NOMA is a promising radio access technique for next-generation wireless networks. In this article, we investigate the NOMA-based cooperative relay network. We begin with an introduction of existing relay-assisted systems by classifying them into three categories: uplink, downlink, and composite architectures. Then discuss their principles key features, provide comprehensive comparison from perspective spectral efficiency, energy total transmit power. A novel strategy called hybrid power...

In this paper, we study the performance of a downlink non-orthogonal multiple access-based cooperative relay system with single over Nakagami-m fading channels, where both decode-and-forward (DF) and amplify-and-forward (AF) protocols are considered. We assume that only statistical channel state information is available to used determine decoding order cell-edge users' data. For DF relaying, ergodic sum rate outage probability solved in closed form. AF closed-form asymptotic provided....

Non-orthogonal multiple access (NOMA) technique is an expert on channel differences exploiting. In this paper, a dual-hop NOMA-based cooperative relaying network where best relay selected as active node to accomplish the communication between source and destination discussed. We assume that both decode-and-forward (DF) amplify-and-forward (AF) protocols are applied relay. The metrics ergodic sum-rate outage probability investigated, closed-form expressions of latter for DF AF derived....

Non-orthogonal multiple access (NOMA) is an effective solution to improve spectral efficiency since it oversteps the limit of orthogonality imposed on transmitted data flows. In this paper, a NOMA-based dual-hop diamond relay network where source communicates with destination via two decode-and-forward (DF) relays considered. It assumed that either statistical channel state information (S-CSI) or instantaneous (I-CSI) acquired network. Specifically, first, for S-CSI assumption, closed-form...

Since it can offer higher spectral efficiency by granting the served data to share same spectrum resource synchronously, NOMA is considered as a bright multiple access technique for future wireless networks. Accommodating large number of users with mode may easily cause inappropriate power assignment problem and result in performance degradation. As result, existing operation unit mainly focuses on two-user scenario, where centre user only paired an edge user. However, such pairing strategy...

In this letter, we propose an unmanned aerial vehicle (UAV)-carried active reconfigurable intelligent surface (RIS)-assisted cooperative network (UARCN) with a source (S), trustworthy user (U), and untrustworthy (E), which is bridged by multiple half-duplex decode-and-forward relays RIS mounted on hovering UAV. the UARCN, both U, E, receive signal from S through merely in first time slot; then one out of successful decoding selected to further transmit information via direct link second...

Non-orthogonal multiple access (NOMA) is a promising technique for future wireless communications as it results in high spectral efficiency. NOMA differs from recently adopted orthogonal techniques that superimposes data flows at the same time and frequency band but with different power levels, resorts to successive interference cancellation (SIC) decoding. This paper studies dual-hop decode-and-forward (DF) relaying where two relays cooperate deliver messages destination. Specifically,...

Since the intra-group co-channel interference is introduced intentionally by non-orthogonal multiple access (NOMA) technique, reliability of NOMA based networks limited far users, while sum-rate mainly contributed near users. In this paper, a multiband scheduling policy proposed to overcome problem. Unlike conventional where all users are served in single frequency band, scheme divides entire band into sub-bands, and accommodates different manners exploring sub-bands. Particularly, employ...

Maneuvering-target tracking has always been an important and challenge work because the unknown changeable motion-models can easily lead to failure of model-driven target tracking. Recently, many neural network methods are proposed improve accuracy by constructing direct mapping relationships from noisy observations states. However, limited coverage training data, those data-driven suffer other problems, such as weak generalization abilities unstable effects. In this paper, a digital twin...

In this paper, we propose a novel user pairing strategy for non-orthogonal multiple access (NOMA) systems, where the performance of cell-edge is improved with aid two cell-centre users. The global statistical channel state information assumed to be known and used determine decoding order users' data. Assuming Rayleigh fading channels, ergodic sum-rate solved in closed form. fairness comparisons among proposed NOMA, conventional orthogonal (OMA) are also provided. Numerical results verify...

The concept of index modulation (IM) has gained increased attention in recent years. As a member the IM family, orthogonal frequency division multiplexing with (OFDM-IM), which is able to convey additional information bits using indices active subcarriers, emerged as an attractive physical layer transmission technique. Vector OFDM (V-OFDM) inherently good peakto-average-power ratio (PAPR) feature and bit error rate (BER) performance due nearly full diversity gains achieved by most its...

Orthogonal frequency-division multiplexing with index modulation (OFDM-IM) has attracted much attention in recent years. In OFDM-IM, the information bits of a block are generally divided into several subblocks, each which is further split two parts, i.e., and symbol bits. By performing coordinate interleaving operation over constellation symbols, bit-error-rate (BER) performance significantly improved an existing OFDM-IM scheme, called coordinate-interleaved (CI-OFDM-IM). this paper, we...

High effectiveness and high reliability are two fundamental concerns in data transmission. Non-orthogonal multiple-access (NOMA) technology presents a promising solution for high-speed transmission, which has long been pursued by academia industry. However, there is still significant road ahead it to effectively support wide range of applications. This paper provides comprehensive study, comparison, classification the current advanced NOMA schemes from perspectives single-carrier (SC)...

Underwater acoustic (UWA) signal is wideband in nature and suffers doubly selective fading time frequency. In the presence of relative motion, a typical UWA channel can be described by multiscale multilag (MSML) model. To compensate scaling effect channels, many communication systems employ signal-resampling operation single scale at front end receiver. For orthogonal frequency division multiplexing systems, since path scales are different from each other, resampling alleviate but not clean...

This study presents a novel preamble-based timing offset estimation method for orthogonal frequency division multiplexing (OFDM) systems. The proposed is robust, immune to the carrier (CFO), and independent of structure preamble. performance new demonstrated in terms mean square error (MSE) obtained by simulation multipath fading channels. results indicate that significantly improves comparison with existing methods.

This paper considers the application of reconfigurable intelligent surface (RIS) to non-terrestrial non-orthogonal multiple access (NOMA) networks. More specifically, performance a pair users for RIS assisted NOMA networks is investigated over large-scale fading and Nakagami- <math xmlns="http://www.w3.org/1998/Math/MathML" id="M1"> <mi>m</mi> </math> cascaded channel. The exact asymptotic expressions outage probability are derived nearby user distant with imperfect successive interference...

Non-orthogonal multiple access (NOMA) is a promising technique for future wireless communications as it results in high spectral efciency. In this paper, we study NOMA based dual-hop X-relay system, where decode-and- forward relay assists the communication between sources and destinations. We assume that statistical channel state information known to network. such an assumption, achievable sum-rate at signal-to-noise ratio further solved closed form. Especially, corresponding power...

Non-orthogonal multiple access (NOMA) has been widely nominated as an emerging spectral efficiency (SE) technique for the next generation of wireless communication network. To meet growing demands in massive connectivity and huge data transmission, a novel index modulation aided NOMA with rotation signal constellation low power users (IM-NOMA-RC) is developed to downlink transmission. In proposed IM-NOMA-RC system, are classified into far-user group near-user according their channel...

As a new candidate waveform for the next generation of mobile communications, orthogonal chirp division multiplexing (OCDM) has attracted growing attention its high spectrum efficiency and robustness to narrow-band interference or impulsive noise. Under vehicular communication channels with multiple lags Doppler shifts (MLMD), signal suffers doubly selective (DS) fadings in time frequency domain, data symbols modulated on chirps interfere each other. To address problem symbol detection OCDM...

In recent years, orthogonal chirp division modulation (OCDM) has gained attention as a robust communication waveform due to its strong resistance both time-domain and frequency-domain interference. However, similar frequency multiplexing (OFDM), OCDM suffers from high peak-to-average power ratio (PAPR), resulting in increased hardware costs reduced energy efficiency of the transmitter's amplifiers. this work, we introduce novel unitary transform called Generalized Discrete Fresnel Transform...