3,375 research outputs found
Efficient DSP and Circuit Architectures for Massive MIMO: State-of-the-Art and Future Directions
Massive MIMO is a compelling wireless access concept that relies on the use
of an excess number of base-station antennas, relative to the number of active
terminals. This technology is a main component of 5G New Radio (NR) and
addresses all important requirements of future wireless standards: a great
capacity increase, the support of many simultaneous users, and improvement in
energy efficiency. Massive MIMO requires the simultaneous processing of signals
from many antenna chains, and computational operations on large matrices. The
complexity of the digital processing has been viewed as a fundamental obstacle
to the feasibility of Massive MIMO in the past. Recent advances on
system-algorithm-hardware co-design have led to extremely energy-efficient
implementations. These exploit opportunities in deeply-scaled silicon
technologies and perform partly distributed processing to cope with the
bottlenecks encountered in the interconnection of many signals. For example,
prototype ASIC implementations have demonstrated zero-forcing precoding in real
time at a 55 mW power consumption (20 MHz bandwidth, 128 antennas, multiplexing
of 8 terminals). Coarse and even error-prone digital processing in the antenna
paths permits a reduction of consumption with a factor of 2 to 5. This article
summarizes the fundamental technical contributions to efficient digital signal
processing for Massive MIMO. The opportunities and constraints on operating on
low-complexity RF and analog hardware chains are clarified. It illustrates how
terminals can benefit from improved energy efficiency. The status of technology
and real-life prototypes discussed. Open challenges and directions for future
research are suggested.Comment: submitted to IEEE transactions on signal processin
Apollo guidance, navigation, and control: Candidate configuration trade study, Stellar-Inertial Measurement System (SIMS) for an Earth Observation Satellite (EOS)
The ten candidate SIMS configurations were reduced to three in preparation for the final trade comparison. The report emphasizes subsystem design trades, star availability studies, data processing (smoothing) methods, and the analytical and simulation studies at subsystem and system levels from which candidate accuracy estimates will be presented
A Tight Bound for Probability of Error for Quantum Counting Based Multiuser Detection
Future wired and wireless communication systems will employ pure or combined
Code Division Multiple Access (CDMA) technique, such as in the European 3G
mobile UMTS or Power Line Telecommunication system, but also several 4G
proposal includes e.g. multi carrier (MC) CDMA. Former examinations carried out
the drawbacks of single user detectors (SUD), which are widely employed in
narrowband IS-95 CDMA systems, and forced to develop suitable multiuser
detection schemes to increase the efficiency against interference. However, at
this moment there are only suboptimal solutions available because of the rather
high complexity of optimal detectors. One of the possible receiver technologies
can be the quantum assisted computing devices which allows high level
parallelism in computation. The first commercial devices are estimated for the
next years, which meets the advert of 3G and 4G systems. In this paper we
analyze the error probability and give tight bounds in a static and dynamically
changing environment for a novel quantum computation based Quantum Multiuser
detection (QMUD) algorithm, employing quantum counting algorithm, which
provides optimal solution.Comment: presented at IEEE ISIT 2002, 7 pages, 2 figure
縦型ボディチャネルMOS Field-Effect Transistorを用いたマイクロプロセッサ向け高効率・高集積DC-DCコンバータとそのパワーマネジメントに関する研究
Tohoku University遠藤哲郎課
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