Statistical Beamforming Techniques for Power Domain NOMA System

Power-domain non-orthogonal multiple access (NOMA) assigns different power levels for near and far users in order to discriminate their signals by employing successive interference cancellation (SIC) at the near user. In this context, multiple-input-single-output NOMA (MISO-NOMA), where the base station (BS) is equipped with multiple antennas while each mobile user has a single antenna receiver, is shown to have a better overall performance by using the knowledge of instantaneous channel state information (CSI). However, this requires prior estimation of CSI using pilot transmission, which increases the transmission overhead. Moreover, its performance is severely degraded in the presence of CSI estimation errors. In this work, we provide statistical beamforming solutions for downlink power-domain NOMA that utilize only knowledge of statistical CSI, thus reducing the transmission overhead significantly. First, we derive the outage probabilities for both near and far users in the multi-user NOMA system without imposing strong assumptions, such as Gaussian or Chi-square distribution. This is done by employing the exact characterization of the ratio of indefinite quadratic form (IQF). Second, this work proposes two techniques to obtain the optimal solution for beam vectors which rely on the derived outage probabilities. Specifically, these two methods are based on (1) minimization of total beam power while constraining the outage probabilities to the QoS threshold, and (2) minimization of outage probabilities while constraining the total beam power. These proposed methods are non-convex function of beam vectors and, hence, are solved using numerical optimization via sequential quadratic programming (SQP). Since the proposed methods do not require pilot transmission for channel estimation, they inherit better spectral efficiency. Our results validate the theoretical findings and prove the supremacy of the proposed method.

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Downlink multi-user algorithms for millimeter-wave wideband linear arrays on PD-NOMA-based squint steering beams

EURASIP Journal on Advances in Signal Processing ◽

10.1186/s13634-021-00772-0 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Xiaoliang Pan ◽

Luxi Yang

Keyword(s):

Interference Cancellation ◽

Channel Model ◽

Linear Array ◽

Base Station ◽

Main Beam ◽

Single Antenna ◽

Power Domain ◽

Planar Array ◽

Virtual Array ◽

User Interference

AbstractThis article investigates using a phased linear antenna array instead of the planar array to circumvent the problem that two frequency squint steering main beams cannot cover any two beam directions simultaneously. First, we approximate the donut-shaped main beam of the linear array by means of multiple pencil-shaped main beams of a virtual planar array for matching the steering main beam of the linear array with the multi-path sparse scattering channel model mathematically and give a method for calculating the number of antenna elements of the virtual array. Second, we cope with possible inter-user interference on a single squint main beam of the linear array in some scenarios by means of the power-domain non-orthogonal multiple access (PD-NOMA) technique, making it possible to support communication with two users on a single squint main beam at the base station (BS) side. The feasible domain of PD-NOMA is given when a single antenna is used for both the BS and the user end, assuming a two-user successive interference cancellation (SIC) decoding power ratio limit. Third, three algorithms are given for serving multi-user at the BS via squint beams of the linear array. Finally, numerical results show that the second proposed algorithm supporting PD-NOMA pairing within a single donut-shaped squint main beam significantly increases the number of simultaneous users served within a single cellular system.

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Rate-Splitting Multiple Access for Intelligent Reflecting Surface aided Multi-User Communications

10.36227/techrxiv.15057579.v1 ◽

2021 ◽

Author(s):

Ankur Bansal ◽

Keshav Singh ◽

Bruno Clerckx ◽

Chih-Peng Li ◽

Mohamed-Slim Alouini

Keyword(s):

Interference Cancellation ◽

Multiple Access ◽

Base Station ◽

Control Technique ◽

Decode And Forward ◽

Cell Edge ◽

Single Antenna ◽

Rate Splitting ◽

Reflecting Surface ◽

The Impact

Intelligent reflecting surface (IRS) has recently emerged as a promising technology for 6G wireless systems, due to its capability to reconfigure the wireless propagation environment. In this paper, we investigate a Rate-Splitting Multiple Access (RSMA) for IRS-assisted downlink system, where the base station (BS) communicates with single-antenna users with the help of an IRS. RSMA relies on rate-splitting (RS) at the BS and successive interference cancellation (SIC) at the users and provides a generalized multiple access framework. We derive a new architecture called IRS-RS that leverages the interplay between RS and IRS. For performance analysis, we utilize an \textit{on-off control technique} to control the passive beamforming vector of the IRS-RS and derive the closed-form expressions for outage probability of cell-edge users and near users. Moreover, we also analyze the outage behavior of cell-edge users for a sufficiently large number of reflecting elements. Additionally, we also analyze the outage performance of cooperative RS based decode-and-forward (DF)-assisted framework called DF-RS. Through simulation results, it is shown that the proposed framework outperforms the corresponding DF-RS, RS without IRS and IRS-assisted conventional non-orthogonal multiple access (NOMA) schemes. Furthermore, the impact of various system's parameters such as the number of IRS reflecting elements and the number of users on the system performance is revealed.

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Design of novel approach for emerging power-domain superposition coding (SC)-using hybrid NOMA-OFDM for 5G communications

International Journal of Intelligent Unmanned Systems ◽

10.1108/ijius-07-2021-0056 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Y.K. Shobha ◽

H.G. Rangaraju

Keyword(s):

Interference Cancellation ◽

Multiple Access ◽

Mimo System ◽

Minimum Mean Square Error ◽

Research Work ◽

Base Station ◽

Superposition Coding ◽

Content Type ◽

Minimum Mean Squared Error ◽

Power Domain

PurposeThe suggested work examines the latest developments such as the techniques employed for allocation of power, browser techniques, modern analysis and bandwidth efficiency of nonorthogonal multiple accesses (NOMA) in the network of 5G. Furthermore, the proposed work also illustrates the performance of NOMA when it is combined with various techniques of wireless communication namely network coding, multiple-input multiple-output (MIMO), space-time coding, collective communications, as well as many more. In the case of the MIMO system, the proposed research work specifically deals with a less complex recursive linear minimum mean square error (LMMSE) multiuser detector along with NOMA (MIMO-NOMA); here the multiple-antenna base station (BS) and multiple single-antenna users interact with each other instantaneously. Although LMMSE is a linear detector with a low intricacy, it performs poorly in multiuser identification because of the incompatibility between LMMSE identification and multiuser decoding. Thus, to obtain a desirable iterative identification rate, the proposed research work presents matching constraints among the decoders and identifiers of MIMO-NOMA.Design/methodology/approachTo improve the performance in 5G technologies as well as in cellular communication, the NOMA technique is employed and contemplated as one of the best methodologies for accessing radio. The above-stated technique offers several advantages such as enhanced spectrum performance in contrast to the high-capacity orthogonal multiple access (OMA) approach that is also known as orthogonal frequency division multiple access (OFDMA). Code and power domain are some of the categories of the NOMA technique. The suggested research work mainly concentrates on the technique of NOMA, which is based on the power domain. This approach correspondingly makes use of superposition coding (SC) as well as successive interference cancellation (SIC) at source and recipient. For the fifth-generation applications, the network-level, as well as user-experienced data rate prerequisites, are successfully illustrated by various researchers.FindingsThe suggested combined methodology such as MIMO-NOMA demonstrates a synchronized iterative LMMSE system that can accomplish the optimized efficiency of symmetric MIMO NOMA with several users. To transmit the information from sender to the receiver, hybrid methodologies are confined to 2 × 2 as well as 4 × 4 antenna arrays, and thereby parameters such as PAPR, BER, SNR are analyzed and efficiency for various modulation strategies such as BPSK and QAMj (j should vary from 8,16,32,64) are computed.Originality/valueThe proposed hybrid MIMO-NOMA methodologies are synchronized in terms of iterative process for optimization of LMMSE that can accomplish the optimized efficiency of symmetric for several users under different noisy conditions. From the obtained simulated results, it is found, there are 18%, 23% 16%, and 8% improvement in terms of Bit Error Rate (BER), Least Minimum Mean Squared Error (LMMSE), Peak to Average Power Ratio (PAPR), and capacity of channel respectively for Binary Phase Shift Key (BPSK) and Quadrature Amplitude Modulation (QAM) modulation techniques.

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SIC-Coding Schemes for Underlay Two-Way Relaying Cognitive Networks

Wireless Communications and Mobile Computing ◽

10.1155/2020/8860551 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Pham Ngoc Son ◽

Tran Trung Duy ◽

Khuong Ho-Van

Keyword(s):

Interference Cancellation ◽

Performance Enhancement ◽

Cognitive Networks ◽

Superposition Coding ◽

Secondary Sources ◽

Coding Schemes ◽

Power Domain ◽

Digital Network ◽

Outage Probabilities ◽

Primary Receiver

In this paper, we propose an underlay two-way relaying scheme with the successive interference cancellation (SIC) solution in which two secondary sources transmit simultaneously their data to each other through secondary relays. The proposed scheme is operated in only two time slots and under an interference constraint of a primary receiver, denoted as the UTW-2TS scheme. In the UTW-2TS scheme, the secondary relays employ the SIC operation to decode successively the data from received broadcast signals and then encode these data by two techniques: digital network coding (DNC) enforced by XOR operations (denoted as the UTW-2TS-DNC protocol) and superposition coding (SC) enforced by power domain additions (denoted as the UTW-2TS-SC protocol). A selected secondary relay which subjects to maximize decoding capacities and to minimize collection time of channel state information in two protocols UTW-2TS-DNC and UTW-2TS-SC experiences residual interferences from imperfect SIC operations. Outage probabilities and throughputs are solved in terms of exact closed-form expressions to evaluate the system performance of the proposed protocols. Simulation and analysis results provide performance enhancement of the proposed protocols UTW-2TS-DNC and UTW-2TS-SC owing to increase the number of the cooperative secondary relays, the interference constraints, and the distances from the secondary network to the primary receiver. The best throughputs are pointed at optimal interference power allocation coefficients and optimal locations of the selected secondary relay. Considering the same power consumption, the UTW-2TS-DNC protocol outperforms the UTW-2TS-SC protocol. Finally, the simulation results are collected to confirm the exact analysis values of the outage probabilities and throughputs.

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Outage Probability and Ergodic Capacity of a Two-User NOMA Relaying System with an Energy Harvesting Full-Duplex Relay and Its Interference at the Near User

Sensors ◽

10.3390/s20226472 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6472

Author(s):

Hoang Van Toan ◽

Tran Manh Hoang ◽

Tran Trung Duy ◽

Le The Dung

Keyword(s):

Energy Harvesting ◽

Fading Channels ◽

Power Distribution ◽

Interference Cancellation ◽

Ergodic Capacity ◽

Base Station ◽

Full Duplex ◽

Distribution Factor ◽

Relay System ◽

Outage Probabilities

In this paper, we consider a two-user downlink full-duplex (FD) non-orthogonal multiple access (NOMA) relay system where the FD relay uses an energy harvesting (EH) technique to assist the communication between the base station and far user over flat, independent and non-identically Rayleigh fading channels. Importantly, since the relay operates in FD mode, we take into account the effect of the interference caused by relay on the near user. Considering this EH-FD-NOMA relay system, we derive the exact mathematical expressions of the outage probabilities and ergodic capacities of near and far users. Monte–Carlo simulations verify the accuracy of our analytical method. Numerical results provided in this paper allow system designers to clearly see not only the impacts of the power distribution factor and the self-interference cancellation capacity of the relay but also the influence of the strength of inter-user interference at the near user on the outage performances and ergodic capacities of both users.

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Uplink Power-Domain Non-Orthogonal Multiple Access (NOMA)

International Journal of Interdisciplinary Telecommunications and Networking ◽

10.4018/ijitn.2020100105 ◽

2020 ◽

Vol 12 (4) ◽

pp. 65-73

Author(s):

Faeik T. Al Rabee ◽

Richard D. Gitlin

Keyword(s):

Channel Estimation ◽

Interference Cancellation ◽

Multiple Access ◽

Signal To Noise Ratio ◽

Estimation Error ◽

Channel Estimation Error ◽

Estimation Errors ◽

Channel Estimation Errors ◽

Fifth Generation ◽

Power Domain

Non-orthogonal multiple access (NOMA) has been proposed as a promising multiple access (MA) technique in order to meet the requirements for fifth generation (5G) communications and to enhance the performance in internet of things (IoT) networks by enabling massive connectivity, high throughput, and low latency. This paper investigates the bit error rate (BER) performance of two-user uplink power-domain NOMA with a successive interference cancellation (SIC) receiver and taking into account channel estimation errors. The analysis considers two scenarios: perfect (ideal) channel estimation and a channel with estimation errors for various modulations schemes, BPSK, QPSK, and 16-QAM. The simulation results show that, as expected, increasing of the modulation level increases the SIC receiver BER. For example, at a signal-to-noise ratio (SNR) of 5 dB for perfect channel estimation and QPSK modulation, the user that is detected first has a BER of 0.005 compared to 0.14 for the user that is detected with the aid of the SIC receiver. Similarly, the BER of QPSK, assuming 0.25 channel estimation error of user 1, is equal to 0.06 at SNR = 15 dB compared to 0.017 for perfect estimation.

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Energy Harvesting for Internet of Things with Heterogeneous Users

Wireless Communications and Mobile Computing ◽

10.1155/2017/1858532 ◽

2017 ◽

Vol 2017 ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

Desheng Wang ◽

Haizhen Liu ◽

Xiaoqiang Ma ◽

Jun Wang ◽

Yanrong Peng ◽

...

Keyword(s):

Energy Harvesting ◽

Internet Of Things ◽

Minimum Energy ◽

Optimal Solution ◽

Base Station ◽

Power Splitting ◽

Zero Forcing ◽

Single Antenna ◽

Dirty Paper Coding ◽

The Internet Of Things

We study the energy harvesting problem in the Internet of Things with heterogeneous users, where there are three types of single-antenna users: ID users that only receive information, EH users that can only receive energy, and ID/EH users that receive information and energy simultaneously from a multiantenna base station via power splitting. We aim to maximize the minimum signal-to-interference-plus-noise ratio (SINR) of the ID users and ID/EH users by jointly designing the power allocation at the transmitter and the power splitting strategy at the ID/EH receivers under the maximum transmit power and the minimum energy harvesting constraints. Specifically, we first apply the semidefinite relaxation (SDR), zero-forcing (ZF), and maximum ratio transmission (MRT) techniques to solve the nonconvex problems. We then apply the zero-forcing dirty paper coding (ZF-DPC) technique to eliminate the multiuser interference and derive the closed-form optimal solution. Numerical results show that ZF-DPC provides higher achievable minimum SINR than SDR and ZF in most cases.

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On secure system performance over SISO, MISO and MIMO-NOMA wireless networks equipped a multiple antenna based on TAS protocol

EURASIP Journal on Wireless Communications and Networking ◽

10.1186/s13638-019-1586-y ◽

2020 ◽

Vol 2020 (1) ◽

Author(s):

Thanh-Nam Tran ◽

Miroslav Voznak

Keyword(s):

Fading Channels ◽

System Performance ◽

Interference Cancellation ◽

Base Station ◽

System Throughput ◽

Experimental Investigations ◽

Single Input Single Output ◽

Single Antenna ◽

Single Output ◽

The Individual

AbstractThis study examined how to improve system performance by equipping multiple antennae at a base station (BS) and all terminal users/mobile devices instead of a single antenna as in previous studies. Experimental investigations based on three NOMA down-link models involved (1) a single-input-single-output (SISO) scenario in which a single antenna was equipped at a BS and for all users, (2) a multi-input-single-output (MISO) scenario in which multiple transmitter antennae were equipped at a BS and a single receiver antenna for all users and (3) a multi-input-multi-output (MIMO) scenario in which multiple transmitter antennae were equipped at a BS and multiple receiver antenna for all users. This study investigated and compared the outage probability (OP) and system throughput assuming all users were over Rayleigh fading channels. The individual scenarios also each had an eavesdropper. Secure system performance of the individual scenarios was therefore also investigated. In order to detect data from superimposed signals, successive interference cancellation (SIC) was deployed for users, taking into account perfect, imperfect and fully imperfect SICs. The results of analysis of users in these three scenarios were obtained in an approximate closed form by using the Gaussian-Chebyshev quadrature method. However, the clearly and accurately presented results obtained using Monte Carlo simulations prove and verify that the MIMO-NOMA scenario equipped with multiple antennae significantly improved system performance.

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Mitigation of Imperfect Successive Interference Cancellation and Wavelet-Based Nonorthogonal Multiple Access in the 5G Multiuser Downlink Network

Wireless Communications and Mobile Computing ◽

10.1155/2021/8876026 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Muneeb Ahmad ◽

Sobia Baig ◽

Hafiz Muhammad Asif ◽

Kaamran Raahemifar

Keyword(s):

Wavelet Transform ◽

Interference Cancellation ◽

Communication Systems ◽

Multiple Access ◽

Industrial Revolution ◽

Symbol Error Rate ◽

Base Station ◽

Successive Interference Cancellation ◽

Signal Pulse ◽

Power Domain

The fourth Industrial Revolution is expected to lead to an era of technological innovation and digitization that would require connectivity by the users, anywhere and anytime. The fifth generation of wireless communication systems and the technologies therein are being explored to cater to high connectivity needs that encompass high data rates, very low latencies, energy-efficient systems, etc. A multiuser environment is anticipated that would require multiple access techniques, such as Nonorthogonal Multiple Access (NOMA). The user data in the power domain NOMA is superimposed, at the transmitter base station, which is in turn subjected to Successive Interference Cancellation at the user end. In the multiuser downlink, the desired user’s signal is subjected to imperfect SIC due to incomplete cancellation of the undesired user’s signal. Pulse-shaping of NOMA symbols using wavelet transform is proposed to mitigate the multiuser interference due to imperfect SIC. Closed-form symbol error rate (SER) expression is derived for the wavelet NOMA system for a three-user scenario. Analytical results show that wavelet transform pulse-shaped NOMA performs better compared to Fourier transform pulse-shaped NOMA symbols in mitigating SIC and thereby minimize the residual error due to imperfect SIC.

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