Next-generation Mobile Communication Research Articles

Microwave Irradiation Process for Al\u2013Sc Alloy Production

Scandium is being explored as an alloying element for aluminium alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. Sc-rich ScAlN thin films show strong piezoelectricity and can be fabricated on a hard substrate for use as wideband surface acoustic wave filters in next-generation wireless mobile communication systems. However, the use of ScAlN thin films in microelectromechanical system devices is limited by the high cost of metallic Sc, which is due to the difficulty in smelting of this material. Here, we propose a novel microwave irradiation process for producing Al-Sc alloys, with Mg ions as a reducing agent. Although scandium oxide is thermodynamically stable, intermetallic Al3Sc is obtained in high yield (69.8%) via a low-temperature (660 °C) reduction reaction under microwave irradiation. Optical spectroscopy results and thermodynamic considerations suggest a non-thermal equilibrium reaction with the univalent magnesium ions excited by microwave irradiation.

A Review on Next Generation Mobile Communication-5G

Abstract In the upcoming years (expected 2020), 5G technology is going to deploy all around the world. Presently a lot of researches and project on the fifth generation mobile communication system are finalized and tested successfully in the research labs. Within two to three years, 5G technology is going to replace the present technology and many mobile gadgets are coming with 5G support. The main focus of this technology is to provide better spectrum utilization, ultra speed communication, QoS, etc. In this article, the comprehensive analysis of next-generation mobile communication system is provided and it includes technologies employed for 5G. This work will give a detailed investigation and discussion on the features of 5G technology.

Nyquist filter design

Designing a new pulse-shaping filter that satisfies the Nyquist condition to mitigate inter-symbol interference and achieve better stopband attenuation is a new step towards the development of next-generation mobile communication systems. In this study, the authors propose a novel Nyquist filter based on the convolution of a rectangular and a truncated sinc pulses. Introducing two-time parameters in the filter function provides more degrees of freedom and high flexibility to shape different Nyquist pulses. Four Nyquist pulse shapes are introduced, examined in terms of time and frequency characteristics, and compared with those of the two most popular pulses in the literature: root-raised cosine (RRC) and PHYDYAS. The results demonstrate an improvement in the eye pattern, impulse response, and spectrum behaviours. The error rates are evaluated over a noisy channel, and the new pulses offered better performance than PHYDYAS and RRC. The intrinsic interference was examined by determining the autocorrelation and cross-correlation coefficients of the prototype filters in the frequency-time grid. The results for the proposed filters portray good interference confinement either in time or frequency axis. The reduction in the out-of-band emission makes the proposed filter an efficient candidate for future filter bank multicarrier scheme.

5G network slicing strategies for a smart factory

Factories become increasingly dependent on network connectivity. The next generation of mobile communications, 5G, will enable better flexibility and service quality through network slicing. Network slicing is a means of creating logically separated use case specific virtual networks over the same physical network. However, there is a lack of techno-economic research related to the management of network slices. Network slice management needs to take into account the multiple network domains, business actors and value networks involved in a vertical such as smart factories. The key for network slices to succeed where other resource reservation and quality of service technologies have previously failed is with well-defined feasible management models and strategies. In this paper, we focus on network slice management, possible strategies and implications for a smart factory. We study a state-of-the-art electronics assembly factory in Finland to find existing need for network slicing and missing capabilities to support smart factory use cases. Next, we define use case specific network slices and develop a network slice management model based on 5G specifications. The model allows for distribution of network functions between business actors over multiple network domains. The value network analysis method is utilized to develop alternative configurations that constitute the network slicing strategies facilitated by the model. Factory managers can decide on the most feasible strategy based on traditional factors such as make or buy, security, and level of automation. The strategies also differ in their technical applicability to different use cases. A feasibility study reveals the strategic differences from factory, local network operator and large mobile network operator perspectives.

Modified DSLM Technique for PAPR Reduction in FBMC System

In the modern age, wireless communication has taken on a wide range of applications in different aspects of a human life. Ever increasing demand for higher data rates led the interest of research in FBMC (Filter Bank Multi-Carrier) as a new transmission system for the next-generation mobile communication system. FBMC is a multicarrier technique which utilized filters at the transmitting and the receiving side of the system. It is considered as one of the most promising waveform for fifth generation mobile communication system (5G). But, high value of Peak Average Power Ratio (PAPR) is considered to be one of the giant problems in FBMC. The PAPR reduction techniques used in OFDM cannot be utilized in FBMC due to its overlapping structure. Hence, new PAPR reduction techniques for FBMC have diverted the attention of researchers. In this work, dispersive selective mapping (DSLM) PAPR reduction technique is proposed. Further, the proposed technique is compared to selected mapping (SLM) and clipping PAPR reduction techniques. The simulation results show that the proposed DSLM technique gives the better performance in terms of bit error rate (BER), PAPR and complexity as compared to the SLM and clipping PAPR reduction techniques.

A 12.1 fJ/Conv.-Step 12b 140 MS/s 28-nm CMOS Pipelined SAR ADC Based on Energy-Efficient Switching and Shared Ring Amplifier

This brief presents an ultra-low-power two-channel 12b 140 MS/s 28-nm CMOS analog-to-digital converter (ADC) for use in next-generation mobile communications systems. The proposed ADC employs a two-stage pipelined successive-approximation register (SAR) ADC architecture, where the SAR ADC at each stage determines 5b and 8b, respectively. In the first-stage 5b SAR ADC, the switching power consumption is significantly reduced due to the switching operation by only a separate digital-to-analog converter (DAC) with a small unit capacitance, which generates the comparator decision threshold. When this setup is applied to an actual system, the reference voltage driver of the system is less burdened. Furthermore, the SAR ADC employs a custom-encapsulated capacitor to improve the limited linearity of a DAC caused by parasitic capacitance. A residue amplifier employs an ultra-low power ring amplifier structure. The amplifier is shared by each channel to reduce not only the power consumption and die area but also channel mismatches. The prototype ADC in a 28-nm CMOS process demonstrates a measured differential non-linearity and integral non-linearity within 1.50 LSB and 2.85 LSB at 12b, respectively, with a maximum signal-to-noise-and-distortion ratio and a spurious-free dynamic range of 58.0 dB and 73.7 dB at 140 MS/s, respectively. The ADC occupies an active die area of 0.202 mm2 and consumes 1.1 mW at a 0.8-V supply voltage, corresponding to a figure of merit of 12.1 fJ/conversion-step.

300 GHz Optoelectronic Transmitter Combining Integrated Photonics and Electronic Multipliers for Wireless Communication

THz communications systems at carrier frequencies above 200 GHz are the key to enable next-generation mobile communication networks with 100 Gbit/s wireless data rates. One of the key questions is, which carrier frequency generation technique will be the most suitable. This is currently addressed by two separate approaches, electronics-based and photonics-based. We present in this paper a truly microwave photonic approach that benefits from the main key features of each, bandwidth, tunability, stability and fiber compatibility from photonics and power handling capability from the electronics. It is based on a Photonic Local Oscillator (PLO), generating a 100 GHz frequency, fed into an electronic frequency multiplier. A high speed uni-travelling carrier photodiode (UTC-PD) provides the 100 GHz PLO for Schottky tripler diodes, generating 300 GHz signal. To feed the UTC-PD, we present a photonic integrated mode locked laser source. According to the simulations and measurements, the developed transmitter can produce a maximum of 12 μW of THz power at 280 GHz.

Joint Wavelength, Antenna, and Radio Resource Block Allocation for Massive MIMO Enabled Beamforming in a TWDM-PON Based Fronthaul

Massive multiple input multiple output (mMIMO) enabled beamforming is a promising technology in the next generation of mobile communication. It allows multiple antennas transmit the same data to a user to improve the signal strength and quality. However, beamforming may incur redundant data transmission over fronthaul in the centralized radio access networks. When accommodating a set of beam requests, a key problem is how to coordinate radio and optical resources to maximize the beamforming throughput and minimize the fronthaul bandwidth. In this paper, we study on the joint wavelength, antenna, radio resource block allocation (WARA) in a time and wavelength division multiplexed passive optical network, which is an economic fronthaul solution for the mMIMO. We formulate the WARA into an integer linear programming (ILP) model. Three heuristic algorithms are proposed to optimize fronthaul bandwidth, radio resource block (RB) utilization, and both. We compare ILP with the proposed algorithms under different sizes of antenna arrays. A tradeoff is shown to exist between fronthaul bandwidth and radio RB utilization. Also, we find that the optimization goal depends on the number of antennas in an optical network unit.

Radio resource allocation in multi-cell and multi-service mobile network based on QoS requirements

Modern networks offer many service types that need to be considered for a fair distribution of the available radio resources. One of the main strategies of the next generation of mobile communications to deal with that traffic demand is to reduce the distances between transmitters and receivers, in order to maximize the number of available channels per area. However, this solution also comes with a drawback: the inter-cell interference becomes more significant. In this work, we present new channel-aware Physical Resource Block (PRB) assignment problems for planned and unplanned small-cell networks. The problems are modeled as Integer Linear Programming (ILP) problems in order to handle the inter-cell interference issue, considering minimum data rate requirements per User Equipment (UE). We consider a Cloud-Radio Access Network (C-RAN), in which the PRB assignment within the network can be globally managed. Specifically for planned networks, the proposed formulation guarantees a minimum data rate in different coverage regions of each cell based on UEs’ traffic services. The proposed problems differ from other C-RAN PRB assignment approaches from the literature in the sense that our proposal guarantees solutions with minimum satisfaction for each mobile service provided by the network. Since the optimal solutions of the proposed problems have exponential complexity, this work also proposes a low-complexity heuristic solution which has polynomial complexity. In the most challenging simulated scenario, the proposed heuristic achieves 3.5% of data rate loss compared with the optimal solution, while a benchmark from the literature achieves 18.5%. In another scenario, we evaluate the outage probability, i.e., the relative frequency in which an algorithm is not capable of finding a feasible solution to the problem. In that scenario we show that the outage rate of the optimal and proposed solutions are similar, achieving 15% and 17.5%, respectively, whereas the benchmark solution presents a significantly higher outage rate of 36%.

Novel 5G Authentication Protocol to Improve the Resistance Against Active Attacks and Malicious Serving Networks

The security of mobile communication largely depends on the strength of the authentication key exchange protocol. The 3rd Generation Partnership Project (3GPP) Group has standardized the 5G AKA (Authentication and Key Agreement) protocol for the next generation of mobile communications. It has been recently shown that the current version of this protocol still contains several weaknesses regarding user localization, leakage of activity, active attackers, and in the presence of malicious serving networks, leading to potentially major security leaks. We propose a new version of the 5G AKA protocol to overcome all the currently identified weaknesses in the protocol. In the new protocol, we replace the sequence numbers with random numbers, making it possible to drastically reduce the number of required communication phases and steps in the protocol. The usage of random numbers for the 5G AKA protocol is possible since the current Universal Subscriber Identity Modules (USIMs) are now capable of performing randomized asymmetric encryption operations. Moreover, the proposed protocol provides two additional security features, i.e., post-compromise security and forward security, not present in the current 5G AKA protocol. Finally, we evaluate the performance, both computation and communication efficiency, of the proposed AKA protocol and show its improvements compared to the current 5G AKA protocol.

Trading-Based Dynamic Spectrum Access and Allocation in Cognitive Internet of Things

Next-generation mobile communication networks promise the support for vast number of IoT devices with strong demand for spectrum access. The cater for the continuous growth of IoT applications, one of the challenges to mobile communication network providers is to allow dynamic spectrum access to a gigantic number of densely distributed and low-power IoT networks. In this paper, a novel dynamic spectrum access method is proposed based on spectrum trading for distributed IoT devices. The notion of access benefit is introduced which is based on the purchased band number and modulation mode provided to the mobile user. In the proposed solution, IoT users aim achieve optimization of their spectrum access by ensuring that the spectrum price will not exceed the access benefits from the spectrum trading by solving the spectrum optimization function. Due to the complexity of optimization objective function, pattern search algorithm is utilized to complete the final spectrum allocation optimization. Numerical results are also provided to testify the performances of the proposed spectrum optimization method.

Network slicing as enablers for 5G services: state of the art and challenges for mobile industry

The next generation of mobile communications, 5G, is expected to enable global economic output of USD 12.3 trillion by 2035. This would be achieved by applying 5G networks not only to mobile broadband, but also to diverse use cases such as machine-type communications and ultra-reliable low-latency communications. The diverse use cases and requirements are best handled by network slicing, which creates virtual networks over a single physical network. In this paper, we provide an overview of the standardization landscape of network slicing and identify major challenges for mobile operators such as end-to-end scope, roaming, interoperability, and migration. We conclude that the mobile industry and academia should focus on virtualizing base stations and sharing wireless spectrum resources, while selecting set verticals for which to create standardized slices and to formulate relevant requirements, where the GSM Association is a major player to be monitored. The industry should also provide a resolution to ensure the interoperability of network slicing, and study measures to ensure the stable and seamless migration from the physical to virtual networks. With the challenges resolved, mobile operators will be able to harness the full potential of network slicing in their mobile networks.

A 5G-Enabling Technology: Benefits, Feasibility, and Limitations of In-Band Full-Duplex mMIMO

The substantial growth in mobile Internet and Internet of Things traffic has made system capacity enhancement the most important requirement for next-generation mobile communication systems. Massive multiple-input, multiple-output (mMIMO) is a key technology for fulfilling the traffic requirements because of its strong potential to boost spectral efficiency (SE). However, the uplink and downlink of mMIMO usually operate in time-division duplex (TDD) or frequency-division duplex (FDD), which results in an insufficient utilization of time-frequency resources.

Anywhere Decoding: Low-Overhead Uplink Interference Management for Wireless Networks

Inter-cell interference (ICI) is one of the major performance-limiting factors in the context of modern cellular systems. To tackle ICI, coordinated multi-point (CoMP) schemes have been proposed as a key technology for next-generation mobile communication systems. Although CoMP schemes offer promising theoretical gains, their performance could degrade significantly because of practical issues such as limited backhaul. To address this issue, we explore a novel uplink interference management scheme called anywhere decoding, which requires exchanging just a few bits of information per coding interval among the base stations (BSs). Despite the low overhead of anywhere decoding, we observe considerable gains in the outage probability performance of cell-edge users, compared to no cooperation between BSs. Additionally, asymptotic results of the outage probability for high-SNR regimes demonstrate that anywhere decoding schemes achieve full spatial diversity through multiple decoding opportunities, and they are within 1.5 dB of full cooperation.

Possible Security Attack Modeling in Ultradense Networks Using High-Speed Handover Management

The next generation of mobile communication has progressed toward the deployment of small cells to meet the growing demands of increased capacity and QoS as compared to the conventional method, where all the computations were performed by the base station (BS)'s only. To reduce burden at the BS side, small cells deployment has been stressed upon, thus resulting in the formation of ultradense networks (UDN) having high concentration of small cells (e.g., picocell, femtocell, hotspots) and as a counter effect of which distance between two small cells is reduced to a greater extent. With such a close association of cells in UDN, the probability of frequent handovers also increases abruptly. As a result, the chances for attacker to spoof the bandwidth also increases many folds. In this paper, we have analyzed SNR, signal-to-interference-plus-noise ratio, and channel quality information channel parameters, such that the position of moving users at which handover is initiated in picocell deployment of UDN can be traced out successfully or region where the probability of attackers presence is high. Through this paper, we have tried to introduce the attacking scenario for the high mobility conditions in UDN.

Improving reliability of cloud computing services for next generation mobile communication networks

In the future, the virtualized (cloned) smartphone is called the virtual network device, which is hosted in the private and the public cloud environments. This is a major research field in next-generation mobile communication networks. Cloud computing platforms provide efficient and flexible ways to offer services and computation facilities to users. However, reliability in the cloud is an important factor to measure the performance of a virtualized cloud computing platform. The paper proposes a new approach to improve reliability of cloud computing platforms for next communication networks.

W-band radio-over-fiber propagation of two optically encoded wavelength channels

We propose a W-band wavelength-division multiplexing (WDM)-over-optical code-division multiple access radio-over-fiber system. This system offers capacity expansion by increasing the working frequency to millimeter wave region and by introducing optical encoding and multiwavelength multiplexing. The system’s functionality is investigated by software modeling, and the results are presented. The generated signals are data modulated at 10 Gb/s and optically encoded for two wavelength channels and transmitted with a 20-km length of fiber. The received signals are optically decoded and detected. Also, encoding has improved the bit error rate (BER) versus the received optical power margin for the WDM setting by about 4 dB. In addition, the eye-diagram shows that the difference between received optical power levels at the BER of 10−12 to 10−3 is about 1.3% between two encoded channels. This method of capacity improvement is significantly important for the next generation of mobile communication, where millimeter wave signals will be widely used to deliver data to small cells.

The Impact of Antenna Height on 3D Channel: A Ray Launching Based Analysis

Three-dimensional (3D) multi-input-multi-output (MIMO) is one of the enabling technologies for next-generation mobile communication. As the elevation angle in the 3D MIMO channel model might vary against the height of the base station (BS) antenna, it should be considered within channel modeling. In this paper, the impact of antenna height on the channel characteristics of the 3D MIMO channel is investigated by using the intelligent ray launching algorithm (IRLA). Three typical street scenarios, i.e., the straight street, the forked road, and the crossroad, are selected as benchmarks. The joint and marginal probability density functions (PDFs) of both the elevation angle of departure (EAoD) and the elevation angle of arrival (EAoA) are obtained through simulations. Moreover, the elevation angle spread (AS) and the elevation delay spread (DS) under various antenna heights are jointly discussed. Simulation results show that the characteristics of the PDFs of EAoD will vary under different street scenarios. It is observed that in order to obtain the maximum or minimum value of the AS and the DS, the BS antenna should be deployed at half of the building height.

Propagation at mmW Band in Metropolitan Railway Tunnels

The next generation of mobile communications, 5G, will provide a wideband network based on microwave and millimeter‐wave (mmW) communication radio links with the goal of fulfilling the strict and severe requirements of the future test cases. In particular, this paper research is focused on mmW bands in metropolitan railway tunnels. For that purpose, a propagation measurement campaign was performed at 24 GHz band in a passenger train on a realist subway environment, and these results were combined with simulations ad hoc for tunnels and a theoretical modal propagation model. A narrowband and a wideband study have been conducted with the aim of obtaining the path loss, fading, power‐delay profile, and angle of arrival, taking into consideration horizontal and vertical polarization in the receiving and transmitting antennas. This validation can be used to design and deploy wideband mobile communication networks at mmW bands in railway scenarios.

Power Allocation for Downlink NOMA Heterogeneous Networks

Non-orthogonal multiple access (NOMA) and heterogeneous network (HetNet) are two significant and promising enabling techniques to further improve overall system performance for next-generation mobile communication systems. In this paper, we develop a novel NOMA HetNet through applying NOMA technique to both macrocell and small-cell of conventional HetNet, which improves the spectral efficiency whereas results in a more complex interference environment. To tackle this complicated interference problem and maximize the overall throughput of this NOMA HetNet, meanwhile ensure the desired quality of service (QoS) of each user, we mathematically formulate a power allocation problem which proves to be an NP-hard problem. Then, to deal with this optimization problem, we propose a users scheduling scheme and an iterative distributed power control algorithm. The simulation results demonstrate that compared with the conventional orthogonal multiple access (OMA) HetNet systems and single-tier NOMA networks, the combination of OMA technique and HetNet with the proposed algorithm can greatly improve the system performance in terms of spectral efficiency and outage performance.