Generation Mobile Radio Systems Research Articles

Koncept budućih bežičnih mreža šeste generacije - 6G

Simultaneously with the beginning of the implementation of the fifth generation wireless networks (5G systems), the research of the next generation mobile wireless systems - the sixth generation network 6G, has began. Having in mind the already started considerations on the components of the future 6G technology, it is necessary to follow the given technological trends, which are waiting for us beyond 5G era. This paper will explain the range of communication needs and technologies within the future 6G. 6G is expected to include three main aspects, mobile ultra broadband, super Internet-of-Things (IoT) and Artificial Intelligence (AI). The paper will present an overview of the crucial technology that is planned to achieve the first two aspects. In particular, THz communication could be used to support mobile ultra-broadband, while symbiotic radio and satellite communications to support super IoT. For each technology, the basic basic principle of functioning, key challenges and currently current approaches and solutions will be given. It will be especially emphasized what 6G brings in relation to 5G, ie what are the key new characteristics.

STEERABLE TOROIDAL BIFOCAL LENS-ARRAY ANTENNA IN 57–64 GHZ RANGE

Introduction. Currently, one of the most promising approaches of the 5th generation mobile wireless systems development is the deployment of heterogeneous networks based on existing LTE cellular systems with large and small cells. The main elements of such networks can be small low cost relay stations equipped with highly directional steerable antenna systems to connect small cells with LTE base station serving macrocell. Objective. Existing solutions are either too expensive or not allowing flexible rearrangement of current information transmission lines. The objective of this work is to develop antenna equipment for low cost relay stations based on simple steerable antenna systems of millimetre wavelength (57-64 GHz), which allow beamsteering in both azimuth and elevation planes. Methods and materials. The developed steerable bifocal lens antenna system is a lens of a special shape made of a high molecular weight polyethylene and integrated with a phased array antenna. A key feature of the designed antenna system is a wide-angle beamsteering in the azimuth plane and ability to adjust the beam in the elevation plane. The calculation of the lens profiles was carried out by means of an approximation of geometrical optics in Matlab, and the main technical characteristics of the lens antenna system were obtained by direct electromagnetic modelling in CST Microwave Studio. Results. The prototype of the steerable bifocal lens-array antenna system is developed and its characteristics are studied. The following technical characteristics are achieved in the 57–64 GHz range: beamsteering in the elevation plane is ±3º, beamsteering in the azimuth plane is ±40º, and antenna gain is from 20 to 27.5 dBi for all angles. Conclusion. It was shown that the developed antenna system can be successfully used as receiving and transmission antenna equipment of small relay stations that transmit information in the frequency range of 57-64 GHz over a distance of 100-300 m.

Enabling Efficient System Configurations for Dynamic Wireless Applications Using System Scenarios

Next generation mobile wireless systems (4G) support a wide range of communication protocols and services, thus opening new design challenges. The desired flexibility requires an effective utilization of system resources. In this article, we introduce the concept of system scenarios in wireless baseband engine signal processing optimization and in digital front-end power optimization. The scenario methodology classifies the system behavior from a cost perspective and provides the necessary information for an effective system tuning. We propose improvements for the clustering of the system executions into scenarios and the detection of scenarios at run time achieving a better trade-off between cost estimation accuracy and detection overhead. The first case study of the paper, using the WLAN communication protocol, demonstrates the accurate prediction of the execution time of each block of bits, which on average is 92 % shorter than the worst case allowing us to use the remaining time for the optimization of specifications like power consumption. In the second case study, we concentrate on the efficient signal power management during a WLAN transmission reducing the total energy consumption 50–94 % based on the throughput utilization.

On the design of algorithms for mobile multimedia systems: A survey

SUMMARYIn the past few years, we have seen a global flurry of the Internet in the rapid roll‐out of multimedia—the commercial products such as PPlive, YouTube, and Skype have occupied a large portion of Internet bandwidth. One reason behind the continual growth of multimedia services is due to the increasingly deployed and offered broadband networks. Besides the traditional wired end users, Internet service providers (ISPs) are expected to provide multimedia services, especially video streaming, to wireless end users as well in that it allows ISPs to strengthen their competitiveness by offering these new services. However, the existing solutions to multimedia in wired networks cannot directly apply to wireless networks with lower bandwidth, higher latency, and higher burst error rate. Furthermore, these services could suffer from user's mobility and the heterogeneity caused by different wireless technologies (e.g. CDMA2000, WCDMA, TD‐SCDMA, Wi‐Fi, Long‐Term Evolution (LTE), and WiMAX). This paper surveys several key issues of mobile multimedia, focusing on multirate multicast, scalable video coding (SVC), and QoS management. Besides, the opportunities as well as the challenges of providing multimedia services in the next generation wireless mobile systems—3GPP LTE—are investigated. Copyright © 2011 John Wiley & Sons, Ltd.

EFFICIENCY OF THE LDPC CODES IN THE REDUCTION OF PAPR IN COMPARISON TO TURBO CODES AND CONCATENATED TURBO-REED SOLOMON CODES IN A MIMO-OFDM SYSTEM

Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems are the potential candidate for fourth generation (4G) mobile radio communication systems. The MIMO OFDM systems further provide an increase in the data throughput without an increase in the bandwidth and also provide a reduction in the fading. However, the main drawback of OFDM systems is the high peak to average power ratio (PAPR). This disadvantage can be reduced by a number of methods but most of them cause an increase in the bit error rate (BER), data rate loss and an increase in the computational complexity. Thus, the coding methods have been used to reduce the PAPR. LDPC codes were one of the first codes to allow data transmission rates close to the theoretical maximum, the Shannon limit. Although LDPC codes were discovered before turbo codes, the latter was significant in the early years. They have grown to become the standard in the market for highly efficient data transmission methods. These codes show improved performance over an AWGN channel. The Reed Solomon codes, when concatenated with Turbo codes also have been found to improve the performance over wireless channel. However, a comparison of these coding techniques – LDPC, turbo and concatenated turbo-Reed Solomon codes shows that LDPC is most efficient in the reduction of PAPR in a MIMO-OFDM system.

Space-Time-Block-Coded Transmissions for Downlink MC-CDMA Transmissions Over Frequency-Selective Fading Channels

Mitigation of multipath fading effects and suppression of multiuser interference (MUI) constitute major challenges in the design of the third generation wireless mobile systems. Space-time (ST) coding offers a attractive solution to cope with mutipath fading, but most existing ST coding schemes assume flat fading channels that may not be realistic for wide-band communications. Especially multiuser ST block-coded transmissions through multipath fading channels present unique challenge in suppressing not only MUI but also intersymbol/chip interference. In this paper, we design ST multiuser transceivers for MC-CDMA quasi-synchronous systems, capable to reliably transmit over frequency-selective multipath downlink channels. The proposed system is able to provide transmit diversity and to guarantee symbol recovery in multiuser environments, regardless of unknown multipath. Unlike existing approaches, the mobile does not need to know the channel of other users. In addition to decoding simplicity, computer simulations show the performance merits of the proposed transceiver.

Enancement The Reverse Link Capacity of Third Generation Mobile Radio System

Enancement The Reverse Link Capacity of Third Generation Mobile Radio System

Robustness of IFDMA as Air Interface Candidate for Future High Rate Mobile Radio Systems

Abstract. The Interleaved Frequency Division Multiple Access (IFDMA) scheme is a candidate for next generation mobile radio systems. IFDMA is based on compression, repetition and subsequent user dependent frequency shift of a modulated signal. As in OFDMA, multiple access is enabled by the assignment of overlapping but mutually orthogonal subcarriers to each user. It provides various advantages such as low peak to average power ratio, orthogonality of the signals of different users even for transmission over a time dispersive channel and low complexity. However, IFDMA is sensitive to frequency offsets. In this paper, a derivation of IFDMA based on a generalised OFDMA signal model with specific precoding and specific subcarrier allocation is presented. Moreover, simulation results showing the robustness properties of IFDMA against frequency errors are given.

Analytical Performance Evaluation of Inter-System Handover

In this paper, we analyze the behavior of inter-system handover between second generation (GSM) and third generation (UMTS) mobile radio systems. A mathematical model is proposed to evaluate the handover performance. The handover initiation algorithm is based on the absolute signal strength thresholds. The algorithm performs handover when the averaged signal strength from the serving base station drops below a given threshold and that from the candidate base station exceeds a preset threshold. Handover rate and handover initiation delay are used as performance metrics. Based on numerical results, threshold parameter settings are determined for optimum handover performance.

WWRF - the Wireless World Research Forum

Third generation mobile radio systems are currently being deployed in different regions of the world. Future systems beyond the third generation are already under discussion in international bodies and forums such as ITU, WWRF and R&D programmes of the European Union and in other regions. These systems will determine the research and standardisation activities in mobile and wireless communication in the next years. Based on experience of the third generation, future systems will be developed mainly from the user perspective with respect to potential services and applications including traffic demands. Therefore, the Wireless World Research Forum was launched in 2001 as a global and open initiative of manufacturers, network operators, SMEs, R&D centres and the academic domain. WWRF is focused on the vision of such systems - the Wireless World-and potential key technologies. This paper describes the international context of activities on systems beyond third generation, the goals, objectives and structure of WWRF, the user perspective as the starting point for a future system design and the key enabling technologies for the Wireless World.

Multi-user detection in multicarrier-CDMA systems

The upcoming third generation mobile radio system in Europe is based on UMTS (Universal Mobile Telecommunications Standard). In order to supply access to a common transmission channel for several users, UMTS incorporates Code Division Multiple Access (CDMA). Besides a lot of practical advantages, CDMA suffers from multi-user interference limiting spectral efficiency dramatically. However, bandwidth is a very valuable resource and should be used as efficiently as possible. One appropriate mean to increase spectral efficiency of CDMA systems is multi-user detection. This paper gives an overview of different multi-user detection techniques and compares them with the conventional single-user detection including channel coding. Specifically, linear as well as nonlinear multi-user detectors are considered. Efficient realizations of linear detectors are presented and extended to improved nonlinear techniques. It is shown that nonlinear MUD including channel decoding can achieve a spectral efficiency twice as high as that of the well-known GSM standard (Global System for Mobile Communications) employing TDMA and FDMA.

The Wireless World Research Forum—WWRF

Third generation (3G) mobile radio systems are currently being deployed in different regions of the world. Future systems beyond the 3G are already under discussion in international bodies and forums such as ITU, the Wireless World Research Forum (WWRF) and R&D programs of the European Union and in other regions. These systems will determine the research and standardization activities in mobile and wireless communication in the coming years. Based on the experience of the 3G, future systems will be developed mainly from the user perspective with respect to potential services and applications including traffic demands. Therefore, the WWRF was launched in 2001 as a global and open initiative of manufacturers, network operators, SMEs, R&D centers and the academic domain. WWRF is focused on the vision of such systems—the Wireless World—and potential key technologies. This paper describes the international context of activities on systems beyond 3G, the goals, objectives and structure of WWRF, the user perspective as the starting point for a future system design and the key enabling technologies for the Wireless World. This paper is the introduction to a series of articles in this special issue on the achievements of WWRF.

The Wireless World Research Forum—WWRF

Third generation (3G) mobile radio systems are currently being deployed in different regions of the world. Future systems beyond the 3G are already under discussion in international bodies and forums such as ITU, the Wireless World Research Forum (WWRF) and R&D programs of the European Union and in other regions. These systems will determine the research and standardization activities in mobile and wireless communication in the coming years. Based on the experience of the 3G, future systems will be developed mainly from the user perspective with respect to potential services and applications including traffic demands. Therefore, the WWRF was launched in 2001 as a global and open initiative of manufacturers, network operators, SMEs, R&D centers and the academic domain. WWRF is focused on the vision of such systems—the Wireless World—and potential key technologies. This paper describes the international context of activities on systems beyond 3G, the goals, objectives and structure of WWRF, the user perspective as the starting point for a future system design and the key enabling technologies for the Wireless World. This paper is the introduction to a series of articles in this special issue on the achievements of WWRF.

Heterogeneous Networks to Support User Needs with Major Challengesfor New Wideband Access Systems

Third generation mobile radio systems are currently being deployed in different regions of the world. Future systems beyond the third generation are already under discussion in international bodies and forums such as ITU, WWRF and R&D programs of the European Union and in other regions. These systems will determine the research and standardization activities in mobile and wireless communication in the next years. Based on the experience from the third generation future systems will be developed mainly from the user perspective with respect to potential services and applications including traffic demands. This is directly related to the paradigm shifts from the first generation to systems beyond third generation. International bodies are already discussing basic system requirements. The basic system architecture of heterogeneous networks with different complementing access systems is from the today's perspective the most economic approach for systems beyond 3G to satisfy user and operator needs for reasonable cost. Such system architectures enable the deployment of system capacity according to the traffic requirements with the user experience ``Optimally Connected, Anywhere and Anytime'' with seamless service provision between different access systems. New radio interface components with high data rate as additional components of systems beyond 3G are being proposed in international bodies. Key issues of such systems are coverage due to reduced range and the huge spectrum demand. In this paper the international context, the user perspective, revenue and traffic expectations are presented. This results in the basic system requirements and the potential system architecture of heterogeneous networks. Major challenges for the new wideband radio interfaces are the impact on range and spectrum demand. Basic investigations are presented on these issues to critically review requirements on future systems.

Smart antennas for UTRA TDD

AbstractDue to the increasing number of users in mobile communications and the demand for mobile multimedia services with high data rates, third generation mobile radio systems are currently one of the key communication technologies in research, development, and international standardization bodies. Smart antennas can be used to increase the capacity of wireless communication systems even further. TDD systems are particularly attractive for the employment of smart antennas, since the channel information (e. g., in terms of spatial covariance matrices) estimated on the uplink can be used directly for downlink beamforming. In this paper, we discuss efficient uplink and downlink processing techniques with smart antennas for UTRA TDD, the TDD mode of third generation mobile radio systems that is based on TD—CDMA. On the uplink, joint space—time processing is used to eliminate co—channel interference created by other users that transmit on the same frequency and in the same time slot. These joint detection techniques are efficiently implemented in the frequency domain. On the downlink, the data is only transmitted in the direction of the desired mobile user while interference in the direction of co—channel users is avoided. Moreover, short—term spatial channel estimates can be improved by projecting them into the dominant subspace of the long—term spatial covariance matrix. System level simulations have been performed to evaluate the gain in spectral efficiency (available bit rate per bandwidth per cell) if simple downlink beamforming techniques are used at the base stations. There is a two— to three—fold spectral efficiency gain if antenna arrays of M = 8 elements are deployed in a sectorized macro—cellular environment.

Development of Mobile Communications Systems Beyond Third Generation

Second generation mobile radio systems have been successfully deployed worldwide. These systems are evolved to higher data rates and packet transmission. Third generation mobile radio systems will ...

Low cost MMSE algorithm for UTRA TDD mode downlink receiver

A low cost receiver algorithm is presented for the downlink in the emerging third generation mobile radio system time division duplexed mode. The receiver implements a minimum mean square error process at the same cost as a matched filter. This simplifies handset design and allows the network maximum flexibility in allocating timeslots and code channels.

A Generalized View on Multicarrier CDMA Mobile Radio Systems with Joint Detection (Part II)

This communication presents a generalized view on multicarrier code division multiple access (MC-CDMA) concepts for mobile radio applications. A comprehensive introduction to CDMA and the arising multiple access interference (MAI) will be presented. It will be explained why joint detection (JD) is a mandatory prerequisite for hybrid frequency and time divided code division multiple access (F/T/CDMA) which is a viable basis for third generation mobile radio systems. The benefits of MC-CDMA over other CDMA concepts will be discussed in an illustrative manner and a flexible MC-CDMA concept will be introduced and explained in detail. The signal generation in MC-CDMA will be described in continuous-time and discrete-time form revealing the close relationship between the presented flexible MC-CDMA and the well known joint detection CDMA (JD-CDMA) concept. The discrete-time transmission model which results from the continuous-time representation will be introduced to facilitate digital signal processing. This transmission model takes coherent receiver antenna diversity (CRAD) explicitly into account. Four viable JD techniques suitable for the discussed flexible MC-CDMA concept will be presented. Their structure and mode of operation will be explained in detail and their uplink performance will be studied in a variety of transmission conditions.

Known and novel diversity approaches as a powerful means to enhance the performance of cellular mobile radio systems

The main requirements to be met by third generation mobile radio systems are high cellular spectrum efficiency and high flexibility. The authors focus on high cellular spectrum efficiency, which is difficult to achieve due to the time variance and frequency selectivity of the mobile radio channel and due to interference. It is known that the degrading effects of these adverse characteristics of the mobile radio channel and of interference can be mitigated by diversity. The way how diversity influences cellular spectrum efficiency is derived in general. As a reference point, the types of diversity used in GSM are analyzed. In GSM, the potential for diversity enhancement inherent in code-division multiple-access (CDMA) is not exploited. A joint detection code-division multiple-access (JD-CDMA) system concept aimed at third generation mobile radio systems has been proposed which introduces a CDMA feature into systems based on time-division multiple-access (TDMA) and frequency-division multiple-access (FDMA) like GSM and also advanced TDMA (ATDMA). The gains achievable by different types of diversity in GSM as well as in the JD-CDMA system concept are investigated. It is shown that considerable gains can be achieved by different types of antenna diversity and by exploiting the additional diversity potential of CDMA. Therefore, third generation standards should be flexible in order to allow the use of as many types of diversity as possible to enhance the cellular spectrum efficiency.

Second generation mobile radio telephone system in japan

Second generation mobile radio telephone system in japan