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.

Method and apparatus for interference cancellation for antenna arrays

Abstract: Embodiments of the claimed subject matter provide methods and apparatuses for interference cancellation. One embodiment of a method includes estimating, for an antenna in an antenna array including a plurality of antennas, interference parameters using analog signals received at the antenna on each of a plurality of subcarriers. Each interference parameter is associated with one of a plurality of symbols transmitted to one of a plurality of users on one of the plurality of subcarriers. This embodiment also includes canceling interference from analog signals received by the antenna on the plurality of subcarriers using the estimated interference parameters.

Uplink power efficiency of multiuser MIMO with very large antenna arrays

Abstract: A multiplicity of autonomous terminals simultaneously transmits data streams to a compact array of antennas. The array uses imperfect channel-state information derived from transmitted pilots to extract the individual data streams. The power radiated by the terminals can be made inversely proportional to the square-root of the number of base station antennas with no reduction in performance. In contrast if perfect channel-state information were available the power could be made inversely proportional to the number of antennas. A maximum-ratio combining receiver normally performs worse than a zero-forcing receiver. However as power levels are reduced, the cross-talk introduced by the inferior maximum-ratio receiver eventually falls below the noise level and this simple receiver becomes a viable option.

Interference Reduction in Multi-Cell Massive MIMO Systems With Large-Scale Fading Precoding

Abstract: A wireless massive multiple-input multiple-output (MIMO) system entails a large number of base station antennas serving a much smaller number of users, with large gains in spectral efficiency and energy efficiency compared with the conventional MIMO technology Until recently, it was believed that as the number of base station antennas tends to infinity, the performance of such systems is limited by directed inter-cellular interference caused by unavoidable re-use of training sequences (pilot contamination) by users in different cells We devise a new concept of large-scale fading precoding (LSFP) that leads to the effective elimination of inter-cell interference The main idea of LSFP is that base stations linearly combine messages aimed at users from different cells that re-use the same training sequence Crucially, the combining coefficients depend only on the large-scale fading coefficients between the users and the base stations These coefficients change slowly and their number does not depend on the number of base station antennas Thus, the traffic between base stations stays constant even if the number of antennas tends to infinity Furthermore, we derive a capacity lower bound for massive MIMO systems with LSFP and a finite number of base station antennas In this regime, mitigation of all types of interference, not only the pilot contamination, is required We consider optimal and suboptimal LSFP precodings that take into account all sources of interference Our simulations results show that LSFP provides significant gain even for the case of moderate number of base station antennas

Energy Efficiency of Massive MIMO: Cell-Free vs. Cellular

Abstract: Cell-free Massive MIMO (Multiple Input Multiple Output) employs a large number of AP's (Access Points) that are distributed throughout the intended coverage area to simultaneously serve a much smaller number of user AT's (Access Terminals). Conjugate beamforming is the simplest precoding method for the downlink transmission, and allows decentralized precoding processing. Max-min power control maximizes the minimal effective SINR (Signal-to-Interference-plus-Noise Ratio) among all the active users, therefore provides a uniform throughput to all users. Cell- free Massive MIMO with conjugate beamforming precoding and max-min power control is naturally radiated energy efficient due to two facts: a well-known fact that with high probability at least one AP is nearby every user, and a surprising fact that, with max-min power control, a large portion of the AP's does not transmit with full power. We find that a cell-free Massive MIMO can deliver more than 80 Mb/joule in urban, and more than 40 Mb/joule in suburban and rural scenarios. We compare its energy efficiency and spectral efficiency with single cell Massive MIMO systems and demonstrate that in suburban and rural scenarios, cell-free systems can more than double the radiated energy efficiency and at the same time dramatically increase the 95% likely per user throughput, while in an urban scenario, the gain in radiated energy efficiency can be moderate at less than 50% with a comparable 95% likely per user throughput.

Special issue on Massive MIMO

Abstract: Demand for wireless communications is projected to grow by more than a factor of forty or more over the next five years. A potential technology for meeting this demand is Massive MIMO (also called Large-Scale Antenna Systems, Large-Scale MIMO, ARGOS, Full-Dimension MIMO, or Hyper-MIMO), a form of multiuser multipleantenna wireless which promises orders-of-magnitude improvements in spectral-efficiency over 4G technology, and accompanying improvements in radiated energy-efficiency. The distinguishing feature of Massive MIMO is that a large number of service-antennas ? possibly hundreds or even thousands ? work for a significantly smaller number of active autonomous terminals. Upsetting the traditional parity between service antennas and terminals in this manner is a game-changer: The simplest multiplexing precoding and decoding algorithms can be nearly optimal, expensive ultra-linear forty-Watt power amplifiers are replaced by many low-power units, and the favorable action of the law of large numbers can greatly facilitate power-control and resource-allocation.

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.