Non-Orthogonal Physical Layer (NOPHY) Design towards 5G Evolution and 6G

Since the emergence of mobile communication systems as networks specifically for telephone service, they have experienced rapid progress. The evolution of mobile generations has seen a diversity of services, which includes data as the first service, then video, and other services. The fifth-generation network (5G) is the future of information networks. It is not really a further advancement of the fourth generation (4G) but another kind of mobile system model that supports high frequencies, extreme node densities, large-scale antennas, high bandwidth huge, etc. In this context, 5G networks can call on a wide range of new technologies. This allows for a leap in performance that eclipses its predecessors. These innovations will affect the transmission and design of the physical layer in addition to introducing disruption to the upper layers of the network. In fact, 5G New Radio (NR) will use many key technologies to achieve new levels of performance and efficiency. Some of the potential innovations in the 5G physical layer include Non-orthogonal Multiple Access (NOMA). The users are superimposed in the power domain, and the decoding mode is based on the Successive Interference Cancellation (SIC). To aim with the challenges in NOMA method, the deep learning (DL) models are a recommended solution. In this paper, we treat the technique NOMA for 5G and how the use of deep learning techniques can improve the performance of network.Keywords5GNRMultiple accessNOMASICCSIOFDMADL

Vehicle-to-everything (V2X) communications are regarded as the key technology in future vehicular networks due to its ability in providing efficient and reliable massive connections, improving traffic efficiency and safety, and supporting in-vehicle entertainment and working. Recently, non-orthogonal multiple access (NOMA), as a promising solution in the fifth-generation (5G) mobile communication systems, has drawn much attention because it can significantly improve the network throughput and lower the accessing and transmission latency to meet the quality-of-service (QoS) requirements of many 5G-enabled applications. Noticing these, in this paper, we consider a device-to-device (D2D)-enhanced V2X network, in which NOMA is introduced to increase the capacity. In our studied NOMA-V2X system, except for the NOMA-based intra-group resource reuse, the D2D-enabled resource sharing based on spatial reuse among all the V2X communication groups is also permitted through centralized resource management, leading to a significantly improved network performance but a more complicated and challenging interference scenario. In order to efficiently manage the interference and allocate the resource in the NOMA-V2X network, we create a weighted 3-partite interference hypergraph (IHG) to imitate the complex interference environment in our studied scenario. Then, with the help of this hypergraph, we make another step to put forward an IHG-based 3-dimensional matching (IHG-3DM) resource allocation protocol with a greedy 3DM algorithm and an iterative 3DM algorithm. As a consequence, the network throughput is significantly improved with the help of our proposed IHG-3DM resource allocation protocol for the investigated NOMA-integrated V2X communications, which is verified by the simulation results.

Vehicular networking belongs to one of the most attractive techniques under the context of 5th Generation (5G) and Beyond 5G (B5G) wireless communication system. It opens diverse new concepts and applications, e.g. Vehicular-to-Vehicular (V2V), Vehicular-to-Infrastructure (V2I). One of the key components to support autonomous driving is to allow vehicles to share information about their awareness of the environment, i.e. perception layer of neighbor vehicles. In this paper, we focus on low overhead, low latency MAC layer design, enabling perception layer sharing in V2V environment, and PHY layer design, enabling Multi-User Detection (MUD) with V2V environment by means of Non-Orthogonal Multiple Access (NOMA), which is one of the key physical layer technologies of 5G New Radio (NR). Numerical results of link level simulation exhibit that our solution generates and exchanges the NOMA user signature flexibly, i.e. supports both synchronous and asynchronous traffic with low bit error rate. Furthermore, it enables small packet communication with low computational complexity, thus low latency.

We consider the problem of quality of service (QoS) routing in multi-hop wireless networks where data are transmitted from a source node to a destination node via multiple hops. The routing component of a QoS-routing algorithm essentially involves the link and path metric calculation which depends on many factors such as the physical and link layer designs of the underlying wireless network, transmission errors due to channel fading and interference, etc. The task of link metric calculation basically requires us to solve a tandem queueing problem which is the focus of this paper. We present a unified tandem queue framework which is applicable for many different physical layer designs. We present both exact and approximated decomposition approaches. Using the queueing framework, we can derive different performance measures, namely, end-to-end loss rate, end-to-end average delay, and end-to-end delay distribution. The proposed decomposition approach is validated and some interesting insights into the system performance are highlighted. We then present how to use the decomposition queueing approach to calculate the link metric and incorporate this into the route discovery process of the QoS routing algorithm. The extension of the queueing and QoS routing framework to wireless networks with class-based queueing for QoS differentiation is also presented.

Vehicle-to-everything (V2X) communications are regarded as the key technology in future vehicular networks due to its ability in improving the traffic efficiency and safety, and reducing congestion. Recently, non-orthogonal multiple access (NOMA), as a promising solution in the fifth generation (5G) mobile communication systems, has drawn much attention because it can significantly improve the network throughput and lower the accessing and transmission latency to meet the requirements of many 5G-enabled applications. Noticing these, in this paper, we propose to introduce NOMA in device-to-device (D2D)-enhanced V2X networks, where D2D-enabled resource sharing based on spatial reuse for different V2X communication groups are permitted through centralized resource management. Such an enhanced NOMA-V2X architecture results in a more complicated and challenging interference scenario. In order to efficiently solve the interference management and resource allocation problem in the NOMA-V2X network, we construct a weighted 3-partite interference hypergraph to model the relationships among different communication groups. Then, based on the constructed hypergraph, we further propose an interference hypergraph-based 3-dimensional matching (IHG-3DM) resource allocation protocol with a greedy 3DM algorithm. Simulation results verify the efficiency of our proposed IHG-3DM resource allocation protocol for NOMA-V2X communications in improving the network throughput.

Vehicular communication network is a core application scenario in the fifth generation (5G) mobile communication system which requires ultra high data rate and ultra low latency. Most recently, non-orthogonal multiple access (NOMA) has been regarded as a promising technique for future 5G systems due to its capability in significantly improving the spectral efficiency and reducing the data transmission latency. In this paper, we propose to introduce NOMA in D2D-enabled V2X networks, where resource sharing based on spatial reuse for different V2X communications are permitted through centralized resource management. Considering the complicated interference scenario caused by NOMA and spatial reuse-based resource sharing in the investigated NOMA-integrated V2X networks, we construct an interference hypergraph to model the interference relationships among different communication groups. In addition, based on the constructed hypergraph, we further propose an interference hypergraph-based resource allocation (IHG-RA) scheme with cluster coloring algorithm, which can lead to both effective and efficient QoS-guaranteed resource block (RB) assignment with low computational complexity. Simulation results verify the efficiency of our proposed IHG-RA scheme for NOMA-integrated V2X communications in improving the network sum rate.

The rapid evolution of the wireless communication technologies along with the growing number of connected vehicles and the limitation of available radio resources make scheduling tasks very important for the fifth generation (5G) mobile communication system Thus, to handle the challenges of access collisions, the scarcity of spectral efficiency due to the limited bandwidth and massive connectivity, non-orthogonal multiple access (NOMA) schemes have been introduced as a potential solution for 5G wireless networks. Accordingly, this paper presents a new optimal scheduling algorithm for V2X connections called Dynamic Scheduling Algorithm based on NOMA with Priority Assignment for vehicular Networks (DSA-PA-NOMA), which improves performances in terms of Quality of Service (QoS), throughput and bit error rate (BER). The proposed algorithm consider the traffic classification imposed by V2X exigency and aims to maximize the system throughput by taking into account the channel conditions of Vehicular User Equipment (VUE) expressed by the Signal-to-Interference-plus-Noise Ratio (SINR) value. The optimal distribution of the available Resources Blocks (RBs) is based on a dynamic reallocation process depending in the average blocking rate value (ABR) especially for vehicular Safety Traffic (ST).

Among the key technologies that have been identified as capacity boosters for fifth generation - 5G - mobile networks, are millimeter wave (mmWave) transmissions and non-orthogonal multiple access (NOMA). The large amount of spectrum available at mmWave frequencies combined with a more effective use of available resources, helps improving the overall capacity. NOMA, unlike orthogonal multiple access (OMA) methods, allows sharing the same frequency resources at the same time, by implementing adaptive power allocation. In this paper we present a performance analysis of NOMA in mmWave cells, using OMA as a benchmark. The results show that up to 70% channel capacity gain can be achieved when using NOMA instead of OMA. Most of the NOMA studies to the date focus mainly on the capacity gain; therefore we also present an analysis of the required signal-to-interference-plus-noise ratio (SINR) in NOMA, needed to achieve a target block error rate (BLER). The results show that an average SINR penalty of 12 dB is present when choosing NOMA over OMA.

Vehicular communication network is a core application scenario in the fifth generation (5G) mobile communication system which requires ultrahigh data rate and ultralow latency. Most recently, nonorthogonal multiple access (NOMA) has been regarded as a promising technique for future 5G systems due to its capability in significantly improving the spectral efficiency and reducing the data transmission latency. In this paper, we propose to introduce NOMA in device-to-device-enhanced vehicle-to-everything (V2X) networks, where resource sharing based on spatial reuse for different V2X communications are permitted through centralized resource management. Considering the complicated interference scenario caused by NOMA and spatial reuse-based resource sharing in the investigated NOMA-integrated V2X (NOMA-V2X) networks, we construct an interference hypergraph (IHG) to model the interference relationships among different communication groups. In addition, based on the constructed IHG, we further propose an IHG-based resource allocation (IHG-RA) scheme with cluster coloring algorithm, which can lead to both effective and efficient resource block assignment with low computational complexity. Simulation results verify the efficiency of our proposed IHG-RA scheme for NOMA-V2X communications in improving the network sum rate.

Multi-User Multiple-Input Multiple-Output (MU-MIMO) and Non-Orthogonal Multiple Access (NOMA) belong to the key physical layer technologies under the context of 5th Generation (5G) New Radio (NR) communication. Both MU- MIMO and NOMA exhibit capability to significantly enhance the spectral efficiency from different aspects. In this paper, we investigate and compare MU-MIMO and NOMA in link level with respect to some practical issues, e.g. imperfect channel estimation, imperfect sectorization. Numerical results reveal that the coexistence of MU-MIMO and NOMA provide the degrees of freedom to allow the system to selectively focus on spectral efficiency per user or the number of supported users, and effectively be associated with scheduled traffic and contention-based traffic, respectively.

This paper investigates the optimal resource allocation of a downlink non-orthogonal multiple access (NOMA) system consisting of one base station and multiple users. Unlike existing short-term NOMA designs that focused on the resource allocation for only the current transmission timeslot, we aim to maximize a long-term network utility by jointly optimizing the data rate control at the network layer and the power allocation among multiple users at the physical layer, subject to practical constraints on both the short-term and long-term power consumptions. To solve this problem, we leverage the recently-developed Lyapunov optimization framework to convert the original long-term optimization problem into a series of online rate control and power allocation problems in each timeslot. The power allocation problem, however, is shown to be non-convex in nature and thus cannot be solved with a standard method. However, we explore two structures of the optimal solution and develop a dynamic programming based power allocation algorithm, which can derive a globally optimal solution, with a polynomial computational complexity. Extensive simulation results are provided to evaluate the performance of the proposed joint rate control and power allocation framework for NOMA systems, which demonstrate that the proposed NOMA design can significantly outperform multiple benchmark schemes, including orthogonal multiple access (OMA) schemes with optimal power allocation and NOMA schemes with non-optimal power allocation, in terms of average throughput and data delay.

This paper concerns the cross-layer design between physical layer and MAC (multiple access control) layer in asynchronous wireless random access network. The proposed cross-layer design consists of two parts: a MPR (Multiple Packet Reception) physical layer and a collision- aware MAC layer. In the physical layer design, different spreading codes are assigned to packets according to their frame types at the transmitter, and at the receiver, an enhanced synchronization method and MUD (Multi-user Detection) are utilized to synchronize the collided packets and recover packets. In order to reduce the computational complexity of the receiver, interference cancellation is performed at the receiver by utilizing the known preamble and the partially known frame header information. In the MAC layer design, collisions are divided into different types according to frame types and packet arrival time, and different operations are developed for different collision types to tactically access the channel. Simulation results show that the proposed cross-layer design can significantly improve the network throughput and reduce the transmission delay.

Non-orthogonal multiple access (NOMA) is emerging as a popular radio access technique to serve multiple users under the same resource block to improve spectral efficiency in 5G and 6G communication. But the resource sharing in NOMA causes concerns on data security. Since power domain NOMA exploits the difference in channel properties for bandwidth-efficient communication, it is feasible to ensure data confidentiality in NOMA communication through physical layer security techniques. In this work, we propose to ensure resistance against internal eavesdropping in NOMA communication through a secret key derived from channel randomness. A unique secret key is derived from the channel of each NOMA user; which is used to randomize the data of the respective user before superposition coding (SC) to prevent internal eavesdropping. The simulation results show that the proposed system provides very good security against internal eavesdropping in NOMA.

Currently, the standardization of fifth generation mobile communication system (5G), which realizes 10 Gbps transmission, is in progress. In mobile communications, it is generally difficult to perform high-capacity transmission because of channel fading. Therefore, an adaptive resource allocation scheme based on users' channel conditions is adopted to enhance the system capacity. Recently, it has been shown that a nonorthogonal multiple access (NOMA) scheme can achieve a higher system capacity than orthogonal multiple access scheme. However, anticipating a continuous increase of mobile traffic, it is desired to further enhance the capacity of NOMA scheme. Therefore, we propose an application of code division multiplexing to NOMA scheme using successive interference canceller to improve the throughput performance. The improved performance is demonstrated through numerical simulations.

Non-orthogonal multiple access (NOMA) is one of the key technology of the fifth generation mobile communication systems to increase the network capacity and data rate. The combination of multi-input multi-output (MIMO) technique and non-orthogonal multiple access (NOMA) systems can further improve the spectrum efficiency. In this paper, we investigate the power allocation problem in downlink MIMO-NOMA system. We first formulate the power allocation problem as a weighted sum rate maximization problem. Then, a series transformations based on quadratic transformation and Lagrange dual transformation are introduced to convert the original problem into a convex problem. Moreover, we propose an iterative algorithm to obtain the optimal solution of power allocation. Numerical results show the excellent convergence of our proposed power allocation approach and reveal that the proposed scheme improves the weighted sum rate significantly in MIMO-NOMA systems.