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In Wireless Local-Area Networks (WLANs), most of the wireless Access Points (APs) work at the full power level. So, the conflicting channels may have a significant and inevitable impact on throughput and transmission delay when the density of the APs is increasing. This paper proposes a power control algorithm, Dynamic Power Control called DPC based on NetFlow. DPC applies a fine tuning idea to get...
Due to overlapping frequency bands, IEEE 802.11a WLAN and Ultra Wide-Band systems potentially suffer from mutual interference problems. This paper proposes a method for inserting frequency notches into the IR-UWB power spectrum to ensure compatibility with WLAN systems. In contrast to conventional approaches where complicated waveform equations are used, the proposed method uses a dual-pulse frequency...
Wireless backhaul has received much attention as an enabler of future broadband mobile communication systems because it can reduce deployment cost of pico-cells, an essential part of high capacity system. A high throughput with a minimum delay network is highly appreciated to sustain the increasing proliferation in multimedia transmissions. In this research, we propose a backhaul network using the...
Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
Frame delay variance in CSMA/CA networks is large. Wireless applications may require both, limited mean delay and limited delay jitter. These parameters can be derived easily from cumulative distribution function (CDF) of frame delay. This paper applies Signal Flow Graphs (SFGs) to calculate the CDF of frame delay in IEEE 802.11 DCF WLANs. SFGs allow to establish a mathematical WLAN model for precise...
This paper proposes Ultra-Wideband (UWB) bandpass filters with dual notched band for the purpose of avoiding the interference between the UWB radio system and the existing WLAN system. The 5 GHz WLAN (Wireless Local Area Network) IEEE 802.11a exists in 5.15-5.35 GHz and 5.725-5.825 GHz which are called as lower and upper band respectively. The filter is based on ring resonator with interdigital coupling...
This paper describes an approach to detect Quality of Service degradation due to packet congestion within wireless networks. The proposed approach can assist management systems to detect a degradation based on easy determinable packet metrics. Metrics like interface queue length, round trip times and retry ratio are evaluated regarding thresholds and detection performance. With a combination of metrics,...
In recent years the research on Vehicular Ad Hoc Network (VANET) has been paid much attention due to the development of wireless network becoming mature, people think highly of traffic safety issue, the popularity of Global Positioning System (GPS), promising applications of VANET being exploited. However, VANET has the essential property of rapid change of large scale network topology. Besides, the...
The quick market growth and ubiquitous acceptance of VoIP are primarily due to cheap service. VoIP services can be availed in mobile devices at a very low cost by employing IEEE 802.11 to provide last mile coverage. But call capacity is very low in these networks and call jitter occurs if voice quality requirements are not precisely met. We present a VoIP call capacity model for 802.11 networks which...
Position messages will be the foundation for many emerging traffic safety applications based on wireless communications. These messages contain information about the vehicle's position, speed, direction, etc. and are broadcasted periodically by each vehicle. The upcoming IEEE 802.11p standard, intended for vehicle ad hoc networks (VANETs) has flaws caused by the unpredictable behavior of its medium...
A sub-band based ultra wideband (SUWB) system is proposed for energy efficient short range wireless communications. The proposed technique divides the bandwidth of 500 MHz into number of sub-bands that may be utilized for higher data rate or higher reliability or multi user access depending on system requirements. The energy efficiency is achieved by reducing the sampling rate requirements and also...
802.11e HCCA (Hybrid coordination function Controlled Channel Access) exhibits good QoS provisioning for constant bit rate (CBR) video streams in a single collision domain. However, its performance degrades significantly for variable bit rate (VBR) video streams particularly in multi-collision domains. In addition, HCCA has the disadvantage of high complexity. In this paper, we introduce a deterministic...
The use of unlicensed bands, e.g., ISM (industrial, science and medical) bands is getting more and more attention nowadays due to the high scarcity and high costs of radio spectrum. Due to this, there is a high risk of interference, which degrades the performance and fails to support Quality of Service (QoS) for systems operating in these bands. Therefore, spectrum sharing between coexisting competing...
The combination of RTS/CTS and EIFS enhancements has not adequately addressed the hidden terminal problem (HTP) in the receiver neighbourhood. The EIFS scheme protects ACK packets, while DATA packets are not shielded as the EIFS expires before they are delivered. Our proposed scheme is designed to address the shortcomings of the EIFS in protecting data packets. We propose a scheme which implements...
In dynamic networks such as highly mobile swarms of micro unmanned aerial vehicles (MUAV) the round trip time (RTT) is a crucial key figure for the reliability and viability of the system. For this purpose the deployed protocols and underlying network architecture have to be designed in awareness of the available and allocatable throughput. In this paper we are investigating a network and protocol...
In this paper, we investigate the effect of interference on the performance of IEEE 802.11g wireless networks. We study different network configurations and evaluate their corresponding throughput performances with the aid of the ns2 simulator. We also provide recommendations for network deployment in order to minimize interference and improve the quality of service.
Implementing multiple channels among the multi-radio nodes of wireless mesh networks (WMNs) improve the capacity of the network. In this paper, we propose channel aware routing metric (CARM) as a new routing metric that facilitates the use of available channels in 802.11 WMNs. It chooses a route that has better link quality, reduced switching delay and better channel diversity. Unlike all the other...
This study deals to quantify the impact of adjacent channel interference (ACI) in multi-radio 802.11a based wireless nodes designed for WLAN. The nodes are equipped with three 802.11a wireless interfaces, two for backhaul connectivity with directional antennas and one for access point (AP) functionality. Adjacent channels in 802.11a are considered to be non-overlapping and expected ACI would be almost...
The use of wireless local area networks (WLANs), as well as the proliferation of the use of multimedia applications has grown fast in recent years. Some factors affect the quality of service(QoS) received by the user. The interference is an example. This work presents an empirical study of the QoS parameters of a VoIP application in the presence of an interference network, as well as the relevance...
Wireless mesh network (WMN) is a promising technology for broadband Internet access due to its low cost, ease of deployment, increased coverage, and robustness. Equipping each mesh router with multiple radios can greatly improve the capacity of WMNs since the radios at each node can simultaneously transmit data on orthogonal channels. Channel assignment is an important problem in multi-radio multi-channel...
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