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.

Interference Reduction in Multi-Cell Massive MIMO Systems I: Large-Scale Fading Precoding and Decoding

Abstract: A wireless massive MIMO system entails a large number (tens or hundreds) of base station antennas serving a much smaller number of users, with large gains in spectral-efficiency and energy-efficiency compared with conventional MIMO technology. Until recently it was believed that in multi-cellular massive MIMO system, even in the asymptotic regime, as the number of service antennas tends to infinity, the performance is limited by directed inter-cellular interference. This interference results from unavoidable re-use of reverse-link training sequences (pilot contamination) by users in different cells. We devise a new concept that leads to the effective elimination of inter-cell interference in massive MIMO systems. This is achieved by outer multi-cellular precoding, which we call Large-Scale Fading Precoding (LSFP). The main idea of LSFP is that each base station linearly combines messages aimed to users from different cells that re-use the same training sequence. Crucially, the combining coefficients depend only on the slow-fading coefficients between the users and the base stations. Each base station independently transmits its LSFP-combined symbols using conventional linear precoding that is based on estimated fast-fading coefficients. Further, we derive estimates for downlink and uplink SINRs and capacity lower bounds for the case of massive MIMO systems with LSFP and a finite number of base station antennas.

Self-steering directional hearing aid and method of operation thereof

Abstract: A hearing aid and a method of enhancing sound. In one embodiment, the hearing aid includes: (1) a direction sensor configured to produce data for determining a direction in which attention of a user is directed, (2) microphones to provide output signals indicative of sound received at the user from a plurality of directions, (3) a speaker for converting an electrical signal into enhanced sound and (4) an acoustic processor configured to be coupled to the direction sensor, the microphones, and the speaker, the acoustic processor being configured to superpose the output signals based on the determined direction to yield an enhanced signal based on the received sound, the enhanced signal having a higher content of sound received from the direction than sound received at the user.

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 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. Earlier A. Ashikhmin and T. Marzetta proposed (under the name of Pilot Contamination Precoding) Large Scale Fading Precoding (LSFP) and 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.

Multiplex antenna communication system and method therefor

Abstract: PROBLEM TO BE SOLVED: To enhance cost-effectiveness and to simply realize high bit rate by transmitting a virtual transmitting signal through the partial aggregation of a virtual sub-channel by using propagation information. SOLUTION: A first unit 12 transmits a diagonal matrix D to a channel encoder/modulator 24 in transmission from the first unit 12 to the second unit 14 so as to encode and modulate an information stream from a data source 28. The channel encoder/modulator 211 encodes and modulate the information stream, forms plural sub-information streams which differ in accordance with the non-zero value of the diagonal matrix D and generates a virtual transmitting signal. The virtual transmitting signal is expressed as a vector and its respective configuration components are transmitted by the respective virtual sub-channels. Moreover, a unitary conversion block 30 executes the unitary conversion of the virtual transmitting signal by multiplexing the virtual transmitting signal through the use of the conjugate transposition of a unitary matrix ϕ. Finally, the first unit 12 utilizes the result of unitary conversion 30 so as to generate the base band version of the actual transmitting signal.

Capacity performance of multicell large-scale antenna systems

Abstract: The performance of a multicell large scale antenna system (LSAS) is conveniently characterized by capacity lower-bounds that explicitly account for channel-estimation error, the type of linear spatial multiplexing/de-multiplexing (conjugate beamforming or zero-forcing on the forward link and matched-filtering or zero-forcing on the reverse link), power-control, non-coherent inter-cell interference, and coherent inter-cell interference due to pilot-contamination.

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.