120 research outputs found
Non-coherent Massive SIMO Systems in ISI Channels: Constellation Design and Performance Analysis
A massive single-input multiple-output (SIMO) system with a single transmit
antenna and a large number of receive antennas in intersymbol interference
(ISI) channels is considered. Contrast to existing energy detection (ED)-based
non-coherent receiver where conventional pulse amplitude modulation (PAM) is
employed, we propose a constellation design which minimizes the symbol-error
rate (SER) with the knowledge of channel statistics. To make a comparison, we
derive the SERs of the ED-based receiver with both the proposed constellation
and PAM, namely and . Specifically, asymptotic
behaviors of the SER in regimes of a large number of receive antennas and high
signal-to-noise ratio (SNR) are investigated. Analytical results demonstrate
that the logarithms of both and decrease
approximately linearly with the number of receive antennas, while
degrades faster. It is also shown that the proposed design is of less cost,
because compared with PAM, less antennas are required to achieve the same error
rate
Performance Analysis of Energy-Detection-Based Massive SIMO
Recently, communications systems that are both energy efficient and reliable
are under investigation. In this paper, we concentrate on an
energy-detection-based transmission scheme where a communication scenario
between a transmitter with one antenna and a receiver with significantly many
antennas is considered. We assume that the receiver initially calculates the
average energy across all antennas, and then decodes the transmitted data by
exploiting the average energy level. Then, we calculate the average symbol
error probability by means of a maximum a-posteriori probability detector at
the receiver. Following that, we provide the optimal decision regions.
Furthermore, we develop an iterative algorithm that reaches the optimal
constellation diagram under a given average transmit power constraint. Through
numerical analysis, we explore the system performance
Design and Performance Analysis of Non-Coherent Detection Systems with Massive Receiver Arrays
Harvesting the gain of a large number of antennas in a mmWave band has mainly
been relying on the costly operation of channel state information (CSI)
acquisition and cumbersome phase shifters. Recent works have started to
investigate the possibility to use receivers based on energy detection (ED),
where a single data stream is decoded based on the channel and noise energy.
The asymptotic features of the massive receiver array lead to a system where
the impact of the noise becomes predictable due to a noise hardening effect.
This in effect extends the communication range compared to the receiver with a
small number of antennas, as the latter is limited by the unpredictability of
the additive noise. When the channel has a large number of spatial degrees of
freedom, the system becomes robust to imperfect channel knowledge due to
channel hardening. We propose two detection methods based on the instantaneous
and average channel energy, respectively. Meanwhile, we design the detection
thresholds based on the asymptotic properties of the received energy.
Differently from existing works, we analyze the scaling law behavior of the
symbol-error-rate (SER). When the instantaneous channel energy is known, the
performance of ED approaches that of the coherent detection in high SNR
scenarios. When the receiver relies on the average channel energy, our
performance analysis is based on the exact SER, rather than an approximation.
It is shown that the logarithm of SER decreases linearly as a function of the
number of antennas. Additionally, a saturation appears at high SNR for PAM
constellations of order larger than two, due to the uncertainty on the channel
energy. Simulation results show that ED, with a much lower complexity, achieves
promising performance both in Rayleigh fading channels and in sparse channels
Capacity of SIMO and MISO Phase-Noise Channels with Common/Separate Oscillators
In multiple antenna systems, phase noise due to instabilities of the
radio-frequency (RF) oscillators, acts differently depending on whether the RF
circuitries connected to each antenna are driven by separate (independent)
local oscillators (SLO) or by a common local oscillator (CLO). In this paper,
we investigate the high-SNR capacity of single-input multiple-output (SIMO) and
multiple-output single-input (MISO) phase-noise channels for both the CLO and
the SLO configurations.
Our results show that the first-order term in the high-SNR capacity expansion
is the same for all scenarios (SIMO/MISO and SLO/CLO), and equal to , where stands for the SNR. On the contrary, the second-order
term, which we refer to as phase-noise number, turns out to be
scenario-dependent. For the SIMO case, the SLO configuration provides a
diversity gain, resulting in a larger phase-noise number than for the CLO
configuration. For the case of Wiener phase noise, a diversity gain of at least
can be achieved, where is the number of receive antennas. For
the MISO, the CLO configuration yields a higher phase-noise number than the SLO
configuration. This is because with the CLO configuration one can obtain a
coherent-combining gain through maximum ratio transmission (a.k.a. conjugate
beamforming). This gain is unattainable with the SLO configuration.Comment: IEEE Transactions on Communication
Deep Energy Autoencoder for Noncoherent Multicarrier MU-SIMO Systems
We propose a novel deep energy autoencoder (EA) for noncoherent multicarrier
multiuser single-input multipleoutput (MU-SIMO) systems under fading channels.
In particular, a single-user noncoherent EA-based (NC-EA) system, based on the
multicarrier SIMO framework, is first proposed, where both the transmitter and
receiver are represented by deep neural networks (DNNs), known as the encoder
and decoder of an EA. Unlike existing systems, the decoder of the NC-EA is fed
only with the energy combined from all receive antennas, while its encoder
outputs a real-valued vector whose elements stand for the subcarrier power
levels. Using the NC-EA, we then develop two novel DNN structures for both
uplink and downlink NC-EA multiple access (NC-EAMA) schemes, based on the
multicarrier MUSIMO framework. Note that NC-EAMA allows multiple users to share
the same sub-carriers, thus enables to achieve higher performance gains than
noncoherent orthogonal counterparts. By properly training, the proposed NC-EA
and NC-EAMA can efficiently recover the transmitted data without any channel
state information estimation. Simulation results clearly show the superiority
of our schemes in terms of reliability, flexibility and complexity over
baseline schemes.Comment: Accepted, IEEE TW
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