Multi-user Shared Access Research Articles

Signalling overhead diminution in M-MIMO using NOMA transmission

With the increase in demand for mobile and Internet of Things devices, Orthogonal Multiple Access (OMA) cannot manage the maximum number of users. In this technique, the number of radio frequencies must be equivalent to the number of users. It causes to increase in signalling overhead. Therefore, it requires special attention to reduce the signalling overhead to escalate the spectral and energy efficiency. This paper investigates different Non Orthogonal Multiple Access (NOMA) techniques, and the results are compared with OMA techniques. A novel NOMA technique Multi User Shared Access (MUSA) is applied. It adjusts maximum users and has good spectral and energy efficiency compared to OMA techniques. In this proposed technique, maximum complex spreading codes are generated for the users and each user picks that code and transmits its data at the same radio frequency chain. The proposed scheme MUSA-NOMA has 12.8% more energy efficiency and 6.51% spectral efficiency compared to SCMA-NOMA and 32% more energy efficiency and 18.5% spectral efficiency compared to OMA.Article highlightsImagine you're using your phone in a crowded area where many people are also trying to connect, signalling congestion will occur. In traditional setups, it is difficult to manage everyone's signals.Instead of dealing with each person's signal separately, NOMA allows the communication system to treat similar groups together, streamlining the process.It's like having group discussions instead of one-on-one talks, making the whole communication setup more efficient and less complicated. This way, your phone and the network can handle many connections more smoothly, providing a better experience for everyone.

Clustering Approach for Reliable Wireless Communication

Multiple access techniques for 5G systems are based on principles related to security, efficiency, and performance increase. Multi-user shared access (MUSA) is included in code-domain non-orthogonal multiple access (CD-NOMA) techniques with multiple benefits including multiple-access interference minimization and system capacity increase. The additional benefits of MUSA include its grant-free nature, which makes it applicable to scenarios involving random access channels, minimal latency communications, etc. Depending on the high-frequency diversity of the fading-affected channels, this technique is also used to lessen their effects. This paper illustrates the concept of code correlation used in MUSA by proposing a method to allocate MUSA codes to active users in an uplink data transmission system based on clusters. This clustering approach (grouping of 3GPP TR 38.812 spreading codewords) enables performance improvement in different system configurations by implementing various scenarios and providing reliable results. It is demonstrated that four-length spreading code selection from 3GPP family codes is a satisfactory solution, and this cluster grouping can be designed in a less overloaded multi-user system. The challenges, advantages, and limitations of the proposed method are outlined throughout the study.

Evaluating the Efficiency of Non-Orthogonal MU-MIMO Methods in Smart Cities Technologies & 5G Communication

Many cutting-edge technologies, such as MIMO, cognitive radio, multi-carrier modulation, and network coding, have been proposed for wireless communication to satisfy needs for a higher data rate in the upcoming time, leading to improved quality of service (QoS) regardless of the weather. Orthogonal and non-orthogonal multiple access techniques are two categories into which multiple access technologies can be subdivided. Large networking with effective implementation of wireless devices is supported by non-orthogonal multiple access techniques. Massive NOMA has been implemented to advance access efficiency by permitting several users to share a similar spectrum. Because of the robust co-channel interference between mobile users presented by NOMA, it offers important tasks for system model and resources management. In this study, two additional sets of demanding codes are explored. Multi-user shared access methods and expanded multi-user shared access (EMUSA) methods are both employed. In the MUSA technique, an algorithm is used for the allocation of resources to achieve minimum intercorrelation to the maximum extent in 5G networks. A novel idea proposed in this paper is to create complex codes starting from PN codes (i.e., ePN), thereby achieving promising results in the overall system performance. The first part of this paper describes the fundamental principles of MUSA, and in the next part the main idea of the proposed technique will be studied in detail. Using Monte-Carlo MATLAB simulation, the performance of the suggested approach is assessed in terms of BER vs. SNR. The efficiency of the proposed approach is evaluated in various settings, and the outcomes are contrasted with those of the traditional CDMA technique, using parameters, such as the number of active users and antennas at the receiver.

MUSA Grant-Free Access Framework and Blind Detection Receiver

Recently, a non-orthogonal multiple access scheme called multi-user shared access (MUSA) was proposed to provide massive connection capability of low-complexity devices in the 5G networks. MUSA achieves higher spectral efficiency allowing independent devices to transmit data on the same physical layer time-frequency resources. Furthermore, MUSA introduces a grant-free transmission and a blind multi-user detection at the receiver, reducing the complexity on the transmit side. This approach is interesting for Internet of Things applications over mobile communication networks, where the devices have limited power and processing capacity. The references available in the literature about this multiple access scheme do not bring sufficient details about the MUSA multi-user detector. This limitation makes it difficult to evaluate the MUSA performance and to propose improvements for this new technique. The main goal of this paper is to provide a framework describing the entire communication chain using MUSA as multiple access. This paper also brings a proposal for a blind multi-user detection, where the information about the MUSA parameters and the channel state information are unknown at the receiver side. The performance of the MUSA multi-user detector is improved by a deep learning based processing that improves the quality of the channel estimation provided by a initial minimum mean square error estimator. The proposed deep neural network architecture employed to improve the channel estimation allows more users to share the same time-frequency resources for a given target block error rate, increasing the overall spectrum efficiency of the system.

Autonomous Power Decision for the Grant Free Access MUSA Scheme in the mMTC Scenario.

Non-orthogonal multiple access schemes with grant free access have been recently highlighted as a prominent solution to meet the stringent requirements of massive machine-type communications (mMTCs). In particular, the multi-user shared access (MUSA) scheme has shown great potential to grant free access to the available resources. For the sake of simplicity, MUSA is generally conducted with the successive interference cancellation (SIC) receiver, which offers a low decoding complexity. However, this family of receivers requires sufficiently diversified received user powers in order to ensure the best performance and avoid the error propagation phenomenon. The power allocation has been considered as a complicated issue especially for a decentralized decision with a minimum signaling overhead. In this paper, we propose a novel algorithm for an autonomous power decision with a minimal overhead based on a tight approximation of the bit error probability (BEP) while considering the error propagation phenomenon. We investigate the efficiency of multi-armed bandit (MAB) approaches for this problem in two different reward scenarios: (i) in Scenario 1, each user reward only informs about whether its own packet was successfully transmitted or not; (ii) in Scenario 2, each user reward may carry information about the other interfering user packets. The performances of the proposed algorithm and the MAB techniques are compared in terms of the successful transmission rate. The simulation results prove that the MAB algorithms show a better performance in the second scenario compared to the first one. However, in both scenarios, the proposed algorithm outperforms the MAB techniques with a lower complexity at user equipment.

Multi-user Shared Access (MUSA) procedure for device discovery in D2D communication

In a wireless self-organizing and the network-assisted Device-to-Device (D2D) network, proximal Device Discovery (DD) plays a noteworthy role. It is the foundation for self-governing, coverage expansion and performance improvement for example, cooperative and multi-hop transmission. Energy efficiency and discovery accuracy are critical performance measures for proximal DD. A novel DD procedure using Non-orthogonal Multiple Access based Multi-user Shared Access (MUSA) is proposed in this article for network-assisted D2D communication. The proposed shared access scheme uses a complex spreading pattern to accommodate dense device discovery and enhance discovery distance in the cellular systems. A discovery signal shared access method with supplementary schemes for multi-user detection is also designed. With MUSA and its spreading pattern demodulation, 12% enhanced energy efficiency, and 98% overall improved accuracy is achieved contrasted with the customary DD methods.

MULTI USER BASED PERFORMANCE ANALYSIS IN UPCOMING 5G TECHNIQUES

The 5G technology will provide high spectral efficiency and low latency for users around the world. To address the requirements the non-orthogonal schemes such as sparse code multiple access (SCMA), multiuser shared access (MUSA), pattern division multiple access (PDMA) are considered in this article. The Symbol error rate (SER) performance is calculated and plotted for different number of users, the analysis of PDMA and SCMA is examined for same factor graph. The average SER is calculated for three NOMA techniques for different users in the hexagonal shape cell under different Signal to Noise Ratio values. The SCMA shows 3% improvement in average SER value when compare to PDMA and MUSA techniques.

A Multi User based Joint Bit Error Rate improvements in PDMA

The development of mobile Internet and Internet of things (IoT), the 5th generation (5G) wireless communications will foresee explosive increase in mobile traffic. To address challenges in 5Gisuchiasihigherispectraliefficiency,imassive connectivity,iandilowerilatency,isomeiNon-OrthogonaliMultipleiAccessi(NOMA)ischemesihaveibeenirecentlyiactivelyiinvestigatediincludingipower-domainiNOMA,imultipleiaccess with Low-Density Spreading (LDS), Sparse Code Multiple Access (SCMA), Multi-user Shared Access (MUSA), pattern division multiple access (PDMA). Pattern Division Multiple Access is the key technique for analyzing group of users at a time. In this paper we investigate BER performance for 5G systems with different multiple accesses schemes, i.e Orthogonal Frequency Division Multiplexing (OFDM), Filter Bank Multicarrier (FBMC), Generalized Frequency Division Multiplexing (GFDM),in comparison to these we design a closed form analysis method of Multi-user FDMC technique far better. Simulation results show that MU FDMC performs better than conventional methods.

Multi-user shared access in massive machine-type communication systems via superimposed waveforms

With the development of the mobile internet and Internet of things (IoT), the number of connected devices is increasing exponentially. Services that are required to support a large number of users, such as massive machine-type communications (mMTC), suffer from limited radio resources. Non-orthogonal multiple access (NOMA) is a promising access scheme for mMTC systems to meet the massive connectivity and heterogeneous network demands with low latency and high throughput. Motivated by the problems of an mMTC system, we propose a novel waveform that superimposes the users on the same resources with a family of orthogonal functions. The proposed model, which we call superimposed multi-user shared access (MUSA), is able to support more users than the conventional MUSA scheme. Furthermore, we combine the superimposed MUSA scheme with generalized frequency division multiplexing (GFDM) technique to achieve low latency with high overloading ratio. The performances of the superimposed MUSA and superimposed MUSA with GFDM are investigated over Rayleigh fading channel model. It is shown that the overloading ratio with three layers of superimposed orthogonal functions becomes three times that of the conventional MUSA scheme with low latency by using the GFDM structure.

Performance analysis of 5-ary MUSA and SCMA for uplink transmission

<p>Multiple access is one of the core technologies of wireless communications, which enables wireless base stations to deal with a large number of different users and provide the service for each of them at the same time. Meeting the 5G challenges, non-orthogonal multiple access is the main concerned point in 5G technologies. In this paper, two types of non-orthogonal multiple access schemes, namely, 5-ary Multi User Shared Access (MUSA) and Sparse Code Multiple Access (SCMA), are studied. The Bit Error Rate performance (BER) analysis in terms of user overloading for an uplink 5-ary MUSA and SCMA systems are analyzed.</p>

Multi-Stage Partial Parallel Interference Cancellation Algorithm for MUSA Systems

Multi-User Shared Access is a non-orthogonal multiple access scheme of 5G,which has a high computational complexity and a large time delay due to the usage of successive interference cancellation detection algorithm. This paper proposes a multi-stage partial parallel interference cancellation detection algorithm, which does not require repeated ordering and repeated matrix inversion. In the first stage of detection, the bits of these users with good channel conditions will be outputted, and the influence of multiple access interference on users with bad channel conditions in the second stage will be decreased. Theoretical analysis and simulation results show that the symbol error rate of the proposed algorithm is slightly better than that of the two-stage MMSE-PIC, and the complexity is reduced. In the meanwhile, the computational complexity is significantly reduced without SER performance degradation when compared with MMSE-SIC algorithm.

Non-orthogonal transmission technology in LTE evolution

Non-orthogonal transmission, although not entirely new to the wireless industry, is gaining more attention due to its promised throughput gain and unique capability to support a large number of simultaneous transmissions within limited resources. In this article, several key techniques for non-orthogonal transmission are discussed. The downlink technique is featured by MUST, which is being specified in 3GPP for mobile broadband services. In the uplink, grantfree schemes such as multi-user shared access and sparse code multiple access, are promising in supporting massive machine-type communication services. The multi-antenna aspect is also addressed in the context of MUST, showing that MIMO technology and non-orthogonal transmission can be used jointly to provide combined gain.

On Novel Access and Scheduling Schemes for IoT Communications

The Internet of Things (IoT) is expected to foster the development of 5G wireless networks and requires the efficient support for a large number of simultaneous short message communications. To address these challenges, some existing works utilize new waveform and multiuser superposition transmission schemes to improve the capacity of IoT communication. In this paper, we will investigate the spatial degree of freedom of IoT devices based on their distribution, then extend the multiuser shared access (MUSA) which is one of the typical MUST schemes to spatial domain, and propose two novel schemes, that is, the preconfigured access scheme and the joint spatial and code domain scheduling scheme, to enhance IoT communication. The results indicate that the proposed schemes can reduce the collision rate dramatically during the IoT random access procedure and improve the performance of IoT communication obviously. Based on the simulation results, it is also shown that the proposed scheduling scheme can achieve the similar performance to the corresponding brute-force scheduling but with lower complexity.

A survey: Several technologies of non-orthogonal transmission for 5G

One key advantage of 4G OFDM system is the relatively simple receiver implementation due to the orthogonal resource allocation. However, from sum-capacity and spectral efficiency points of view, orthogonal systems are never the achieving schemes. With the rapid development of mobile communication systems, a novel concept of non-orthogonal transmission for 5G mobile communications has attracted researches all around the world. In this trend, many new multiple access schemes and waveform modulation technologies were proposed. In this paper, some promising ones of them were discussed which include Non-orthogonal Multiple Access (NOMA), Sparse Code Multiple Access (SCMA), Multi-user Shared Access (MUSA), Pattern Division Multiple Access (PDMA) and some main new waveforms including Filter-bank based Multicarrier (FBMC), Universal Filtered Multi-Carrier (UFMC), Generalized Frequency Division Multiplexing (GFDM). By analyzing and comparing features of these technologies, a research direction of guiding on future 5G multiple access and waveform are given.

Non-orthogonal multiple access for 5G: solutions, challenges, opportunities, and future research trends

The increasing demand of mobile Internet and the Internet of Things poses challenging requirements for 5G wireless communications, such as high spectral efficiency and massive connectivity. In this article, a promising technology, non-orthogonal multiple access (NOMA), is discussed, which can address some of these challenges for 5G. Different from conventional orthogonal multiple access technologies, NOMA can accommodate much more users via nonorthogonal resource allocation. We divide existing dominant NOMA schemes into two categories: power-domain multiplexing and code-domain multiplexing, and the corresponding schemes include power-domain NOMA, multiple access with low-density spreading, sparse code multiple access, multi-user shared access, pattern division multiple access, and so on. We discuss their principles, key features, and pros/cons, and then provide a comprehensive comparison of these solutions from the perspective of spectral efficiency, system performance, receiver complexity, and so on. In addition, challenges, opportunities, and future research trends for NOMA design are highlighted to provide some insight on the potential future work for researchers in this field. Finally, to leverage different multiple access schemes including both conventional OMA and new NOMA, we propose the concept of software defined multiple access (SoDeMA), which enables adaptive configuration of available multiple access schemes to support diverse services and applications in future 5G networks.