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An asymmetric microstrip-fed tri-band monopole antenna with a C-shaped ground stub loaded is investigated. Two strips and a crooked stub connected to the ground through a via-hole are use to obtain the frequency ranges of 2.4–2.52 GHz, 3.4–3.65 GHz, and 5.16–6.2 GHz, which is met the specifications of WLAN 2.4/5.2/5.8 GHz and WiMAX 3.5/5.5 GHz. Besides, the proposed antenna not only exhibits almost...
In this paper, we describe a practical model of analyzing the performance of 802.11n Wireless Local Area Networks (WLANs) carrying real-time voice over IP (VoIP) traffic. In particular, we determine the response-time and packet loss of client nodes using traffic generators and network monitors. We demonstrate that there exists a correlation between the number of VoIP calls on a WLAN and the response...
In this paper, we propose the architecture of a wide area file service infrastructure, called I-Shadow. I-Shadow can provide both short delay file access and dependable file management for mobile users by using a set of active rules. We also show that average file access time of I-Shadow is shorter than that of cache based Coda distributed file system through a simulation study.
A compact dual-band monopole antenna for WLAN applications is proposed and investigated. The proposed antenna is basically composed of two strips and an asymmetric microstrip-fed line. The measured results show the proposed antenna can provide two separate impedance bandwidths of 150 MHz (about 6.1% centered at 2.45 GHz) and 1124 MHz (about 18.2% centered at 5.5 GHz), making it easy to cover the specifications...
In this paper, we design a high-speed and wide-bandwidth continuous-time sigma-delta modulator (CT-SDM). We emphasize the design of low power wide-bandwidth (10MHz) CT-SDM for WLAN Std. 802.11b receiver. In the application of wireless receiver, continuous-time sigma-delta ADC is more suitable than pipeline ADC. Instead of active-RC filter, we use Gm-C filter in our CT-SDM design because Gm-C filter...
New PHY and MAC layer enhancements have been introduced in different IEEE 802.11 WLAN standards. These improvements have given birth to a wide range of bandwidth channels (up to 160MHz) and very high transmission data rates (> 1Gbps) to keep up with current and up-coming multimedia applications. The major reason for the inefficiency of different WLANs is that the current MAC layer randomly allocates...
In this paper, a new miniaturized ultra-wideband (UWB) antenna fed by coplanar waveguide (CPW) is proposed. Gear-shaped structures are employed around the circular disc radiator to impove the current distribution for the antenna miniaturization. Moreover, the gear-shaped structures can produce a wide impedance bandwidth and miniaturization structure. The antenna exhibits a wider bandwidth characteristic...
A novel planar dual-spiral monopole antenna with circular polarization (CP) operation is proposed. Dual asymmetrical strip-sleeves are utilized and shorted at the ground plane, the proposed CP design for 2.45 GHz band can easily be achieved and provides the impedance bandwidth (RL ≧10 dB) of about 240 MHz and the 3 dB axial-ratio (AR) bandwidth of about 130 MHz. The measured peak gain and radiation...
The capability of bending, twisting and folding offered by mechanically flexible films and/or substrates along with size, weight and cost constraints are among the main challenges in future wearable electronic devices. In this paper, the effects of bending on a planar flexible CPW- IFA antenna operating at WLAN (IEEE 802.11) 2.4/5.2/5.8 GHz bandwidths is proposed. The flat antenna achieves a relative...
Nowadays, the request for wireless services is greatly exploded to receive a good services from internet. So, many APs for WLAN are thoughtlessly deployed in various places. At this environments, inter-basic service set (BSS) interference might be happened. If the APs locating in same overlapped region are operated in the same channel, the CSMA/CA is well worked, that is multiple APs are operated...
The recent advances in both wireless technologies and mobile devices, fuelled by increased user interest, have driven the latest development of mobile 3D video services. However, the limited wireless bandwidth is one of the critical challenges for mobile 3D video delivery, especially as the 3D content requires higher bandwidth than the conventional 2D video. This paper proposes a network reputation-based...
IEEE 802.11ah enables new use cases such as smart grid and smart metering for 802.11 with an increased transmission range that reaches up to 1 km at 150 kbps. However, such a large outdoor network creates more hidden nodes due to a much higher path loss between stations than between a station to an access point (AP). 802.11ah has adopted a slotted medium access scheme and an AP assisted medium access...
Dual-band antenna covering IEEE 802.11a/b/g bands is presented using a miniaturized II-shaped monopole antennas with modified rectangular strip ground plane for dualband WLAN operation over the frequency band of 2.400–2.484 GHz, 5.150–5.350 GHz and 5.725–5.825GHz. The II-shaped monopole antenna and with modified rectangular ground plane are etched onto a piece of printed circuit board (PCB) with an...
We consider the problem of allocating two network resources (wireless bandwidth and backhaul router buffer) to support fair QoS in WLAN. We transform the QoS requirements to multi-resource demands and apply the DRF scheme to achieve fair allocation of the two different types of resources. We define a QoS utility function which measures the user QoS satisfaction. We briefly prove the property of resource-based...
An asymmetric microstrip-fed tri-band monopole antenna with a C-shaped ground stub loaded is investigated. Two strips and a crooked stub connected to the ground through a via-hole are use to obtain the frequency ranges of 2.4–2.52 GHz, 3.4–3.65 GHz, and 5.16–6.2 GHz, which is met the specifications of WLAN 2.4/5.2/5.8 GHz and WiMAX 3.5/5.5 GHz. Besides, the proposed antenna not only exhibits almost...
A compact dual-band monopole antenna for WLAN applications is proposed and investigated. The proposed antenna is basically composed of two strips and an asymmetric microstrip-fed line. The measured results show the proposed antenna can provide two separate impedance bandwidths of 150 MHz (about 6.1% centered at 2.45 GHz) and 1124 MHz (about 18.2% centered at 5.5 GHz), making it easy to cover the specifications...
In this manuscript, a reduced ground plane size printed antenna suitable for wireless universal serial bus (USB) dongle application is proposed. By creating notches and embedding slots into a rectangular patch, multiple resonances with effective bandwidth enhancement is achieved. The antenna is designed on the FR-4 substrate of length, width and thickness 35 mm, 15 mm and 0.8 mm, respectively. The...
The upcoming wireless LAN standard IEEE 802.11ac extends the channel bandwidth from conventional 20 or 40 MHz to 80 or 160 MHz to increase the data rate. Consequently, there could be stations supporting different channel bandwidths in one area. Stations belonging to the same basic service set (BSS) have to operate on the primary channel, which is a common 20 MHz sub-channel. In such a situation, the...
Quality of Service (QoS) is considered as the standard check of a conveyance system to show provided services and its availability. For illustration application like video conferencing, voice over ip (VOIP), streaming videos, real time operation feel necessity for draconian assurance on jitter, packet loss, prioritization of services and end-to-end delay. So to overcome these issues a novel scheme...
IEEE 802.11ac is a next generation wireless local area network (WLAN) standard employing multi-user multiple-input multiple-output (MU-MIMO) scheme for the first time. Since precoding and user selection schemes influence the performance of MU-MIMO transmission, accurate channel state information (CSI) is required to select users and obtain precoding matrix. In this paper, we evaluate the performance...
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