Nowadays, wireless communications have become an essential part of our lives. Billions of electronic devices such as smartphones, cell phones, televisions, laptops, tablets, and even cars use wireless communication standards to access Internet, connect to other devices, or receive information. Most of the latest standards of wireless communications use orthogonal frequency-division multiplexing (OFDM) due to its high spectral efficiency. In wireless links, the multipath fading of the transmitted signal can severely degrade the bit error rate (BER) in the receiver. Antenna diversity is a technique commonly utilized to counteract the effect of multipath fading, however it has several limitations due to the additional radio frequency (RF) chains that it requires. To overcome this problem, an OFDM receiver using an electronically steerable passive array radiator (ESPAR) antenna was previously proposed to improve the BER without requiring additional RF chains.
In the first part of the presentation, a multiple input multiple output-orthogonal frequency-division multiplexing (MIMO-OFDM) receiver using a 3-element ESPAR antenna is introduced. This diversity receiver, which only has two RF chains in the receiver side, obtains a BER close to a conventional 2x4 MIMO-OFDM system that has four RF chains. The simulation results show that the receiver can obtain a diversity gain of about 14 dB using perfect channel state information (CSI). For the channel estimation, two channel estimators are proposed. The results show that the compressed sensing-based channel estimation obtains a good accuracy while requiring a low computational cost.
Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) is a digital TV standard developed and used in Japan that utilizes OFDM technology. In on-vehicle ISDB-T receivers, the received signal can be severely affected by multipath fading and the movement of the car. The usual solution to overcome these problems is to use an ISDB-T receiver with antenna diversity, but the additional antennas and cabling are important drawbacks in terms of installation time. The second part of this presentation introduces two ESPAR antenna-assisted ISDB-T receivers that only require one antenna, thus its installation in a car can be simplified. An ISDB-T receiver with 3-element ESPAR antenna is presented and its performance is evaluated considering the ideal and real models of the ESPAR antenna. Then, an ISDB-T receiver with 4-elements ESPAR antenna is proposed and it also uses compressed sensing-based channel estimation. The results show that this receiver also obtains an important improvement in the BER performance.