploit multi-path scheduling for TCP connections, this paper presents...
Routing is a key factor in the design of modern communication networks, especially in wireless ad-hoc networks (WANs). In WANs, both selfish and malicious nodes are the misbehaving nodes and are significant routing and security problems. The proposed mechanism presents a trust model to detect selfish and malicious nodes to avoid these nodes becoming routing nodes. In addition, the proposed paper provides...
Sharing of information leads to the need to transfer data between geographically distant locations. Identifying the most appropriate time period to execute the data transfer is essential to achieve the best data transfer throughput; e.g. one can forecast network traffic, identify future low network traffic activities between two entities, and plan the data transfer accordingly. This forecasting can...
Switch fabrics for 100 Gigabit Ethernet systems pose high demands in terms of delay and scalability. In this paper we analyze the performance of a Clos-based switch fabric under uniform and bursty traffic, and compare its performance to a crossbar-based switch design for benchmarking. In particular, we focus on a Clos-design using a Space-Memory-Memory (SMM) configuration, which has recently gained...
The most challenging issue in WiMAX network planning is to measure and enhance the Quality of Service (QoS) of WiMAX networks. In this paper, a comprehensive WiMAX simulator is proposed to evaluate the performance of the system. The key parts of the simulator are described including end-to-end communication path, traffic generation, Medium Access Control (MAC) and Physical (PHY) layers, resource allocation,...
Mobile WiMAX is a burgeoning network technology with diverse applications, one of them being used for VANETs. The performance metrics such as Mean Throughput and Packet Loss Ratio for the operations of VANETs adopting 802.16e are computed through simulation techniques. Next we evaluated the similar performance of VANETs employing 802.11p, also known as WAVE (Wireless Access in Vehicular Environment)...
In the pioneering works, network coding has shown great potential to improve the performance of wireless networks. However, most of them are implemented under specific traffic pattern. Since various traffic patterns will affect the promising gains of network coding, in this paper, we study how traffic pattern affects the benefits of general practical network coding scheme-Multi-hop Network Coding...
We propose an efficient MAC protocol for OFDMA PONs that eliminates the synchronization requirement of ONUs and also exploits the statistical multiplexing gain among traffic of all ONUs for high performances in throughput and delay.
A method and system design of controlling user's traffic in broadband access segments to enhance fairness among users are proposed and demonstrated. A proposed bandwidth control system utilizes QoS-related functions of existing heterogeneous access equipments, and provides a mechanism for maintaining bandwidth assignment based on each user's profile and usage.
In the present heterogeneous wired networks, reliability priority consideration is important. Quality of Service (QoS) varies according to congestion in the network and it can be avoided by different TCP Agents using congestion control algorithms. Previously, researches had only analyzed TCP agents, we extend their work to practical simulation for the multisource scenario to compare performance evaluation...
In this paper, we apply a discrete-time Markov Chain model to analyse the performance of IEEE 802.15.4 MAC Protocol with acknowledgement (ACK) frame transmission under unsaturated traffic conditions. We evaluate the system performance in terms of aggregate throughput and average power consumption of a node. Analytical results are substantiated through ns2 simulations. The effects of frame arriving...
In this paper we propose a frame traffic control algorithm in the media access control (MAC) layer for IEEE802.11 wireless local area networks (WLANs), namely the Adaptive Frame Size Proportion Optimization (AFSPO) algorithm. The algorithm adaptively adjusts the sending frame size of each station in the network based on the real-time proportion of data frames, to weaken the self-similar characteristics...
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