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The exponential growth of wireless technologies attracted many research to improve the quality of service (QoS) of global wireless networks such as 802.11 and 802.16. In specific, research targeted the physical layer (PHY) parameters and medium access control (MAC) mechanisms to improve QoS. In this paper we provide a simple yet efficient model to maintain the quality of service for wireless networks...
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...
The link scheduling in wireless multi-hop networks is addressed. Different from most of work that adopt the protocol interference model which merely take consideration of packet collisions, our proposed algorithms use the physical interference model to reflect the aggregated signal to interference and noise ratio (SINR), which is a more accurate abstraction of the real scenario. We first propose a...
In this paper, it is shown that the achievable throughput capacity of wireless networks suffers from a fundamental limitation under finite node resource constraints. It is shown that this reduction results from a fundamental lower bound on the error performance of the wireless-channel model. In particular, the problem is addressed for the classic parallel-unicast problem introduced by Gupta-Kumar...
This paper introduces a novel paradigm for designing the physical and medium access control (MAC) layers of mobile ad hoc or peer-to-peer networks formed by half-duplex radios. A node equipped with such a radio cannot simultaneously transmit and receive useful signals at the same frequency. Unlike in conventional designs, where a node's transmission frames are scheduled away from its reception, each...
This paper proposes an adaptive bandwidth control scheme for autonomous distributed networks. Based on the consideration that the carrier sense multiple access with collision avoidance (CSMA/CA) is not efficient in terms of throughput due to its strict collision avoidance process, this paper employs a dynamic spectrum control (DSC) in which a certain number of discrete spectra having the highest signal...
Self-optimisation will enable future wireless networks to manage themselves in a continuous and independent way. By dynamically adjusting relevant radio parameters during network operation a system that adapts to environmental changes can be created. This paper presents a novel self-optimisation algorithm based on Fuzzy Logic Controlling. Taking into consideration measurements gathered from the network,...
The growing problem of spectrum scarcity and the inefficient spectrum utilization in the licensed bands, are addressed by the emerging Cognitive Radio (CR) paradigm. It is seen that the choice of the spectrum bands, called as spectrum decision, must be organized carefully by considering the challenges in the spectrum availability over time, the short term fluctuations in the availability, and the...
In this paper, we propose an interference aware throughput maximizing scheduler for cognitive radio networks (CRNs) as part of a MAC layer resource allocation framework. In the considered CRN scenario, the cognitive users with multiple antennas are coordinated by a centralized cognitive base station. We evaluate the performance of our proposed scheme using analysis of variation (ANOVA) technique....
Distributed beamforming has the great potential of performance improvement in wireless networks while the carrier synchronization overhead will reduce its performance gain. In this paper the effects of carrier synchronization on link throughput of distributed beamforming is studied. The expressions of the frequency and initial phase used by each cooperative node are derived for the existing round-trip...
In this paper, we compare communication schemes in scenarios of interest for underwater networks where multiple nodes collaborate towards the accomplishment of a target detection and tracking task. We consider two specific cases: in Scenario 1, a mobile Autonomous Underwater Vehicle (AUV) i) collects data from a set of fixed sensors deployed on the seafloor or ii) transmits data to the same nodes...
It has long been recognised that a wireless communication system can be more efficient if link-layer parameters such as modulation order are adapted to the channel conditions. The most common optimising criterion is spectral efficiency (bps/Hertz) subject to very low bit-error constraint. But this criterion is not appropriate for practical communication networks fitted with strong data-packet error...
Over the last decade, VoIP has had a fast growth particularly in Small Office Home Office environments overloading the wireless accesses in the last mile. Network Coding schemes have advantageous features for throughput performance but VoIP is a delay critical service requiring fast routing algorithms. In this paper, we design, implement and measure experimental values for a network coding based VoIP...
Wireless ad hoc networks are an emerging and popular technology to the world; however, the benefits of them are actually their fragility, too. Owing to mobile node movement, the link break problem always occurs in the network. The problem greatly influences the throughput, delay, jitter, and lots of performance issues of a routing protocol. Hence, this article is proposed to evaluate the influence...
The class of Gupta-Kumar results give the asymptotic throughput in multi-hop wireless networks but cannot predict the throughput behavior in networks of typical size. This paper addresses the non-asymptotic analysis of the multihop wireless communication problem and provides, for the first time, closed-form results on multi-hop throughput and delay distributions. The results are non-asymptotic in...
Opportunistic Spectrum Access has recently emerged as a set of approaches that seek to minimize the problems of scarcity and inefficient use of radio spectrum caused by its current policies of administration and allocation. This paper presents some modifications and adjustments made to the Opportunistic Spectrum Access model developed by Urgaonkar, R. and Neely, M. (2008). We evaluate the applicability...
Wireless internet has become popular in recent years due to the tremendous growth in the number of mobile computing devices and high demand for continuous network connectivity regardless of physical locations. In this paper, we investigate the effects of routing protocols on the performance of Transmission Control Protocol (TCP) variants in multi-hop wireless networks. Through simulations we study...
Wireless video multicasting/broadcasting is an efficient method for simultaneous transmission of data to a group of users. But the multicasting rates are fixed in current IEEE 802.11 PHYs standard. In this paper, we propose a novel collision-detection based rate-adaptation scheme (CDRA), which fully exploits the potential of rate adaptation capability of wireless physical layer, to improve service...
This paper proposes a spatial time-division multiple access (STDMA) based scheme (STBS) to enhance the system throughput in cognitive radio wireless networks. Especially, the proposed scheme is suitable for the situation when the available number of channels is far less than the number of secondary users (SUs). The system design includes: 1) a novel criterion based on SINR constraint (SC) to determine...
This paper investigates the problem of uplink subcarrier and power allocation in a Cognitive Radio (CR) network that operates opportunistically within vacant licensed Primary Users (PUs)spectrum. The resource allocation algorithm aims to maximize the CR network throughput under PUs interference constraints. In this paper, CR interference introduced into PUs sub-bands is modeled as a composite of two...
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