Terrestrial Mobile Communication Research Articles

Physical random access signal design for 5G mobile satellite communication systems

In view of the distinctive characteristics of satellite communication, the physical random access signals used in the terrestrial mobile communication system have to be modified or redesigned for the satellite communication system. In this paper, we boost the random access signal energy by repeating the short Zadoff–Chu (ZC) sequence based preamble signal used in the terrestrial system. Different long ZC sequences are used to scramble this cascaded sequence to distinguish different random access signals for multiple random access user equipments. For correlation performance optimization, properties of the roots for both the short and long ZC sequences are mathematically analyzed and derived. Finally, we illustrate how to construct a root set for these different long ZC sequences based on the obtained propositions in a practical way. This analytical framework provides a useful insight into ZC sequence-based random access signal design and performance analysis in mobile satellite communication systems.

The HPDPU—High-Performance Data Processing Unit for Future Satellite Communication Systems

Efficient data processing is a key enabler to compete with the excessive requirements of next generation satellite systems. In particular, connecting LEO satellite-constellations to existing terrestrial mobile communication services becomes increasingly important as this measure allows truly ubiquitous connectivity, but comes at the cost of significantly higher processing and inter satellite communication effort. To address this issue, we propose the High-Performance Data Processing Unit (HPDPU), possessing a powerful processing core that is available as radiation-hardened and COTS version in order to operate in traditional space and NewSpace scenarios, respectively. To achieve high re-usability, a modular cPCI-SS connector is used, that enable an easy a low-cost assembly, integration and testing of hardware units also during the design time. For a further increase of processing power, application-specific extension boards can be integrated by mezzanine connectors. To demonstrate the performance, an innovative transceiver signal processing chain is proposed that allows a reliable and low-latency data transmission. For evaluation, a real field test analysis of the transmission quality, a hardware performance comparison and a power estimation is presented. The results highlight the HPDPU to be a powerful solution in order to challenge the demanding requirements of high-end satellite communication systems of the near future.

A Study of Standardizing Frequencies Using Channel Raster for Underwater Wireless Acoustic Sensor Networks.

In this paper, we propose the method to standardize acoustic frequencies for underwater wireless acoustic sensor networks (UWASNs) by applying the channel raster used in the terrestrial mobile communications. The standardization process includes: (1) Setting the available acoustic frequency band where a channel raster is employed via the frequency specification analysis of the state-of-the art underwater acoustic communication modems. (2) Defining the center frequencies and the channel numbers as a function of channel raster, and the upper limit of the value of channel raster. (3) Determining the value of the channel raster suitable for the available acoustic frequency band via simulations. To set the value, three performance metrics are considered: the collision rate, the idle spectrum rate, and the receiver computational complexity. The simulation results show that the collision rate and the idle spectrum rate according to the value of channel raster have a trade-off relationship, but the influence of channel raster on the two performance metrics is insignificant. However, the receiver computational complexity is enhanced remarkably as the value of channel raster increases. Therefore, setting the value of channel raster close to its upper limit is the most adequate in respect of mitigating the occurrence of a collision and enhancing the reception performance. The standardized frequencies based on channel raster can guarantee the frequency compatibility required for the emerging technologies like the Internet of Underwater Things (IoUT) or the underwater cognitive radio, but also improves the network performance by avoiding the arbitrary use of frequencies.

Potential key challenges for terahertz communication systems

The vision of 6G communications is an improved performance of the data rate and latency limitations and permit ubiquitous connectivity. In addition, 6G communications will adopt a novel strategy. Terahertz (THz) waves will characterize 6G networks, due to 6G will integrate terrestrial wireless mobile communication, geostationary and medium and low orbit satellite communication and short distance direct communication technologies, as well as integrate communication, computing, and navigation. This study discusses the key challenges of THz waves, including path losses which is considered the main challenge; transceiver architectures and THz signal generators; environment of THz with network architecture and 3D communications; finally, Safety and health issues.

System integration of terrestrial mobile communication and satellite communication —the trends, challenges and key technologies in B5G and 6G

Mobile communication standards have been developed into a new era of B5G and 6G. In recent years, low earth orbit (LEO) satellites and space Internet have become hot topics. The integrated satellite and terrestrial systems have been widely discussed by industries and academics, and even are expected to be applied in those huge constellations in construction. This paper points out the trends of two stages towards system integration of the terrestrial mobile communication and the satellite communications: to be compatible with 5G, and to be integrated within 6G. Based on analysis of the challenges of both stages, key technologies are thereafter analyzed in detail, covering both air interface currently discussed in 3GPP for B5G and also novel network architecture and related transmission technologies toward future 6G.

Worldwide Coverage Mobile Systems for Supra-Smart Cities Communications: Featured Antennas and Design

Current terrestrial mobile communications networks can’t provide worldwide coverage. Satellite communications are expensive, and terminals are large and heavy. Worldwide mobile coverage requires the use of satellites providing an appropriate QoS, including polar regions. The analysis of the potential satellite constellations demonstrates that LEO one is the best solution. A new generation of low cost, small size, lightweight and global mobile coverage LEO satellites is emerging. The main limitation of the terminals is the antenna size factor, and innovative antennas must be developed to meet this goal. This paper investigates the technologies and techniques for designing and developing antennas aimed at LEO satellite communications in Smart Cities and beyond, which are especially beneficial for mobile communications in areas without 4G/5G coverage. The paper focuses on the terrestrial segment and future mobile devices, remarking the design constraints. In this scenario, the paper reviews the most relevant technologies and techniques used to design suitable antennas. The investigation analyses the state-of-the-art and most recent advances in the design of antennas operating in the Ku-band. The main contribution of the authors is a novel antenna design approach based on SIW technology. The antenna features are compared with other approaches, highlighting the benefits, advantages and drawbacks. As a conclusion, the proposed antenna demonstrates to be a good solution to meet the design constraints for such an application: light, low cost, small size factor.

System Design of Gigabit HAPS Mobile Communications

High-altitude platform stations (HAPSs) are expected to provide ultrawide-coverage areas and disaster-resilient networks from the stratosphere at around 20 km by installing wireless equipment on HAPS. Because their altitude is much lower than that of communications satellites, HAPSs can provide mobile communications services directly to smartphones, which are commonly used in terrestrial networks, such as fourth generation Long Term Evolution. Considering the widespread nature of mobile broadband communications and the importance as a backup line in case of disaster, HAPSs are expected to provide a large capacity in the future. A cellular system with single-cell frequency reuse using multiple cells similar to terrestrial mobile communications should be introduced to achieve such a capacity. The number of cells that a HAPS can accommodate ranges from 1 to more than 100, depending on unmanned aerial vehicle (UAV) ability. By contrast, the optimal cell configuration, which depends on the number of available cells, has not been clarified in previous research. In this paper, we propose an optimization method for the cell configuration for HAPS mobile communications using a genetic algorithm, which can be generally applied regardless of the number of cells and can clarify the optimal cell configuration. Although many cells are required to achieve gigabit-class HAPS mobile communications, the heightened power consumption due to the large number of cells is a critical problem for UAVs. Thus, we also investigate the reduction of the total transmission power and demonstrate the feasibility of energy-efficient gigabit HAPS mobile communications with wide coverage.

Adaptive Bootstrap Design for Hybrid Terrestrial Broadcast and Mobile Communication Networks

The bootstrap in ATSC 3.0 is expected to act as a universal wake-up signal for various wireless systems in addition to broadcast network. However, the signaling decoding performance of the standardized bootstrap degrades significantly in channels of fast time-variation and strong multipath. Furthermore, part of available bandwidth is reserved to ensure the compatibility with mobile communication network (MCN), which puts a limitation on the performance improvement. In this paper, to make the best of the available bandwidth, we introduce the bandwidth-concerned version information to enable an adaptive bandwidth configuration for the proposed bootstrap. Moreover, a 2-D signaling scheme is used to increase signaling capacity by selecting different gold sequences in frequency domain (FD) and simultaneously applying cyclic shift in time domain (TD). At the receiver side, we first provide improved estimators of symbol timing offset (STO) and fine frequency offset (FFO) for the bootstrap with special TD structure. Meanwhile, a learning-based binary classifier taking the output of STO estimator as training data is provided to generate an SNR-independent threshold for spectrum sensing without requiring the knowledge of channel conditions nor noise estimator. Afterwards, an inverse fast Fourier transform (IFFT)-based algorithm is used to decode FD signaling in the presence of unknown TD signaling, which allows 3-bit higher signaling capacity. Numerical analysis and simulation results demonstrate that the proposed adaptive bootstrap design as well as corresponding receiver algorithms significantly outperform the standardized one in terms of synchronization, detection and signaling decoding.

A Novel Low Profile Rectangular Microstrip Patch Antenna for L-Band Applications Using High Permittivity Substrate

A novel low-profile and miniaturized patch antenna on a substrate material of high dielectric constant has been designed, fabricated and tested in an indigenous laboratory. It is highly important to reduce the size of patch antenna as it limits the reduction of the sizes of the devices using this antenna. A number of techniques have been given for the size reduction of patch such as DGS (Defected Ground Structure), use of fractals and the use of metamaterials but in this paper the technique of high permittivity substrate has been implemented. The substrate as well as this conventional antenna has been prepared locally in Pakistan. A ceramic material of chemical composition {(Sr0.5Pb0.25Ca0.25)-Tio3-3Bi2O3.TiO2} having a high dielectric constant has beenused in the substrate of the antenna. The fabricated prototype was investigated experimentally for important parameters using Vector Network analyzer. The total measure of the antenna is 20.5x26.5x1.5 mm3. The antenna presented a large bandwidth of 186 MHz (1070-1256 MHz)in L-Band with a Return Loss of 21.10 dB at resonance. The VSWR (Voltage Standing Wave Ratio) remained under the standard value of 2 in the whole operating range. The proposed antenna may be employed in GPS (Global Positioning System) devices, Amateur Radio, Terrestrial Mobile Communication, Aeronautical and Maritime Mobile and other Military and Low Earth Orbit Satellite Communications.

Feasibility of LTE-Based GEO Satellite Mobile Communication Systems to Support VoIP for Handheld Terminals

To facilitate the integration of terrestrial and satellite mobile communication systems in the future, the new generation of satellite mobile communication system should be Long-term evolution (LTE)-based. In LTE, voice is carried by Internet protocol (IP) packets (voice over IP, VoIP). The feasibility of LTE-based Geosynchronous earth orbit (GEO) satellite mobile communication systems for VoIP is discussed. Detailed link budgets are created for typical handheld terminals. The effectiveness of Physical resource block (PRB) bundling and Transmission time interval (TTI) bundling for the capacity improvement of downlink and uplink are evaluated, and further uplink improvement for low level terminals by Narrowband resource block (NRB) scheme is also studied. The analysis results show that the downlink VoIP transmission is mainly power limited, and optimization of PRB or TTI bundling can maximize the capacity. For uplink, only highlevel terminals can support VoIP under the normal LTE frame structure, and TTI bundling and Resource block (RB) block techniques can help the low-level terminals support VoIP transmission.

Delay Tolerant Network and the Algorithms of DTN Routing

Delay Tolerant Network (DTN) is a new type of network, which is different from traditional TCP / IP communication protocol network. It is suitable for extreme environment where end-to-end communication connection cannot be established stably. Firstly, the characteristics and structure of DTN are analyzed, then the characteristics of nodes in the network are also analyzed. Secondly, the DTN routing problem is explained. Next, the classification of DTN routing algorithms and some classical routing algorithms are introduced. Finally, some other problems of DTN are proposed. The stable operation of the TCP/IP protocol relies mainly on three underlying link features: (1) There is a stable and reliable end-to-end link between the source node and the destination node; (2) The maximum round trip time RTT (Round Trip Time) between any nodes is not long; (3) The probability of message loss during transmission is low [2]. DTN extends the application of IPN to terrestrial mobile communications, emergency communications, underwater communications and wildlife monitoring. DTN can make up for the shortcomings of existing communication networks and realize communication connections in extreme or special environments. In recent years, research on DTN has made great progress. Further in-depth research on the DTN network in the future will inevitably promote and promote network communication.

NPVT: Network Protocol Validation Testbed for Integrated Space-Terrestrial Network

With the development of the terrestrial network and the increase in demand for providing global Internet access, using the integrated space-terrestrial network (ISTN) has attracted significant attention to provide the global Internet service. However, ISTN faces a unique set of challenges, such as time-varying link quality and dynamic link connection in its space network, and the significant differences between space network and the terrestrial network of ITSN. These unique characteristics may impose an adverse impact on network protocols of ISTN. The focus of this paper is to design a network protocol validation testbed (NPVT) for ISTN. Using the static hardware devices with real network protocols, the proposed testbed was designed to emulate the dynamic space network based on the satellite operational data, and then to provide a near-real space network environment for the validation of diverse network protocols. To further support network protocol validation when space network and terrestrial network are integrated, we integrated the testbed with the terrestrial operational next-generation Internet (i.e., CERNET2) and mobile communication network at the backbone level. The extensive experiments demonstrated that NPVT is capable of validating diverse network protocols in complicated and dynamic scenarios.

Research on maritime leapfrog emergency communication coverage technology based on satellite relay

According to the Long Term Evolution (LTE) communication technology with a high data transmission rate, a maritime leapfrog emergency communication coverage technology basing on satellite relay is proposed. It solves the problem that has accessible to access the public communication network quickly. This research introduces the components and corresponding functions of the communication system, which provides timely and effective emergency communication support for maritime emergency. The emergency communication system uses unmanned surface vehicle (USV) as a mobile platform, integrating the satellite communication system with a terrestrial mobile communication system. It can achieve the coverage of 4G emergency networks in the rescue area, Internet calls, data and video transmission etc. Using bionic “frog leaping” to improve the flexibility of deployment of marine emergency communication system, it can provide more efficient data transmission services for maritime rescue operations.

Non-orthogonal multi-carrier transmission for internet via satellite

As the important complementary to terrestrial mobile communications, Internet via satellite can extend the coverage of communication and improve the continuity of data services. To build a space-terrestrial integrated communication system is the inevitable trend in the future. Taking into account combination of 5th generation (5G) terrestrial mobile communication system and satellite communication system, it is necessary to evaluate the promising 5G air interface waveform which can be adopted by satellite. In this paper, several non-orthogonal multi-carrier transmission schemes are evaluated and generalized frequency division multiplexing (GFDM) is advised as potential scheme of space-terrestrial integrated communication system. After the overview of GFDM, the implementation of GFDM transceiver is discussed respectively in time-domain and in frequency-domain. By deriving and comparing implementation complexity, GFDM modulation in time-domain is more suitable for satellite communication system. Then the properties of demodulation algorithms are specified. Based on designed pilot subcarriers, a new improved receiving algorithm is proposed in the end of the paper. The improved algorithm solves the problem of inter subcarriers interference (ICI) in matched filtering (MF) receiver and improves the receiving symbol error rate (SER) obviously. The simulation and analysis prove that the proposed algorithm is effective.

Broadband Hybrid Satellite-Terrestrial Communication Systems Based on Cognitive Radio toward 5G

The development of 5G terrestrial mobile communications technology has been a driving force for revolutionizing satellite mobile communications. Satellite mobile communications, which carry many unique features, such as large coverage and support for reliable emergency communications, should satisfy the requirements for convergence between terrestrial mobile communications and satellite mobile communications for future broadband hybrid S-T communications. On the other hand, CR is an attractive technique to support dynamic single-user or multi-user access in hybrid S-T communications. This article first discusses several key issues in applying cognitive radio to future broadband satellite communications toward 5G. Then we present an overview of future broadband hybrid S-T communications systems, followed by an introduction to a typical application scenario of futuristic CR-broadband hybrid S-T communication systems toward 5G. Moreover, we propose a space segment design based on a spectrum-sensing-based cooperative framework, in consideration of the presence of MUs. An experiment platform for the proposed CR-based hybrid S-T communications system is also demonstrated.

MIMOSA–a dual approach to detailed land mobile satellite channel modeling

SUMMARYAs multiple‐input‐multiple‐output (MIMO) transmission technologies are common in terrestrial mobile communications and getting attention for mobile broadcasting satellite systems, the need for a comprehensive MIMO channel model for the dual‐polarized land mobile satellite (LMS) channel arises. In the course of the Characterisation of the MIMO Channel for Mobile Satellite Systems (MIMOSA) project, two complementary modeling approaches have been developed that form a dual model. They provide a scalable modeling solution, which permits a user selectable level of simulation complexity and detail. The models have been evaluated by comparing their results with data gathered from the extensive field trials carried out within the MIMOSA project. This paper describes the dual wideband‐modeling and narrowband‐modeling approaches, provides examples of the usage and provides some evaluation results. Copyright © 2014 John Wiley & Sons, Ltd.

A Novel Satellite Telephone Communication System Based on SIGSO Satellite

In recent years, the coverage of terrestrial mobile communication network is more and more extensive, and the mobile phones have occupied the vast majority of voice communications in almost all countries. However, satellite voice communication system is still playing an irreplaceable role on the vast sea and the land area which are not covered by the land mobile communication network. The motion characteristics of the SIGSO satellites and its new demands and characteristics to the system are analyzed, and a novel very low rate satellite telephone system is put forward. The speech coding algorithms are studied, and a suitable speech coding algorithm and coding rate of 600bps is selected for the SIGSO satellite communication system. The overall design of the satellite voice communication network is given, including link budgets, network structure, system components, system signaling and so on. This satellite telephone system can get access to the PSTN network through ground gateway to achieve interoperability with the public network.

LTE-satellite: Chinese proposal for satellite component of IMT-Advanced system

As a complementary to terrestrial mobile communication systems, mobile satellite communication system can fill the gaps that cannot be covered by terrestrial network, and provides an irreplaceable solution for emergency communication in disaster. To pave the road for future satellite/terrestrial integrated communication networks, ITU-R invited proposals for candidate Radio Interface Technology (RIT) for the satellite component of International Mobile Telecommunications (IMT)-Advanced. China proposed the RIT of Long Term Evolution (LTE)-satellite as a candidate to be considered as IMT-Advanced satellite technology. The submitted LTE-satellite candidate RIT is specified based on terrestrial LTE-Advanced FDD standards that are developed in 3GPP. Considering satellite requirements, a number of modifications to LTE-Advanced are made to adapt to satellite radio transmission environments. This paper provides a general introduction of the new characteristics of LTE-satellite.

Block Edge Mask의 대역 외 방출 기준치 유도 및 간섭 영향 분석

최근 무선 멀티미디어 통신 수요의 팽창에 따른 주파수 부족 문제를 해결할 수 있는 방안으로 기술 및 서비스 중립성을 가지는 개방형 주파수 할당 방식의 도입이 예상되면서 여기에 적합한 새로운 간섭 관리의 모렐 및 기준 설정이 요구된다. 본 논문에서는 우리나라의 이러한 새로운 간섭 관리를 위한 모델로 여러 가지 후보 방식들을 고려한 결과, Block Edge Mask (BEM) 방식을 가장 적합한 모델로 선정한다. 그리고 BEM의 기준치 설정에 따른 간섭 영향을 알아보기 위해 디지털 방송 전환 여유 대역에 LTE 시스템의 사용을 가정하여, 이종 시스템인 디지털 지상파 텔레비전 방송 (DTV) 서비스와 LTE 이동통신 서비스의 경계 대역에서의 BEM의 대역 외 방출(Out-of-band emission) 기준을 유도하고 보호 대역의 설정에 따른 영향을 알아본다. As an introduction of an open spectrum allocation approach with technology and service neutrality is expected as a way to solve problems of frequency shortage due to the expansion of demand for wireless multimedia communications, recently, the new management model of interferences and its standard setting are required. In this paper, as a model for this new interference management considering several candidates, Block Edge Mask(BEM) approach is chosen as the most appropriate model. And to investigate the effects of interference resulting from the standard setting of BEM, assuming the use of LTE systems in the Digital Dividend, BEM out-of-band baseline in the boundaries between digital terrestrial television (DTV) service and LTE mobile communications services which are heterogeneous systems for analysis is derived and the effect of setting guard band is analyzed.

Satellite‐based vessel Automatic Identification System: A feasibility and performance analysis

AbstractThe Automatic Identification System (AIS) is a VHF communication system that provides identification/location information to vessels and shore stations by exchanging data such as position, identification, course, speed, etc. Recently, the interest in detecting and tracking ships at distances from coastlines larger than what can be accomplished by normal terrestrial VHF communications has grown, driven by requirements of long‐range applications such as better handling of hazardous cargo, improved security and countering illegal operations. This paper presents an extension of AIS to a long‐range positioning reporting through a constellation of LEO satellites. It outlines technical challenges like the high rate of message collisions from ships in the field of view of a satellite. Technical solutions are proposed at system and sub‐system level to address these challenges. A computer‐based system simulator is used to assess the system performance and carry out a high‐level system sizing. Results show that a relatively small constellation of LEO satellites can guarantee good ship position detection probability as well as a reporting time interval of a few hours. System performance aspects to be addressed in future work are the possible impact of terrestrial mobile communications interference as well as variations of the estimated traffic data. Copyright © 2009 John Wiley & Sons, Ltd.