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In this paper, a module has been presented which can perform a seamless interoperation between Bluetooth and Wi-Fi interfaces. The work is really challenging to achieve as both the interfaces work in the frequency band of 2.4 GHz creating a high possibility of interference. The challenge of implementing such an interoperable application atop OSGi framework has been discussed in this paper as well...
In this paper we propose a power control policy over an imperfect fading channel within a cognitive spectrum sharing area. In particular, our proposed scheme maximizes the secondary user effective capacity subject to the average interference power and the secondary user transmit power constraints. We also investigate the minimization of average interference power at the Primary Receiver (PR) under...
Power conservation for maximizing the lifetime of the limited battery powered ad hoc networks are one of the most important factors in a network design. Transmitting at high power may assure network connectivity but sacrifice network lifetime and increases the interference as well. Meanwhile transmitting at lower power reduces the interference on the expense on network robustness. We investigate the...
The relay technology is an essential piece of LTE-Advanced in its pursuit of cost effective capacity enhancement and coverage extension. Simple RF repeaters have been widely used in cellular technologies to offer coverage extension. However, they cannot distinguish desired signals from interference and noise and are unable to operate with sophisticated mechanisms, such as power control, beam-forming,...
In this paper we introduce a new architecture for dynamic spectrum sharing called the distributed dynamic spectrum leasing (D-DSL) and a game theoretic framework for its implementation on a cognitive radio network. In D-DSL, it is assumed that each channel is assigned to a primary user who may lease the channel to secondary users. The spectrum owners can thus dynamically adjust the amount of interference...
Wireless Personal Area Networks (WPANs) are used for a wide variety of applications. Earlier WPANs, like Bluetooth, offer data rates only for low rate communication. Nowadays, consumer electronic devices have high demands on communication systems, e.g. for high definition video transmission. Users expect future WPANs to act like wired systems by means of reliability, that is, packet loss and distortion...
In this paper, we analyze the performance gain achieved when a channel-aware deferring (CaD) strategy is applied to defer the allocation of users with transitory bad channel state in a mobile OFDMA system. Users with good channel conditions receive more resources and the radio resource utilization improves. To reduce the impact of the CaD strategy on the quality of service (QoS) provisioning for the...
Cognitive wireless mesh networks have great potential to green communication. One of the critical challenges for realizing such networks is how to adaptively match transmit powers and allocate frequency resources among secondary users of the licensed frequency bands whilst maintaining the quality-of-service (QoS) requirement of the primary users, even in mutually entangled interferences environment...
This paper proposes a novel channel allocation method for multi-cells OFDMA-FDD networks with a reused frequency factor (RFF) of one. The proposed algorithm predicts the co-channel interference (CCI) of active mobile stations (MSs) before allocating suitable subcarriers to a new MS. In order to maintain a desired quality of service (QoS) of the network, only subcarriers having signal-to-interference-plus-noise...
QoS routing in wireless mesh networks (WMNs) is a daunting task. Finding a path for a given flow depends not only on the bandwidth-delay requirements of that flow but also on the available bandwidth of all the nodes in that path and the amount of bandwidth consumption caused by that flow along its path. Contrary to the wired networks, these two parameters are not fixed and depend on the interference...
Cognitive Radio Networks (CRNs) operate on the principle of opportunistically exploiting unused capacity in the primary network via Dynamic Spectrum Sensing. In this paper we propose a novel suite of transmit opportunity detection methods that effectively exploit the white/gray space in high traffic packet networks. We present a radically different paradigm to exploit the excess Signal-to-Noise ratio...
In the case of densely distributed unmanned aerial vehicle (UAV), an inter-node interference degrades the received signal to interference noise ratio (SINR). In this paper, we focused on the interference effects of densely distributed nodes so that variation of transmission efficiency can be numerically analyzed. Simulation results show that the received SINR highly depends on the antenna directivity...
In this paper we discuss joint beamforming and power control for downlink multiuser MIMO systems with target signal-to-interference+noise ratios (SINR) constraints. We derive necessary conditions for minimizing total interference at downlink receivers and present an algorithm which adapts the beamforming vectors and powers incrementally to meet specified SINR targets with minimum powers. The proposed...
In this paper, we propose to design a spectrum mobility strategy using Fuzzy Logic System for cognitive radio networks (CRN). The proposed strategy enables cognitive radios (CR) to vacate the spectrum if primary user (PU) needs it back or to adjust its transmit power in order to avoid interference with PU or nearby CR. Using our scheme, CR switches between the bands only if it is not able to modify...
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.
In radio mobile cellular networks, the users located at the cell border are suffering from a bad quality of service (QoS). Cooperative communications is a promising technique that can overcome this weakness by allowing the users to profit from powerful benefits of the spatial diversity. Nevertheless, abstraction is usually made on the impact of the additional multiple access interference inherent...
Cognitive radio (CR) has been considered as the most prominent technique for flexible spectrum utilization. Protecting primary users (PUs) from any harmful interference is the most important issue in CR networks. Secondary users (SUs) periodically sense the channels in order to detect the PU's appearance. Without a proper sensing schedule, however, sensing operation may degrade the quality of service...
Cognitive users (CUs) are allowed to access licensed bands without causing harmful interference to primary users (PUs). However, the quality of service (QoS) of CUs can not be guaranteed when CUs experience bad channel conditions in direct transmission between the cognitive source and its destination. In this paper, we consider the problem of cooperative transmission in cognitive radio networks. The...
This paper presents some experimental results about the robustness of a WiMAX system against interfering signals. In particular, this work presents a WiMAX performance comparison when two different types of interfering signals were generated: a continuous wave and a rectangular pulsed wave. Both of them were tuned at the same working frequency of the WiMAX system (i.e. 2.55 GHz). The former is typical...
Today spectrum demand for wireless communication is tremendous and even keeps growing. In contrast, there are no blank spots in the spectrum map. Additional spectrum opportunities are available in unlicensed bands and so-called non-exclusively licensed bands which are currently made available. This non-exclusive spectrum can be exploited whenever a license holder is not active. These spectrum opportunities...
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