Information Transmission and Radio Communications

Research focus

The Peer review has evaluated this group as Excellent

The most important research activities of this group are concerned with transmission of information, with applications in particular to radio channels. The technical background of the components of the group is modulation, detection theory, channel estimation and equalization, synchronization, information theory, block codes and algebraic decoding, and turbo-like codes with iterative decoding. The group expertise is mainly applied to broadband digital radio, cellular radio systems like, e.g., WiMax, indoor wireless communications, and Ultra Wide Band (UWB) impulse radio communications. Interference mitigation in MIMO-OFDM systems, smart and reconfigurable antennas, multiuser diversity, crosslayer (PHY/MAC) optimisation and channel scheduling, cooperative transmission and relay systems, design and analysis of the physical layer features for multiple access, adaptive modulation and coding, multiuser scheduling, and code division multiple access are some of the system aspects dealt with by the group. A standard activity in coding theory is the design and the evaluation of performance of turbo product codes and convolutional turbo codes, in particular in the error floor region. Much experience in this area has been gained, and new methods for the design of the interleaver and the evaluation of the distance spectrum of turbo codes have been developed. Also the application of high rate turbo codes to multilevel modulations, to achieve high bandwidth efficiency, has been studied. Classical block codes, like Reed Solomon codes, are receiving renewed interest since efficient soft decoding of these codes is becoming feasible. Maximum likelihood decoding is still too complex. Hence, there is much interest in simplified decoders. As to channel estimation and equalization, there are many situations in which maximum likelihood sequence estimation (MLSE) is unacceptably complex. The complexity of MLSE grows exponentially with the size of the constellation, with the number of MIMO antennas, and with the channel memory. Space-time codes add further complexity. Much work has been devoted to simplifications of the MLSE detector, retaining as much as possible of its performance. Simplified sequence detectors are useful not only in radio applications, but also, for instance, in digital recording on magnetic media where the demand for higher and higher data density is all the time pressing. The expertise in near optimal detection is being applied also to these channels, which have some specific features, as noise is neither additive nor white and depends on the recorded information. Channel estimation and turbo equalization with iterative decoding are typical aspects of indoor wireless communications. The aim is of exploiting channel diversity to combat spatial interference, with much emphasis on complexity reduction. The design of SISO equalizers and decoders characterized by highly parallel architectures and high speed is a side activity.

Dipartimento di afferenza

Dipartimento di Elettronica e Informazione (DEI)

Docenti afferenti

Sandro Bellini (full professor)
Guido Tartara (full professor)
Arnaldo Spalvieri (associate professor)
Maurizio Magarini (assistant professor)
Luca Reggiani (assistant professor)