J. Granado

Multi-carrier Receiver for Broadband Power Line Communications

This paper presents the design of a broadband power line communication (BPLC) receiver optimized for reduced hardware complexity. To this end, the Radio-Frequency (RF) stage uses a direct conversion architecture while some innovative solutions are used in the base-band signal processing, such as a new frequency offset synchronization scheme based on the frequency domain. Every part of the receiver has been optimized using a new non-commercial hardware-software co-simulation package named BROCOLI (Broadband Co-simulation Library) based on a set of hierarchical models, specially developed for this application. A prototype of the BPLC transceiver has been built and some experimental results are shown which validate the design process and the implemented solutions.

Design of an efficient CORDIC-based architecture for synchronization in OFDM

This paper presents a new architecture to estimate the time and frequency offsets required to synchronize packed-based orthogonal frequency division multiplexing (OFDM) modulation receivers. The proposed estimators, which operate in the frequency-domain, use CORDIC (coordinate rotation digital computer) processors to achieve an efficient hardware implementation which is simpler than other computational intensive estimators based on processing in the time-domain. The hardware saving is twofold: the proposed implementation does not require complex cells such as multipliers or dividers; and some cells already existing in OFDM receivers for pay-load demodulation are reused during the synchronization phase. In addition, this paper also shows how to optimize the CORDIC cells, in terms of number of iterations, to provide a given signal-to-noise ratio (SNR) due to approximation error, and proposes an error propagation model for the proposed synchronization architecture

Using broadband power line communications in non-conventional applications

Power Line Communication (PLC) is a mature technology with application to different fields such as automated meter reading or indoor data communication. However, PLC shows a high potential for other nonconventional fields, like communications in vehicles, where little has been reported. This paper presents experimental results obtained with two broadband PLC modems in two different vehicles. The channel capacity and the impulsive noise are analyzed, and a propel model is proposed which can be of interest to guide future deployment of PLC technology in this new application field.

Modeling Airfield Ground Lighting Systems for Narrowband Power-Line Communications

Airfield ground lighting (AGL) systems are responsible for providing visual reference to aircrafts in the airport neighborhood. In an AGL system, a large number of lamps are organized in serial circuits and connected to current regulators that supply energy to the lamps. Controlling and monitoring lamps (including detection and location of burnt-out lamps) are critical for cost-saving maintenance and operation of AGL systems. Power-line Communications (PLC) is an attractive technology to connect elements of the AGL, reusing the power distribution cable as a transmission medium. PLC technologies avoid the installation of new wires throughout the airport infrastructure. This paper proposes a new model for power-line communication links in AGL systems. Every element (isolation transformer, primary circuit cable, and lamps) has been analyzed in laboratory and modeled using SPICE. The resulting models have been integrated to build a complete power-line link model. Simulation results are compared to experimental results obtained in real conditions in the Airport of Seville (Spain).

Reduced complexity ICI cancellation scheme for OFDM DVB-SH receivers

Mitigating the negative effects of Doppler spread is crucial in the future Digital Video Broadcasting Satellite to Handheld (DVB-SH) terminals. The implementation of conventional methods, such us the Decision Feedback Equalization (DFE), to estimate the intercarrier interference is not suitable for low cost DVB-SH terminals. To solve this problem, we propose a new technique, and its hardware architecture, that extremely reduces the consumption of hardware resources. We demonstrate that a reduced implementation of the proposed method, that requires only six multiplications and five additions, performs similar to the DFE method that needs high complexity cells.

Performance evaluation of complementary code combining diversity in DVB-SH

In this paper, the application of code combining diversity in Digital Video Broadcasting Satellite to Handheld (DVB-SH) systems is analyzed. The complementary code combining diversity is a simple and efficient technique that exploits the advantages of a hybrid satellite/terrestrial system. A meaningful diversity gain can be obtained in multiple frequency networks, allowing an improvement of the receiver robustness in both static and mobile scenarios. Furthermore, for typical DVB-SH terminals with two receiver branches, this gain can be easily obtained without increasing the hardware complexity.

A new method for simultaneous fine time synchronization and frequency offset estimation in OFDM with simple hardware

The paper presents a new method to provide simultaneous time and frequency offset estimation that operates in the frequency domain by analyzing the modulus and angle of a synchronization symbol. When compared to those estimators based on computational intensive time-correlations, the main advantage of the proposed estimator is in the hardware implementation. In the proposed method, no additional hardware is required, as the already existing FFT processor and the polar coordinates translator (typically a CORDIC processor) used for OFDM normal operation are reused in the synchronization phase. Simulation results are presented using different conditions and channel models showing a negligible decrease in performance when compared to other methods.

Low Complexity Intercarrier Interference Cancellation for DVB-SH Receivers

In this paper, the authors survey the system degradation due to mobility and propose a new technique to combat the effects of Doppler spread in Digital Video Broadcasting Satellite to Handheld (DVB-SH) receivers. This paper proposes a very low complexity Intercarrier Interference (ICI) cancellation scheme that performs as other existing methods, while reducing significantly the hardware resources consumption. The proposed method is based on implementing a reduced version of the leakage matrix, that models the ICI in a mobile channel. Simulation results show a gain in the carrier to noise ratio C/N up to 9 dB for a bit error rate BER = 10−5 when compared to a DVB-SH receiver with no ICI compensation. In terms of receiver speed, simulations show an improvement up to 50 % in the best case.

Frequency offset estimation in WIMAX receivers

This paper evaluates the performance of a new estimator for fine frequency offset in OFDM packed-based applications. The estimator, which operates in the frequency domain, is based on the inter-carrier interference (ICI) in the received preamble. A new theoretical expression for the estimator as a function of the input frequency offset is proposed. The estimator performance is evaluated for WIMAX receivers, showing an estimation error variance similar to that obtained with other well-known methods based on the processing in the time domain.