recentpopularlog in

pierredv : mimo   15

Massive MIMO inventor Marzetta takes over leadership of NYU Wireless from Rappaport | FierceWireless
"NYU Wireless appointed Thomas Marzetta, who is credited as the originator of Massive MIMO technology, as director of the research center at the NYU Tandon School of Engineering, replacing founder Theodore (Ted) Rappaport."
MIMO  FierceWireless  NYU  Ted-Rappaport 
27 days ago by pierredv
Beyond Massive MIMO: The Potential of Data Transmission With Large Intelligent Surfaces - IEEE Journals & Magazine
Via Marina Petrova, May 2019

In this paper, we consider the potential of data transmission in a system with a massive number of radiating and sensing elements, thought of as a contiguous surface of electromagnetically active material. We refer to this as a large intelligent surface (LIS), which is a newly proposed concept and conceptually goes beyond contemporary massive MIMO technology. First, we consider capacities of single-antenna autonomous terminals communicating to the LIS where the entire surface is used as a receiving antenna array in a perfect line-of-sight propagation environment. Under the condition that the surface area is sufficiently large, the received signal after a matched-filtering operation can be closely approximated by a sinc-function-like intersymbol interference channel. Second, we analyze a normalized capacity measured per unit surface, for a fixed transmit power per volume unit with different terminal deployments. As terminal density increases, the limit of the normalized capacity [nats/s/Hz/volume-unit] achieved when wavelength λ approaches zero is equal to half of the transmit power per volume unit divided by the noise spatial power spectral density. Third, we show that the number of independent signal dimensions that can be harvested per meter deployed surface is 2/λ for one-dimensional terminal deployment, and π/λ 2 per square meter for two- and three-dimensional terminal deployments. Finally, we consider implementations of the LIS in the form of a grid of conventional antenna elements, and show that the sampling lattice that minimizes the surface area and simultaneously obtains one independent signal dimension for every spent antenna is the hexagonal lattice.
MIMO  antennas  smart-materials  nanomaterials  LIS  metamaterials 
may 2019 by pierredv
Massive MIMO Will Create More Wireless Channels, But Also More Vulnerabilities - IEEE Spectrum, Nov 2018
"As wireless communications systems have to accommodate an ever-increasing number of data transfers, a lack of sufficient protocols for ensuring that data is transferred to the correct user could leave systems open to an attack."

"A major constraint of this approach, especially as the number of communication channels for each base station continues to grow, is the limited number of pilots available. Sometimes, users must be assigned the same pilot sequence, which can interfere with the proper transfer of data and lead to poor system performance. This is called pilot contamination. But this contamination can also be harnessed by an attacker to purposely interfere with data transfers. "

"when an attacker is close to the base station, within 300 meters or closer, he or she can impose their own pilots strongly enough to reduce the total transmission rate of a massive MIMO system by more than 50 percent"

"Pilot contamination can also be used to siphon off data transfers if the attacker’s pilot signals are strong enough, threatening the privacy of wireless communications. "
IEEE-Spectrum  spectrum  cybersecurity  cyber-spectrum  MIMO 
november 2018 by pierredv
Hybrid beamforming for 5G MIMO arrays | EDN Feb 2018
"Designers have two options for beamforming, one more practical than the other. If cost and power were not constrained in 5G systems, dedicated receive and transmit paths could be added for each MIMO array element. This type of “all digital” beamforming architecture would provide the most flexibility from a system-level standpoint to form beams in large multiuser scenarios.

Cost and power are constrained, however, and that leaves hybrid beamforming – “hybrid” in that analog phase shifters are integrated with the digital circuitry. And whenever digital and analog are integrated, that’s another place where a system-level approach to design is recommended. "
antennas  5G  beamforming  MIMO 
october 2018 by pierredv
RFS - Beamforming vs. MIMO antennas, Mar 2014
Last updated on 01-Mar-2014
Written by Written by Chuck Powell, RFS Meriden

MIMO (Multiple Input Multiple Output) antennas operate by breaking high data rate signals into multiple lower data rate signals in Tx mode that are recombined at the receiver. Beamforming arrays are inherently different from MIMO in that the multiple columns of dipoles work together to create a single high gain signal. While both techniques work well, an antenna optimized for one method, does not work well for the other. Compromise geometries exist, but the user is sacrificing the performance of the system in order to save money on the relatively inexpensive antenna.
RFS’ white paper discusses the architectural differences between an antenna that has been designed for MIMO performance and one that has been optimized for beamforming. It will explain why antenna characteristics that are desirable for MIMO will result in a degradation of the beamforming ability of the antenna.
The paper will also talk about the differences of beamforming antennas that are used in active and passive systems.
antennas  MIMO  beamforming  antenna-arrays 
october 2018 by pierredv
MIMO testbed with an insight into signal strength distribution around transmitter/receiver sites - IEEE Conference Publication
This paper presents a high precision test-bed to obtain an insight into the operation of a multiple element antenna (MEA) communication system in an indoor environment. In this system, transmitter and receiver are equipped with 180deg or 90deg 3 dB hybrids whose two output ports are terminated with co-polar monopole antennas. By feeding the signal to one of the remaining two ports of the hybrids various radiation patterns are established. These in turn create various communication channels formed by MEA and a surrounding scattering environment. The testbed allows for the signal strength measurements around the receiver/transmitter sides for various radiation pattern modes generated by transmitting and receiving array antennas operating in conjuncture with the hybrids. Details concerning mechanical, electrical and electronics hardware and associated measurement software are described. Initial measurement results in the ISM 2.4 GHz band for a 2times2 MIMO system that includes Bluetooth modules equipped with planar monopoles and 180deg/90deg hybrids are given
IEEE-Xplore  MIMO  antennas  signal-strength  statistics 
october 2018 by pierredv
Industry Voices—Madden: A shake-up is coming to RRH semiconductors for LTE base stations | FierceWireless
"In the market for mobile infrastructure, the change to Massive MIMO is shaking up the established order. Comfortable players like Xilinx and Analog Devices are developing radically different and new semiconductor modules to capture a larger share of the future market, with higher levels of integration. As one simple example, we will see integration of data converters with the digital front end, to cut power consumption by 40%. The size of the radio will shrink by 70% or more, so that the OEMs can line up 64 radios together in a Massive MIMO array. It’s not your father’s base station anymore."

"For the 80-100 chip vendors that support the RRH, this year is a critical time. Each supplier must choose a direction for 2018-2019 products, and the uncertainty around 16T16R or 128T128R is paralyzing many of them. But there’s no time to wait: The wide bandwidth and high performance required in 5G will drive a new profit cycle in RF semiconductors, so chip vendors can’t miss the 2019-2020 wave of deployment."
FierceWireless  opinion  semiconductors  cellular  infrastructure  MIMO  massive-MIMO  trends  5G 
july 2017 by pierredv
Qualcomm exec: MU-MIMO, 802.11ad, smart gateway show maturation of Wi-Fi - FierceWirelessTech
Qualcomm and other Wi-Fi vendors are bringing technologies from the cellular space like MIMO and OFDMA into the Wi-Fi industry to make Wi-Fi connections more reliable and efficient. . . [Todd Antes, vice president of product management at Qualcomm Atheros] "said that the company is now offering "multi-user" MIMO technology in Wi-Fi, dubbed MU-MIMO" "Qualcomm is also showing off its 802.11ad technology, which works in the 60 GHz band and is based on Qualcomm's acquisition of Wilocity last year ... Qualcomm is sampling 802.11ad chips now and expects products with the chips to be released next year."
Qualcomm  Wi-Fi  MU-MIMO  802.11ad  MIMO  60GHz 
january 2015 by pierredv
[1304.6690] Massive MIMO for Next Generation Wireless Systems
"Multi-user Multiple-Input Multiple-Output (MIMO) offers big advantages over conventional point-to-point MIMO: it works with cheap single-antenna terminals, a rich scattering environment is not required, and resource allocation is simplified because every active terminal utilizes all of the time-frequency bins. However, multi-user MIMO, as originally envisioned with roughly equal numbers of service-antennas and terminals and frequency division duplex operation, is not a scalable technology. Massive MIMO (also known as "Large-Scale Antenna Systems", "Very Large MIMO", "Hyper MIMO", "Full-Dimension MIMO" & "ARGOS") makes a clean break with current practice through the use of a large excess of service-antennas over active terminals and time division duplex operation. Extra antennas help by focusing energy into ever-smaller regions of space to bring huge improvements in throughput and radiated energy efficiency. Other benefits of massive MIMO include ..."
MIMO  research  arXiv 
february 2014 by pierredv
Google's Moto X tops LTE network connectivity test - FierceWirelessTech
"Google's (NASDAQ:GOOG) Motorola Mobile division scored a win as its Moto X smartphone impressively outperformed devices from Samsung, LG and HTC in tests of network connectivity undertaken by Signals Research Group." "noted the handset garnered more than 35 percent higher average throughput than the other devices across all correlated and uncorrelated test scenarios. In addition, the Moto X could sustain a data call at signal levels as much as 9 dB lower than levels for the other devices tested" "The disparity in the devices' performance was partly a reflection of how well the devices leveraged MIMO capabilities. "
Google  Motorola  FierceWireless  LTE  MIMO  devices 
january 2014 by pierredv
Cambium pitches new 5 GHz platform for broadband access in rural, unserved markets - FierceWireless:Tech
"Cambium's ePMP is an integrated point-to-point (PTP) and point-to-multipoint (PMP) fixed wireless access solution, which the vendor said can deliver at least 200 Mbps of throughput using 2x2 MIMO-OFDM technologies. The vendor said ePMP is able to handle up to 120 subscribers per unit without service degradation due in part to spectral efficiency achieved through GPS sychronization. "
MIMO  point-to-point  microwave  GPS  5GHz 
october 2013 by pierredv
Prof. Robert W. Heath Jr.
coordination between users can help overcome the limiting effects of interference generated by simultaneous transmission
interference  cellular  MIMO  RF  ** 
february 2012 by pierredv

Copy this bookmark:

to read