Mobile Satellite Services Research Articles

Performance Evaluation of High-Frequency Mobile Satellite Communications

Communication satellites have a much longer propagation delay than terrestrial communication networks such as cellular or WiFi. In addition, as the carrier frequency moves up, mobile satellite communications show worse performances than the conventional fixed satellite communications. The mobile satellite service (MSS) has not been actively pursued with long latency at high-frequency bands for future applications. In this paper, the adverse impact of long propagation delay in the conventional satellite system is investigated with various user mobility and Doppler-shifted carrier frequency. The satellite network is modeled as a basic delayed feedback channel system and the communication performance is analyzed under delayed channel state information (CSI) for assessing the system feasibility in mobile conditions. The results of performance analysis are provided at high-frequency bands with high-speed user movement, specifically on the outage probability and the channel capacity exploiting three types of channel models: conventional land mobile satellite (LMS) channel models of E. Lutz and C. Loo, and Nakagami fading model. In the circumstance with various user speeds, system performances are evaluated with different propagation delays in the LMS channel models and for line-of-sight (LOS) components in the Nakagami fading. In addition, the conventional models are compared depending on different altitudes for geostationary orbit (GEO), medium earth orbit (MEO), and low earth orbit (LEO) satellites, as well as high-altitude platforms (HAP).

Simulation/Optimization Modeling for Robust Satellite Data Unit for Airborne Network

The objective of this paper is to present a Simulink model–based approach for simulation and optimization of a robust satellite data unit (SDU) able to deliver safety and nonsafety aeronautical mobile satellite services, including capabilities to operate in an airborne network. For this purpose, analysis and modeling of the main avionics system signals and data traffic to be treated in an SDU were performed. The main contribution here is the design of the SDU data traffic model, which integrates different simulation models in avionics systems, such as automatic dependent surveillance—broadcast, aircraft communications addressing and reporting system, and in-flight connectivity for future implementation and optimization, thus allowing the characterization of a device onboard in a modular framework. To conclude, this paper describes a modeling and analysis tool aimed at providing the aviation industry with the means to reduce the amount of equipment onboard (and thus the weight of aircraft to reduce fuel consumption) and fulfill passengers’ demand for connectivity. Finally, note that this modeling is a step further toward the development of a device that ensures greater operational safety and ease of repair and maintenance.

A multi-band switchable antenna for Wi-Fi, 3G Advanced, WiMAX, and WLAN wireless applications

AbstractThis paper presents a hexa-band frequency reconfigurable planar antenna, printed on a 1.6 mm thicker FR 4 substrate and backed by a truncated ground plane. The given antenna operates in four different frequency modes, depending on the state of the two lumped element switches. The proposed antenna works at six frequencies, 2.10, 2.40, 3.35, 3.50, 5.28, and 5.97 GHz. These frequency bands are dedicated to useful wireless applications, including 3G Advanced (2.10 GHz), Wireless Fidelity (Wi-Fi) (2.40 GHz), WiMAX (3.35 GHz), WiMAX (3.5 GHz), WLAN (5.28 GHz) and fixed-satellite and mobile satellite services (5.97 GHz). Satisfactory gain of 1.96, 2.20, 2.671, 2.81, 3.80, and 3.88 dBi, efficiency of 92.5, 94.5, 94.56, 95.0, 93.8, and 97.0% and bandwidth of 332, 485, 1020, 1080, 512, and 465 MHz has been obtained at 2.10, 2.40, 3.35, 3.50, 5.28, and 5.97 GHz, respectively. The modeling and simulations are conducted in CST MWS (2014). The simulated reflection coefficient and radiation pattern are validated in antenna measurement facility. In addition, the specific absorption rate of the antenna on a flat section of human body is also studied. The antenna is compact, low profile, and vastly suitable for multi-band wireless devices.

Joint Coding and Multicast Subgrouping Over Satellite-eMBMS Networks

Mobile satellite services are extremely important when continuity of service is requested while the user is moving over a wide area. A notable example is represented by live TV services, or more in general by the Multimedia Broadcast/Multicast Services (MBMSs) and its evolved version enhanced MBMS. In this paper, we present the combined use of multicast resource allocation schemes based on subgrouping and application layer joint coding to enhance the performance of live video streaming in mobile satellite systems. The reference architecture foresees a satellite-based long term evolution transmission using orthogonal frequency division multiple access in the forward link. The results show that the combined use of multicast subgrouping resource allocation and application layer joint coding allows high-throughput transmissions with satisfactory user quality of experience of the received video over different satellite channel propagation environments.

Design of an Antenna for Mobile Satellite Services

Design of an Antenna for Mobile Satellite Services

Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems.

The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS) in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO) mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS) framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS) is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework.

M-shape electromagnetic-bandgap structures for enhancement in antenna performance

Design of circular annular ring patch with circular polarization for surface wave suppression by embedding electromagnetic band-gap structures in its ground plane is considered. The ground plane consists of an M-shaped EBG structure inscribed in the unit square metal patch of dimension 6mm×6mm with conducting vias located at centre of each EBG cell. The antenna is first designed as a simple circular annular ring patch without EBG and then in a planar and double layer form with EBG to resonate at centre frequency of 2GHz. The circular annular ring patch when surrounded by two rows of M-shaped EBG structure shows improvement in the antenna performance parameters such as impedance bandwidth, axial ratio bandwidth and gain, in comparison to antenna without EBG structures. The circular polarization purity is excellent over the stop band of 296.2MHz for the M-shape EBG structure. The maximum co-polarized gain is 6.77dB and cross-polarized gain is −12.55dB for main lobe direction. The proposed double layer antenna with M-shape EBG structure embedded in its ground plane can be a good candidate for the Mobile Satellite Service band (1990–2025) MHz and for UMTS, WCDMA (1920–2170) MHz applications.

Special issue on main results of Call‐off Order 3 (CoO3) in SatNEx III

Special issue on main results of Call‐off Order 3 (<scp>CoO3</scp>) in <scp>SatNEx</scp> III

Receiver memory management method for HARQ in LTE-based satellite communication system

Summary For the successful deployment of the long term evolution (LTE)-based mobile satellite service, the price of a user terminal is one of the major factors. A user terminal for the LTE-based satellite communication needs to be implemented with a similar hardware size that is used for a terrestrial LTE user terminal. However, for quality of service provision, the satellite user terminal needs a larger size of memories than the terrestrial terminal does. This is very evident by considering that the N-channel stop and wait hybrid automatic repeat request requires proportionally increasing memory size by the propagation delay, resulting in unmanageable amount of memories in the satellite system. To resolve this problem, we propose an efficient memory management method at the user terminal when the size of memory is insufficient. The simulation results in this paper reveal that the proposed method can increase the throughput about 20.7% when a user terminal is operated under very low throughput condition with an insufficient memory size, compared with the case without memory management scheme. In addition, we show that the additional throughput gain can be obtained by the packet scheduling using the information of receiver memory status. Copyright © 2015 John Wiley & Sons, Ltd.

Special issue on ‘integrated mobile satellite service systems and technologies’ ‐ guest editorial message

Special issue on ‘integrated mobile satellite service systems and technologies’ ‐ guest editorial message

Analysis of interference and availability between satellite and ground components in an integrated mobile‐satellite service system

SummaryAn integrated mobile‐satellite service (MSS) system is one of the most promising infrastructures for the efficient use of satellite frequency, and the satellite coverage can be extended by reusing the satellite frequency in its ground components. However, the co‐channel interferences caused by the frequency reusing technique may lead to the performance degradation. This paper presents the interference analysis for an integrated MSS system that is composed of a multi‐beam satellite, complementary ground components (CGCs), and mobile earth stations, by using statistical simulations. These statistical results are then used to evaluate the availability of the system. Our simulation results reveal that the satellite frequency reuse in the CGCs of the integrated MSS system can increase efficiency of satellite spectrum utilization with a tradeoff between CGC network capacity and intra‐system interferences. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Instances of Worst-Case Scenario Based Analysis Pushback by the FCC

The FCC frequently uses worst-case scenario analysis as the basis for its decisions. However, there are instances where the FCC pushes back on these worst-case scenarios. In these instances, the FCC bases its decision on the practical realities of a situation and adopts a final decision that balances a range of factors implicated in the situation. This pushback occurred in a variety of contexts including dismissing concerns about out-of-band emissions in an advanced wireless services rule change, balancing daytime-only AM radio station post-sunset power limits with interference concerns, adopting a procedure for setting a separation distance that reflects practical interference concerns, developing realistic restrictions for UHF noise figure requirements, dismissing interference concerns around the use of ancillary terrestrial services by mobile satellite service providers, considering a waivers request by ultrawideband service providers, and refusing to act on unrealistic interference scenarios when considering whether to approve new satellite services. Two factors were present in each of these decisions. First, the worst-case scenario was implausible because it required several unlikely events to occur simultaneously. Second, if the worst-case scenario dictated the decision, the FCC would be required to adopt a conservative approach that overvalued one factor relative to other important factors in the decision mix. Where the FCC rejected worst-case driven decision-making, it adopted a final decision that balanced a range of pertinent factors.

Bandwidth Enhancement of Corporate Fed Bowtie Antenna Array operating in L Band by Changing the Substrate Material and Ground Plane Length

This paper presents analysis of Multiband Corporate fed Bowtie Antenna Array having tuned in L Band. Bandwidth performance is analyzed for different substrate materials and effect of ground plane is presented. Simulation result shows that proposed antenna using Roggers RT/Duroid matarial is tuned at frequencies 1.05 GHz, 1.63GHz, 2.25GHz and 2.92GHz and provides 40.95%, 18.40%, 14.66% and 17.97% bandwidth respectively. Proposed antenna can be used for applications such as WCDMA, Mobile Satellite services, point to point, TV pickup and subscriber radio system (SRS). The antenna is simulated on HFSS virtual tool. General Terms Antenna design & analysis, RF design, Wireless communication, Microstrip antennas.

Reach the Unreached -IIRS Outreach program for enhanced learning to all

Abstract. With the advent of Information and Communication Technology and improved broadband internet connectivity has enhanced the scope of learning any time anywhere, going beyond the traditional classroom approach. To support distance learning, Indian Space Research Organisation, Government of India has launched dedicated communication satellite called EDUSAT in 2004. The satellite is widely used for variety of applications like Tele-education, Tele-medicine, Village Resource Centres, mobile satellite services, disaster management support and television broadcasting educating farmers for agriculture and other purposes. One of the prime applications of EDUSAT satellite is tele-education at various levels (i.e. school level/UG /PG level) by different ministries / autonomous organizations / departments/institutions/universities in India effectively utilized the EDUSAT for Tele-education. The initial focus of IIRS was to use EDUSAT/INSAT 4CR satellite for distance learning but extended the scope to use broadband internet so that access to large number of institutions/universities /individuals with little cost the User. IIRS distance learning program initiated in 2007 and successfully conducted 12 programs in the last eight years. The first course was attended from twelve universities and the number of institutions /universities increased manifold. The thirteenth course is progress with more than 210 institutions /universities /departments /individuals with more than 3200 number of participants attending the program live and interactive. IIRS program is unique and interactive and demand is increasing not only universities but among research institutions, user departments and individuals.

Miniaturised multiband two‐element coaxial continuous transverse stub antenna for satellite C‐band applications

The continuous transverse stub (CTS) technology incorporates the use of coaxial lines to produce effective microwave antenna structures that radiate an omnidirectional pattern with high efficiency and low return loss. In this paper a two-element coaxial CTS antenna array is designed to operate in the C-band with improved efficiency and gain. The proposed prototype of the C-band antenna, with design operating frequencies –5.18, 6.536 and 7.42 GHz, finds numerous applications in C-band satellite communications. During simulation, the efficiency at these frequencies had been observed to be 89.5, 87.6 and 95.9% and their corresponding gains were observed to be 7.54, 5.24 and 7.51 dB, respectively. The measured results of the C-band antenna prototype for the above stated frequencies were observed to be 5.185, 6.845 and 7.313 GHz, respectively. This antenna can be used in INSAT/super extended C-band, fixed-satellite services which include space to earth, earth to space as well as mobile satellite services. The radiation of the designed structure is omnidirectional in the horizon plane, with minimum return loss. These simple and low-cost coaxial CTS structures can be adopted in wireless communication systems.

Study of Vehicle Vibration for High-Performance Land Mobile Satellite Tracking System for Telemedicine

The land mobile satellite service (LMSS) is a key component of telemedicine and an important technology for grasping the status of a patient in an ambulance. However, rough road surfaces can destabilize satellite tracking and disturb data communications with the ambulance carrying the patient. Nevertheless, accurate estimates of the location of the vehicle at any given time and rapid reconfiguration of the tracking antenna based on past data can allow stable and effective data communications. This study examined positions characterized by large vibration amplitudes from past data on vehicle vibrations due to rough road surfaces as feature points to provide the vehicle system in advance with reference pitch angle vibration data. Drawing on reference vibration data for convolution and a cost function, The authors synchronized past data with real-time vibration data and accurately estimated the point at which the ambulance or other vehicle passes on the road. They also discuss limits on the range of vibrations that can be used for data synchronization. This study demonstrates that the present method enables high-precision estimates of vehicle location.

Sophisticated Wireless Interference Analysis: A Case Study for Spectrum Sharing Policy

Access to sufficient wireless spectrum is important for sustaining the growth of wireless broadband and enabling next-generation wireless technology. However, freeing additional spectrum for wireless broadband is often a difficult and contentious process. As policymakers look to new mechanisms of sharing spectrum to meet growing wireless needs, the specific terms of sharing are central to the utility of the wireless resource. For this reason, nuanced understanding of interference risks - which drive spectrum sharing policies - is needed to maximize the productive use of the spectrum.Commonly proffered interference analyses are static and simplified, while the real world of wireless is dynamic and ever changing. Improving the technical information on which policymakers rely is therefore critical to the success of spectrum sharing as a policy strategy. In this paper, we demonstrate how sophisticated simulation of wireless coexistence can yield important insights, in contrast to simplified models normally offered by advocates. We focus on a portion of the 5 GHz Wi-Fi band, which is crucial for enabling capacity and throughput, and is the global home to the next-generation mass market Wi-Fi standard known as 802.11ac. In this analytic context, outdated FCC rules designed to protect mobile satellite service (MSS) from harmful interference rendered Wi-Fi access to 100 megahertz of the band, known as UNII-1, unsuitable for wide-scale deployment. Today, a single MSS company occupies this entire 100 megahertz, and a far lower level of MSS utilization exists than assumed would be the case when the FCC established rules many years ago. Our paper develops a sophisticated coexistence simulation, which shows that satellite phone users are extremely unlikely to experience any service diminution (harmful interference) as a result of liberalized Wi-Fi access to UNII-1. This analysis was submitted to the FCC in January 2014, and served as the primary basis for action to expand Wi-Fi access to UNII-1 in March of that year.

위성항법시스템을 위한 항재밍 기술 분석

위성항법시스템을 위한 항재밍 기술 분석

Overview and comparison of on‐ground and on‐board beamforming techniques in mobile satellite service applications

SUMMARYThe objective of this paper is to review state‐of‐the‐art techniques of beamforming in mobile satellite systems and evaluate the potential benefits/drawbacks of on‐ground beamforming compared with on‐board beamforming approach. The paper also provides a short analysis of beamforming error sources in on‐ground beamforming such as propagation effects at feeder link level, on‐board degradations at payload level, differential atmospheric perturbations, and Doppler shift effect. An investigation of signal processing techniques is also performed to provide a preliminary assessment of the interest for employing adaptive beamforming and precoding techniques in multi‐spots mobile satellite systems. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Coexistence studies on the interference performance between mobile satellite system and LTE network

The interference coexistence performance between the systems of a Long Term Evolution (LTE) network and Mobile Satellite Service (MSS) system, both of which work around the frequency of approximately 2 GHz according to the bandwidth allocation in China, is proposed in this article. The related background of an MSS system and the common terminologies are introduced. Further, the coexistence scenarios of different coverage situations shared by the two systems are discussed. The interference impact of an MSS transmission on an LTE system is evaluated using a specific Monte Carlo method. Finally, simulation results show that although no crucial issues for the coexistence of an LTE downlink and the MSS are observed, the LTE uplink suffers a considerable amount of interference from the MSS transmission. Given the insufficient isolation between LTE and MSS existing networks, and the rapid advance in the field of LTE, problems may emerge in the near future. Further, this article can be of significance in providing reference for frequency spectrum planning in the existing LTE networks.