The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In wireless LANs (WLANs), a power-hungry transceiver is used for both the control (carrier sense) and data exchanges. As a result, when many nodes contend to access a same channel, the WLAN transceiver performs carrier sense during most time, which wastes much energy. To solve this problem, we study separating the control and data operations in WLANs, by tightly integrating a lower power wake-up radio...
Multi-radio platforms are an interesting design concept. Executing multiple radios on a shared platform presents opportunities not only for component re-use but also for better data throughputs, as non-active radios may dynamically yield resources for active ones. This enhances the conventional SDR approach in the RF domain and provides means to optimize resources in platform level when taking the...
Interference management is one of the most critical operations for CSMA/CA protocols. In this paper we investigate how specific PHY-layer operations, designed to mitigate the effect of interference, can cause the radio-receiver circuitry to over-estimate the channel occupation status, thus unnecessarily limiting the overall spatial reuse or impeding the synchronization to incoming frames. We individuated...
It is well known that rate anomaly may occur when more than two stations communicating with an AP use different data rates in IEEE 802.11 WLANs. This statement may be valid based on the assumption that each station equally attempts channel access. However, this paper confirms that if stations suffer from different time-correlated fading channels, they have a different access rate, i.e., the stronger...
A very common conclusion of many experimental studies about IEEE 802.11 outdoor network deployments is that their poor performance results derive from the unfavorable interference and multi-path signals in which the WLAN-cards are required to operate. Goal of this paper is to show that this condition does not always hold, and unexpected and inaccurated PHY layer implementations can be a primary cause...
In this study, the electromagnetic interference of an MB-OFDM UWB system with an IEEE802.11a wireless LAN was evaluated using a GTEM cell. Band #3 (out-of-band radiation for 11a) in the band plan of the MB-OFDM UWB system and Band #4 (in-band radiation for 11a) were assumed to be two different types of interference. As a result, when the frequencies of the MB-OFDM UWB corresponded to Band #3, the...
We propose QUEST (QUality ESTimation), a new method that accurately estimates IEEE 802.11 wireless link quality with no in-band signaling overhead. Existing link quality estimation methods either are based on hello exchanges by fixing or varying transmission rates or rely on the history (e.g., delivery ratio) of previously sent data packets in a per-rate/-neighbor manner. QUEST on the other hand,...
This paper addresses the practical design issues of a multi-standard RF sub-sampling front-end. The system level design flow of a dual-standard sub-sampling receiver is provided with focus on two important design issues. The first critical design issue is the careful selection of the sampling rate and consequently the frequency plan of the receiver. This is done in this paper based on a novel proposed...
Orthogonal Frequency Division Multiplexing has become a key element of todays wireless communication systems. However, its sensitivity to oscillator phase noise is responsible for common phase error (CPE) and inter-carrier interference (ICI) which greatly degrades the overall system performance. In this contribution, we address the problem of reducing the effects of phase noise in an OFDM system operating...
In this paper, a simulation of cascaded LNA and RF amplifier for front-end direct conversion receiver at 5.8-GHz frequency band is presented. By using direct conversion architecture, the image rejection performance is improved, lower complexity and the component is reduced. The cascading LNA and RF amplifier has 27 dB gain and 2.17 dB noise figure. The LNA and RF amplifier is simulated using Ansoft...
In data communication system, the outdoor of Wireless Local Area Network (WLAN) technology can be implemented in bridge connection. It allows LANs in separated buildings to be connected over the distance ranging in several hundred meters. In RF system design level, the performance of the WLAN bridge also relies on the RF receiver system where it must be well designed to minimize distortions in the...
In this paper we present an algorithm, based on power management of access points (AP), to reduce congestion in wireless local area networks (WLANs). The algorithm finds the most congested access point (MCAP) and adjusts its transmitted power in discrete steps and determines the optimal userspsila assignment such that an optimal load distribution is achieved. Results show that the algorithm is capable...
This paper discusses the performance of the wavelet based filtered multi-tone (WFMT) modulation. The novel WFMT modulation was proposed in 2003 for improving characteristics of wireless and DSL multicarrier systems. In this paper we describe a main idea of WFMT and discuss the advantages of this novel modulation. The WFMT modulation in comparison with OFDM and DMT has low level of out-of-band side...
This paper investigates the effective gain of antennas in indoor channels. A metric called instantaneous effective gain is proposed, and a multiple-cluster 3D channel model is used to facilitate the proposed antenna effective gain. In the multiple-cluster channel model, Laplacian and double exponential distribution are utilized to model azimuth and elevation signal power distribution respectively,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.