• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.6
• /
• pp.2546-2566
• /
• 2016

This paper investigates an efficient transmission scheme for the remote wireless sensors to receive information which is rarely discussed in the integrated remote wireless sensor and multibeam satellite networks (IWSMSNs). The networks can be employed to exchange sensing information for emergency scenario, ocean scenario, and so on, which are isolated from available terrestrial networks. As the efficient transmission link is important to the IWSMSNs, we propose a hybrid full frequency (HFF) precoding by taking advantage of frequency reuse and multiple-input multiple-output (MIMO) precoding. Considering energy efficiency and sinks fairness are crucial to transmission link, thus the HFF precoding problems are formulated as transmit power minimization (TPM) and max-min fair (MMF) received signal to interference plus noise ratio (SINR) problems, which can be transformed to indefinite quadratic optimization programs. Then this paper presents a semi-definite programming (SDP) algorithm to solve the problems for the IWSMSNs. The promising potential of HFF for the real IWSMSNs is demonstrated through simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.2
• /
• pp.386-404
• /
• 2013

In broadband satellite multimedia (BSM) system, burst time plan (BTP) is always periodically generated. We find that this method can have a great effect on the system response ability to bandwidth requests. A general analysis model of BTP generation method is given. An optimized BTP generation (O-BTPG) method is presented by deducing the optimal bandwidth allocation period (BAP) and bandwidth allocation latency (BAL) without considering the signaling overhead caused by BTP. Then a novel asynchronous BTP generation (A-BTPG) method in which the BTP is generated asynchronously according to the traffic load from users' bandwidth requests is proposed. Simulation results show that A-BTPG can flexibly realize a trade-off between the system response ability and BTP signaling overhead. What's more, it can be widely used in various regenerative onboard switching BSM systems.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.11
• /
• pp.4419-4435
• /
• 2015

The use of an efficient packet scheduling scheme for a forward link in satellite communication networks is very important to support fairness for each return channel satellite terminal (RCST) and the service differentiations for user traffics. To support fairness and QoS for each RCST with service-level agreement (SLA), the Adaptive Coding and Modulation (ACM) system in a satellite hub has to process packets with considering modulation and coding (MODCOD) and packet types. Although a DVB-S2 system with ACM scheme has higher transmission efficiency, it cannot offer fairness or quality of service (QoS) to RCSTs. Because the data are transmitted with high MODCOD in regions with clear skies, while data are transmitted using low MODCOD in regions experiencing rain events. In this paper, we propose a two-step scheduling scheme offering fairness and QoS to RCSTs, while minimizing a decrease in throughput. The proposed scheme is carried out performance evaluations using a computer simulation. As results of this simulation, the proposed scheduler was shown to support bandwidth fairness to an individual RCST, and provide a level of QoS differentiation for user traffics.

• Journal of Internet Computing and Services
• /
• v.10 no.6
• /
• pp.191-203
• /
• 2009

Simulation is the work that identifies the characteristics of some problem through the simulated experiments. During the experiments it is frequently required to change or replace the simulation models, algorithms, or input/output data. Especially, in the case of the simulation works performed by replacing algorithms, if a replaceable component that implements a specific algorithm is not correct with respect to its functionality it is very difficult to carry out the simulation works successfully. In this paper, we suggest a test framework that verifies functional correctness of the replaceable component in the software-based GNSS (Global Navigation Satellite System) simulation environments. When a component is replaced, this framework enables us to properly execute the functional test for the component according to its context.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.5
• /
• pp.169-173
• /
• 2019

In this paper, SAR payload operation mode design method, results and performance analysis results are suggested. To SAR payload design, pramary parameter should be identified and designed. It is designed considering the small satellite of less than 100kg operated in low earth orbit. Also, an antenna structure for small size and light weight is proposed. Performance analysis is performed by applying the design values.

• Advances in aircraft and spacecraft science
• /
• v.9 no.6
• /
• pp.525-536
• /
• 2022

The current state of telecommunications infrastructure in the Arctic does not allow providing a wide range of required services for people, businesses and other categories, which necessitates the use of non-traditional approaches to its organization. The paper proposes an innovative approach to building a combined communication network based on tethered high-altitude platform station (HAPS) located at an altitude of 1-7 km and connected via radio channels with terrestrial and satellite communication networks. Network configuration and composition of telecommunication equipment placed on HAPS and located on the terrestrial and satellite segment of the network was justified. The availability of modern equipment and the distributed structure of such an integrated network will allow, unlike existing networks (Iridium, Gonets, etc.), to organize personal mobile communications, data transmission and broadband Internet up to 100 Mbps access for mobile and fixed subscribers, rapid transmission of information from Internet of Things (IoT) sensors and unmanned aerial vehicles (UAV). A substantiation of the possibility of achieving high network capacity in various paths is presented: inter-platform radio links, subscriber radio links, HAPS feeder lines - terrestrial network gateway, HAPS radio links - satellite retransmitter (SR), etc. The economic efficiency of the proposed solution is assessed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.28-35
• /
• 2006

Global Flood Alert System (GFAS) is an attempt to make the best use of satellite rainfall data in flood forecasting. The project of GFAS is promoted both by Ministry of Land, Infrastructure and Transport-Japan (MLIT) and Japan Aerospace Exploration Agency (JAXA), under which Infrastructure Development Institute-Japan (IDI) has been working on the development of Internet-based information system and just launched trial run of GFAS in April 2006 on International Flood Network (IFNet) website. The function of GFAS is to connect space agencies and hydrological services/river authorities in charge of flood forecasting and warning by providing global rainfall information in maps, text data e-mails and so on which is produced from binary global rainfall data downloaded from National Aeronautics and Space Administration (NASA) website. Although the effectiveness of satellite rainfall data in flood forecasting and warning has yet to be verified, satellite rainfall is expected to play an important role to strengthen existing flood forecasting systems by diversifying hydrological data source.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.05a
• /
• pp.744-748
• /
• 2003

Developing an interactive satellite multi­media system, such as a digital video broadcasting (DVB) return channel via satellite (RCS) system, is gaining popularity over the world To accommodate the increasing traffic demand we are motivated to investigate an alternative for improving return channel utilization We develop an efficient method for optimal packet scheduling in an interactive satellite multimedia system using hybrid CDMA/TDMA channels. We formulate the timeslot-code assignment problem as a binary integer programming (BIP) problem, where the throughput maximization is the objective, and decompose this BIP problem into two sub-problems for the purpose of solution efficiency. With this decomposition, we promote the computational efficiency in finding the optimal solution of the original BIP problem Since 2001, ETRI has been involved in a development project where we have successfully completed an initial system integration test on broadband mobile Internet access via Ku-band channels using the proposed resource allocation algorithm.

• Journal of Satellite, Information and Communications
• /
• v.2 no.1
• /
• pp.7-13
• /
• 2007

A new and effective Doppler effects compensation method based on constellation estimation as well as an average power saving strategy by modified modulation scheme utilizing zero point constellation are presented with theoretical analysis and relevant simulations. The suggested schemes are proved to be very effective for satellite OFDM signals relayed by power limiting transponder for the mobile terminal on high speed vehicles.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.12C
• /
• pp.1633-1641
• /
• 2004

In satellite digital broadcasting and satellite internet, severe burst errors occur in the high-speed return channel from the satellite to mobiles. In this paper, we analyze the performance of the forward error correction (FEC) coding method in the Rayleigh fading return channel. We first investigate the channel model of Loo, LutB, Vucetic and Corazza. We then compare the performance of the convolutional, Reed-Solomon (RS), convolution-RS concatenation, and Turbo codes in rayleigh fading channel.