1,004 research outputs found
Performance of Spatial Modulation using Measured Real-World Channels
In this paper, for the first time real-world channel measurements are used to
analyse the performance of spatial modulation (SM), where a full analysis of
the average bit error rate performance (ABER) of SM using measured urban
correlated and uncorrelated Rayleigh fading channels is provided. The channel
measurements are taken from an outdoor urban multiple input multiple output
(MIMO) measurement campaign. Moreover, ABER performance results using simulated
Rayleigh fading channels are provided and compared with a derived analytical
bound for the ABER of SM, and the ABER results for SM using the measured urban
channels. The ABER results using the measured urban channels validate the
derived analytical bound and the ABER results using the simulated channels.
Finally, the ABER of SM is compared with the performance of spatial
multiplexing (SMX) using the measured urban channels for small and large scale
MIMO. It is shown that SM offers nearly the same or a slightly better
performance than SMX for small scale MIMO. However, SM offers large reduction
in ABER for large scale MIMO.Comment: IEEE Vehicular Technology Conference Fall 2013 (VTC-Fall 2013),
Accepte
Massive MIMO with Non-Ideal Arbitrary Arrays: Hardware Scaling Laws and Circuit-Aware Design
Massive multiple-input multiple-output (MIMO) systems are cellular networks
where the base stations (BSs) are equipped with unconventionally many antennas,
deployed on co-located or distributed arrays. Huge spatial degrees-of-freedom
are achieved by coherent processing over these massive arrays, which provide
strong signal gains, resilience to imperfect channel knowledge, and low
interference. This comes at the price of more infrastructure; the hardware cost
and circuit power consumption scale linearly/affinely with the number of BS
antennas . Hence, the key to cost-efficient deployment of large arrays is
low-cost antenna branches with low circuit power, in contrast to today's
conventional expensive and power-hungry BS antenna branches. Such low-cost
transceivers are prone to hardware imperfections, but it has been conjectured
that the huge degrees-of-freedom would bring robustness to such imperfections.
We prove this claim for a generalized uplink system with multiplicative
phase-drifts, additive distortion noise, and noise amplification. Specifically,
we derive closed-form expressions for the user rates and a scaling law that
shows how fast the hardware imperfections can increase with while
maintaining high rates. The connection between this scaling law and the power
consumption of different transceiver circuits is rigorously exemplified. This
reveals that one can make the circuit power increase as , instead of
linearly, by careful circuit-aware system design.Comment: Accepted for publication in IEEE Transactions on Wireless
Communications, 16 pages, 8 figures. The results can be reproduced using the
following Matlab code: https://github.com/emilbjornson/hardware-scaling-law
Application of Space-Time Diversity/Coding For Power Line Channels
The purpose of the present work is to evaluate the application of space-time block codes to the transmission of digital data over the power-line communication channel (PLC). Data transmitted over the power-line channel is usually corrupted by impulsive noise. In this work we analyse
the performance of space-time block codes in this type of environment and show that a significant performance gain can be achieved at almost no processing expense
Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities
Recently there has been a flurry of research on the use of reconfigurable
intelligent surfaces (RIS) in wireless networks to create smart radio
environments. In a smart radio environment, surfaces are capable of
manipulating the propagation of incident electromagnetic waves in a
programmable manner to actively alter the channel realization, which turns the
wireless channel into a controllable system block that can be optimized to
improve overall system performance. In this article, we provide a tutorial
overview of reconfigurable intelligent surfaces (RIS) for wireless
communications. We describe the working principles of reconfigurable
intelligent surfaces (RIS) and elaborate on different candidate implementations
using metasurfaces and reflectarrays. We discuss the channel models suitable
for both implementations and examine the feasibility of obtaining accurate
channel estimates. Furthermore, we discuss the aspects that differentiate RIS
optimization from precoding for traditional MIMO arrays highlighting both the
arising challenges and the potential opportunities associated with this
emerging technology. Finally, we present numerical results to illustrate the
power of an RIS in shaping the key properties of a MIMO channel.Comment: to appear in the IEEE Transactions on Cognitive Communications and
Networking (TCCN
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