9 research outputs found
On the performance of non-orthogonal multiple access (NOMA) using FPGA
In this paper, non-orthogonal multiple access (NOMA) is designed and implemented for the fifth generation (5G) of multi-user wireless communication. Field-programmable gate array (FPGA) is considered for the implementation of this technique for two users. NOMA is applied in downlink phase of the base-station (BS) by applying power allocation mechanism for far and near users, in which one signal contains the superposition of two scaled signals depending on the distance of each user from the BS. We assume an additive white Gaussian noise (AWGN) channel for each user in the presence of the interference due to the non-orthogonality between the two users’ signals. Therefore, successive-interference cancellation (SIC) is exploited to remove the undesired signal of the other user. The outage probability and the bit-error rate performance are presented over different signal-to-interference-plus-noise ratio (SINR). Furthermore, Monte-Carlo simulations via Matlab are utilized to verify the results obtained by FPGA, which show exact-close match
Application-Based Coexistence of Different Waveforms on Non-orthogonal Multiple Access
The coexistence of different wireless communication systems such as LTE and
Wi-Fi by sharing the unlicensed band is well studied in the literature. In
these studies, various methods are proposed to support the coexistence of
systems, including listen-before-talk mechanism, joint user association and
resource allocation. However, in this study, the coexistence of different
waveform structures in the same resource elements are studied under the theory
of non-orthogonal multiple access. This study introduces a paradigm-shift on
NOMA towards the application-centric waveform coexistence. Throughout the
paper, the coexistence of different waveforms is explained with two specific
use cases, which are power-balanced NOMA and joint radar-sensing and
communication with NOMA. In addition, some of the previous works in the
literature regarding non-orthogonal waveform coexistence are reviewed. However,
the concept is not limited to these use cases. With the rapid development of
wireless technology, next-generation wireless systems are proposed to be
flexible and hybrid, having different kinds of capabilities such as sensing,
security, intelligence, control, and computing. Therefore, the concept of
different waveforms' coexistence to meet these concerns are becoming impressive
for researchers.Comment: Submitted to IEEE for possible publication. arXiv admin note: text
overlap with arXiv:2007.05753, arXiv:2003.0554
Rate compatible modulation for non-orthogonal multiple access
We propose a new Non-Orthogonal Multiple Access (NOMA) coding scheme based on the
use of a Rate Compatible Modulation (RCM) encoder for each user. By properly designing the encoders
and taking advantage of the additive nature of the Multiple Access Channel (MAC), the joint decoder from
the inputs of all the users can be represented by a bipartite graph corresponding to a standard point-topoint RCM structure with certain constraints. Decoding is performed over this bipartite graph utilizing the
sum-product algorithm. The proposed scheme allows the simultaneous transmission of a large number of
uncorrelated users at high rates, while the decoding complexity is the same as that of standard point-to-point
RCM schemes. When Rayleigh fast fading channels are considered, the BER vs SNR performance improves
as the number of simultaneous users increases, as a result of the averaging effect
PNC Enabled IIoT: A General Framework for Channel-Coded Asymmetric Physical-Layer Network Coding
This paper investigates the application of physical-layer network coding
(PNC) to Industrial Internet-of-Things (IIoT) where a controller and a robot
are out of each other's transmission range, and they exchange messages with the
assistance of a relay. We particularly focus on a scenario where the controller
has more transmitted information, and the channel of the controller is stronger
than that of the robot. To reduce the communication latency, we propose an
asymmetric transmission scheme where the controller and robot transmit
different amount of information in the uplink of PNC simultaneously. To achieve
this, the controller chooses a higher order modulation. In addition, the both
users apply channel codes to guarantee the reliability. A problem is a
superimposed symbol at the relay contains different amount of source
information from the two end users. It is thus hard for the relay to deduce
meaningful network-coded messages by applying the current PNC decoding
techniques which require the end users to transmit the same amount of
information. To solve this problem, we propose a lattice-based scheme where the
two users encode-and-modulate their information in lattices with different
lattice construction levels. Our design is versatile on that the two end users
can freely choose their modulation orders based on their channel power, and the
design is applicable for arbitrary channel codes.Comment: Submitted to IEEE for possible publicatio
A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond
Today's wireless networks allocate radio resources to users based on the
orthogonal multiple access (OMA) principle. However, as the number of users
increases, OMA based approaches may not meet the stringent emerging
requirements including very high spectral efficiency, very low latency, and
massive device connectivity. Nonorthogonal multiple access (NOMA) principle
emerges as a solution to improve the spectral efficiency while allowing some
degree of multiple access interference at receivers. In this tutorial style
paper, we target providing a unified model for NOMA, including uplink and
downlink transmissions, along with the extensions tomultiple inputmultiple
output and cooperative communication scenarios. Through numerical examples, we
compare the performances of OMA and NOMA networks. Implementation aspects and
open issues are also detailed.Comment: 25 pages, 10 figure