Generation Mobile Communication Systems Research Articles

Design and Performance Analysis of OFDM and FBMC Modulation Techniques

Abstract Researchers have already proved that data consumption in coming years will increase by leaps and bounds, so the present technologies like 3G, OFDM (Orthogonal Frequency Division Multiplexing) cannot hold the addition of huge capacitance, data use and demand of high data-rate. Hence, on that point is a necessity of fifth generation mobile communication system (5G). Presently the rollout for 5G is going virtually everywhere in the world and among several issues; selection of better modulation techniques is seen as unitary of the significant issues in the implementation of the 5G. In this work, we designed and analyse the performance of OFDM and FBMC (Filter Band Multi Carrier) multicarrier modulation schemes on the basis of Bit Error rate (BER) and Signal to Noise Ratio (SNR). Simulation results and mathematical analysis have confirmed that the performance and spectrum utilization of FBMC is better or equivalent as compared to OFDM, which can be very useful in next generation mobile communication and Internet of Things (IOT).

Elastic Optical Networking for 5G Transport

The 5th generation of mobile communication system (5G) is expected to change the communication landscape by 2020. 5G will provide a unified platform for connecting billions of devices and offering a wide range of networking services. The use-cases and the disruptive capabilities of 5G will bring forward a number of challenges for both the wireless radio and wired part of a 5G network. The wired transport network, typically consisting of access and core domains, has to adopt tailored networking solutions satisfying differentiated quality of service requirements as envisioned in 5G. While optical transport technology has been prevalent in core segments, it is also perceived as a key enabler for the 5G access networks due to its very high capacity and low transmission delay. However, existing optical transport technologies are hindered by inflexibility, poor resource utilization, and high costs, and cannot be stretched to 5G scale. On the other hand, optical technologies have been going through a paradigm shift towards an elastic optical network that is considered as the promising solution for future high-speed transport networks. This paper outlines key challenges for the design of a flexible, programmable, and dynamic 5G transport network, and discusses the enabling technologies and directions to address these challenges.

Orthogonal frequency division multiplexing simulation based on MATLAB

OFDM (Orthogonal Frequency Division Multiplexing) is one of the core technologies in the fourth generation mobile communication system. It is a widely-used method of the multi-carrier modulations based on IFFT and FFT transform, it can achieve the lowest complexity and effectively combat frequency selective fading. In this paper, we successfully use MATLAB to do the simulation of OFDM, and obtained good results, in which successful recovery out of the original signal under real channel condition, and error is less than 5% with the original signal.

Sparse inverse fast Fourier transform‐based channel estimation for millimetre‐wave vector orthogonal frequency division multiplexing systems

Millimetre-wave propagation is a promising broadband transmission technology for future fifth generation mobile communication systems. For a vector orthogonal frequency division multiplexing system, the authors investigate the millimetre-wave propagation through a sparse multipath channel in a sense that it has a large time delay spread but with only a few non-zero taps. By exploiting the sparse nature of millimetre-wave channel, any sparse multipath channel can be characterised by the multipath delays and their corresponding channel coefficients. They first study an ideal case that the pilot signals are transmitted through a sparse channel without noise, and an exactly sparse inverse fast Fourier transform (SIFFT) algorithm is performed to estimate the non-zero channel taps with reduced complexity. Then, they consider a more practical scenario that the pilot signals through a sparse channel with noise interference, and an approximately SIFFT algorithm is employed to estimate the effective channel taps, while the remaining small coefficients interfered by noise can be wiped out. Through numerical analysis, they demonstrate that the proposed SIFFT algorithms can reduce the computational complexity while keeping the root mean squared error of channel estimation at a low level.

3-D MIMO: How Much Does It Meet Our Expectations Observed From Channel Measurements?

By taking advantage of the elevation domain, three-dimensional (3-D) multiple input and multiple output (MIMO) with massive antenna elements is considered as a promising and practical technique for the fifth Generation mobile communication system. So far, 3-D MIMO is mostly studied by simulation and a few field trials have been launched recently. It still remains unknown how much does the 3-D MIMO meet our expectations in versatile scenarios. In this paper, we answer this based on measurements with 56 × 32 antenna elements at 3.5 GHz with 100-MHz bandwidth in three typical deployment scenarios, including outdoor to indoor (O2I), urban microcell (UMi), and urban macrocell (UMa). Each scenario contains two different site locations and 2-5 test routes under the same configuration. Based on the measured data, both elevation and azimuth angles are extracted and their stochastic behaviors are investigated. Then, we reconstruct two dimensional and 3-D MIMO channels based on the measured data, and compare the capacity and eigenvalues distribution. It is observed that 3-D MIMO channel which fully utilizes the elevation domain does improve capacity and also enhance the contributing eigenvalue number. However, this gain varies from scenario to scenario in reality, O2I is the most beneficial scenario, then followed by UMi and UMa scenarios. More results of multiuser capacity varying with the scenario, antenna number and user number can provide the experimental insights for the efficient utilization of 3-D MIMO in future.

Analysis of Characteristics and Requirements for 5G Mobile Communication Systems

Abstract One of the main objectives of the fifth generation (5G) mobile communication systems, also known as IMT-2020, is to increase the current data rates up to several gigabits per second (Gbit/s) or even up to 10 Gbit/s and higher. One of the possibilities to consider is the use of higher frequencies in order to enlarge the available bandwidth. Wider bandwidth is necessary to achieve much higher data rates. It should be noted that wireless broadband transmission technologies require frequencies for their development. The main goal of the research is to investigate the characteristics and requirements of 5G mobile communication systems. The paper provides an insight into deployment scenario and radio wave propagation in frequencies above 24 GHz of IMT-2020.

On Indoor Millimeter Wave Massive MIMO Channels: Measurement and Simulation

The millimeter wave (mmWave) communications and massive multiple-input multiple-output (MIMO) are both widely considered to be the candidate technologies for the fifth generation mobile communication system. It is thus a good idea to combine these two technologies to achieve a better performance for large capacity and high data-rate transmission. However, one of the fundamental challenges is the characterization of mmWave massive MIMO channel. Most of the previous investigations in mmWave channel only focus on single-input single-output links or MIMO links, whereas the research of massive MIMO channels mainly focus on a frequency band below 6 GHz. This paper investigates the channel behaviors of massive MIMO at a mmWave frequency band around 26 GHz. An indoor mmWave massive MIMO channel measurement campaign with 64 and 128 array elements is conducted, based on which, path loss, shadow fading, root-mean-square (RMS) delay spread, and coherence bandwidth are extracted. Then, by using our developed ray-tracing simulator calibrated by the measurement data, we make the extensive ray-tracing simulations with 1024 antenna elements in the same indoor scenario, and get insights into the variation tendency of mean delay and the RMS delay with different array elements. It is observed that the measurement and the ray-tracing-based simulation results have reached a good agreement.

6–100 GHz research progress and challenges from a channel perspective for fifth generation (5G) and future wireless communication

Radio frequency is a valuable resource for wireless communication systems. The high-frequency band from 6 GHz up to 100 GHz, where continuous and broad spectra exist, is promising to meet the high spectrum requirement of fifth generation (5G) mobile communication systems by 2020. To date, many groups from academia and industry have contributed to devising approaches to allocate and utilize frequency resources from 6 GHz to 100 GHz for 5G and future wireless communication systems. In this paper, we present global efforts to allocate potential frequency bands and field trial progress from 6 GHz to 100 GHz for 5G. From a channel perspective, we summarize research progress and challenges, including channel measurement platforms and channel parameter analysis, both of which are important to extract the inherent channel characteristics and use a high-frequency band for 5G and future wireless communication systems.

Neighbors’ interference situation-aware power control scheme for dense 5G mobile communication system

The next generation mobile communication (5G) systems is targeting very high data rate by deploying more number of small cells, but this deployment results in high cross-tier interference because of using the same frequency band. To solve this challenge, an efficient power control scheme is desired specially for the case of uplink scenario. Thus, to solve this challenge, we propose the neighbors’ interference situation-aware uplink power control (IA-ULPC) scheme to reduce the cross-tier interference. In this scheme, we consider the interference situation of the neighbor cells while controlling the power of the users. Moreover, we also derive the target signal-to-interference and noise-ratio ( $$P_0$$ ) equation to dynamically adjust it based on the neighbors’ base station interference situation. We compare the performance of the proposed IA-ULPC with the conventional fractional power control scheme (C-FPC). The extensive system-level simulations are carried out to prove the validity of the proposed IA-ULPC scheme which almost doubles the user average throughput and also decreases the interference around 20% in dense two-tier heterogeneous network environment as compared to C-FPC.

Joint precoding and scheduling algorithm for massive MIMO in FDD multi-cell network

Massive multiple-input multiple-output (MIMO) systems, in which base stations are equipped with a large number of antennas in a two-dimensional antenna array, is one of the most promising technologies to improve the spectral efficiency of the fifth generation mobile communication systems (5G). Since there is no short-term channel reciprocity, the frequency-division duplexing (FDD) massive MIMO system has to obtain channel state information with the help of uplink feedback with acceptable overhead. To cope with this issue, we propose the design of joint precoding and scheduling algorithm in FDD multi-cell network. In the algorithm, all the users are firstly grouped by the statistics of channel correlation matrix, then the inter-group interference exiting among intra-cell and inter-cell is eliminated at the first precoding stage. Then users are adaptively scheduled and beamformed at the second precoding stage based on the low dimension effective channel. Finally, the effectiveness of the proposed algorithm is presented through simulations.

3-D-MIMO With Massive Antennas Paves the Way to 5G Enhanced Mobile Broadband: From System Design to Field Trials

Three-dimensional (3D) multiple input and multiple output (3D-MIMO) with massive antennas is a key technology to achieve high spectral efficiency and user experienced data rate for the fifth generation (5G) mobile communication system. To implement 3D-MIMO in 5G system, practical constraints on the product design should be considered. This paper proposes a systematic design for the 3D-MIMO product by considering the restrictions of both base band and the hardware, including cost, size, weight, and heat dissipation. The design has been implemented for 2.6-GHz time-division duplex band, and field trials have been conducted for performance validation with practical intercell interference in commercial network. The trial results show that this 3D-MIMO design can meet the spectral efficiency requirement of the 5G enhanced mobile broadband services. The performance gain of 3D-MIMO varies with the traffic load. When the traffic load is heavy, 3D-MIMO can enhance the cell throughput by 4~6.7 times. When the traffic load is low, the performance gain of this 3D-MIMO design decreases. The results from field trial also show that the performance of 3D-MIMO degrades in mobility scenarios, where further enhancement on acquiring instant channel status information are necessary to improve the robustness of 3D-MIMO to mobility.

A System Concept for Online Calibration of Massive MIMO Transceiver Arrays for Communication and Localization

Massive multiple-input multiple-output (MIMO) techniques are being considered for the fifth generation (5G) mobile communication systems in order to deliver high multiplexing gain. However, hardware impairments like quadrature imbalance in mixers violate the requirement for channel reciprocity and may change, e.g., with temperature or while aging. In addition, advanced wireless localization techniques and the generation of predefined beam patterns require knowledge about all antenna phase center positions and the time and phase delay of all transmit and receive channels. Thus, an efficient online compensation method is needed that scales well for very large numbers of transceiver modules. We propose to extend the transmitter with a small measurement feature at the transmitter output based on one uncalibrated power detector per module as well as a single, external four-element backscatter array for the entire matrix. These enhancements facilitate a fast and efficient iterative calibration, which recognizes and mitigates all major error sources. Beside optimal communication throughput and energy efficiency, it thereby brings localization capabilities to mobile networks as an additional major benefit. For verification, a system of multiple cost-efficient 5.8-GHz massive MIMO transceivers with 150-MHz bandwidth and a backscatter array has been implemented. Measurement results demonstrate the capability of the proposed concept to efficiently compensate major error sources as well as its robustness.

Optimal Cooperative Content Caching and Delivery Policy for Heterogeneous Cellular Networks

To address the explosively growing demand for mobile data services in the 5th generation (5G) mobile communication system, it is important to develop efficient content caching and distribution techniques, aiming at significantly reducing redundant data transmissions and improving content delivery efficiency. In heterogeneous cellular network (HetNet), which has been deemed as a promising architectural technique for 5G, caching some popular content items at femto base-stations (FBSs) and even at user equipment (UE) can be exploited to alleviate the burden of backhaul and to reduce the costly transmissions from the macro base-stations to UEs. In this paper, we develop the optimal cooperative content caching and delivery policy, for which FBSs and UEs are all engaged in local content caching. We formulate the cooperative content caching problem as an integer-linear programming problem, and use hierarchical primal-dual decomposition method to decouple the problem into two level optimization problems, which are solved by using the subgradient method. Furthermore, we design the optimal content delivery policy, which is formulated as an unbalanced assignment problem and solved by using Hungarian algorithm. Numerical results have shown that the proposed cooperative content caching and delivery policy can significantly improve content delivery performance in comparison with existing caching strategies.

Characterization of In-Body Radio Channels for Wireless Implants

Body-centric wireless communication, which is accepted as an important part of the fourth generation mobile communications systems, provides a prospective communication solution for implantable devices in personal health care. In this paper, an inhomogeneous human body model was proposed to study the in-body radio channels for wireless implants, and numerical simulations were carried out with the finite-difference time-domain method. Specifically, parameters, such as channel gain and group delay, were studied for different links according to implant locations, namely, from intra-brain to the surface of chest, abdomen, upper arm, and thigh, respectively, over different frequencies (from 5 to 100 MHz). The influences of electrode size and type were also studied at 45 MHz. The results showed that all channels had the maximum gain of more than -12 dB at 5 MHz. Group delay was almost independent of channels. The model was verified by experimental measurements. The results showed that the simulations were in good agreement with the measurements.

LTE 기반 철도통합망(LTE-R)과 재난통신망(PS-LTE)의 기능 분석

철도통신기능은 안전한 열차 운행을 위한 운영자간의 통신 기능과 열차제어를 위한 데이터 전송 기능으로 분류된다. 관련 기술은 2004년 영업 운전을 시작한 유럽의 GSM-R이 가장 대표적인 철도통신 기술로 주어진다. 국내의 경우, 국가재난망에서 임대한 TRS가 철도 운영자간의 통신 기능으로 사용되고 있지만, 열차제어용 데이터 통신은 적용되지 못하고 있는 실정이다. 그러나 2014년 국내의 LTE 기술을 이용한 LTE-R의 개발이 세계 최초로 철도에 적용하여 성능 검증 및 국내 표준 제정에 성공하였다. 이를 응용한 LTE 기반의 국가재난안전망(PS-LTE)도 2016년 시범구축사업이 강원도에서 성공적으로 완료되었다. 본 논문은 철도통신의 핵심인 LTE-R의 통신기능과 데이터 전송 기능을 PS-LTE와 GSM-R의 기능과 비교, 검토하였다. 검토 결과는 LTE-R의 데이터 전송 기능이 GSM-R의 기능보다 우수함은 물론 철도통신기술은 PS-LTE의 요구 기능도 대부분 만족함을 시험을 통해 입증하였다. Due to the evolution of wireless communications technology, Long Term Evolution (LTE), which is a <TEX>$4^{th}$</TEX> generation mobile communications system, has been adopted as a railway communications system. This LTE Railway (LTE-R) system is composed of various elemental functions, which are largely categorized into public safety and wireless communications for train control. Research on the public safety functions of railway communications have their roots in TRS based national public safety communication systems, and research on wireless communications functions for train control have their roots GSM-R, which is utilized by the ETCS in Europe. Based on these circumstances, this paper first analyzes the requirements for developing public safety technology in LTE-R, and compares those requirements with the functions of public safety LTE (PS-LTE), which is being deployed for the first time in the world by the South Korean government. Based on an analysis of the common and specific functions of LTE-R and PS-LTE, we conclude that there is little problem in integrating LTE-R and PS-LTE from the perspective of functionality. Second, this paper provides a comparison of the LTE-R requirements for the Quality of Service (QoS) with those of GSM-R utilized by the ETCS. This offers a guideline to allow LTE-R to be applied to a 500km/h train control system.

Migration from Microwave to Millimeter-wave for Next Generation Mobile Communication Systems

Communications systems have continued to evolve after ground-breaking research works by various researchers in the 19th and 20th centuries. Mobile wireless communication networks due to their inherent advantages and the availability of ubiquitous broadband internet along with other technological developments in semiconductor science and the convergence of technology have continued to generate an insatiable demand for higher data rates. Since the bandwidth/frequency spectrum is finite and hence limited in availability to telecommunication operators, various techniques have been proffered as solutions to the capacity problem from the first to the fourth generations (1G – 4G). However, as the data explosion continues to the big-data age, there is a need to migrate from the utilization of the microwave frequencies to the millimeter-wave frequency to solve the capacity issue. This principle is the core behind the Fifth Generation (5G). This paper is therefore set to present the millimeter-wave technology and its contribution to the expectations for Next Generation Networks (NGN).

Energy‐efficient active offloading with collaboration communication and power allocations for heterogeneous ultradense networks

AbstractFor the booming capacity requirements for the 5th generation mobile communication system (5G) to be supported, heterogeneous ultradense network (H‐UDN) is believed as a promising solution. The corresponding standardization and filed deployments of H‐UDN have been conducted. But the lower energy efficiency and severer interferences caused by densely deployed base stations (BSs) are still the 2 main obstacles for H‐UDNs. This paper addresses on above challenges and proposes active green offloading (AGO) strategy with collaboration communications to improve the system energy efficiency and decrease interferences. We propose the auction theory–based AGO for energy efficient objectives, which provides flexible user associations for H‐UDNs. Furthermore, aiming to guarantee the offloaded user performances and decrease interferences, we explore the collaboration communications with introducing the strongest interfering BS into the coordinated transmission BS set. This will change the interference signal into useful signal and then decreases interferences. Moreover, we introduce the supermodel game–based power allocation for further improvements of system energy efficiency after collaboration communications. Simulation results evaluate the 3‐stage improvements of system energy efficiency achieved by AGO, collaboration communications, and power allocation separately, which proves the benefits of AGO in H‐UDNs.

5G green mobile communication networks

With the popularization of wireless multimedia communications, the wireless traffic is predicated to be increased more than 1000 time in the next decade. Some new technologies, e.g., massive multi-input multi-output antennas, millimeter wave and small cell networks are developed to support high speed wireless transmission in future fifth generation (5G) mobile communication systems. On the other hand, it is a great challenge how to face the quick growth of energy consumption in 5G mobile communication networks due to the massive wireless traffic. However, detailed investigation of the energy efficiency of 5G mobile communication networks from three aspects of theory models, technology developments and applications is surprisingly rare in the open literature. Fortunately, the scholarly writing, 5G Green mobile communication networks, published by Publishing House of Electronics Industry in November 2016, points out the directions and research advance of 5G green mobile communication networks.

Metamaterial-Based Thin Planar Lens Antenna for Spatial Beamforming and Multibeam Massive MIMO

A metamaterial (MTM)-based thin planar lens antenna is proposed for spatial beamforming and multibeam massive multiple-input multiple-output systems. The antenna consists of a planar lens and a linear array of receive/transmit elements. To lower the insertion and reflection loss, the lens is formed by the two-layered ultrathin MTM-based surface separated with air and fed by substrate integrated waveguide-fed stacked-patch antennas. The effects of the focal-to-diameter ( f/D) on the power distribution of the lens are investigated to work out a design method. A planar lens antenna fed with seven elements is, for example, designed to operate at 28-GHz bands. The measured results show that the proposed antenna can achieve a scanning coverage of ±27° with a gain tolerance of 3.7 dB and a maximum gain of 24.2 dBi with an aperture efficiency of 24.5% over the operating bandwidth of 26.6-29 GHz. The lens antenna also features the advantages of compact size, low cost, lightweight, simple feeding network, and easy integration with other circuits for the next generation mobile communication and radar systems.

High-speed radio-resource scheduler with hardware accelerator for fifth generation mobile communications systems

High-speed radio-resource scheduler with hardware accelerator for fifth generation mobile communications systems