Thomas L. Marzetta

Bio: Thomas L. Marzetta is an academic researcher from New York University. The author has contributed to research in topics: MIMO & Precoding. The author has an hindex of 57, co-authored 206 publications receiving 45509 citations. Previous affiliations of Thomas L. Marzetta include Mathematical Sciences Research Institute & Alcatel-Lucent.

MIMO System Having A Plurality Of Service Antennas For Data Transmission And Reception And Method Thereof

Abstract: Embodiments provide a MIMO system having a plurality of service antennas and method for data transmission and reception. The system includes a plurality of service antennas, where each service antenna is configured to simultaneously serve a plurality of terminals and independently receive a pilot sequence from the plurality of terminals. The system further includes a plurality of channel estimation units configured to independently generate an antenna-specific channel estimate based on the received pilot sequence and a plurality of pre-coding units configured to independently generate a coded signal to be transmitted to the plurality of terminals via a respective service antenna based on a set of data symbols and the antenna-specific channel estimate.

What is the Value of Joint Processing of Pilots and Data in Block-Fading Channels?

Abstract: The spectral efficiency achievable with joint processing of pilot and data symbol observations is compared with that achievable through the conventional (separate) approach of first estimating the channel on the basis of the pilot symbols alone, and subsequently detecting the data symbols. Studied on the basis of a mutual information lower bound, joint processing is found to provide a non-negligible advantage relative to separate processing, particularly for fast fading. It is shown that, regardless of the fading rate, only a very small number of pilot symbols (at most one per transmit antenna and per channel coherence interval) should be transmitted if joint processing is allowed.

Uplink interference reduction in Large Scale Antenna Systems.

Abstract: A massive MIMO system entails a large number (tens or hundreds) of base station antennas serving a much smaller number of terminals. These systems demonstrate large gains in spectral and energy efficiency compared with the conventional MIMO technology. As the number of antennas grows, the performance of a massive MIMO system gets limited by the interference caused by pilot contamination. Ashikhmin and Marzetta proposed (under the name of Pilot Contamination Precoding) large scale fading precoding (LSFP) and large scale fading decoding (LSFD) based on limited cooperation between base stations. They showed that zero-forcing LSFP and LSFD eliminate pilot contamination entirely and lead to an infinite throughput as the number of antennas grows. In this paper, we focus on the uplink and show that even in the case of a finite number of base station antennas, LSFD yields a very large performance gain. In particular, one of our algorithms gives a more than 140 fold increase in the 5% outage data transmission rate! We show that the performance can be improved further by optimizing the transmission powers of the users. Finally, we present decentralized LSFD that requires limited cooperation only between neighboring cells.

Holographic MIMO Communications Under Spatially-Stationary Scattering

Abstract: Holographic MIMO is a spatially-constrained MIMO system with a massive number of antennas, possibly thought of, in its ultimate form, as a spatially-continuous electromagnetic aperture. Accurate and tractable channel modeling is critical to understanding the full potential of this technology. This paper considers arbitrary spatially-stationary scattering and provides a 4D plane-wave representation in Cartesian coordinates, which captures the essence of electromagnetic propagation and allows to evaluate the capacity of Holographic MIMO systems with rectangular volumetric arrays. The developed framework generalizes the virtual channel representation, which was originally developed for uniform linear arrays.

Interference Reduction in Multi-Cell Massive MIMO Systems II: Downlink Analysis for a Finite Number of Antennas

Abstract: Sharing global channel information at base stations (BSs) is commonly assumed for downlink multi-cell precoding. In the context of massive multi-input multi-output (MIMO) systems where each BS is equipped with a large number of antennas, sharing instant fading channel coefficients consumes a large amount of resource. To consider practically implementable methods, we study in this paper interference reduction based on precoding using the large-scale fading coefficients that depend on the path-loss model and are independent of a specific antenna. We focus on the downlink multi-cell precoding designs when each BS is equipped with a practically finite number of antennas. In this operation regime, pilot contamination is not the dominant source of interference, and mitigation of all types of interference is required. This paper uses an optimization approach to design precoding methods for equal qualities of service (QoS) to all users in the network, i.e.,maximizing the minimum signal-to-interference-plus-noise ratios (SINRs) among all users. The formulated optimization is proved to be quasi-convex, and can be solved optimally. We also propose low-complexity suboptimal algorithms through uplink and downlink duality. Simulation results show that the proposed precoding methods improve 5% outage rate for more than 10 3 times, compared to other known interference mitigation techniques.

Capacity of Multi‐antenna Gaussian Channels

Abstract: We investigate the use of multiple transmitting and/or receiving antennas for single user communications over the additive Gaussian channel with and without fading. We derive formulas for the capacities and error exponents of such channels, and describe computational procedures to evaluate such formulas. We show that the potential gains of such multi-antenna systems over single-antenna systems is rather large under independenceassumptions for the fades and noises at different receiving antennas.

Cognitive radio: brain-empowered wireless communications

Abstract: Cognitive radio is viewed as a novel approach for improving the utilization of a precious natural resource: the radio electromagnetic spectrum. The cognitive radio, built on a software-defined radio, is defined as an intelligent wireless communication system that is aware of its environment and uses the methodology of understanding-by-building to learn from the environment and adapt to statistical variations in the input stimuli, with two primary objectives in mind: /spl middot/ highly reliable communication whenever and wherever needed; /spl middot/ efficient utilization of the radio spectrum. Following the discussion of interference temperature as a new metric for the quantification and management of interference, the paper addresses three fundamental cognitive tasks. 1) Radio-scene analysis. 2) Channel-state estimation and predictive modeling. 3) Transmit-power control and dynamic spectrum management. This work also discusses the emergent behavior of cognitive radio.

What Will 5G Be

Abstract: What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

Millimeter Wave Mobile Communications for 5G Cellular: It Will Work!

Abstract: The global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm-wave) frequency spectrum for future broadband cellular communication networks. There is, however, little knowledge about cellular mm-wave propagation in densely populated indoor and outdoor environments. Obtaining this information is vital for the design and operation of future fifth generation cellular networks that use the mm-wave spectrum. In this paper, we present the motivation for new mm-wave cellular systems, methodology, and hardware for measurements and offer a variety of measurement results that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.