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IEEE 802.16e-based Mobile WiMAX has gained considerable popularity recently. However, there is no current simulation model that provides feature completeness and performance accuracy. In this paper we propose the design and implementation methodology of a complete, accurate, realistic and versatile simulation model to support Mobile WiMAX for the NS-2 simulation platform. In the proposed simulation...
Modular methodologies and lambda calculus have garnered limited interest from both analysts and statisticians in the last several years. In this work, we verify the understanding of board general testing system based on PXI Bus, our new framework for general testing system, is the solution to all of these obstacles.
In this paper, we consider a noncooperative cognitive radio network with M selfish secondary users (SUs) opportunistically access N licensed channels. Every SU chooses one channel to sense and subsequently compete to access (based on the sensing outcome) to obtain the channel utility. Different channels may have different utilities. Each SU selfishly makes a sensing decision to maximize its obtained...
A cognitive OFDM-based relay network is considered in this paper. Communication between any node pair occurs on a spectrum pool of OFDM subcarriers where the subcarriers are not used by primary users. Therefore, the available spectrum for different transmitter-receiver pairs is distinct due to their location difference and so on. To satisfy different traffic demand and improve system performance,...
TinyOS is an open-source operating system, using Component Description Language NesC for development. TinyOS is designed mostly for wireless sensor network, in which nodes have very limited resources. A representative scheduling mechanism in TinyOS is analyzed and its shortcomings are listed in this paper. An improved design of the priority-based soft real-time task scheduling strategy is proposed...
This paper considers the problem of applying network coding in input and output queued (IOQ) packet switch loaded with both unicast and multicast flows. With network coding the switch can transmit the linear combination of multicast packets which prominently improves the switching efficiency in terms of throughput. The key idea is to use Vandermonde Matrix as the coding coefficient matrix while applying...
The advantages and the flexibility introduced into the hardware implementation by partial dynamic reconfiguration have rapidly changed the design flow of embedded systems. Configuration management is an important issue in operating system for dynamically reconfigurable system-on-chip. Reconfiguration overhead affects the performance of reconfigurable system. This paper presents a hardware implemented...
In this paper, we investigated the end-to-end throughput of a chain in Cognitive Radio Networks (CRNs). We found that, the end-to-end throughput is dependant on both the primary usage patterns and the transmission scheduling scheme being used. In addition, to increase the end-to-end throughput of a Cognitive Radio (CR) chain, the scheduling scheme should be adjusted according to the primary usage...
Cognitive radio makes it possible for an unlicensed user to access a licensed spectrum opportunistically on the basis of non-interfering. This paper addresses the problem of resource allocation for multiaccess channel (MAC) of OFDMA-based cognitive radio networks, taking into account of the interference temperature constraints. The objective is to maximize the system utility, which is used to quantify...
In wireless communications, packet size is one of the most significant parameters that have an impact on the quality of service (QoS). The optimal packet size depends on wireless channel condition and reception performance. However, it is difficult to determine the optimal packet size under time-varying channel in advance. Besides, performance characteristic of wireless devices is virtually unpredictable...
Streaming service becomes an essential service in the third-generation cellular mobile network and its evolutions. Packet scheduling plays an important role in radio resource management to guarantee QoS of streaming service. In this paper, a novel fast packet scheduling algorithm called MAF (Minimum Ahead First) is proposed for HS-DSCH (High Speed Downlink shared channel) in HSDPA (High Speed Downlink...
Because of the wide deployment of 802.11 equipments in the past decade, current applications are not limited anymore to only single access points (AP) deployments for indoor usage, but have been extended to multi-hop networks to fulfill the need of high speed connectivity in mobile environments, where the analysis of multi-hop networks is extremely complicated. The behavior of an AP is dependent not...
In this study we present our findings of important IEEE 802.16e-2005 performance characteristics. This study is part of our ongoing study of wireless communications technologies for the FRA and provides details about our approach to modeling various channel effects, such as Doppler shift and Rician fading, details of the effect of link quality conditions, expected throughput and distance characteristics,...
In centralized wireless networks, reducing the transmission power normally leads to higher network transport throughput. In this paper, we investigate power control in a different scenario, where the network adopts distributed MAC layer coordination mechanisms. We first consider widely adopted RTS/CTS based MAC protocols. We show that an optimal power control protocol should use higher transmission...
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