18,072 research outputs found
Adaptive Resource Allocation Based on Factor Graphs in Non-Orthogonal Multiple Access
In this paper, we propose a non-orthogonal multiple access with adaptive resource allocation. The proposed non-orthogonal multiple access assigns multiple frequency resources for each device to send packets. Even if the number of devices is more than that of the available frequency resources, the proposed non-orthogonal access allows all the devices to transmit their packets simultaneously for high capacity massive machine-type communications (mMTC). Furthermore, this paper proposes adaptive resource allocation algorithms based on factor graphs that adaptively allocate the frequency resources to the devices for improvement of the transmission performances. This paper proposes two allocation algorithms for the proposed non-orthogonal multiple access. This paper shows that the proposed non-orthogonal multiple access achieves superior transmission performance when the number of the devices is 50% greater than the amount of the resource, i.e., the overloading ratio of 1.5, even without the adaptive resource allocation. The adaptive resource allocation enables the proposed non-orthogonal access to attain a gain of about 5dB at the BER of 10-4
Optimal Joint Power and Subcarrier Allocation for MC-NOMA Systems
In this paper, we investigate the resource allocation algorithm design for
multicarrier non-orthogonal multiple access (MC-NOMA) systems. The proposed
algorithm is obtained from the solution of a non-convex optimization problem
for the maximization of the weighted system throughput. We employ monotonic
optimization to develop the optimal joint power and subcarrier allocation
policy. The optimal resource allocation policy serves as a performance
benchmark due to its high complexity. Furthermore, to strike a balance between
computational complexity and optimality, a suboptimal scheme with low
computational complexity is proposed. Our simulation results reveal that the
suboptimal algorithm achieves a close-to-optimal performance and MC-NOMA
employing the proposed resource allocation algorithm provides a substantial
system throughput improvement compared to conventional multicarrier orthogonal
multiple access (MC-OMA).Comment: Submitted to Globecom 201
Low Complexity WMMSE Power Allocation In NOMA-FD Systems
In this paper we study the problem of power and channel allocation with the
objective of maximizing the system sum-rate for multicarrier non-orthogonal
multiple access (NOMA) full duplex (FD) systems. Such an allocation problem is
non-convex and, thus, with the goal of designing a low complexity solution, we
propose a scheme based on the minimization of the weighted mean square error,
which achieves performance reasonably close to the optimum and allows to
clearly outperforms a conventional orthogonal multiple access approach.
Numerical results assess the effectiveness of our algorithm.Comment: 5 pages conference paper, 3 figures. Submitted on ICASSP 202
Dynamic non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) in 5G wireless networks
In this paper, a novel dynamic multiple access
technology selection among orthogonal multiple access (OMA)
and non-orthogonal multiple access (NOMA) techniques is proposed. For this setup, a joint resource allocation problem is
formulated in which a new set of access technology selection
parameters along with power and subcarrier are allocated for
each user based on each user’s channel state information. Here,
a novel utility function is defined to take into account the
rate and costs of access technologies. This cost reflects both
the complexity of performing successive interference cancellation
and the complexity incurred to guarantee a desired bit error
rate. This utility function can inherently capture the tradeoff
between OMA and NOMA. Due to non-convexity of the proposed
resource allocation problem, a successive convex approximation
is developed in which a two-step iterative algorithm is applied. In
the first step, called access technology selection, the problem is
transformed into a linear integer programming problem, and
then, in the second step, a nonconvex problem, referred to
power allocation problem, is solved via the difference-of-convexfunctions (DC) programming. Moreover, the closed-form solution
for power allocation in the second step is derived. For diverse
network performance criteria such as rate, simulation results
show that the proposed new dynamic access technology selection
outperforms single-technology OMA or NOMA multiple access
solutions
Dynamic Non-Orthogonal Multiple Access (NOMA) and Orthogonal Multiple Access (OMA) in 5G Wireless Networks
In this paper, facilitated via the flexible software defined structure of the
radio access units in 5G, we propose a novel dynamic multiple access technology
selection among orthogonal multiple access (OMA) and non-orthogonal multiple
access (NOMA) techniques for each subcarrier. For this setup, we formulate a
joint resource allocation problem where a new set of access technology
selection parameters along with power and subcarrier are allocated for each
user based on each user's channel state information. Here, we define a novel
utility function taking into account the rate and costs of access technologies.
This cost reflects both the complexity of performing successive interference
cancellation and the complexity incurred to guarantee a desired bit error rate.
This utility function can inherently demonstrate the trade-off between OMA and
NOMA. Due to non-convexity of our proposed resource allocation problem, we
resort to successive convex approximation where a two-step iterative algorithm
is applied in which a problem of the first step, called access technology
selection, is transformed into a linear integer programming problem, and the
nonconvex problem of the second step, referred to power allocation problem, is
solved via the difference-of-convex-functions (DC) programming. Moreover, the
closed-form solution for power allocation in the second step is derived. For
diverse network performance criteria such as rate, simulation results show that
the proposed new dynamic access technology selection outperforms
single-technology OMA or NOMA multiple access solutions.Comment: 28 pages, 6 figure
Cache-Aided Non-Orthogonal Multiple Access
In this paper, we propose a novel joint caching and non-orthogonal multiple
access (NOMA) scheme to facilitate advanced downlink transmission for next
generation cellular networks. In addition to reaping the conventional
advantages of caching and NOMA transmission, the proposed cache-aided NOMA
scheme also exploits cached data for interference cancellation which is not
possible with separate caching and NOMA transmission designs. Furthermore, as
caching can help to reduce the residual interference power, several decoding
orders are feasible at the receivers, and these decoding orders can be flexibly
selected for performance optimization. We characterize the achievable rate
region of cache-aided NOMA and investigate its benefits for minimizing the time
required to complete video file delivery. Our simulation results reveal that,
compared to several baseline schemes, the proposed cache-aided NOMA scheme
significantly expands the achievable rate region for downlink transmission,
which translates into substantially reduced file delivery times.Comment: Accepted for presentation at IEEE ICC 201
The Application of MIMO to Non-Orthogonal Multiple Access
This paper considers the application of multiple-input multiple-output (MIMO)
techniques to non-orthogonal multiple access (NOMA) systems. A new design of
precoding and detection matrices for MIMO-NOMA is proposed and its performance
is analyzed for the case with a fixed set of power allocation coefficients. To
further improve the performance gap between MIMO-NOMA and conventional
orthogonal multiple access schemes, user pairing is applied to NOMA and its
impact on the system performance is characterized. More sophisticated choices
of power allocation coefficients are also proposed to meet various quality of
service requirements. Finally computer simulation results are provided to
facilitate the performance evaluation of MIMO-NOMA and also demonstrate the
accuracy of the developed analytical results
Energy-Efficient Resource Allocation in SWIPT Enabled NOMA Systems
In this paper, we investigate joint power allocation and time switching (TS) control for energy efficiency (EE) optimization in a TS-based simultaneous wireless information and power transfer (SWIPT) non-orthogonal multiple access (NOMA) system. Our aim is to optimize the EE of the system whilst satisfying the constraints on maximum transmit power, minimum data rate and minimum harvested energy per-terminal. The considered EE optimization problem is formulated and then transformed according to the duality of broadcast channels (BC) and multiple access channels (MAC). The corresponding non-linear and non-convex optimization problem, involving joint optimization of power allocation and time switching factor, is difficult to solve directly. In order to tackle this problem, we develop a dual-layer algorithm where a convex programming-based Dinkelbach's method is proposed to optimize the power allocation in the inner-layer and an efficient search method is then applied to optimize the TS factor in the outer-layer. Numerical results validate the theoretical findings and demonstrate that significant performance gain over orthogonal multiple access (OMA) scheme in terms of EE can be achieved by the proposed algorithm in a SWIPT-enabled NOMA system
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