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.

Performance of pilot reuse in multi-cell Massive MIMO

Abstract: Pilot reuse in multiple cell Massive MIMO induces coherent inter-cell interference that does not disappear with large numbers of antennas. A simple way to mitigate pilot contamination is to use a pilot reuse factor that is greater than one, which surrounds the home cell by one or more rings of non-contaminating cells. The penalty for this measure is that training consumes an increasing fraction of the slot. We perform comprehensive multiple cell semi-analytical simulations for various scenarios in order to determine the optimum pilot reuse factor. We find that in dense urban deployments, the relatively small cell size combined with low user mobility dictates pilot reuse seven. Conversely in suburban deployments pilot reuse three is optimal. Our conclusions are at variance with others who advocate pilot reuse one, which we attribute to a great extent to the fact that our performance criterion is 95% likely per user throughput rather than sum throughput.

A large scale antenna system with overlaying small cells

Abstract: A large-scale antenna system (LSAS) base station transmits one or more first signals on one or more first channels corresponding to one or more first access terminals associated with the LSAS base station concurrently with nulling one or more second channels corresponding to one or more second access terminals associated with one or more small cells. The first signal(s) is/are transmitted synchronously with the second signal (s) transmitted by the small cell(s).

Nonparametric spectral analysis with missing data via the EM algorithm

Abstract: We consider nonparametric complex spectral estimation of data sequences with missing samples occurring in arbitrary patterns. Several nonparametric algorithms have recently been developed to deal with the missing-data problem. They include, for example, GAPES for gapped data and PG-APES, PG-CAPON for periodically gapped data. However, they are not really suitable for the general missing-data problem where the missing data samples occur in arbitrary patterns. In this paper, we deal with a general missing-data spectral estimation problem for which we develop two nonparametric missing-data amplitude and phase estimation (MAPES) algorithms, both of which make use of the expectation maximization (EM) algorithm. Numerical results are provided to demonstrate the effectiveness of the proposed algorithms.

Coordinated Multi-Point Massive MIMO Cellular Systems with Sectorized Antennas

Abstract: Non-cooperative cellular Massive MIMO, combined with max-min power control, is known to give substantial improvements in per-user throughput compared with conventional 4G technology. We investigate further refinements to Massive MIMO, first, in the form of three-fold sectorization, which can be viewed as an effective reduction in cell size, and second, three-fold sectorization combined with coordinated multi-point operation, in which the three sectors cooperate in the joint service of their users. We analyze the downlink performance of the system for zero-forcing precoding and propose centralized and decentralized power control schemes. The simulation results reveal that sectorization, and multi-point coordinated sectorization lead to 2.36× and 8.56× improvements in the 95%-likely per-user throughput, respectively.

Fourier Plane-Wave Series Expansion for Holographic MIMO Communications.

Abstract: Imagine a MIMO communication system that fully exploits the propagation characteristics offered by an electromagnetic channel and ultimately approaches the limits imposed by wireless communications. This is the concept of Holographic MIMO communications. Accurate and tractable channel modeling is critical to understanding its full potential. Classical stochastic models used by communications theorists are derived under the electromagnetic far-field assumption. However, such assumption breaks down when large (compared to the wavelength) antenna arrays are considered - as envisioned in future wireless communications. In this paper, we start from the first principles of wave propagation and provide a Fourier plane-wave series expansion of the channel response, which fully captures the essence of electromagnetic propagation in arbitrary scattering and is also valid in the (radiative) near-field. The expansion is based on the Fourier spectral representation and has an intuitive physical interpretation, as it statistically describes the angular coupling between source and receiver. When discretized, it leads to a low-rank semi-unitarily equivalent approximation of the spatial electromagnetic channel in the angular domain. The developed channel model is used to compute the ergodic capacity of a point-to-point Holographic MIMO system with different degrees of channel state information.

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.