André Noll Barreto

Learn More
—The downlink capacity tends to be the limiting factor in future communications systems. In this paper, we propose two schemes for the downlink of code-division multiple-access systems that help reduce the multiuser interference by jointly precoding the transmitted signal based on knowledge of the downlink channel. Methods that operate on blocks of bits(More)
The Rake receiver is a well known technique in spread spectrum systems, which is used to obtain signal diversity in multipath environments. In TDD systems, a technique known as pre-Rake has been proposed recently, in which the signal-processing is transferred to the transmitter, and it has been shown that this technique provides a capacity increase in the(More)
In this paper we propose two precoding schemes for the downlink of CDMA systems which help reduce the multiuser interference by jointly precoding the transmitted signal based on knowledge of the downlink channel. These methods provide a substantial capacity increase without requiring complex multiuser detectors at the mobile terminals and can be applied for(More)
Spread-spectrum systems are used to transmit over frequency selective fading channels. The RAKE receiver is a well-established technique to exploit the multipath diversity. However, if the channel impulse response (CIR) is known a priori in the transmitter, the signal can be precoded to increase the SNR at the receiver while the transmit power remains(More)
In this paper we present a flexible air interface for an Integrated Broadband Mobile System, which utilises adaptive antenna arrays in three configurations. These correspond to different classes of users which support different data rates and Quality of Service requirements. Due to the complexity of smart antenna algorithms, a trade-off between data rate(More)
In this paper we present an interference analysis which reveals capacity reserves for a hierarchical GSM radio network. In the investigated concept a low-power Cordless Telephony System reuses the frequencies of a cellular GSM system based on Total Frequency Hopping (T-FH) multiple access. Based on a novel simulation method, which considers the dynamics of(More)
'Mobile communications is characterized by a fast growing number of users and an increasingly heterogeneous data traffic due to emerging multimedia packet services. Likewise, users desire more mobility support, thus demanding permanent availability at any place and any speed. The conventional answer to this problem is building new wireless standards. But(More)