HF radio network simulation based on automatic link establishment (ALE) and distributed routing policies

The US Navy has all but ceased to use high frequency (HF) radio for long-haul ship-shore communications. Satellite systems have rightfully assumed this role, but the antiquated nature of the Navy HF system has soured planners on even considering HF for supplementary uses or other roles. In an attempt to dispel this undeserved reputation and gain operating experience for application of automation to new shipboard HF systems, an HF radio communications system incorporating automatic link establishment (ALE), single-tone serial modems and 500-watt transceivers was deployed on USS TARAWA (LHA-1) and to serving Navy shore communications stations during her recent deployment to the Indian Ocean and Persian Gulf. The authors describe the use of this system for bidirectional 600 baud message traffic. This is the first application of the combination of MIL-STD-188-141A ALE and MIL-STD-188-100A single tone serial modem technology in a US Navy operational environment. The ALE radio system was used to automatically test and select the best channel from among several assigned frequencies and establish a link between ship and shore. Accumulated message traffic was then passed over the single-tone serial modem to the distant end. Technical details of the installation and operational techniques are presented along with a discussion of how automation greatly reduced the level of skill and experience needed to successfully operate this HF system. Test results are presented which illustrate the success enjoyed in maintaining communications over paths which had long been considered unworkable with existing shipboard HF equipment and techniques. The potential for application of automated HF to short-range over-the-horizon (OTH) communication needs for littoral warfare is also discussed. >

The author describes an attempt to use HF automatic link establishment (ALE) radio equipment as a ship-shore sounder in the Mediterranean Sea. The method selected as potentially most effective for HF channel selection purposes was a state-of-the-art HF ALE radio system. This system consists of fully automatic microprocessor-controlled HF radio transceivers incorporating the ALE control protocols and waveform specified in MIL-STD-188-141A. The primary result of the test was that the use of the HF ALE radio system as a sounder to support VFCT (voice frequency carrier telegraph) HF terminations provided no operating advantage in the Mediterranean operating areas. It is concluded that, in spite of the inability to find a ready solution for HF communications in the Mediterranean, this was a very successful test. The ALE radio system performance data obtained provides a first real-world glimpse at how MIL-STD-188-141A might serve the navy in future automated HF communications system. >

The SoDark cipher is used to protect transmitted frames in the second and third generation automatic link establishment (ALE) standards for high frequency (HF) radios. The cipher is primarily meant to prevent unauthorized linking and attacks on the availability of HF radio networks. This paper represents the first known security analysis of the cipher used by the second generation ALE protocol—the de facto world standard—and presents a related-tweak attack on the full eight round version of the algorithm. Under certain conditions, collisions of intermediate states several rounds into the cipher can be detected from the ciphertext with high probability. This enables testing against the intermediate states using only parts of the key. The best attack is a chosen-ciphertext attack which can recover the secret key in about an hour with 100% probability, using 29 chosen ciphertexts.

This paper examines existing automatic link establishment (ALE) techniques for high frequency (HF) radio systems, identifying areas of improvement in calling techniques and protocols for ALE. Automated HF radio systems improved in these areas have been implemented, and results of these implementations are presented. Compromises between link establishment time and reliability are also considered.

 Abstract—This paper describes a simulation architecture developed to address the need in the defence and aerospace industry for a rapid prototyping capability to test new and existing network protocols and systems where analytical methods no longer suffice. In particular, the simulator introduced here allows study of High Frequency (HF) radio networks and other unorthodox systems that cannot be easily modelled using existing communications network simulators. This paper describes the architecture and gives an example use case - modelling an HF System using the 2G Automatic Link Establishment (ALE) linking protocol under a variety of conditions; exploring the effects of changing the number of nodes in the network, and of altering the input data rate to the system. The network performance was analysed under a wide range of combinations of conditions, and it was found that increasing the number of nodes in these networks causes specific latency increases and an overall throughput decrease, both in the unidirectional and bidirectional case, although it is better tolerated in the unidirectional case. Increasing the input data rate causes an overall throughput increase up to a threshold point, after which it saturates and then decreases as data remains unsent, due to the physical limits of the system (including networking overhead) being surpassed. This simulator, known as CommNetSim has been developed for use in evaluating the technical capabilities of, and business cases for, real-world applications to be developed by Thales UK. Index Terms—Communication networks, discrete event simulation, high frequency radio, modelling, simulation.

Traditionally, high frequency (HF) communications have been difficult to manage efficiently, mainly due to the variable nature of the propagating conditions. An automatic radio control system (ARCS) consisting of automatic channel selection (ACS), automatic link establishment (ALE), and automatic link maintenance (ALM) will provide an automated system which will alleviate operator workload and improve communications availability at HF. Effective network management is fundamental to such a system. Computer modelling and simulation is a powerful method for testing the suitability of parameter values and how they affect the operation of a communications systems. Various networks can be simulated highlighting the shortcomings and also the positive aspects of each configuration. This paper describes the current status and capabilities of a computer based ARCS network simulation designed to be used as an aid to developing the ARCS specification. It also presents some initial results.

Their have been major advances in the field of automatic and adaptive radio communication systems. Advances in such diverse areas as frequency management, automatic link establishment, modem technology, networking protocols and message handling systems have led to the possibility of separating the user from the radio. They have led to the concept of HF as a transparent subnetwork within a wider communications infrastructure, and they have led to the idea of radical new approaches to the allocation and utilisation of the HF band itself. A system that consolidates many of these advances is under development for the Swedish armed forces. The contract was awarded by the Swedish Defence Material Administration (Forsvarets Materielverk) to GEC-Marconi after an extensive evaluation of the proposed solution involving computer simulations and on-air trials over an 18 month period. This paper describes some of the key concepts of the system and outlines the main elements involved in its implementation.

The manually operated high frequency radio requires operators with extensive training, knowledge, and experience. The resurgence of interest in HF radio has led to increased automation of the operator functions, thus allowing operation by personnel with only a minimum of training. Although the automatic link establishment (ALE) system provides the basic system automation, there are a number of additional automation functions being developed. The future adaptive radios will be devices that can sense their communication environment and automatically adapt to enhance their communications links as well as mitigate against detractors. >

The rapid proliferation of heterogeneous devices in Power Internet of Things (PIoT) presents significant challenges for efficient routing and energy management in large-scale deployments. This paper proposes a novel adaptive routing protocol that integrates edge computing and federated learning to address the complexities of heterogeneous device coordination and energy efficiency optimization in PIoT environments. The proposed approach employs a hierarchical architecture where edge nodes serve as distributed processing points, enabling local decision-making while maintaining global optimization through federated learning mechanisms. The adaptive routing algorithm dynamically adjusts routing parameters based on real-time network conditions, device characteristics, and energy constraints, while the federated learning framework enables collaborative optimization without centralized data sharing. Comprehensive experimental evaluation demonstrates that the proposed protocol achieves 35-50% higher network throughput, 40-60% reduction in end-to-end delay, and 45-65% energy savings compared to traditional routing protocols. The results validate the protocol's superior scalability and robustness, maintaining consistent performance across networks of up to 10,000 devices while traditional approaches exhibit significant performance degradation beyond 1000 devices.

In the few last years, there is an increasing need of QoS guarantees for multimedia and real time applications in mobile ad hoc networks. While several QoS routing protocols were proposed, adaptive routing has not be enough exploited. We propose in this paper a new delay oriented adaptive routing protocol for mobile ad hoc networks. We integrate a mean delay estimation model at each node in our protocol in order to avoid synchronization problem. Adaptive mean delay routing (AMDR) protocol proposed in this paper uses two kinds of exploration packets having the task of gathering delay information of available paths and updating probabilistic routing tables. To reduce the overhead generated by AMDR protocol, we propose the use of a new MPR selection algorithm called Flooding Optimization Algorithm (FOA) based on mean delay.

In this paper, The Concept of Adaptive Routing in Cognitive Radio Mobile Ad-Hoc Network (CR-MANET) is proposed. Cognitive Radio (CR) is technology that is widely considered as a promising technology to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage. It is an enabling technology that allows unlicensed (secondary) users to exploit the spectrum allocated to licensed (primary) users in an opportunistic manner. While in classical CR networks the central network entity such as a base-station in cellular networks is responsible for spectrum and routing management, in CR-MANET networks this responsibility lies on end-user devices. Therefore, routing protocols in CR-MANET need to be robust and must adaptively cooperate with spectrum sensing methods. The proposed Concept of Adaptive Routing in CR-MANET is therefore composed of function blocks that are able to perform spectrum sensing, intelligent channel management and adaptive routing.

Knowledge of the state of the upper atmosphere, and in particular its ionospheric part, is very important in several applications affected by space weather, especially the communications and navigation systems that rely on radio transmission. To better classify the ionosphere and forecast its disturbances over Europe, a data collection endeavour called the European Digital Upper Atmosphere Server (DIAS) was initiated in 2004 by a consortium formed around several European ionospheric stations that transmit in real-time ionospheric parameters automatically scaled. The DIAS project is a collaborative venture of eight institutions funded by the European Commission eContent Programme. The project seeks to improve access to digital information collected by public European institutes and to expand its use. The main objective of the DIAS project is to develop a pan-European digital data collection describing the state of the upper atmosphere, based on real-time information and historical data collections provided by most of the operating ionospheric stations in Europe. Various groups of users require data specifying upper atmospheric conditions over Europe for nowcasting and forecasting purposes. The DIAS system is designed to distribute such information. The successful operation of DIAS is based on the effective use of observational data in operational applications through the development of new added-value ionospheric products and services that best fit the needs of the market. DIAS is a unique European system, and its continuous operation will efficiently support radio propagation services with the most reliable information. DIAS began providing services to users in August 2006. The Need for Accurate Ionospheric Products Radio frequency communications and satellite positioning and navigation systems are applications most affected by ionospheric disturbances. Such disturbances can cause drastic and large-scale changes in the usable ranges of high frequency (HF) or below HF bands affecting standard ground-to-ground and submarine communication systems. The characteristics of an ionospheric propagation channel, whether it is HF or transionospheric frequencies, are highly variable on timescales ranging from a few seconds to the 11-year solar cycle. Even during its quietest periods, the Sun produces electromagnetic radiation and solar wind, both of which can affect a variety of geomagnetic and ionospheric phenomena, which in turn affect radio waves propagating through the ionosphere. Hence day-to-day and hour-to-hour changes in propagation channel characteristics can occur.

Multichannel communication has been proposed as alternative to adaptive (single-channel) routing protocols for mitigating the impact of interference and link dynamics in wireless sensor networks. While several studies have advocated features of both techniques (not without running up against contradicting arguments) a comprehensive study that aligns these results is still lacking. This paper aims at filling this gap. We present an experimental test bed setup used to perform extensive measurements for both single-channel and multichannel communication. We first analyze single-channel and multichannel communication over a single-hop in terms of packet reception ratio, maximum burst loss, temporal correlation of losses, and loss correlations across channels. Results show that multichannel communication with channel hopping significantly reduces link burstiness and packet loss correlation. For multi-hop networks, multi-channel communication and adaptive routing show similar end-to-end reliability in dense topologies, while multichannel communication can outperform adaptive routing in sparse networks with bursty links.

Objective: Quantitative measurement of the dynamic changes in autonomic nervous system (ANS) during and after exercise has great significance in clinical, sports training and other fields. A consecutive ultra-short-term (30 s, UST) heart rate variability (HRV) method was proposed to track the exercise-induced autonomic control of heart rate (HR). Approach: Twenty-three healthy young men participated in the study. The first four stages of the Modified Bruce Protocol (S0–S3) were performed. Six HRV indices, i.e. HF (power of high frequency ranged from 0.15 to 0.4 Hz), LF (power of low frequency ranged from 0.04 to 0.15 Hz), LF/HF, SD1 and SD2 of Poincaré plot, and SD2/SD1, over 30 s were calculated every 5 s over 3 min RR time series during, as well as after, exercise. Main results: The results showed that during exercise, SD1, SD2, HF and LF dropped down quickly and tended to stabilize. Particularly, SD1 and HF showed a slight upward trend in the lower three stages while the declining time of SD2 in S3 lasted longer than the other stages. SD2/SD1 increased rapidly first and then decreased slowly. The values of SD2/SD1 in S3 remained higher than those in the other stages. After exercise, SD1, SD2, HF and LF kept increasing first and then declined slowly or fluctuated with decaying amplitudes. SD2/SD1 increased initially, then decreased and fluctuated slightly. Significance: Compared with the indices in frequency domain, the Poincaré indices were more sensitive and accurate in UST measurement of ANS during exercise. The results demonstrated that the UST method could characterize the dynamic changing tendency of ANS during and after exercise and quantify the differences of changes in ANS induced by exercise with different intensities. In particular, the vagal branch functioned dominantly in controlling HR in S0 but the effect of the sympathetic branch on HR enhanced with the increase of exercise intensity. In addition, the transient changes of ANS related with the sudden onset of exercise could also be reflected, despite perhaps being limited by the computation window width to some extent. Thus, the consecutive UST Poincaré indices could provide a feasible and simple method to measure quantitatively the exercise-induced dynamic changes in ANS.

Transient receptor potential cation channels, vanilloid subfamily, member 5 (TRPV5) plays a key role in active Ca(2+) reabsorption in the kidney. Variations in TRPV5 occur at high frequency in African populations and may contribute to their higher efficiency of Ca(2+) reabsorption. One of the African specific variations, A563T, exhibits increased Ca(2+) transport ability. However, it is unclear how this variation influences the channel pore. On the basis of the structure of TRPV1, a TRPV5 model was generated to simulate the structural and dynamical changes induced by the A563T variation. On the basis of this model, amino acid residue 563 interacts with V540, which is one residue away from the key residue, D542, involved in Ca(2+) selectivity and Mg(2+) blockade. The A563T variation increases secondary structure stability and reduces dynamical motion of D542. In addition, the A563T variation alters the electrostatic potential of the outer surface of the pore. Differences in contact between selective filter residues and residue 563 and in electrostatic potential between the two TRPV5 variants were also observed in another model derived from an alternative alignment in the selective filters between TRPV5 and TRPV1. These findings indicate that the A563T variation induces structural, dynamical, and electrostatic changes in the TRPV5 pore, providing structural insight into the functional alterations associated with the A563T variation.