Harsh Communication Environment Research Articles

Research on chaotic secure optical communication system based on dispersion keying with time delay signatures concealment

In response to the possibility of time delay (TD) signatures (TDSs) leakage becoming a serious problem in chaotic optical communication, from the perspective of improving the security of chaotic optical communication, this paper proposes a chaotic secure optical communication system based on dispersion keying, which generates signals with TDSs concealment characteristics. In this scheme, a common laser is used to drive chaotic synchronization between the transmitter and the receiver. The complex chaotic signal is generated by the combination of all-optical feedback and optical injection, and the TDSs are hidden by using the structure of dual filters and setting the parameters of each device reasonably. The switch is controlled by binary message to connect fiber Bragg gratings (FBGs) with different dispersion coefficients and maps different symbols to different chaotic attractors instead of the traditional way of directly sending messages to the channel. In addition, the generated signal no longer suffered from return map attacks. FBGs can compress and expand signals in the time domain to enhance the complexity of chaotic signals, and the dispersion value is an important key to effectively increasing the key space. Finally, the performance of TDSs concealment, sensitivity of parameter mismatch, and return map attack in this scheme are discussed in detail. The scheme still achieves a bit error rate (BER) of 1.74 × 10−4 when transmitting at a rate of 10Gbit/s under harsh communication environments such as 10 dB signal-to-noise ratio (SNR), which provides a reference for realizing high-speed and secure optical communication at the physical layer.

Channel characteristics of underwater optical communication system

Underwater communication technology has seen significant development in recent years, with a focus on finding efficient and secure techniques for exploring the underwater world. While acoustic and electromagnetic waves have limitations in water, the use of optical communication has become a focus of research due to its high bandwidth and low delay. Research has shown that blue and green lights are absorbed less than other wavelengths in water, making them suitable for underwater optical communication. In recent years, people have been working with optical communication in harsh environments. The optical system and the acoustic system have been combined to achieve certain development. Several high-speed underwater laser transmission systems have also been developed, with varying transfer rates and distances. This paper focuses on the theory of underwater optical systems and their communication channel characteristics.

Brain inspired optoelectronic integrated receiver chip for wireless optical communication

Inspired by the mechanism of visual attentional selection, a wireless optical communication (WOC) Integrated receiver consisting of a vertical double junction photodetector (VDJ-PD) and an attentional selection circuit (ASC) is presented. The whole receiver is fabricated in standard CMOS technology. The VDJ-PD can realize optical signal detection and wavelength identification. The attentional selection circuit activates the competition among the two PN junctions in VDJ-PD to select the signal with significant feature in real-time while discarding non-significant signals. A higher-order signal modulation scheme is applied by the proposed receiver to obtain a high transfer rate, and all data are decoded using color features. The optical testing results show that parallel and real-time communication of the red and blue light can be achieved, and the rise time is 4.47 μs. To measure the anti-interference performance of the receiver, a water tank is used to simulate a harsh communication environment. Results indicate that the real-time and reliable communication requirements in a harsh channel condition are satisfied. When the percentage ratio between the intensity of stray light relative to the light with maximum intensity is 84%, an accurate information decoding can still be achieved. Moreover, the whole processing procedure does not require the participation of ADC, CPU and memory, consequently avoiding the von Neumann bottleneck.

Edge-Enabled Anti-Noise Telepathology Imaging Reconstruction Technology in Harsh Environments

With the advent of the 5G era, telemedicine and mobile health play an increasingly important role in our daily lives. In the diagnosis process of telemedicine, image processing of telepathology is particularly important to doctors, pathologists, and relevant researchers. In this article, we propose an intelligent telepathology imaging terminal system, the images of which are obtained by Fourier ptychographic microscopy (FPM). For the proposed system, a CNN model is designed and trained to perform the FPM reconstruction to increase the quality of the images and improve the speed of reconstruction. Furthermore, edge learning technology is used in the proposed system to reduce the pressure of data storage and transmission. The proposed scheme is applied in harsh communication environments of low signal-to-noise ratio. The theoretical analysis and experimental results show that the proposed system achieves high-quality digital images and phase maps of histological samples.

A New-Dynamic Adaptive Data Rate Algorithm of LoRaWAN in Harsh Environment

The adaptive data rate (ADR) algorithm is used in LoRaWAN, allocating an appropriate transmission rate for terminal equipment to improve channel utilization and reduce power consumption. However, the standard ADR algorithm is only suitable for static terminal equipment. In addition, due to the complexity of the external environment, the selected data rate will not match the new environment and communication packets will be lost. Therefore, this article proposed a novel and more effective ADR algorithm called new-dynamic ADR (ND-ADR). The algorithm mainly solves two problems, i.e., the standard ADR algorithm cannot be applied to mobile terminal devices and the poor communication quality and high packet loss rate in harsh environments. In this study, we also developed a frame for LoRaWAN (FLoRaWAN), a simulation framework for the star network topology LoRaWAN in OPNET. Furthermore, we built an OKUMURA–HATA model and additionally introduced a noise factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta$ </tex-math></inline-formula> to simulate the loss of wireless communication in harsh environments. Finally, extensive simulation results showed that the number of data packets required by different end nodes for rate allocation was different. Compared with the standard ADR algorithm, even for mobile nodes in harsh environments, the ND-ADR algorithm reduced network energy consumption by about 13%, reduced network delay by about 18%, and increased effective throughput by about 15%. Therefore, the improved ND-ADR algorithm is more suitable for wireless communication of removable nodes in harsh environments. Its advantages are better awareness of link environment, faster data rate regulation, improved channel utilization, and further reduction of network energy consumption.

Harsh Communication Environment Oriented Consortium Blockchain Construction on Edge for Internet of Things

In recent years, the Internet of Things has developed rapidly, and users have gradually become more precise in their control of IoT devices. The use of mobile cloud services in IoT has become a new trend. However, its information security and traceability strategies are still to be studied. This article introduces the application of edge computing architecture in harsh communication environments, and analyzes its deployment requirements for consortium blockchain in combination with IoT application scenarios. The consortium blockchain framework for the harsh communication environment of IoT is proposed, and the overall structure, node deployment, consensus algorithm and security mechanism are introduced, the basic process is finally explained. It provides credible solutions for the information security, traceability, and sharing of IoT devices in harsh communication environments.

A dynamic source routing protocol based on path reliability and link monitoring repair.

The two most essential factors for mobile self-organizing networks applicable to drones are reliability and stability. In harsh communication environments, such as mountainous regions and natural disasters, the use of satellites and terrestrial communication stations has severe time delays due to the high speed of UAVs, resulting in frequent communication interruptions with UAVs. Therefore, UAVs need to establish self-organizing networks for communication and information sharing. High-speed movement will lead to rapid changes in the network topology, resulting in established links being in an unstable connection state and even frequent routing errors, thus preventing the establishment of stable communication links. In order to improve the communication quality of UAVs under high-speed movement, we propose a dynamic source routing protocol based on path reliability and monitoring repair mechanism (DSR-PM). The model performs data transmission by filtering the best reliability path. The link state information is monitored during transmission and broken links are repaired in time to ensure the communication stability and reliability of the links and improve the data transmission efficiency. We simulated the approach in NS2 software and the simulation results show that the DSR-PM protocol effectively reduces parameters such as overhead, packet loss and delay, improves network throughput, and provides better communication performance.

On the robustness of consensus-based behaviors for robot swarms

In swarm robotics, behaviors requiring consensus, meaning having the robots agree on a set of variables, have attracted great attention over the years. Determining the robustness and applicability of these behaviors in harsh communication environments is an open area of research. In this paper, we propose the use of a formal software engineering technique, statistical model checking, to model and assess the robustness of consensus-based behaviors from a communication standpoint. We validate our approach on two common scenarios for a robot swarm: the election of a leader and the allocation of a set of tasks. With the proposed model, we verify the functional correctness of these consensus-based algorithms, as well as assessing their robustness to communication loss and robot failures.

Signal Detection for Underwater IoT Devices With Long and Sparse Channels

Underwater acoustic communication often suffers from extended channel impulse response (CIR) and large Doppler spread such that signals become difficult to detect and decode. For the underwater Internet-of-Things (IoT) applications, the challenges are even bigger, because the IoT devices usually transmit very short messages due to severe power constraints, and the length of pilots are often shorter than that of CIR. Therefore, conventional pilot-assisted channel estimation and equalization approaches are incapable of detecting the information data. Moreover, the existing blind channel equalization algorithms, which do not require pilots, are not able to detect information data either, because the number of transmitted symbols is too small to approximate the expected loss with empirical loss, where the loss refers to as the error of estimated signal envelopes. In this article, a new equalization and decoding algorithm is proposed for the underwater IoT devices under harsh communication environments. Inspired by the recent blind deconvolution and compressive sensing techniques, we construct an optimization problem with the objective function rewarding sparsity of the estimated CIR using l4-norm and convexify the feasible set of the problem while guarantee the same solution. Then, we develop a pruned tree search initialization method and use gradient descent to find an optimal solution efficiently. The new algorithm is first verified by simulations, which show that the proposed algorithm outperforms conventional methods, such as the linear minimum mean square error (LMMSE) equalizer and a constant modulus algorithm (CMA). The proposed algorithm, along with a practical procedure for compensating large Doppler spread and carrier frequency offset, is further employed to process the real-world underwater IoT data collected in a fish-tag project. It shows that the proposed algorithm can equalize and detect the IoT data which were corrupted by channels whose lengths are longer than that of pilots, but the existing algorithms, such as LMMSE equalizer and CMA-based blind equalizer are not able to accomplish. It also shows that the proposed algorithm can provide a very impressive improvement compared to raw detection (no equalization or decoding) and decoding-only approaches.

The effect of region-based message selective delivery strategy on post-disaster emergency network

Stricken areas are shut off from the world, as large-scale infrastructures (e.g. bridges, roads and power equipments) have been destroyed after earthquakes, floods, and other disasters. Large-scale and cross-regional communication in the disaster area is difficult to achieve due to the harsh communication environment, such as unstable communication links and limited network resources, especially for remote isolated areas. Delay tolerant networks (DTNs) use the way of a “store-carry-forward” to transfer messages, which is suitable for the large transmission delay and intermittent link communication. In this paper, the DTNs based on regional center node and Unmanned Aerial Vehicle (UAV) is proposed to build the post-disaster emergency communication network. Further, a region-based message selective delivery routing policy is proposed for the emergency communication network. The received messages are classified according to its destination address at the regional center node and the UAV ferry node. In this way, the data packets can be accurately delivered to the corresponding area, and redundant data packets will be reduced in the network. The effect of the routing policy on network performance is evaluated. Simulation results show that the policy can effectively improve the data delivery rate, reduce the overhead ratio and significantly reduce the transmission delay.

Optimisation of delay tolerance in wireless sensor networks based on unscented Kalman filter estimation

Delay tolerance in wireless sensor network can be applied to complex and harsh communication environment. In order to improve the communication performance of delay tolerance in wireless sensor network, the optimisation of delay tolerance in wireless sensor network based on Unscented Kalman filter estimation is studied. Firstly, the model of delay tolerance in wireless sensor network is established according to the theory of dynamics and position constraints, and then an unscented Kalman filter estimation algorithm is used. Through analysing the basic state and measurement equation of delay tolerance in wireless sensor network model, the measurement equation of round-trip delay model is obtained. The pre handover time estimated by unscented Kalman filter is set, to effectively reduce the pre handover time and energy consumption, and optimise the delay wireless sensor network. The experimental results show that the delay tolerance of wireless sensor network optimised by the proposed method is within 30 ms under different observation noises, and the packet loss rate and energy consumption are low.

Flooding Message Mitigation of Wireless Content Centric Networking for Last-Mile Smart-Grid

In view of Smart-Grid architecture, wireless Last-Mile Network (LMN) devices as smart meters and intelligent home control machines are normally installed in harsh and lossy communication environment. In order to improve communication reliability of LMN, we proposed Wireless Topology Aware Content Centric Networking (TOP-CCN) protocol. TOP-CCN reduces channel access overhead of traditional Content Centric Networking and supports efficient multicast message transmission by using Multiple Point Relay (MPR), and Publisher MPR (PMPR). In addition, TOP-CCN LMN provides simple multi-hop forwarding scheme that can reduce the traditional routing control message overhead in multi-hop wireless LMN environment. The simulation result shows TOP-CCN can improve the service provisioning time and reliability compared to traditional IP based network model in LMN.

Compressed Sensing in Multi-Hop Large-Scale Wireless Sensor Networks Based on Routing Topology Tomography

Data acquisition from multi-hop large-scale outdoor wireless sensor network (WSN) deployments for environmental monitoring is full of challenges. This is because of the severe resource constraints on tiny battery-operated motes (e.g., bandwidth, memory, power, and computing capacity), the data acquisition volume from large-scale WSNs, and the highly dynamic wireless link conditions in outdoor harsh communication environments. We present a novel compressed sensing approach, which can recover the sensing data at the sink with high fidelity when a very few data packets need to be collected, leading to a significant reduction of the network transmissions and thus an extension of the WSN lifetime. Interplaying with the dynamic WSN routing topology, the proposed approach is both efficient and simple to implement on the resource-constrained motes without motes’ storing of any part of the random projection matrix, as opposed to other existing compressed sensing-based schemes. We further propose a systematic method via machine learning to find a suitable representation basis, for any given WSN deployment and data field, which is both sparse and incoherent with the random projection matrix in compressed sensing for data collection. We validate our approach and evaluate its performance using a real-world outdoor multi-hop WSN testbed deployment in situ . The results demonstrate that our approach significantly outperforms existing compressed sensing approaches by reducing data recovery errors by an order of magnitude for the entire WSN observation field while drastically reducing wireless communication costs at the same time.

VALIDATION OF PERFORMANCE ANALYSIS FOR OPTIMIZED VEHICULAR AD HOC NETWORK USING TAGUCHI METHOD

Vehicular Ad Hoc Network (VANET) is quite different from other ad hoc networks in term of functionality because of the variable node density, high node mobility, and unpredictable and harsh communication environment. There are two major application VANETs, namely safety applications and non-safety applications. Network optimization is one way to maintain the existing protocols and other network parameter rather than costly efforts for design and implementing new improved protocols. Motivated with the reasons to save effort of time and cost this paper presents the validation of optimized vehicular network for throughput, average delay and packet delivery ratio using Taguchi method. Highway scenario is chosen as the evaluation condition for this paper. From the performance evaluated the performance of optimized setting gives better results than non-optimized setting for both safety and non-safety applications. It is proved that Taguchi Method is applicable to optimize vehicular ad hoc network.

AeroMTP: A fountain code-based multipath transport protocol for airborne networks

Airborne networks (ANs) are special types of ad hoc networks that can be used to enhance situational awareness, flight coordination and flight efficiency in civil and military aviation. Compared to ground networks, ANs have some unique attributes including high node mobility, frequent topology changes, mechanical and aerodynamic constrains, strict safety requirements and harsh communication environment. Thus, the performance of conventional transmission control protocol (TCP) will be dramatically degraded in ANs. Aircraft commonly have two or more heterogeneous network interfaces which offer an opportunity to form multiple communication paths between any two nodes in ANs. To satisfy the communication requirements in ANs, we propose aeronautical multipath transport protocol (AeroMTP) for ANs, which effectively utilizes the available bandwidth and diversity provided by heterogeneous wireless paths. AeroMTP uses fountain codes as forward error correction (FEC) codes to recover from data loss and deploys a TCP-friendly rate-based congestion control mechanism for each path. Moreover, we design a packet allocation algorithm based on optimization to minimize the delivery time of blocks. The performance of AeroMTP is evaluated through OMNeT++ simulations under a variety of test scenarios. Simulations demonstrate that AeroMTP is of great potential to be applied to ANs.

Differentiated service strategies for ad-hoc wireless sensor networks in harsh communication environments

In some wireless sensor network applications, sensor nodes will be deployed in harsh communication environments. In such environments, the deployment may not be adequately controlled, and nodes may have to communicate with a single destination node. For nodes to alert the destination on critical data that has been sensed, in addition to the harsh communication environment, contention resulting from both the deployment and network density must be appropriately overcome. In this paper, we create theoretical models for the behavior of Timeout-MAC (T-MAC) protocol, and evaluate five possible solutions, each designed to be easy to implement on a device by simply tuning T-MAC parameters, so as to overcome these environment-specific issues and effectively alert the destination to critical data. Our results indicate that slight changes to the behavior of the network can improve the awareness of the destination to critical regions in the environment, and that these changes have different levels of effectiveness at different network densities.

On the reliability and performance of real-time one-hop broadcast MANETs

Recently, broadcast communications in mobile ad hoc networks (MANETs) have been deployed in many mission-critical applications. So far, most investigations of such broadcast networks focus on multi-hop connectivity taking all one-hop links for granted. In this paper, the reliability and performance of real-time one-hop broadcast services in IEEE 802.11 based MANETs are investigated analytically and by simulation. Having specified possible applications and the features of IEEE 802.11 broadcast communication in dynamically self-organized networks under harsh communication environment, analyses are conducted to derive closed form expressions of the reliability and performance indices for both one-dimensional (1-D) and two-dimensional (2-D) broadcast MANETs: packet reception rate (PRR) and packet transmission delay. The proposed analytical models account for the impact of broadcast hidden terminal problem, message arrival interval, backoff counter process, space distributions of nodes, and fading transmission channel on the reliability and performance of the broadcast MANETs. As an example, the proposed models are applied to the evaluation of safety-related inter-vehicle communication on a highway. From the obtained numerical results under various offered traffic and network parameters, new observations and effective enhancement suggestions are given.

A technique to exploit cooperation for packet retransmission in wireless ad hoc networks

In wireless data communication systems, retransmission of an erroneous packet is inevitable due to the harsh communication environment. In this paper, an efficient retransmission scheme using cooperation from neighboring nodes is investigated. In the cooperative retransmission scheme, an erroneous packet is transmitted to the destination by cooperative nodes which have favorable channels. This cooperative retransmission scheme requires no a priori information of neighboring nodes and has no limitation on the number of cooperating nodes. Distributed beamforming is used to accommodate multiple cooperating nodes. Phase and frequency offsets of cooperating signals are extracted from the NACK message and used to co-phase retransmitted data packets. The outage probability of the cooperative retransmission scheme is analyzed for the case of perfect synchronization and when the offsets are estimated. To reduce the impact of the residual phase and frequency offsets in cooperating signals, a low-rate feedback scheme is also investigated. It is shown that improved outage probability and reduced packet error rate (PER) performance can be achieved even for long data packets. The proposed cooperative retransmission scheme is found to outperform simple retransmission by the source as well as decode-and-forward cooperation.