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A secondary distributed synchronization protocol in the Overlay based Hybrid Automatic Repeat request cognitive radio has been proposed. A detailed description for our protocol is given and simulation runs have been carried out. Our results show how secondary users can achieve synchronous reception on the primary receiver with the transmission from the primary transmitter. This synchronization represents...
In this paper a distributed authentication scheme based on independent session key per access network (HOISKA) is proposed for the decentralized multi-service group key management scheme in a wireless multicast environment. It enables a handover user Mi involved in multiple multicast service subscriptions to establish the long term credential from the trusted authentication server (As) during initial...
In this paper we investigate the reliability of ray tracing simulator in predicting the indoor radio channel response through a well specified environment. The knowledge of the indoor environment geometric and martial properties led to such site specific modeling. We assess the simulated data by comparing the predicted received power with real filed measurements. The good agreement between the predicted...
In this paper a comparison between two indoor localization algorithms using received signal strength is utilized the vector algorithm and the Comparative Received Signal Strength algorithm. The comparison considered the effect of the radio map resolution, the number of access points, and the operating frequency on the accuracy of the localization process. The experiments were carried out using ray...
Discrete wavelet transform (DWT) for Multiple Input Multiple Outputs (MIMO) bandlimited systems is investigated. The implementation involves using the DWT as the base multiplexing technology at the baseband to process the input signal. Using the Alamouti diversity technique, an investigation for a DWT-MIMO multicarrier system is presented. Results shown are quite interesting; however these were very...
The scattering parameter formulation for the envelope correlation in an (N, N) MIMO antenna array has been modified to take the intrinsic antenna power losses into account. This method of calculation provides a major simplification over the use of antenna radiation field patterns. Its accuracy is illustrated in three examples, which also show that the locations of the correlation minima are sensitive...
Significant improvements in the quality and reliability of indoor WLAN communications are claimed for devices with MIMO technology applying 802.11n standards, that allow users to achieve a theoretical data rate up to 300-600 Mbps on a single transmission. This paper presents an analysis of a commercial 802.11n MIMO 2??e3 dual band (2.4 and 5 GHz) system focusing on the operational throughput performance...
OFDM (Orthogonal Frequency-Division Multiplexing) is a wideband digital modulation scheme which is critically dependent on linearity in the hardware system, due to its reliance on Fourier Transformation and its inherently high peak-to-average power ratio (PAPR), and minimization of nonlinearity is thus a priority. In this paper the effectiveness of a predistortion based on the Hammerstein model dealing...
This paper presents an analysis of a commercial 802.11n MIMO 2×3 dual band (2.4 & 5 GHz) system focusing on the operational throughput performance over an indoor environment with Line of Sight and Non Line of Sight scenarios. Although many authors have provided evidence on the effectiveness of this technology in field strength distribution, throughput or propagation-simulation environments, efforts...
This paper describes the application of a new hybrid method of moments, with generic and sub-gridded finite-difference time-domain approach (MoM-FDTD-(SG)FDTD) for modelling the interaction between an applied excitation placed in close proximity with an inhomogeneous human body model. The source is provided by a small low frequency RFID antenna tag, operating at 900 MHz. Near and far fields performance...
The envelope correlation for a two-element antenna array may be calculated using the antenna radiation fields, or more simply from the scattering parameters of the system. The use of scattering parameters provides a major simplification over the direct use of field data. In this paper we propose a modification of the scattering parameter method which also includes the antenna losses. This approach...
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