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## Über dieses Buch

This two-volume set LNICST 280-281 constitutes the post-conference proceedings of the 10th EAI International Conference on Wireless and Satellite Services, WiSATS 2019, held in Harbin, China, in January 2019. The conference was formerly known as the International Conference on Personal Satellite Services (PSATS) mainly covering topics in the satellite domain.
The 137 full papers were carefully reviewed and selected from 289 submissions. The papers are organized in topical sections on machine learning for satellite-terrestrial networks, human-machine interactive sensing, monitoring, and communications, integrated space and onboard networks, intelligent signal processing, wireless communications and networks, vehicular communications and networks, intelligent 5G communication and digital image processing technology, security, reliability and resilience in internet of things, advances in communications and computing for internet of things.

## Inhaltsverzeichnis

### Alternative Extended Block Sparse Bayesian Learning for Cluster Structured Sparse Signal Recovery

Clustered sparse signals recovery with unknown cluster sizes and locations is considered in this paper. An improved alternative extended block sparse Bayesian learning algorithm (AEBSBL) is proposed. The new algorithm is motivated by the graphic models of the extended block sparse Bayesian learning algorithm (EBSBL). By deriving the graphic model of EBSBL, an equivalent cluster structured prior for sparse coefficients is obtained, which encourages dependencies among neighboring coefficients. With the sparse prior, other necessary probabilistic modelings are constructed and Expectation and Maximization (EM) is applied to infer all the unknowns. The alternative algorithm reduces the unknowns of EBSBL. Numerical simulations are conducted to demonstrate the effectiveness of the proposed method.

Lu Wang, Lifan Zhao, Guoan Bi, Xin Liu

### Design of GEO/LEO Double-Layered Satellite Network Based on Rateless Code for Global Information Distribution

This paper proposes a double-layered satellite network based on the rateless code, which can globally distribute the information with a few satellites. The satellite network is composed of Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites. The GEO satellites which cover the low and middle latitudes serve as the backbone network, whereas the LEO satellites are considered the enhanced network to make up for the shortage of the backbone network. Due to the interruption tolerance of the rateless code, only a few satellites are employed to achieve worldwide information distribution in the design of the satellite network. The coverage performance and the average elevation angle of the user are simulated, and results demonstrate that the network can achieve globally information distribution.

Chuang Wang, Dongming Bian, Xingchen Xu, Jian Cheng, Feilong Li

### A Modified Model-Based Resistance Estimation of Lithium-Ion Batteries Using Unscented Kalman Filter

Lithium-ion batteries are critical components for satellite, and it is necessary to monitor their state of health (SOH). At present, the most common Ah-count method in satellite has errors in long-term health monitoring. Therefore, in this work, resistance is adopted to describe SOH and a resistance estimation method is developed based on unscented Kalman filtering (UKF). To reduce the impact of unstable work condition and battery aging, a simplified electrochemistry model of lithium-ion batteries is built to replace equivalent circuit model (ECM) in UKF. In consideration of battery aging, a linear lithium ions loss model is used in this model. Then, the linear relationship between resistance and capacity is analyzed to demonstrate the ability for SOH description by resistance. Experimental data suggests that this model can effectively track the resistance in discharge process and yield satisfactory results with battery aging. Besides, this method is applicable to estimating battery SOH, as suggested by the linear relationship between estimation of resistance and actual measurements of capacity.

Jing-Long Chen, Ri-Xin Wang

### A Joint Technology of UAV SAR Based on OFDM Waveform

This paper presented a method based on compressed sensing that can be used for a joint technology of unpiloted aerial vehicles (UAV) radar detection and with the orthogonal frequency division multiplexing (OFDM) signal. OFDM is promising waveform in the next-generation future radar, it also brings the possibility of radar detection and wireless communication time-sharing processing under compatibility mode. An imaging method was performed by synthetic aperture radar imaging (SAR) with OFDM signals on the UAVs platform in this paper. Due to burden on data storage and transmission, an effective imaging algorithm is proposed to achieve high resolution with less collection data by UAV SAR based on compressive sensing focusing method. At the same time. The experimental data and simulation testified the proposed method.

Yun Zhang, Xin Qi, Lupeng Guo, Nan Qiao

### Multi-satellite Non-cooperative Communication Based on Transform Domain Communication System

Cognitive communication based on the unoccupied channels of transparent transponders in commercial satellites is a promising method to solve the shortage of satellite spectrum resource. However, most opportunity spectrum access systems cannot obtain real-time channel information from a commercial satellite. Although some systems can achieve non-cooperative communication, they usually utilize single satellite, which limits their overall performance. In this paper, to take full use of unoccupied satellite spectrum without disturbing primary users, a non-cooperative communication method by using satellites of different types is proposed based on transform domain communication system. Compared with existing methods, it is compatible with different transparent transponder parameters, such as frequency, bandwidth, primary user type, and delay. Besides, it also can achieve transmitting rate adaptation without signaling overhead.

Cheng Chang, Zhe Li, Guowei Yao, Yun Xia, Shuo Shi

### Intelligent Dynamic Timeout for Efficient Flow Table Management in Software Defined Satellite Network

Software Defined Network (SDN) modify the architecture of traditional satellite network into Software Defined Satellite Network (SDSN) by decoupling its control and data planes. However, SDSN encounter several issues, such as satellite link handover and limited space of Ternary Content Addressable Memory (TCAM), which results into increasing the number of flow rule entries and flow drop. To solve these issues this paper presents a novel three-layer architecture of SDSN and propose Intelligent Dynamic Timeout (IDT) algorithm. The algorithm predicts dynamic timeout for the eviction of unused flow entries in order to reduce the size of flow table, drop flow rate and number of table miss packets. Simulation results show that the average size of flow table, drop flow rate and number of table miss packets are reduced by 39.55%, 11.2% and 10.18% respectively when comparing the performance of IDT with different static idle timeout values.

Shahid Jan, Qing Guo, Min Jia, Muhammad Kamran Khan

### A Spectrum Prediction Technique Based on Convolutional Neural Networks

Secondary users in cognitive radio system use spectrum sensing technology to detect the primary users in the frequency band and use spectrum holes to communicate. Spectrum prediction technology is based on the existing spectrum sensing results to predict the future channel occupancy, so as to reduce the blocking rate, avoid malicious dynamic interference and other purposes. In this paper, a spectrum prediction method based on convolution neural network is proposed and some applications of this method in practical communication systems are given. This method can be trained in real time and has a certain adaptability to the dynamic environment. Using this method, the predicted results can be used to allocate resources reasonably, and the spectrum resource utilization rate is high. In addition, the time-consuming of broadband spectrum sensing can be shortened by combining the spectrum prediction method based on convolution neural network. At the end of this paper, the simulation results of spectrum prediction method based on convolution neural network are given and the efficiency of the algorithm is discussed.

Jintian Sun, Xiaofeng Liu, Guanghui Ren, Min Jia, Qing Guo

### TOA Estimation of Unknown Chirp Signal Based on Short Time FRFT and Hough Transform

This paper studies the time-of-arrival (TOA) estimation problem for unknown chirp signals. The signal envelope is assumed to be trapezoidal, and TOA is defined as the arrival time for envelope to rise to the half-platform value. The current state-of-the-art technique is based on short time fractional Fourier transform (STFRFT). It utilizes STFRFT to obtain the time-profile of time-frequency spectrum, and proves that the profile can be used to estimate TOA. However, this method uses only the peak of profile, which induces information losses and thus degrades the estimation accuracy. To alleviate this, in this paper, Hough Transform is combined with STFRFT to make better use of the time-frequency spectrum. On the other hand, the chirp rate of signal is conventionally assumed to be accurately detected by a previous FRFT step. But the accuracy is actually limited by the computational complexity of FRFT. Hence, a dechirp technique is also involved to make improvements on this aspect. Numerical results show that the dechirp technique brings advantages in detecting chirp rate; and combining Hough Transform with STFRFT is beneficial for TOA estimation.

MengZhu Liu, YiCheng Jiang, Yun Zhang, Min Jia

### A Deep Learning Method Based on Convolution Neural Network for Blind Demodulation of Mixed Signals with Different Modulation Types

In recent years, deep learning is becoming more and more popular. It has been widely used in image recognition, automatic speech recognition and natural language processing. In the field of communication, the signal is considered as time data, which can identify the intrinsic characteristics and information of the signal by the way of deep learning. In the aspect of cognitive radio, if the signal adopts different modulation methods in different time slots for adaptive modulation, it is difficult for the existing signal demodulation system to demodulate it effectively. Usually, it is necessary to identify the modulation mode of the signal first. In this context, the deep learning is introduced into signal demodulation. On the basis of analyzing the structure of convolutional neural network (CNN), an improved CNN structure is proposed, which does not need to recognize modulation methods and realizes blind demodulation of mixed signals with different signal-to-noise ratio (SNR). Through transfer learning and denoising auto-encoder, the network is further optimized to further reduce the bit error rate (BER).

Hongtao Zhu, Zhenyong Wang, Dezhi Li, Qing Guo, Zhenbang Wang

### Robust UAV Communications with Jamming

Unmanned aerial vehicle (UAV) communication has attracted increasing attention recently, benefiting from its high mobility. However, most existing studies concentrate on a perfect scenario, without considering the unintentional interference/intentional jamming and uncertain channel/location information. In addition, the UAV-to-UAV (U2U) communication scenario has not been widely investigated as the UAV-to-Ground case. To fill this gap, this paper investigates the robust U2U communications in the presence of jamming, where the U2U communication channel and jammer location are considered to be uncertain, i.e., only having partial information. For the non-convex optimization with the aim of minimizing the flight time, we propose a successive convex approximation method by introducing S-procedure and slack variables. The inner optimization is transformed into a semidefinite programming problem, which can be optimally solved by standard convex techniques. Simulation results validate the proposed path planning method in the presence of jamming.

Haichao Wang, Junnan Yao, Jin Chen, Guoru Ding, Ling Yu

### DQN Aided Edge Computing in Satellite-Terrestrial Network

In order to support a mass of current satellite applications, it becomes a trend to integrate satellite networks with terrestrial networks, called satellite-terrestrial networks. However, traditional network protocols cannot adapt to the dynamic and complex satellite-terrestrial network. Moreover, the computing and communication capabilities of some satellites cannot meet the requirements of supporting various applications. As a result, the paper proposes an edge computing based software-defined satellite-terrestrial network architecture, which can manage network flexibly by logically centralizing network intelligence and control. Furthermore, a networking and edge computing scheme is proposed by formulating a jointly optimization problem, which is solved by using novel deep Q-learning approach. Simulation results show the effectiveness of the proposed scheme.

Fangmin Xu, Fan Yang, Chao Qiu, Chenglin Zhao, Bin Li

### Adaptive Compressed Wideband Spectrum Sensing Based on Radio Environment Map Dedicated for Space Information Networks

Spectrum sensing is the basis of dynamic spectrum access and sharing for space information networks consisting of various satellite and terrestrial networks. The traditional spectrum sensing method, guided by the Nyquist-Shannon sampling theorem, might not be suitable for the emerging communication systems such as the fifth-generation mobile communications (5G) and space information networks utilizing spectrum from sub-6 GHz up to 100 GHz to offer ubiquitous broadband applications. In contrast, compressed spectrum sensing can not only relax the requirements on hardware and software, but also reduce the energy consumption and processing latency. As for the compressed measurement (low-speed sampling) process of the existing compressed spectrum sensing algorithms, the compression ratio is usually set to a fixed value, which limits their adaptability to the dynamically changing radio environment with different sparseness. In this paper, an adaptive compressed spectrum sensing algorithm based on radio environment map (REM) dedicated for space information networks is proposed to address this problem. Simulations show that the proposed algorithm has better adaptability to the varying environment than the existing compressed spectrum sensing algorithms.

Xiaoluan Zhang, Youping Zhao, Hongbin Chen

### An Adaptive Fingerprint Database Updating Scheme for Indoor Bluetooth Positioning

The accuracy of fingerprint based Bluetooth positioning technology depends on the fingerprint database established in offline phase. However, the change of environment and Access Point (AP) locations has significant impact on wireless signal distribution, resulting a decline in indoor Bluetooth positioning accuracy. In order to solve this problem, this paper presents a fingerprint database updating algorithm. Firstly, RSSI sequence, head, and speed information are extracted from crowdsourcing date. Secondly, the extracted information is used in Pedestrian Dead Reckoning Modification (PDRM) algorithm to get candidate fingerprint. Finally, we propose concepts of standard fingerprint, negative exponential time model, and similarity filtering to update original fingerprint database. The experimental results show that after the proposed fingerprint database updating, fingerprint database positioning accuracy is improved by 0.5 m.

Haifeng Cong, Liangbo Xie, Mu Zhou

### Backscatter Signal Blind Detection and Processing for UHF RFID Localization System

Radio frequency identification (RFID) is widely used in many fields and more recently, there has been a continuously growing interest in RFID-based indoor localization. Compared to RSS and AOA based RFID localization algorithms, the carrier phase-based ultra-wideband localization algorithm has better performance. To implement 3D indoor localization with this method, carrier phase of multiple receivers must be obtained in different frequencies. However, existing RFID systems do not meet the requirement. Therefore, this paper proposes a system consisting of a software-defined radio with custom-made RF front-end (SRCF) and ImpinjR420 COTS reader (R420), which can realize data communication between R420 and tags, and achieve the channel coefficient estimation. Moreover, an algorithm is proposed to detect the EPC data backscatter by the tag without any prior information. Experiment results show that the proposed algorithm can correctly decode the EPC data and obtain the channel coefficient information.

Liangbo Xie, Xin Xiong, Qingfei Kang, Zengshan Tian

### Centimeter-Level Localization Algorithm with RFID Passive Tags

Indoor localization technology of radio frequency identification (RFID) had gained much attention in recent years, but previous works usually need relative motion between a reader and a tag, or reference tags. Such operation brought about more complexities and difficulties for system deployment. This paper proposes an algorithm that enables centimeter accuracy on ranging and localization in line-of-sight (LOS) and non-line-of-sight (NLOS) environments without relative motion and reference tags. By exploiting physical properties to emulate a large virtual bandwidth on off-the-shelf passive RFID tags and combining with frequency hopping continuous wave (FHCW) algorithm, we can achieve centimeter-level ranging accuracy and perform centimeter-level 3D localization at x/y/z dimensions. In case of missing some channel information, we put a Non-uniform Discrete Fourier Transform (NDFT) to identify LOS path and obtain 1D ranging result with centimeter accuracy. For indoor multi-path environments, we propose an optimized multipath suppression algorithm to ensure centimeter-level accuracy on ranging and localization. Emulation results demonstrate that the algorithm can achieve 2 cm ranging accuracy within the distance of 7 m, and the accuracy probability is above 97%.

Liangbo Xie, Die Jiang, Xiaohui Fu, Qing Jiang

### Precise Direction Detector: Indoor Localization System Based on Commodity Wi-Fi

This paper aims to present a novel algorithm for indoor localization by employing the channel state information (CSI) which is collected by Wi-Fi chips that are on common Wi-Fi device to estimate the angle of arrival (AoA) of multipath components accurately. In a complex indoor environment, the proposed direct path identification algorithm can be used to identify the line of sight (LOS) and non-line of sight (NLOS) scenario with the averaged detection rates of 0.814 and 0.920, respectively. Finally, by using the widely-known least squares localization algorithm to locate the target. Extensive experimental results have demonstrated that our system can achieve the median localization error of 0.7 m and be robust to the environment variations.

Xiaolong Yang, Xin Yu, Jiacheng Wang, Qing Jiang, Mu Zhou

### A Novel AoA Estimation Algorithm Based on Phase Compensation of Linear Array

This paper presents a novel algorithm for angle of arrive (AoA) estimation by employing the phase of received signal. First, the phase of the received signal is compensated in all directions. Then, the AoA is estimated by evaluating the fluctuation of the compensated phases from sensors of the array. Meanwhile, since matrix decomposition is not required, the complexity is greatly reduced compared to the conventional methods. Our implementation and evaluation on commodity WiFi devices demonstrate that the proposed algorithm achieves better or comparable performance to SpotFi. In terms of estimation accuracy, the proposed algorithm can estimate the incident angle of the multi-path and the coherent signals effectively. In terms of complexity, since matrix decomposition is not required, the complexity is greatly reduced compared to the conventional methods.

Xiaolong Yang, Yuan She, Jiacheng Wang, Mu Zhou, Zengshan Tian

### Design and Implementation of a RF Transceiver Front-End for UHF RFID Localization System

Current RFID readers have a narrow operating bandwidth and not suitable for carrier-phase based RFID localization system requirements. To solve this problem, this paper designs a hardware circuit of the transceiver front-end of ultra-high frequency (UHF) radio frequency identification (RFID) system with wideband operating frequency range. The proposed front-end includes DDS module, transmission module and reception module. Benefiting from the fast switching frequency and wideband output frequency range of DDS, this system can achieve fast frequency hopping within a wide operating bandwidth, which satisfies the requirements of carrier-phase based localization. The results show that the whole hardware system can work correctly within the bandwidth of 700 MHz to 1 GHz, which can meet the design requirements of UHF RFID transceiver front-end.

WenJun Lv, LiangBo Xie, LingXia Li, Yi Chen, Bin Luo

### Rough Set Reduction Aided Cost-Efficient Indoor WLAN Localization

Due to the popularity of Wireless Local Area Networks (WLAN) applications, more and more access points (APs) are connected to the public network. Therefore, indoor localization technology based on public networks has a predominant development prospect. However, localization in the public network faces a lot of problems, and the excessive number of the APs in one of the most serious problems. Based on this, this paper proposes an indoor localization method based on rough set reduction. In this paper, the Received Signal Strength (RSS) signal strength from APs is used as the condition attribute of the rough set, and the optimal attribute reduction is obtained by the neighborhood rough set operation. After the rough set reduction operation, the number of APs in this paper’s data set has been reduced from 520 to 4 or 5, and the location fingerprint database has been greatly reduced. Finally, this paper applies the reduced fingerprint database for indoor localization and estimates the location of each test point.

Hui Yuan, Mu Zhou, Zhian Deng, Liangbo Xie, Yong Wang, Xiaolong Yang

### Device-Free Stationary Human Detection with WiFi in Through-the-Wall Scenarios

Human detection plays an important role in smart home and health monitoring. WiFi-based device-free detection schemes are widely proposed. The current WiFi-based device-free through-the-wall human detection system can detect moving human behind wall by the theory that RF signals would fluctuate remarkably when objects move within the area of interests, and remain stable in the case of no motion interference. However, stationary human detection is still an open issue, because it is hard to capture the fluctuate of signal caused by the weak movements (such as breathing, writing, etc.) of stationary human behind wall. In order to solve this problem, this paper proposes a novel system which extracts more delicate features for detection. The proposed system extracts features from time of fly (ToF) of signal, and then trains a neural network to classify these features to determine if a stationary human behind the wall. Our experiment shows that the detection accuracy of proposed system can reach 87.7% in typical office environment.

Zhengwu Yuan, Shiming Wu, Xiaolong Yang, Ailin He

### Through-the-Wall Human Behavior Recognition Algorithm with Commercial Wi-Fi Devices

Wi-Fi-based human behavior recognition technology is one of the research hotspots in the field of wireless sensing. However, the traditional Wi-Fi-based human behavior recognition algorithm does not consider the attenuation of Wi-Fi signals in the condition of wall barrier under complex indoor environments. As a result, the robustness of the Wi-Fi indoor human behavior recognition system is poor. In order to solve this problem, this paper proposes a Wi-Fi based behavior recognition algorithm through the wall. Firstly, the Wi-Fi signal distribution is analyzed according to the Wi-Fi signal model. Then, according to the distribution characteristics of different Wi-Fi signals, the principal component analysis (PCA) algorithm is used to reconstruct the signal to complete the de-nosing processing of the Wi-Fi signal. Finally, feature extraction and feature classification in the time-frequency domain is performed to complete the human behavior recognition. The experimental results show that the proposed algorithm has higher recognition accuracy in terms of walking and running than the traditional Wi-Fi based indoor recognition algorithms.

Zhenhua Yang, Xiaolong Yang, Mu Zhou, Shiming Wu

### A Pseudorange Difference Positioning Algorithm for Automatic Driving

Real-time and accurate positioning is very important for automatic driving. Traditional positioning methods, such as radar and inertial sensor, have limitations in universality and accuracy. Therefore, this paper proposes a pseudorange difference positioning algorithm, which combines Global Positioning System (GPS) receiver with reference station. The proposed algorithm achieves sub-meter positioning accuracy that providing a guarantee for automatic driving. The feasibility of the proposed algorithm is verified in static and dynamic environments, respectively. The results show that the positioning error is less than one meter.

Yi Chen, Yong Wang, Wei He, Qing Jiang, Mu Zhou

### Two Dimensional Parameters Based Hand Gesture Recognition Algorithm for FMCW Radar Systems

In recent years, hand gesture recognition has increasingly become important in the field of human-computer interaction. This paper proposes a two-dimension parameter based hand gesture recognition method using frequency modulated continuous wave (FMCW) radar. Specifically, we analyze the time domain of the radar signal and estimate the radial distance and angle parameters of hand gestures, and then construct the parameter dataset. The dataset is fed into an improved convolutional neural network to extract features. Finally, the extracted features are fused and then classified by the full connection layer. Experimental results show that the recognition accuracy of the proposed approach is significantly higher than that of the single-parameter ones.

Yong Wang, Zedong Zhao, Mu Zhou, Jinjun Wu

### WLAN Indoor Passive Intrusion Detection Method Based on SVDD

The existing passive intrusion detection technology has poor adaptability under different monitoring environments and low detection performance, this paper proposes a wireless local area network (WLAN) indoor passive intrusion detection method based on Support Vector Domain Description (SVDD). A-distance is adopted to evaluate multiple features to correctly distinguish the average contribution of the two states of silence and intrusion, screening the extreme difference and variance as the characteristic quantity of the signal change. Then, the paper introduces the single classification method SVDD to train the hypersphere anomaly detection boundary in the high dimensional feature space. We can achieve accurate anomaly detection by determining whether the current sample point is within the hypersphere. In a typical indoor environment, compared with the existing detection algorithms, the proposed method achieves better detection performance under low overhead conditions. F1-measure which is the system evaluation index increased by nearly 4%.

Yong Wang, Xiaoya Zhang, Luoying Gao, Mu Zhou, Lingxia Li

### The Gesture Detection Algorithm Based on 3-DCGAN Range Estimation in FMCW Radar System

Recently, hand gesture detection has gradually become a research hotspot. We propose a Region-based Faster Convolutional Neural Network (F-RCNN) gesture detection method based on Frequency Modulated Continuous Wave (FMCW) radar using 3-Dimensions Deep Convolutional Generative Adversarial Networks (3-DCGAN). Specifically, this paper adopts FMCW radar for hand gesture data acquisition, and estimates the distance of the hand gesture using the regularity of the change of echo frequency and emission frequency of radar signals. Then the semantic label maps of the generated images of distance are sent to the 3-DCGAN to extend datasets. After that, the original images and the images generated by the 3-DCGAN are simultaneously sent to F-RCNN for training. The results show that the proposed approach increases the mAP by 3% compared to the baseline F-RCNN. Besides, the proposed method not only effectively solves the problem of small amount of hand gesture data, but also the manpower and material resources consumed by collecting data.

Xiuqian Jia, Yong Wang, Mu Zhou, Zengshan Tian

### Optimization Methods of Motion Recognition System Based on CSI

Motion recognition system based on WiFi overcomes the limitations of the system based on vision and wearable sensor in the past, it’s the most ideal design for the implementation of this technology. On the basis of realizing the motion recognition system based on CSI amplitude, a joint optimization algorithm based on CSI amplitude and phase difference is proposed in this paper. Through linear transformation and continuation compensation of CSI phase, the problem that phase distribution error can’t be used is overcome. The amplitude of CSI value of received motion signal is obtained. It is combined with the phase difference of multiple antennas at the receiving end as the basis signal. In order to solve the problem of high complexity of the system, an optimization algorithm based on amplitude distribution variance is proposed. The experimental results show that the system can recognize three different motions with high accuracy, and after using the optimization algorithm, the average recognition accuracy of the system is increased by 4.7%, and the distinguishing rate between static and motion behavior is greatly improved, which has a certain universality.

Hongtao Zhu, Dezhi Li, Zhenyong Wang, Qing Guo, Zhenbang Wang

### WiFi CSI Fingerprinting Positioning Based on User Rotation

This paper studies the indoor fingerprinting positioning using Channel State Information (CSI) in commercial WiFi network environment. In this paper, we improve the existing indoor fingerprinting positioning method by considering the influence of human body absorption on CSI signal amplitude and collecting CSI data with user rotation at each reference location. The whole positioning process includes two stage: offline stage and online stage. In the offline stage, we extract features from the filtered CSI data of three APs at each reference location to construct CSI fingerprints. In the online stage, we first compare the feature vectors of filtered CSI data with fingerprints, and then calculate the Euclidean distance between the online CSI feature vector and fingerprints. Finally, user location will be obtained by the K Nearest Neighbor (KNN) algorithm. Experiments proved the performance improvement of the proposed CSI fingerprinting positioning method.

Jiahao Zhang, Ming Zhang, Zuoliang Yin, Zhian Deng, Weijian Si

### A Method of Automatic Code Generation for Spacecraft OBDH Software

The numerous interfaces of spacecraft OBDH software and frequent changes in requirements, resulting in the low efficiency and reliability of the manual coding of OBDH software. An automatic code generation method based on electronic data sheet (EDS) is proposed. The EDS system is introduced, and the output of the EDS system can be used to generate OBDH software code automatically, which improves the efficiency of software development. An structure of OBDH software is designed, which separates the logical code from the parameter code. Due to the EDS system data source is unique, and software code is automatically generated by tools, which avoids the mistakes of coding manually and promotes the reliability of OBDH software and even the reliability of spacecraft is improved.

Hongjun Zhang, Li Pan, Mengmeng Yu

### An Improved RTEMS Supporting Real-Time Detection of Stack Overflow

Aiming at the common problem of stack overflow in satellite software, this paper improves the RTEMS operating system which is supporting real-time stack use depth and overflow detection. Taking the on-board software based on TSC690F processor as an example, the accessible area and unaccessible area are set for each thread stack by using the memory access protection mechanism provided by the processor. The improved RTEMS shared the access protection mechanism among threads through context switching. A trap handler is designed to take over write protection error traps, calculate stack usage depth, and monitor stack overflow in real time. The core module performance test and stack detection instance verification show that the improved RTEMS has little effect on the software performance, so that the software can detect the stack depth online and real-time. By using this method, the software is still manageable in case of stack overflow, rather than runaway crash, and the reliability of the software is improved.

Rui Zhang, Yan Du, Tao Zhang, Qi Qiu, Liang Mao, Jiaxiang Niu

### MPTCP Based Load Balancing Mechanism in Software Defined Satellite Networks

The instability of satellite network links, unbalanced user distribution, and limited resources have caused severe network congestion and load imbalance. To address this problem, we propose a load balancing mechanism based on Multipath TCP (MPTCP) and apply it to software defined satellite networks (SDSN). This mechanism obtains the topology and the state of the whole network through the monitoring function of controller, and then selects k shortest paths from all available paths. It first divides the flow into several subflows according to the cost of different paths, and then establishes the MPTCP connection. To improve the efficiency of the network, we install OpenFlow rules to each switch. In the end, we conduct experiments in the Mininet simulation platform. The results show that the proposed mechanism can achieve load balancing of different links and improve the throughput while reducing delay.

Ziyi Ma, Xiaoqiang Di, Jinqing Li, Ligang Cong, Ping Li

### A Novel Dynamic Multi-source Multi-sink Flow Algorithm over the Satellite Networks

The multi-source multi-sink maximum flow problem can be of great significance in guiding network optimization, service scheduling, and capacity analysis. With intermittent connectivity and time-dependence characteristics of satellite networks, the existing flow algorithms for multi-source multi-sink without temporal dimension involvement can no longer maintain high efficiency in satellite networks. To overcome the problem, we propose a novel dynamic multi-source multi-sink flow algorithm. Specially, the storage time-aggregated graph (STAG) is adopted to depict the time-varying properties of satellite networks. Then, a novel dynamic multi-source multi-sink flow (DMMF) algorithm is proposed to enhance the satellite networks’ resource utilization. At last, the simulation is conducted, and the results with obvious network performance gain verifies our proposed DMMF algorithm.

Peng Wang, Hongyan Li, Tao Zhang, Shun Zhang, Keyi Shi

### Optimum Layout and Simulation of TT&C Antennas on Lunar Exploration Capsule

In the field of deep space exploration, to optimize the layout of TT&C antennas on space capsule, based on heat flux identification and TT&C condition analysis, we place the TT&C antennas shifted from the traditional position on vertical surface. So the TT&C antennas can avoid the high heat flux identification area due to the second cosmic velocity return of the space capsule. At the same time, known the orbit and the position of the ground station, we use STK to simulate the return phase to promise the TT&C antennas are used within their main lobe. The design method of TT&C antennas layout on deep space capsule is optimized, and is proved by the CE-5T project.

Xiaoguang Li, Baobi Xu

### Data Management Software System Design for Spacelab

The technology of propellant refueling is one of the important technologies of spacelab and cargo ship rendezvous and docking mission. With the data management software system, the function of two aircraft docking bus network is established, and the function of data transmission and control is realized. In the spacelab task, a data management software system for propellant refueling of cargo spaceship was proposed. Firstly, the software requirements and design principles are analyzed. Then, the layered software architecture is designed, and the rendezvous and docking task is expatiated. Finally, the realization of propellant refueling process in spacelab and cargo ship is illustrated. The research results can provide an important basis for the design of the data management system for the propellant refueling on space station.

Panpan Zhan, Lan Lu, Xiongwen He, Luyuan Wang, Yong Sun

Weisong Jia, Liang Qiao, Lijun Yang, Tao Zhang

### Design of Spaceborne AIS System

The AIS communication system is a global positioning aided navigation system, which can improve the safety of ship operation and the reliability of navigation. A spaceborne AIS system can dynamically monitoring ships in the global area. But It has many challenges such as message collision and signal transmission loss. This paper first designed a LEO AIS constellation, analyzed the coverage of this constellation, and then carried out the design of the on board AIS receiving system, including an array antenna and a receiver. Finally, the method of multi-user signal separation and detection was expounded.

Xiangyu Lin, Dong Yan, Yufei Huang, Fan Bai, Xiongwen He, Panpan Zhan

### An Energy Efficient Multicast Algorithm for Temporal Networks

Investigating the energy efficient multicast problem in space-ground integrated network (SGIN) is of vital importance for saving satellites transmission resources. However, the time-varying feature of network topology and resources poses great challenges to energy efficient multicast in SGIN. In this paper, we propose an approximation algorithm based on the modified time-expanded graph to minimize energy consumption while completing multicast transmission. At first, the SGIN is depicted by traditional time-expanded graph to capture the correlations between time-varying network resources. Then, to characterize the energy efficient multicast problem for temporal networks, we extend such graph to the Time Expanded Graph for Multicast (TEGM) by adding auxiliary aggregated destination vertices and aggregating edges. Finally, according to TEGM, an approximation algorithm for energy efficient multicast problem is proposed on the basis of the approach presented by Watel to solve the corresponding Directed Steiner Tree problem (DST). Besides, simulation results are conducted to illustrate the superiority of proposed algorithm over that based on dynamic trees.

Keyi Shi, Hongyan Li, Peng Wang, Tao Zhang

### The Application Design of SOIS Electronic Data Sheets in Onboard Integrated Electronic System

This paper analyzes the concept and research status of SEDS (SOIS Electronic Data Sheets) in the field of Spacecraft Onboard Interface Services (SOIS) of Consultative Committee for Space Data Systems (CCSDS). In order to achieve fast integration and testing of the onboard software, this paper discusses how to apply the SEDS standard in the onboard integrated electronic system of Chinese spacecraft. This paper shows the structure of the onboard integrated electronic system, the stratification of the structure, and the functions, services, protocols, and components of each layer. Based on the architecture of the system, the top-level application design of SEDS in the process of the development of onboard integrated electronic systems is presented, Taking the remote sensing and acquisition function of spacecraft as an example, the design and application examples of SEDS and the subsequent expansion methods of SEDS are given. The SEDS is used as input in the development and testing of spacecraft integrated electronic system software. The results show that the application of SEDS is helpful to realize the standardization of onboard interface and promote the spaceborne integrated electronic system and even the whole spacecraft research through automatic code generation and electronic data reuse. Shorten the system cycle.

Lijun Yang, Xiongwen He, Bohan Chen, Yan Du, Luming Li, Liang Mao

### Research on Wireless Networks for Intra-spacecraft

With the rapid development of onboard avionic technology, there are increasing requirements for internetworking, modularization and non-cable of spacecrafts. The onboard wireless networks technology provides one of the most important foundation to enable communication among intelligent nodes inside a spacecraft. This paper studies the application of wireless sensor networks for spacecraft. Wireless networks technology has significant advantages in reducing the weight of spacecraft, saving time in spacecraft integration. Based on wireless sensor networks, a scheme for spacecraft avionic system is put forward. The avionic system overall networks are a combination of wired and wireless networks. The block diagram and key interface design of the spacecraft overall networks are given. The design proposal of the wireless node and the data flow of the spacecraft are also analyzed. The results show that the application of wireless networks scheme is reasonable and feasible. The onboard wireless networks technology can meet the new requirements of the spacecraft in internetworking, modularization and non-cable.

Cuitao Zhang, Xiongwen He, Dong Zhou, Panpan Zhan, Zheng Qi, Yong Xu

### Design and Implementation of Multi-partition Paralleled Image Storage Hardware File System for MARS Rover

Mars rover mission carried many types of cameras, which need to complete complex science exploration and research task, it’s hard to meet the demands of image paralleled storage and access operations using the traditional Chang-E’s multiplex and storage scheme. Due to the speed and memory size limitation of on-board highly reliable radiation-hardened computer, the ground computer file system cannot be realized. This paper designed a FPGA based hardware paralleled image file system to meet the requirement of image data storage management in the Mars rover explore task. In addition the multi-type and multi-camera data file storage system of MARS rover is implemented in the actual rover’s computer which provided multi-partition paralleled reading and writing of multi-image files and on demand addressing and copying functions while ensuring high reliability.

Yong Xu, Cuilian Wang, Lei Zhao, Pangfeng Wu, Wenjuan Li

### Research for Data Communications Based on IPv6 in Integrated Space-Ground Network

The integrated space-ground network and its architecture are the focus and difficulty in research. Aiming at the problems of the incompatibility between satellite networks, satellite networks and ground networks, and the insufficiency of space network address resources, we propose an integrated space-ground network architecture based on the next generation Internet protocol IPv6. It combines the space communication protocols defined by CCSDS. The network layer protocol based on IPv6 is the foundation of the architecture. It ensures the interconnection and interoperability among inter-satellite networks and intra-satellite networks. The protocol of each layer in the architecture is designed. The IPv6 protocol, inter-satellite and intra-satellite transmission format, inter-satellite routing and intra-satellite communications are analyzed and designed. The experimental results show that the designed satellite router realizes the network communication and routing of IPv6 packets in intra-satellite and inter-satellite networks. It shields the differences between the satellite and ground network systems at the protocol level. It makes the satellite networks have good scalability and adaptability as with as the ground networks.

Panpan Zhan, Xiongwen He, ZhiGang Liu, Zheng Qi, Ming Gu, Cuitao Zhang, Dong Yan

### Integration Design of IPv6 and Time-Triggered Ethernet on Spacecraft

Internet protocol (IP) and time-triggered Ethernet (TTE) are two important emerging technologies for spacecraft information systems and networks. How the TCP/IP protocol stack, including the IPv6 protocol and the TTE be integrated into the integrated electronic system of spacecraft is introduced. In particular, it is studied that the implementation method of using IPv6 protocol on the time-triggered Ethernet. The problem that the embedded TTE network card does not have the built-in IPv6 protocol and cannot directly support IPv6 is solved. The integration and application of TTE and IPv6 are realized in the spacecraft integrated electronic software architecture. The experiments and tests can indicate its correctness and the effectiveness.

Ming Gu, Panpan Zhan, Xiongwen He, Dong Yan

### Study on Autonomous Mission Management Method for Remote Sensing Satellites

A remote sensing satellite is an earth observation satellite that acquires ground image information in space. It plays an important role in various areas such as resource surveying, environment monitoring and geological mapping. As the number of satellites increases, observation missions become more diverse and complicated as well as growing rapidly. Current implementations of remote sensing satellite observation missions still greatly depend on the ground operation control system. Multi-satellite and multi-function mission management, planning and uplink control also complicate the use of satellites by users. A key problem is how to improve the intelligence level and observation efficiency of on-orbit remote sensing satellites, while developing the overall efficiency of the satellite system for the convenience of users and also reducing the on-orbit operational cost. This article proposes an autonomous mission management strategy, which is based on the traditional mission management mode used by low-orbit remote sensing satellites. An implementation method for on-orbit mission rationality judgment, decoupling and instruction sequence generation is also established. This strategy aims to improve the intelligence level of remote sensing satellites and provide reference and guidance for future mission implementation of mission-oriented remote sensing satellites.

Lu Chao, Ren Fang

Xianfeng Liu, Lei Yang, Chengguang Fan, Shuai Wu, Jianming Guo, Quan Chen

### Target Evaluation of Remote Sensing Image Based on Scene Context Guidance

The correlation between scenes and targets in remote sensing images can provide useful and important information and guidance for satellite to achieve onboard targets evaluation in order to find valuable targets to image. The relationship between the target and the scene, as well as the spatial location association it contains, determines what the system should “focus on” and “what areas to focus on” in different scenarios. Referring to the guiding role of context information in the visual system, this paper studies how to identify potential targets through the scene context information, and a saliency model based on the task context information to achieve the target evaluation under different scenarios is proposed. At the end of the paper, a simulation experiment is given. It can be seen from the experiment that through scene context guidance, different parameters can be loaded in different scenarios to realize the evaluation and discrimination of different targets.

Wenjuan Li, Shunan Shang, Ling Tong

### Information Centric Networking for Future Deep Space Networks

With the flourish of the space sensing technology, various space information systems are playing an irreplaceable role in space exploration. Delay-Tolerant Networking (DTN) has been proposed to cope with the harsh transmission conditions and it provides a store-forward mechanism to push scientific data to Earth. However, in the future, Deep Space Networking (DSN) is bound to be more richer, while the volume of data transmission will rise considerably and communication services will also be diversified including both push-traffic and pull-traffic. In this way, we think DTN still needs to be improved while Content-Centric Networking (CCN) may be another candidate for these challenges. CCN [14] is a novel networking paradigm which has been used for terrestrial network and it provides both push-traffic and pull traffic for different scenes. Besides of it, cache mechanism can effectively reduce the influence arising from increase in data transmission. Therefore, we think CCN may be a better solution for future Deep Space Networking.

Yongqi Zhou, Wenfeng Li, Kanglian Zhao

### A Weighted Set Cover Model for Task Planning of Earth Observation Satellites

Due to the diversification of observation missions and the differentiation of satellite resources, the task scheduling of Earth observation satellites has always been an NP-hard problem. In this paper, aiming at multi-load Earth observation satellite mission scheduling, considering multi-satellite coordinated observation, facing regional target mission and point target mission, a weighted set cover model is proposed to represent the coupling relationship between multi-satellite and multi-task. The classical greedy approximation algorithm is used to optimize the sum of satellite observation time windows. The model-based algorithm can effectively save satellite storage resources and sensor resources, and realize multi-satellite coordinated observation task scheduling.

Pengyun Li, Hongyan Li, Jun Chang

### Information Flow Design and Verification for Networked Satellite Systems

For efficient information sharing and timely processing, networked satellite constellation with the feature of space and terrestrial network integration will be constructed. Information flow design and verification is necessary for networked satellites with complex information interfaces. This paper describes and analyzes information feature classification, information flow based network architecture design, and information flow functionality validation and performance evaluation for networked satellite systems. We also propose design strategy analysis of information transmission, processing and storage as reference and suggestion. Furthermore, an instance of information flow performance evaluation is introduced.

Jia Guo, Nuo Xu

### Design and Realization of Onboard Router Based on IPv6 and SPP with Software

For the purpose of Spacecraft Networking, considering the factor of the deployment of SPP within SOIS protocol system and the deployment of IPv6 in ground network with its development in the future, we present a set of scheme about design and realization, with software, of onboard router based on IPv6 and SPP. The design and realization of onboard router provides a new idea on constructing the Integrated Space-Ground Network, establishing the foundation of Spacecraft Networking in the future.

Zheng Qi, Xiongwen He, Panpan Zhan, Cuitao Zhang, Ming Gu, Dong Yan

### Adaptive Subcarrier-Bandwidth Multiple Access (ABMA) for High-Mobility Environments

In this paper, adaptive subcarrier-bandwidth multiple access (ABMA) is proposed as a novel downlink multi-user access scheme to support robust wireless communications in the high-mobility environments with different kinds of high-speed receivers. The proposed ABMA allows flexible spectrum resource allocation and subcarrier bandwidth adaptation according to mobile receivers’ velocities. Resource band is used as the unit for spectrum resource allocation. Well-localized bandpass filters are applied on each resource band, in order to control the multiple access interference and achieve coexistence of different subcarrier bandwidth. Universal receiver structure with low implementation complexity is described as part of the scheme. Theoretical and numerical results show that the ABMA scheme is effective in repelling the impact of high-range Doppler effects and performs high robustness in the high-mobility environments.

Jionghui Li, Xiongwen He, Xiaofeng Zhang, Fan Bai

### R/I-Capon for Low-Complexity Direction of Arrival Estimation with Real-Valued Computation

The problem of low-complexity direction-of-arrival (DOA) estimation without knowing sources number is addressed. Real/imaginary-part of array covariance matrix (ACM) can be remodeled as a whole ACM of signal received by virtual array aimed at fast DOA estimate. Based on such a virtual signal model, a novel real/imaginary-part Capon (R/I-Capon) involving the inverse of only the real/imaginary-part of the estimated ACM (EACM) is derived. In-depth insights are provided to prove that the rank of real/imaginary-part of EACM is always equal or greater than that of whole EACM, which indicates that R/I-Capon exceeds conventional Capon under the circumstance with small numbers of snapshots. Further discussion indicates that R/I-Capon is also capable of decreasing about $$75\%$$ complexity with any array structures, which shows an enforcement advantage over state-of-the-art prototype methods. Simulations are finally conducted to verify theoretical analysis and to show practicability of proposed algorithm.

Xiang Li, Feng-Gang Yan, Shuai Liu, Ming Jin

### Energy Efficiency Optimization Based SWIPT in Multiuser OFDM Systems

The research on wireless communication has been mainly focused on improving the system rate. However, while achieving the higher rate, it also consumes a lot of power, which leads to a reduction in energy efficiency. Therefore, in this paper, we propose a new algorithm to maximize energy efficiency in multiuser OFDM systems. More specifically, users can transfer information and collect energy simultaneously by using SWIPT technology, and the energy efficiency is maximized by optimizing the subcarrier allocation under some constraints. We formulate the proposed algorithm at first, and the initial optimization problem is non-convex, so we cannot get the optimal resource allocation directly. Later, by transforming the original objective function, the optimal solution is obtained. Finally, we validate the proposed algorithm with simulation results. The results show that the proposed algorithm can indeed improve energy efficiency. We also find that some variables have a huge impact on system energy efficiency.

Shanzhen Fang, Weidang Lu, Yu Zhang, Bo Li, Xin Liu, Zhenyu Na

### Parameter Estimation of Multiple Satellite Signals Based on Cyclic Spectrum

The cyclic spectral density function is a linear transformation that satisfies the principle of linear superposition. Based on this property, a new method for parameter estimation of multiple satellite signals is proposed. Firstly, the linear superposition characteristics of the cyclic spectrum are introduced. On the basis of this, the spectral characteristics of the mixed satellite signals are analyzed. According to the corresponding relationship between the cyclic spectrum line of multi-signals and the signal parameters. Finally, the parameter estimation of mixed signals is achieved indirectly through the method of detecting the line in specific cyclic frequency section of cyclic spectrum. The simulation results show that the new method has good performance under Gaussian noise.

Yu Du, Jingjing Zheng, Xiaoshuang Jiao

### Repairable Fountain Codes with Unequal Locality for Heterogeneous D2D Data Storage Networks

In this paper, we consider a problem about a novel distributed erasure code, named repairable fountain code (RFC), used in heterogeneous networks (HetNets) including different micro base station (MBS) coverage areas, for data storage and delivery among the devices connected by D2D links. The system model of three-tier MBS distributed data storage network is presented and the basic principle is also detailed illustrated. Then, the downloading and repairing communication costs of RFC are analyzed based on its rateless, systematic and lower locality properties. Particularly, the unequal repair locality of RFC (URL-RFC) is designed and discussed for the adaption to the different mobilities with the Poisson process of the nodes in three MBS coverages, and to further reduce the energy cost. The simulation results show that, the URL-RFC scheme we proposed can obtain the lowest cost performance in the case of instantaneous repair, and the cost of URL-RFC is larger than that of RFC when the repair interval is also larger, but it will finally approach to the RFC communication cost curve.

Yue Li, Shushi Gu, Ye Wang, Wei Xiang, Qinyu Zhang

### Long-Term Object Tracking Method Based on Dimensionality Reduction

Long-term object tracking is challenging as target objects often undergo drastic appearance changes over time. Recently, the FDSST algorithm has performed very well which reduces number of the FFT by dimensionality reduction and operates at real-time. But in case of long-term tracking the performance of FDSST degrades, and the existing long-term tracking methods cannot guarantee the accuracy and real-time performance simultaneously. To solve the above problems, we input a set of sample patches of the target appearance to a multi-channel correlation filter to locate the position of the target in a new frame. At the same time, the number of FFTs is reduced by dimensionality reduction, and an online SVM is trained as the detector to ensure the accuracy of target tracking. Finally, we get a method to track long-term object accurately and in real time. To evaluate the method, we did extensive experiments on a benchmark with 100 sequences. The results show that the proposed method performs well both in accuracy and real-time performance and outperforms than the state-of-the-art methods.

Dongfang Zhao, Wenjing Kang, Gongliang Liu

### Test Scheduling of Interposer-Based 2.5-D ICs Using Enhanced Differential Evolution Algorithm

Interposer-based 2.5-dimensional integrated circuits (2.5D ICs) are seen as an alternative choice and they are rising as a precursor toward 3D integration. However, as the number of dies embedded in the interposer increases, the efficient test of 2.5D ICs becomes more difficult. In the design of test wrapper and test scheduling, both the test-time and the hardware cost have to be take into account. This paper presents an innovative differential evolution algorithm with dynamic subpopulations and adaptive searching strategy for the optimization of 2.5D IC test scheduling and hardware cost control. The whole population are partitioned into subpopulations dynamically using affinity propagation based clustering algorithm. In the subpopulations, a new mutation scheme which is controlled automatically by fitness values and distances between individuals is also presented. Parallelism among subpopulations and the proposed adaptive mutation and rotation crossover strategy can increase the speed of evolution without losing population diversity. Test wrapper scan chain balance design and the test scheduling algorithm, which combine the DE variant algorithm show an excellent performance in optimization ability comparing with the integer linear programming formulation (ILP) and some other configurations. It can make a good balance between the hardware cost and the test-time cost.

Deng Libao, Sun Ning, Fu Ning

### A ICP-Improved Point Cloud Maps Fusion Algorithm with Multi-UAV Collaboration

Using depth sensor devices to obtain 3D reconstruction maps is widely used in robotics and UAVs technology. For instance, large-scale environments reconstruction usually requires multiple or multiple angles to construct local point cloud maps, and then use 3D point cloud fusion technology to obtain global maps. In this paper, we present a complete point cloud fusion system for 3D map reconstruction of indoor environment based on traditional method, including initial fusion and precise fusion. Furthermore, we adopt the method of kd-tree search to match the points in the cloud of two point clouds, and eliminate the wrong matching or the matching point pairs with large error to improve the fusion efficiency. Our experiments show that, the convergence speed of the iterative process is improved, and the time complexity of the whole fusion algorithm is reduced while the final fusion effect achieves the required accuracy.

Hao Li, Xiaohan Qi, Zhihua Yang

### Capacity Analysis of Panoramic Multi-beam Satellite Telemetry and Command System

Compared with the Tracking beam satellite Telemetry and Command system, the Panoramic Multi-beam satellite Telemetry and Command system has the advantages that the spacecrafts can be measured and controlled when they enter the coverage area and the system capacity is large. It uses Code-Division Multiple Access (CDMA) to distinguish users. Since the spreading codes are not completely orthogonal, the received signals will introduce Multiple Access Interference (MAI) and affect the system performance. Based on the panoramic multi-beam satellite telemetry and command system, this paper deduces the formula of ranging error in the presence of MAI, and analyzes the system capacity considering the two cases of perfect power control and imperfect power control. The theoretical and simulation results show that the system can support over 500 space-crafts at the same time, but the system performance deteriorates by 1.6 dB when the power control error occurs.

Yilun Liu, Lidong Zhu

### Markov Decision Based Optimization on Bundle Size for Halo Orbit-Relay Earth-Lunar DTNs

Earth-Lunar communications are important for lunar exploration. Among them, Halo orbit relay satellite communications networks are extremely valuable. However, due to the highly dynamic and long-distance transmission characteristics, Halo Orbit-relay Earth-Lunar Disruption-Tolerant Networks (DTNs) have to endure severe latency. In order to deal with this problem, we propose a new solution that overcomes the impact of transmission characteristics by adjusting bundle size, thereby effectively reducing the latency of the Earth-Lunar relay communication networks. Considering the transmission characteristics and the deep space environment, we derive the delay formula of the Halo Orbit-relay Earth-Lunar DTNs and establish the distance model. In particular, in order to solve this model, we propose a Markov decision method. Finally, the simulation results verify the effectiveness of the Markov decision method.

Yunlai Xu, Ye Wang, Zhihua Yang, Shushi Gu, Yue Li, Peng Yuan

### A Link-Prediction Based Multi-CDSs Scheduling Mechanism for FANET Topology Maintenance

In Flying Ad hoc Network (FANET), maintenance of topology is a quite difficult task due to rapid change of connectivity between flight nodes, i.e. unmanned aerial vehicles (UAVs). Aiming to this issue, in this article, we proposed a link prediction-based multiple Connected Dominating Sets (CDSs) scheduling mechanism for stable maintenance of FANET’s topology. In particular, a group of candidate CDSs are periodically scheduled for developing a stable backbone subnet of the topology. The proposed mechanism could achieve an early detection of topological changes by employing a Markov chain predicting model on the node’s mobility. The simulation results show that the proposed algorithm has a better success rate and less update overheads than the single CDS maintenance method, especially in a typical swarm pattern of UAV team.

Xiaohan Qi, Xinyi Gu, Qinyu Zhang, Zhihua Yang

### The Functional Design of a Multi-protocol Satellite Router

With the rapid development of Space Information Network and users’ demand for communication services, interconnecting heterogeneous space networks becomes a new trend of SIN development. Networks using different protocols, such as TCP/IP, CCSDS and DTN, cannot communicate directly. In order to interconnect heterogeneous networks and face the problems brought by the challenged environment, this paper designs a multi-protocol onboard router which depends on the “store-and-forward” mechanism in DTN network protocol, as a relay with the ability of multi-protocol switching in order to support communication services among heterogeneous networks.

Yushan Wu, Qing Guo, Mingchuan Yang

### Wavelength Routing Assignment of Different Topological Optical Networks Based on Typical LEO Satellite Constellations

Inter-satellite laser communication can fulfill the requirements of huge-capacity transmission of satellite communication. The space-wide all-optical network is a key way to solve problems such as low-latency, huge-capacity transmission and low-cost on-orbit real-time route switching processing through technologies of Wavelength Division Multiplexing (WDM) inter-satellite links (ISLs) and wavelength routing. Then routing and wavelength assignment (RWA) become its core and main technology. Aiming at the RWA issue, this paper takes the typical LEO satellite constellations Iridium and NeLS as examples, establishes a regular ISLs topology, and proposes a simulation model based on the minimum cost routing strategy and wavelength demand. The results of simulations demonstrate that, compared with the link arbitrary topology, the NeLS constellation with regular network topology can save nearly half of the wavelength resource requirement under the condition of slightly sacrificing node connectivity, and the Iridium constellation has the better connectivity with the same wavelength resource demand. Both NeLS and Iridium constellations show a more stable trend in the link duration, wavelength volatility, and node connectivity volatility.

Xue Sun, Suzhi Cao

### DOA Estimation Based on Bayesian Compressive Sensing

In this paper, Bayesian Compressive Sensing algorithm is studied. To deal with signals with multiple snapshots, we extend traditional Bayesian algorithm under the condition of single snapshot to multi-snapshot Bayesian Compressed Sensing (MBCS) algorithm and apply MBCS algorithm to direction of arrival (DOA) estimation of narrowband signals and wideband signals. Simulation shows that the application of BCS to DOA has certain advantages in algorithm performance.

Suhang Li, Yongkui Ma, Yulong Gao, Jingxin Li

### A New Algorithm (ESA-DE) for Designing FIR Digital Filters

This paper proposes a new algorithm called (ESA-DE) for software-designed realization of finite impulse response (FIR) filters. The determination of the optimal order of the filter is always a confusing problem. In this paper, we will confirm the optimal order of the filter. Differential evolution has obtained widely concern as one of the most promising intelligent optimization algorithms in the field of artificial intelligence. The new algorithm (ESA-DE) uses a new mechanism called elite guide with weight and two new self-adaptive parameter distribution techniques to enhance algorithm’s diversity and convergence. Experiments prove that the new algorithm is at least superior to the basic DE and its variants jDE and ODE. The proposed algorithm is applied to solve practical problem that it is to design FIR digital filters, which overcomes the shortcomings of the traditional designing method. In addition, the practical problem about design for digital filter demonstrates that the ESA-DE has a better performance compared with the other three algorithms.

LiBao Deng, Haili Sun, Lili Zhang

### Collaborative Visual SLAM Framework for a Multi-UAVs System Based on Mutually Loop Closing

In a typical visual Simultaneous Localization and Mapping (SLAM) algorithm integrated within a single unmanned aerial vehicle (UAV), the positioning drift will increase cumulatively due to the motion and dynamic of UAV platform, which could be efficiently alleviated by the introduction of loop detection. However, a large number of loop movements by a single UAV will result in too many turns of the drone with significant reduction of coverage area per unit time. Therefore, in this paper, we propose a collaborative framework of visual SLAM algorithm with a multiple UAVs system. In the proposed framework, a series of mutually closed loop will be detected and executed by multiple UAVs within the position map. By this coordination method, the position accuracy of the system could be obviously improved, through the experimental results compared with a single UAV SLAM system.

Haifeng Yu, Hao Li, Zhihua Yang

### Feature Extraction and Identification of Pipeline Intrusion Based on Phase-Sensitive Optical Time Domain Reflectometer

Since fiber distributed vibration sensing (DVS) system based on phase-sensitive optical time domain reflectometer (Φ-OTDR) has the characteristics of identifying intrusion signals, wide monitoring range and high system sensitivity, correct identification of intrusion types by the system is an important issue to promote the engineering of this technology. In this paper, based on the intrusion signal of Φ-OTDR system, a multi-dimensional feature extraction and selection method is proposed. The polynomial least squares method is used to remove the trend term from the vibration signal, and the wavelet threshold denoising method is used to reduce the noise interference. The short-time analysis in the time domain and the wavelet analysis in the wavelet domain are combined to extract the multi-dimensional characteristics of the signal. The feature selection is based on the QUICKREDUCT algorithm. The experimental results show that the feature vector obtained by this method is relatively complete, and it is less affected by the environment, and the recognition rate is higher, reaching over 92%.

Zhanfeng Zhao, Duo Liu, Longwei Wang, Shujun Liu

### Detection of Print Head Defect Based on Image Processing Technology

In the detection of dead pixels in the print head, this paper innovatively proposes a dead pixel detection algorithm based on image processing technology for the low efficiency of manual detection and high labor cost. Firstly, the ROI is extracted based on the maximum connected region. Secondly, the binarized image is preprocessed by morphological processing, and then the texture is extracted based on the periodic structural features of the image. The specific steps of texture extraction are as follows: Firstly, this paper locates the largest connected area and gains the row and column of the connected area according to the polynomial fit. Secondly, according to the up and down translation, a column of texture regions is obtained, and then other texture regions are obtained according to the left and right translation. In addition, the Canny operator is used to detect the edge of the image, getting an image with texture edges and dead pixels. Perform a close operation on the image to remove dead pixels, and then subtracted from the original image, the dead pixels in the print head can be detected. The experimental results show that the algorithm not only can accurately detect the dead pixels in the print head image, but also has low complexity and short processing time, which is good for engineering practicability.

Zhanfeng Zhao, Duo Liu, Longwei Wang

### Half-Duplex Two-Way AF Relaying Network with Energy Harvesting

In this paper, we consider a three-node, half-duplex two-way relaying wireless network where an amplify-and-forward relay harvests energy from radio frequency wave transmitted by the two source nodes. Different from time switching (TS) and power splitting (PS), we group subcarriers to realize the information decoding (ID) and energy harvesting (EH) separately. This two-way relaying transmission is consisted of two phases, which is more efficiency and complicated than one-way relaying. System is orthogonal frequency division multiplexing modulated, and subcarrier grouping scheme is the same for the two source nodes. Subcarrier power of source nodes is average allocated, while that of relay is optimized. In this amplify-and-forward relaying network, subcarrier pairing is also under consideration. With the aim of sum rate maximized, we purpose a joint subcarrier grouping, relay subcarrier pairing and power allocation scheme. We use dual decomposition method to solve this problem, after transforming it into an equivalent convex optimization problem. Simulation results also show the impact of the relay location on subcarrier grouping and on sum rate.

Weilin Zhao, Weidang Lu, Yu Zhang, Bo Li, Xin Liu, Zhenyu Na

### Optimized Power Allocation for Weighted Complementary Coded-CDMA Systems

Complementary codes (CCs) have opened up a whole new frontier in Code Division Multiple Access (CDMA) techniques due to the ideal correlation properties. However, the equal gain combination must be satisfied in such CDMA system, which constrains the system performance over frequency selective fading channels. This paper aims to propose a set of weighted complementary codes (WCCs) to enable variable combination parameters while maintaining ideal correlation properties. Such new WCCs can provide power allocation with more freedom, and more importantly, an optimized power allocation can improve the bit error probability performance of CDMA systems as proved at the end of this paper.

Zaiyang Jiang, Siyue Sun, Guang Liang, Huawang Li

### Low Complexity Sensing Algorithm of Periodic Impulsive Interference

In this paper, a low complexity sensing algorithm based on power spectrum density (PSD) for periodic impulsive interference is proposed. First, the PSD is computed by modified periodogram. Then the time occupancy of spectrum by interference and time interval of interference is computed in multiple detections to determine the presence of impulsive interference. Finally, main parameters of impulsive interference, such as period, duty cycle, bandwidth, and the peak power, are estimated. The computation afford of the proposed algorithm is quite low. The simulation results show that the sensing performance can satisfy the requirement of spectrum sensing.

Yingtao Niu, Yutao Wang, Cheng Li

### Blind Source Separation for Satellite Communication Anti-jamming

In this paper, the feasibility of applying blind source separation (BSS) to satellite communication (SatCom) anti-jamming is studied. And an EASI-based BSS method is introduced for anti-jamming processing for SatCom system. This method achieves the elimination of jamming signal by separation. Meanwhile, the anti-jamming ability of this method is completely dissected herein. Experimental simulations are conducted to demonstrate the availability of the EASI-based anti-jamming processing method. Simulation results show that the EASI-based method can effectively separate the jamming signal. And, after EASI-based anti-jamming processing, the signal-to-jamming-plus-noise ratio nearly approximates the signal-to-noise ratio and the available transmission rate of SatCom system approaches the theory rate.

Hua Yang, Hang Zhang, Jiang Zhang, Liu Yang, Pengfei Wang

### Low Complexity Decoding Scheme for LDPC Codes Based on Belief Propagation Algorithm

The low-density parity check codes (LDPC codes) are block codes whose performances are close to the Shannon limit. LDPC codes have the strong ability for error correction. The decoding algorithm of LDPC codes has a great influence on their performances. The belief propagation (BP) algorithm is a commonly used soft decision decoding algorithm. The algorithm decodes by information iterations, and its complexity does not increase rapidly with the increase of code length. This paper mainly analyze the probabilistic domain BP decoding algorithm, log-domain BP decoding algorithm and minimum sum decoding algorithm, the bit error performance of LDPC codes under BP algorithm is studied, and the influence of the number of iterations on the BP decoding algorithm is also shown by simulation results.

Wenshuo Zhang, Liming Zheng, Yue Wu, Gang Wang, Aijun Liu

### Joint Uplink and Downlink Optimization for Wireless Powered NOMA OFDM Communication Systems

In this paper, an Orthogonal Frequency Division Multiplexing (OFDM) wireless communication system is investigated. For downlink, users perform Information Decoding (ID) and Energy Harvesting (EH) simultaneously. For uplink, users transmit information to Base Station (BS), while BS performs the Non-Orthogonal Multiple Access (NOMA) to decode information from users. In order to maximize the total uplink ID rate in the condition that the total downlink ID rate is ensured, a joint uplink and downlink optimization method based on power and subcarrier allocation is proposed. As shown in simulation results, compared with the existing method, the proposed method can implement the maximum harvested energy for users in the downlink and achieve higher total uplink ID rate.

Mengshu Zhang, Zhenyu Na, Mei Yang, Weidang Lu, Xin Liu

### Research on Detection Algorithm of DSSS Signals Under Alpha Stable Distribution Noise

The detection algorithm of direct sequence spread spectrum (DSSS) signals based on power spectrum reprocessing will significantly degrade in Alpha stable distribution noise environment, in order to solve this problem, the concept of generalized power spectrum reprocessing was proposed. On the basis of studying the generalized power spectrum reprocessing feature of the DSSS signals, the pulse spectrum was extracted as the detection feature to achieve effective detection. Simulation results show that the performance of this method have good performance both in the Alpha stable distribution noise.

Weichao Yang, Yu Du

### Radar Detection Based on Pilot Signals of LTE Base Stations

This paper presented a new signal design method for target detection. As the development of communication equipment, wireless communication has gradually developed to high frequency band and large bandwidth, which makes communication and radar systems gradually have common characteristics in frequency occupancy, system architecture and antenna composition technology. In the context of the LTE base station signal, the pilot signal is inserted into the frame format of the OFDM signal to enhance the target detection performance of the base station. The signal is affected by Doppler shift and the velocity resolution is degraded. This paper presents a new method to improve the speed resolution of the target. Simulation and experiment proved the method has good effect.

Yun Zhang, Jinze Li, Yang Li, Nan Qiao

### Design and Implementation of Stereo Vision System Based on FPGA

By comparing the different methods of vehicle ranging, the stereo vision system is selected for obstacle imaging and ranging. In response to low data transmission rate and low real-time performance and low resolution of the traditional ranging system design method, the stereo vision system is designed with integrated multi-core ARM and FPGA SOC. The system adopts image acquisition, distortion correction, target detection and tracking the image of the obstacle in front of the vehicle to compute the obstacle distance information. The delay and the power consumption of the system is measured by experiments, and it indicates that the system is suitable for vehicle-assisted driving and other image processing technologies field.

Qian Wang, Xin Gu, Hua Wang, Guowei Yao

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