493 research outputs found
Alamouti OFDM/OQAM systems with time reversal technique
Orthogonal Frequency Division Multiplexing with Offset Quadrature Amplitude
Modulation (OFDM/OQAM) is a multicarrier modulation scheme that can be
considered as an alternative to the conventional Orthogonal Frequency Division
Multiplexing (OFDM) with Cyclic Prefix (CP) for transmission over multipath
fading channels. In this paper, we investigate the combination of the OFDM/OQAM
with Alamouti system with Time Reversal (TR) technique. TR can be viewed as a
precoding scheme which can be combined with OFDM/OQAM and easily carried out in
a Multiple Input Single Output (MISO) context such as Alamouti system. We
present the simulation results of the performance of OFDM/OQAM system in SISO
case compared with the conventional CP-OFDM system and the performance of the
combination Alamouti OFDM/OQAM with TR compared to Alamouti CP-OFDM. The
performance is derived by computing the Bit Error Rate (BER) as a function of
the transmit signal-to-noise ratio (SNR)
Contrasting space-time schemes for MIMO FSO systems with non-coherent modulation
International audienc
Open-Loop Spatial Multiplexing and Diversity Communications in Ad Hoc Networks
This paper investigates the performance of open-loop multi-antenna
point-to-point links in ad hoc networks with slotted ALOHA medium access
control (MAC). We consider spatial multiplexing transmission with linear
maximum ratio combining and zero forcing receivers, as well as orthogonal space
time block coded transmission. New closed-form expressions are derived for the
outage probability, throughput and transmission capacity. Our results
demonstrate that both the best performing scheme and the optimum number of
transmit antennas depend on different network parameters, such as the node
intensity and the signal-to-interference-and-noise ratio operating value. We
then compare the performance to a network consisting of single-antenna devices
and an idealized fully centrally coordinated MAC. These results show that
multi-antenna schemes with a simple decentralized slotted ALOHA MAC can
outperform even idealized single-antenna networks in various practical
scenarios.Comment: 51 pages, 19 figures, submitted to IEEE Transactions on Information
Theor
Delay Performance of MISO Wireless Communications
Ultra-reliable, low latency communications (URLLC) are currently attracting
significant attention due to the emergence of mission-critical applications and
device-centric communication. URLLC will entail a fundamental paradigm shift
from throughput-oriented system design towards holistic designs for guaranteed
and reliable end-to-end latency. A deep understanding of the delay performance
of wireless networks is essential for efficient URLLC systems. In this paper,
we investigate the network layer performance of multiple-input, single-output
(MISO) systems under statistical delay constraints. We provide closed-form
expressions for MISO diversity-oriented service process and derive
probabilistic delay bounds using tools from stochastic network calculus. In
particular, we analyze transmit beamforming with perfect and imperfect channel
knowledge and compare it with orthogonal space-time codes and antenna
selection. The effect of transmit power, number of antennas, and finite
blocklength channel coding on the delay distribution is also investigated. Our
higher layer performance results reveal key insights of MISO channels and
provide useful guidelines for the design of ultra-reliable communication
systems that can guarantee the stringent URLLC latency requirements.Comment: This work has been submitted to the IEEE for possible publication.
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