Steve M. R. Jones

On the performance of DWT and WPT modulation for multicarrier systems

The discrete wavelet transform, DWT, is being considered for multicarrier modulation, and intensive investigations are underway on how this scheme can best be deployed. The performance of the DWT and wavelet packet transform (WPT) has been investigated and compared. There are more narrowband sub-channels in WPT than those that exist in DWT owing to the style of multiresolution adopted by the latter. However, it is found that DWT and WPT perform differently as multicarrier modulations over AWGN and multipath channels. This work helps to inform the selection of base-wavelet families when studying or designing a multicarrier system of this kind.

Statistical Analysis of Refractivity Gradient and

In this communication, nine years of local radiosonde meteorological data, from 1997 to 2005, have been used to calculate the vertical refractivity gradient, ΔN, in the lowest atmospheric layer above the ground surface. The values obtained are used to estimate the parameter β₀, which represents the probability of non-standard propagation. Hourly, monthly and yearly distributions of ΔN in the first 100 meters above the ground are given. Monthly and yearly variations of the mean of ΔN and β₀ are provided and the β₀ values are compared with the ITU maps.

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The MIMO technology towards achieving future generation broadband networks design criteria is presented. Typical next generation scenarios are investigated. The MIMO technology is integrated with the OFDM technology for effective space, time and frequency diversity exploitations for high speed outdoor environment. Two different OFDM design kernels (fast Fourier transform (FFT) and wavelet packet transform (WPT)) are used at the baseband for OFDM system travelling at terrestrial high speed for 800MHz and 2.6GHz operating frequencies. Results show that the wavelet kernel for designing OFDM systems can withstand doubly selective channel fading for mobiles speeds up to 280Km/hr at the expense of the traditional OFDM design kernel, the fast Fourier transform. Keywords—Doppler Effect; Doubly selective fading; frequency- selective fading; OFDM; Wavelet; MIMO

Parameter in the Gulf Region

A new simplified approach is proposed to evaluate the vertical refractivity profile within the lowest 1 km of atmosphere from the analysis of surface refractivity N8 in areas where upper-air data are not available. Upper-air measurements from the nearest available radiosonde location with similar surface profile to these sites are utilized. The profiles of N8 and refractivity extrapolated to sea level No obtained from surface meteorological data using both fixed stations and radiosonde are investigated and compared. Vertical refractivity gradient ΔN is evaluated at three atmospheric layer heights within the first kilometer above the ground in addition to propagation parameters relevant to each atmospheric layer. At six sites, different approaches are compared for the analysis of three important parameters; namely effective earth radius factor k anomalous propagation probability parameter βο and point refractivity gradient at 65 m not exceeded for 1% of time dN1 . The k-factor parameter is investigated using a new weighted average approach of ΔN at 65-m, 100-m, and 1-km layers above the ground. The results are compared with the latest ITU maps and tables for the same area.

Towards a Seamless Future Generation Network for High Speed Wireless Communications

Narrowband path loss measurements are reported for the vehicle-to-vehicle channel between a transmitting antenna 50 cm above the ground and a car-roof-mounted receiver array. Calibration procedures and measurement results are reported for typical urban, suburban and rural-motorway environments and compared with existing mobile channel models to give insight into the large-scale fading behavior in the vehicle-to-vehicle channel.

New Methodology for Predicting Vertical Atmospheric Profile and Propagation Parameters in Subtropical Arabian Gulf Region

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 over an indoor environment for Line of Sight (LOS) and Non Line of Sight (NLOS) scenarios. Efforts on combined field strength distribution, throughput, propagation-channel environments, of this system will be elucidated. The work is focusing on the operational performance of the physical measurements and results compared with simulation model over an indoor environment.

Path loss evaluation for mobile-to-mobile wireless channel

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 to the intrinsic losses.

Indoor Channel Measurement and Prediction for 802.11n System

A miniaturized conical helix antenna is presented, which displays vertical polarization with electrically small dimensions of 10mm×10mm×45mm. The resonance of the antenna is made tunable by adding a variable digital MEMS capacitor load at the bottom of the helix, giving a tuning range of 316 MHz to 400 MHz. The antenna demonstrates considerable impedance matching bandwidth and gain over the entire tuning frequency band. Most importantly, the antenna is capable of compact, flexible and easy integration into a wireless device package or for platform installation.

Envelope correlation formula for (N, N) MIMO antenna array including power losses

Simplified designs of multi-antenna systems with optimum efficiency are receiving attentions. Such simplicities also involve low cost architectures. In this study, we report an evaluation of a new multi-antenna scheme, namely, spatial modulation (SM) that is compared with quasi-orthogonal space time block codes (QOSTBC) scheme over Rayleigh fading channel. The SM scheme has been, earlier, compared with space time block codes (STBC) – a two antenna transmit diversity scheme that achieves full diversity when only two antennas are used. This is extended to QOSTBC scheme that absolves some decoding limitations to attain full diversity. It will be shown that, using the QOSTBC of similar architecture with the SM, even better performance can be achieved in favour of QOSTBC.

Miniaturized tunable conical helix antenna

Wavelets are constructed from the basis sets of their parent scaling functions of the two-scale dilation equation (1). Whereas orthogonal wavelets come from one orthogonal basis set, the biorthogonal wavelets project from different basis sets. Each basis set is correspondingly weighted to form filters, either highpass or lowpass, which form the constituents of quadrature mirror filter (QMF) banks. Consequently, these filters can be used to design wavelets, the differently weighted parameters contributing respective wavelet properties which influence the performance of the transforms in applications, for example multicarrier modulation. This study investigated applications for onward multicarrier modulation applications. The results show that the optimum choice of particular wavelet adopted in digital multicarrier communication signal processing may be quite different from choices in other areas of wavelet applications, for example image and video compression.