M. Calvo

Phase noise and sub-carrier spacing effects on the performance of an OFDM communication system

This letter analyzes the phase noise effects on an orthogonal frequency division multiplexing (OFDM) signal and its dependence with the sub-carrier spacing. Pilot-based channel estimation, which has been suggested as a means of combating the channel effects, can also correct the phase noise effects under some circumstances, which are investigated.

Parameter optimization and simulated performance of a DVB-T digital television broadcasting system

A prototype of a digital television terrestrial broadcasting system has been implemented according to the European DVB-T standard. The first step in the construction of this prototype involved parameter optimization via simulation. This paper presents the optimization process of the system parameters and the final achieved BER performance. Important design aspects such as interleaving, convolutional puncturing codes, Viterbi decoding, pilot-based channel correction and optimal pilot power are considered. The DVB-T standard offers some suggested values of the C/N ratio needed to achieve the desired BER requirements in the receiver. However, they have been obtained assuming ideal channel correction and synchronization. Simulation results are provided here in non-ideal conditions.

Performance analysis of hybrid broadband access technologies using PLC and Wi-Fi

As power line communications deployment is gaining momentum higher capacity is being demanded. Actually one possible solution to obtain an improved high speed broadband access can be the use of a hybrid technology in an indoor environment. This paper shows experimentally the advantages that could be obtained if the power line communication is joined with the Wi-Fi technology.

Channel estimation for 3G wideband CDMA systems using the Kalman filtering algorithm

Many of the signal processing operations in the receivers for 3G CDMA systems depend on accurate estimates of the multipath fading channel. The performance of RAKE receivers and transmit diversity arrangements will degrade significantly if channel estimates are not accurate. Hence, one of the challenges in the design of 3G systems is accurate estimation of the underlying channel characteristics. The first generation of channel estimation algorithms proposed for 3G systems relied on using the pilot symbols. However, it has been shown through simulations that the small number of pilot symbols available for estimation leads to poor estimates, especially in fast fading conditions. In this paper, we introduce a Kalman filter algorithm for channel estimation that combines pilot symbol based estimates with a channel model. We derive an ARMA model for a typical mobile channel with a Jakes Doppler spectrum and use this model to derive the Kalman filtering algorithm. Through simulation and analysis we show that the Kalman filter algorithm reduces the variance of the channel estimate significantly compared to an estimate based on pilot symbols alone.

Human operator effect on wide-band radio channel characteristics

We analyze how the presence of the human operator body in the vicinity of the antenna of a portable handset modifies wide-band radio channel characteristics such as the time dispersion of the channel.

Smart antennas performance evaluation and capacity increase for WCDMA UMTS

New mobile communication services are appearing, and the rate of demand is rapidly increasing. Smart antennas are presented as a technology capable of satisfying the increased capacity demand. We present some simulation results obtained for the wideband CDMA UMTS vehicular scenario using switched-beam and adaptive antenna technologies. Switched-beam and 120/spl deg/ sectored antenna performances are compared for different user densities. Both intracell and out-of-cell interference are calculated. User mobility and channel models proposed in the UMTS radio transmission technologies specification are used. Results for different angular spread and number of array elements for the adaptive antenna system are also presented.

A DSP-based implementation of adaptive algorithms for a W-CDMA reverse link beamformer

This paper presents a DSP-based implementation of an adaptive beamformer for the W-CDMA reverse link. A comparative study of LMS and RLS adaptive algorithms is shown, which leads to the implementation taking into account both performance results and computational load. Results for fixed-point DSP implementation and floating point simulations are presented.

Assessing the integration of smart antenna systems in UMTS networks

This paper presents the methodology for the integration of smart antennas in UMTS networks. Preliminary results in a typical deployment scenario are provided. This contribution generalizes the methodology proposed by the authors in other works and provides new results on system-level parameters such as load factor and statistics for power dimensioning.

On The Use Of Simulation For The Improvement And Measurement Validation Of A Smart Antenna Prototype

The benefits of using smart antennas in a wireless mobile system have been thoroughly studied in recent years, showing an improvement in the antenna gain, a reduction of interfering power and, as a consequence, an increase in the system capacity. The real implementation and measurement of a smart antenna for the UMTS system are presented in this paper. Implementation impairments produce undesirable effects, such as frequency mismatch and coupling between RF channels. In order to minimize these effects, some simulations of the real system and the main non-ideal effects were carried out, so the analysis of these effects were affordable. Some solutions to the real implementation impairments were proposed and simulated, and the ones with better performance have been implemented and the obtained results are reported in this paper. Since traditional measurement methods are no longer suitable for the characterization of a smart antenna, a new method to measure the performance of the system is also introduced. The results show the feasibility of the system, which outperforms the performance of a conventional sectored antenna. An improvement of 6 dB in gain and 12.5 dB in carrier to interference ratio (CIR) was obtained with this prototype. The measurements were also validated by comparison with simulation results.

Effects of implementation impairments in the performance of a W-CDMA smart antenna

The benefits of using smart antennas in a wireless mobile system have been thoroughly studied in recent years, showing an improvement in the antenna gain, a reduction of interfering power and, as a consequence, an increase in the system capacity. The real implementation of a smart antenna for the UMTS system is presented in this paper, focusing on the digital processing module. Implementation impairments produce undesirable effects, such as frequency mismatch and coupling between RF channels. In order to overcome these effects some solutions have been proposed and implemented, and the results are reported in this paper. Since traditional measurement methods are no longer suitable for the characterization of a smart antenna a method to measure the performance of the system is also introduced. The results show the feasibility of the system, which outperforms the features of a conventional sectored antenna. An improvement of 6 dB in gain and 12.5 dB in carrier to interference ratio (CIR) was obtained with this prototype.