A compact EHF/SHF dual frequency antenna

The role of commercial services within a military satellite communication system and their ability to support the communication requirements of the fixed and mobile military users has been the subject of considerable interest. Although commercial services are currently employed in the UK military communication systems, their implementation is typically restricted to the leasing of point to point circuits, on an as required basis. This paper considers the potential application of commercial satellite and terrestrial services for the next generation military communication systems. In considering the relative benefits of commercial satcom, it is important to assess not only the provision of in orbit transponders, but also the impact on ground management systems and user terminals, to support an integrated architecture.

Transmission planning for military and commercial satellite communications systems has traditionally followed separate (but parallel) paths and led to the development of distinct sets of tools which can handle either only military satellite systems or only commercial satellite systems. With the need to operate DoD communications networks on both military and commercial satellites a unified transmission planning model is required which can model both types of satellite systems in a common framework. This paper proposes a unified approach to transmission planning for military and commercial satellite systems, and discusses both the common requirements for such a transmission planning model, and those requirements specific to the structure and operation of military satellites such as the use of saturated transponders, null-forming multi-beam antennas, special waveform modulation techniques, jamming threats, etc., which need to be treated differently from their commercial counterparts. Software models are proposed for some of the key requirements, and issues related to their implementation are discussed. The paper also describes the capabilities of existing software which can be used for transmission planning on commercial satellites, and how it can be augmented to function in the military satellite communications environment.

The FHSS and DSSS signals are widely used in military satellite communication systems. In this paper a new concept of "normalized throughput of information" is proposed according to the property of jammed signals, the performance of FHSS and DSSS signal with on-board processing is compared based on the new concept. We conclude that performance of FHSS signal is better than that of DSSS signal, and FHSS signal is suitable to be used in military satellite communications.

한국군은 미래 군 위성통신의 요구 사항에 걸맞은 한국형 군 위성통신 체계 구축을 위하여 고속대용량, 생존성 보장, All IP 통신, 기동성 보장과 같은 발전 방향을 목표로 차기 군 위성통신 체계를 개발하고 있다. 본 논문은 차기 군 위성통신 체계의 최적 자원 할당과 IP 네트워킹 기술에 집중하여, MF-TDMA 자원 할당, 랜덤 액세스, 위성/지상 연동망 구조, 그리고 PEP의 세부 연구 분야에 대하여 연구 내용 조사 및 분석을 실시하였다. 각 연구분야에 대한 기존 연구는 채널 효율 및 처리량의 증가를 위한 연구가 주를 이루고 있다. 이에 더하여 차기 군 위성통신 체계를 위한 연구는 이기종 단말, Full Mesh 환경, 분산망, 위성/지상 연동망, 항재밍 등의 특성 들을 고려해야 한다. 본 논문에서는 이러한 특수성을 고려하여 각 분야 별 핵심 연구 이슈들을 제시하고, 주요 이슈에 대하여는 모의실험을 통한 결과를 제시하였다. Korean military is developing the next generation military satellite communications system in order to achieve the requirements of future military satellite communication such as high speed, high capacity, survivability, all IP networking, and on-the-move. In this paper, we survey and analyze the research interests about optimal resource allocation and IP networking such as MF-TDMA, random access, satellite IP routing, and PEP. Conventional researches have focused on the increase in channel throughput and efficiency. In addition to these measurements, we consider heterogeneous satellite terminals, full mesh topology, distributed network, anti-jamming, and the like which are the special characteristics of the next generation military satellite communications system. Based on this, we present key research issues and evaluation on the issues by simulation.

The article presents the general provisions and essence of the approach to building a mathematical model of the functioning of an automated military radio communication system in the process of its protection against radio reconnaissance by radio exchange along rational routes. The main components of the mathematical model of the functioning of an automated military radio communication system in the process of its protection against radio reconnaissance by radio exchange along rational routes with low intelligence availability are considered. The general structure of a mathematical model of the functioning of an automated military radio communication system in the process of its protection against radio reconnaissance by radio exchange along rational routes is proposed. It is shown that in the basic modeling unit of the subprocess of determining the rational routes of radio exchange among the set of possible ones, an optimization problem is solved. The result of solving this optimization problem is presented in tabular form for convenience. The analytical expressions for the third-rank tensor of the intelligence accessibility of individual branches of the radio communication system structure are obtained.

Commercial-off-the-shelf (COTS) satellite-communications equipment provides many advantages for today's military satellite-communications systems in terms of cost, availability, and flexibility. The relationship and importance of using COTS equipment for military applications and incurring potential vulnerability to enemy jamming and interference is stressed in this paper. In order for a communications system to be of value, it must be reliable and it must be available when needed. The idea of this paper is making the most of the capabilities that do exist commercially in order to improve the probability that communication based on commercial equipment and systems will be available when needed, at least when interference and very modest jamming capability via a transportable terminal are considered. The bit-error probability for commercial satellite-communications modems which employ BPSK or QPSK modulation as well as convolutional coding and concatenated coding is computed analytically taking into account broad-band noise, pulsed noise, and pulsed tone interference. The results show that in broad-band interference at moderate and high values of signal-to-interference-plus-noise ratios, concatenated Reed-Solomon and soft-decision convolutional coding provides the best performance, whereas at low signal-to-interference-plus-noise ratios, the types of coding considered offer worse performance than the uncoded system. When pulsed interference is considered, the optimum coding method depends on the signal-to-interference-plus-noise ratio. Experimental results are also included.

Fast frequency hopped spread-spectrum is used in military satellite communication systems for providing resilience to different types of jamming. Most analyses focus either on the worst case jamming to obtain performance metrics such as Bit Error Rate (BER), or use specific waveforms and evaluate system performance by means of simulations. Recently there has been a growing interest in using Adaptive Coding and Modulation (ACM) and tune the modulation and coding to specific jamming scenarios, in order to maximize system throughput. This paper provides information theoretic bounds for such systems with wide-band and pulse jammers. Developing these bounds also provide insight into how to construct waveforms which maximize system capacity, while providing the desired jamming resistance. Since fast frequency hopped spread-spectrum systems also typically use Time Division Multiple Access (TDMA), there is synchronization overhead. So, information theoretic bounds for capacity, where the transmitter and receiver are not perfectly carrier phase synchronized are also developed. These bounds will prove useful in determining the "best" system capacity, which can then be compared with the actual throughput achieved by a specific waveform.

SYRACUSE - The French military satellite communication system

Many waveforms for future military satellite communication systems rely on spectrally-confined waveforms to increase the number of users and maintain capacity. These waveforms stress the performance of the transmitting amplifiers. The design and planning stages of communication systems often use memory-less nonlinear models, such as amplitude-to-amplitude modulation and amplitude-to-phase modulation models. These models are based on single-tone measurements and do not accurately predict the amplifier performance for wider bandwidth modulations. This paper presents measured comparisons of single-tone characteristics and spectrally-confined waveform performance in solid-state amplifiers at millimeter-wave frequencies. Measurements are performed over a range of data rates with PSK and QAM modulations, with comparison of devices with and without nonlinear memory.

The mobile user objective system (MUOS) is a next generation military satellite communication system based on terrestrial 3GPP WCDMA. In any mobile wireless communication system, user terminal movement forces cell and/or beam handovers. In MUOS, the challenge of maintaining system performance in handovers and in the general class of mobility events, potentially becomes more difficult due to requirements for high speed aircraft terminals with velocities up to 900 mph, requirements for group services for point to multi-point communications, and beam movement resulting from non-geostationary satellite orbit. This paper describes the technical approach for analyzing MUOS system performance in mobility events. An example scenario using realistic user terminal characteristics, user terminal population geographic lay-downs, and moving satellite beam footprints is given. The analysis results show that required MUOS system performance is maintained for two types of network topologies. This approach can be used to evaluate performance for other candidate MUOS terminal platforms such as the Joint Strike Fighter, which can reach maximum speeds of 1200 mph.

This paper describes one layer in the Intersystem protocol hierarchy, which is a mechanism for internetworking among existing and planned military satellite communication systems. With this mechanism, the combined systems form a world-wide satellite communication network serving tens of thousands of end users, many of whom are mobile, using many different communication link protocols. Since the interconnection of separate communication systems via the Intersystem is not allowed to change their internal structure or communication protocols, the Intersystem protocol hierarchy is primarily a common set of higher layer coordination protocols that will overlay the existing protocols in each member system. This paper describes the higher layer coordination protocols.

The transponder simulator designed to simulate the transponder of military satellite communication systems in the geostationary orbit is required to have time delay function, because of 250 ms delay time, when a radio wave transmits the distance of 36,000 km in free space. But, it is very difficult to develop 250 ms time delay device in the transponder simulator of 100 MHz bandwidth, due to unstable operation of FPGA, loss of memory data for the high speed rate signal processing. Up to date, bandwidth of the time delay device is limited to 45 MHz bandwidth. To solve this problem, we propose the new time delay techniques up to 100 MHz bandwidth without data loss. Proposed techniques are the low speed down scaling and high speed up scaling methods to read and write the external memory, and the matrix structure design of FPGA memory to treat data as high speed rate. We developed the satellite link simulator in 100 MHz bandwidth using the proposed new time delay techniques, implemented to the transponder simulator and verified the function of 265 ms time delay device in 100 MHz bandwidth.

In an antijam military satellite communications system, the service provided by a geosynchronous altitude satellite can be significantly enhanced through the use of lightweight, adaptive EHF antennas to provide theater coverage. The communications capabilities provided by payloads with these EHF antennas can include both low data rate services (75 to 2400 b/s per channel) and medium data rate links (with rates up to approximately 1 Mb/s per link). Through the use of EHF waveform standards, the EHF payloads will be compatible with existing and planned EHF terminals. The adaptive antennas on these payloads can be utilized to provide both variable-coverage spot beam patterns and autonomous nulling capabilities. With this type of antenna system, the coverage pattern can be adapted to match changing force deployments and to eliminate interference sources. One of the significant technology challenges is implementing these adaptive antennas in lightweight, compact configurations which enable their use in a variety of payloads. >

The HF long range tactical communication systems currently in use by the Australian Defence Force (ADF) are outdated, inefficient, inflexible, expensive to maintain and operate, and incapable of carrying military traffic of the type and volume envisaged to support command and control in the 21st. century. The ADF's proposed military high frequency communication system (MHFCS) will be the first digital HF communications network of its size in Australia. With its singular features the system design brings with it a number of unique challenges. The overall dimensioning of the system, the need to resort to computer modelling to predict its performance, and the potential for congestion resulting from the requirement for automated connectivity are some of the major issues that have had to be addressed in the design of such a communications network.

With the integration of information and communication systems into military operations, the issue of their cyber defense is becoming increasingly important. The main target for cyberattacks are databases that mostly contain confidential information. One of the most effective approaches to ensuring cybersecurity of databases of military information and communication systems is to use the intelligent capabilities of a SIEM system. SIEM allows real-time monitoring, analysis and response to potential cyber incidents. The article proposes a methodology for detecting cyber incidents by a SIEM system in databases of military information and communication systems. The main emphasis is placed on the multi-level protection of databases, which includes protection at the operating system level, the database level and the database management system, as well as the network level of protection. In order to improve the efficiency of cyber incident detection at the level of SIEM data analysis, an improved methodology based on fuzzy logic is used. Improvement of the methodology is achieved by introducing weights of antecedents in fuzzy rules, which allows, in some cases, to identify cyber incidents more accurately compared to existing models and methods. The weights of the antecedents of fuzzy rules are determined using the method of pairwise comparisons based on the rankings made on the 9-point Saaty scale. A decision-making algorithm for identifying cyber incidents based on the analysis of fuzzy rules and the weights of their antecedents is presented. An example of calculating the weights of antecedents of fuzzy rules using the method of pairwise comparisons based on rank estimates is given.