Zhihua Yang

Bio: Zhihua Yang is an academic researcher from Harbin Institute of Technology. The author has contributed to research in topics: Interplanetary Internet & Bundle. The author has an hindex of 4, co-authored 5 publications receiving 69 citations. Previous affiliations of Zhihua Yang include Harbin Institute of Technology Shenzhen Graduate School.

Analytical characterization of licklider transmission protocol (LTP) in cislunar communications

Abstract: The performance of delay/disruption tolerant networking (DTN) protocols in cislunar and deep-space communication systems has previously been studied by simulation. However, little work has been seen in characterizing in an analytical manner the performance of DTN protocols for space with respect to asymmetric channel rates. We present a performance characterization of the recently developed DTN Licklider transmission protocol (LTP) convergence layer adapter (CLA) (or simply LTPCL) over cislunar space channels with data-rate asymmetry. Analytical models are built to characterize LTPCL with respect to the minimum number of bundle protocol (BP) bundles that should be aggregated to avoid delay in acknowledgment (ACK) transmission and the optimal number of bundles to be aggregated for the best transmission efficiency of BP/LTPCL, with the effect of full overhead at all layers taken into consideration. The models are validated by file transfer experiments running BP/LTPCL protocols using a PC-based testbed.

Memory dynamics for DTN protocol in deep-space communications

Abstract: Considering the signifcant success of the terrestrial Internet, the National Aeronautics and Space Administration (NASA) and other space agencies have been working for a few decades to enable space communications using the Internet-type protocols such as transmission control protocol/ Internet protocol (TCP/IP), namely, space internetworking or simply space Internet. It is well known that long propagation delays, intermittent connectivity, heavy channel noise, and asymmetric link rates in space environments all conspire to limit the effectiveness and performance of TCP over space communication channels, especially in deep-space communications [1]. The space Internet in deep-space interplanetary environments is generally named interplanetary Internet (IPN) [2]. Numerous literature surveys [2]?[7] have been done on IPN architectures and protocols.

CFDP-based two-hop relaying protocol over weather-dependent Ka-band space channel

Abstract: In this paper, we propose a novel relaying protocol based on the Consultative Committee for Space Data Systems File Delivery Protocol (CFDP) over a weather-dependent Ka-band channel, which exploits a dual-hop link instead of the traditional single-hop link for a 100% file delivery service on scientific data return.We designed the specific model of the proposed protocol and provide the analytical results on the expected latency and link efficiency of the file delivery. Based on the proposed model, we discuss the exact location of the relay node that could minimize the expected file delivery delay by examining several practical relay locations for the proposed protocol. The simulation results show that, compared with the traditional CFDP, the proposed file delivery protocol could effectively reduce the total file delivery time by several orders of astronomical units and enhance link efficiency with noticeable increments, especially under conditions of high bit error rates (above 10−5).

On storage dynamics of space delay/disruption tolerant network node

Abstract: Delay/disruption tolerant network (DTN) plays a promising role in prospected information infrastructures for future space activities, such as Interplanetary Internet (IPN) or Solar System Internet (SSI). Over such long-haul and intermittent links, DTN technique makes scientific data return end-to-end reliable by the typical custody transfer and store-and-forward mechanism. Due to lack of enough space spacecrafts deployed for DTN, now and in the near decades, there will be some intermediary nodes which would carry a large proportion of network traffic as DTN routers. Consequently, the behaviors and capabilities of managing bundles in the intermediary nodes would have impacts on the data transport over space DTN. Focusing on the storage dynamics of bundles, in this paper, we propose an analytical framework based on two-dimension Markov chain to evaluate the behaviors of bundles delivery in DTN intermediate nodes. Accordingly, a delay model and a transmission success probability model for bundles delivery over space DTN are developed separately, both dependent closely on the sojourn time in node storages. The evaluation results indicate that: (1) Dividing the source files into bigger bundles for transmission causes a longer storage-occupancy time on intermediary nodes; (2) bundle sizes have more explicit impacts on the storage-occupancy time at a node than segment sizes do; and (3) the transmission success probability of a bundle is more dependent on a DTN bundle size than on a LTP segment size.

A Study of Link Disruption on BP From Spatial and Temporal Perspectives in Deep-Space Vehicle Communications

Abstract: Developed as the main protocol of delay/disruption-tolerant networking (DTN) for space, bundle protocol (BP) is intended to establish an overlay network for reliable data delivery in a heterogeneous networking environment. The effect of a link disruption on reliable data transmission of BP is currently under study. In this paper, a study of the effect of link disruption on BP's reliable data delivery in deep-space vehicle communications, from spatial and temporal perspectives, is presented employing both analytical and experimental methods. The effect is modeled in various transmission cases by considering the physical distance the bundle has traversed when the link disruption starts and ends, the duration of link disruption in time, and the physical span of the link disruption. The models are built to quantify the number of transmission attempts that fail due to link disruption, the total number of transmission attempts, bundle delivery time, and transmission goodput performance for successful bundle delivery in presence of a link disruption. The models are validated by realistic bundle delivery over a PC-based experimental testbed. The validation indicates that the analytical models predict the transmission performance of BP in presence of random link disruption in various aspects of successful bundle delivery.

Unmanned Aerial Vehicles: A Survey on Civil Applications and Key Research Challenges

Abstract: The use of unmanned aerial vehicles (UAVs) is growing rapidly across many civil application domains, including real-time monitoring, providing wireless coverage, remote sensing, search and rescue, delivery of goods, security and surveillance, precision agriculture, and civil infrastructure inspection. Smart UAVs are the next big revolution in the UAV technology promising to provide new opportunities in different applications, especially in civil infrastructure in terms of reduced risks and lower cost. Civil infrastructure is expected to dominate more than $45 Billion market value of UAV usage. In this paper, we present UAV civil applications and their challenges. We also discuss the current research trends and provide future insights for potential UAV uses. Furthermore, we present the key challenges for UAV civil applications, including charging challenges, collision avoidance and swarming challenges, and networking and security-related challenges. Based on our review of the recent literature, we discuss open research challenges and draw high-level insights on how these challenges might be approached.

Software-Defined Next-Generation Satellite Networks: Architecture, Challenges, and Solutions

Abstract: Traditional satellite networks depend on the closed and planned architecture. Thus, there are many challenges such as configuration update, new communication and networking technologies introduction, truly-differentiated services provision, satellite network device interoperability, and the integration of satellite and terrestrial networks. Software-defined networking (SDN) has the features of flexibility, programmability, and logical centralization, which increases network resource utilization, simplifies network management, reduces operating cost, and promotes the evolution and innovation. In this paper, a new software-defined architecture for next-generation satellite networks, called SoftSpace, is presented. The concepts of network function virtualization, network virtualization, and software-defined radio are exploited in the SoftSpace to facilitate the incorporation of new applications, services, and satellite communication technologies. This can not only reduce the capital expenditures and operational expenditures but also integrate satellite networks with terrestrial networks seamlessly, as well as can improve the interoperability of satellite network devices. In addition, we discuss the challenges and solutions for network management. The necessary network management instruments including multi-layer controller architecture, cooperative traffic classification, and utility-optimal network virtualization are presented. Finally, we discuss the challenges and solutions for space networking. The software-defined space networking solutions including quality of experience-aware space routing, SDN-enabled hybrid fault recovery mechanism, and software-defined space mobility management are developed.

Satellite communication and propagation experiments through the alphasat Q/V band Aldo Paraboni technology demonstration payload

Abstract: Current high-throughput satellite (HTS) systems for broadband distributed user access are designed following two main concepts: ▸ The use of Ka band radio frequency (RF) links both for the forward and for the return link; this choice is due to the congestion of lower frequency bands and to the relatively large bandwidth available in the Ka band. Moreover, the RF technology in the Ka band is mature [1], [2]. ▸ The use of multispot coverage: this technique is largely applied to increase the system throughput through frequency reuse and system reconfigurability [2], [3].

Modeling memory-variation dynamics for the Licklider transmission protocol in deep-space communications

Abstract: Delay/disruption-tolerant networking was developed to enable automated network communications despite the long link delay and frequent link disruptions that generally characterize deep-space communications. It uses the well-known approach of store-and-forward with optional custody transfer, in which a node agrees to hold a file in memory (or storage) until its successful reception is acknowledged by the next node. The performance and memory consumption of delay/disruption-tolerant networking's Licklider transmission protocol (LTP) and bundle protocol in deep space will bear on decisions to adopt this technology. There is currently an urgent need to evaluate the performance and memory dynamics for file transmission by LTP and bundle protocol. In this paper, we present a study of memory dynamics for LTP-based transmission in a typical relay-based deep-space communication system characterized by an extremely long signal-propagation delay, lossy data links, and asymmetric data rates. Analytical models are built to quantify the dynamics of memory occupancy/release and memory release latency imposed by the use of LTP for reliable and complete file delivery in deep-space missions. File-transfer experiments are conducted using a test bed to validate the models.

Trust based Intelligent Routing Algorithm for Delay Tolerant Network using Artificial Neural Network

Abstract: In today's world, when every mobile device corresponds with human behavioral patterns. People often come across with various communities having patterns such as mobility, communication and groups. Trust is an intrinsic factor, which plays important role in formation of such communities. It is important to see the inherent risk involved in such socially active communities. Such factors motivate the use of trust as a routing factor in Delay Tolerant Networks (DTNs). This paper proposes a Trust based Intelligent Routing Algorithm, which exploits the Call Data Record from Call Detail Record. The function of Artificial Neural Network is to calculate and learn, trust value that can be shared among network devices. Our algorithm lowers the need of nodes resources like energy consumption, computation time and space overheads. The proposed algorithm enhances the routing performance in DTN. The earlier work claiming better efficiency generally ends up consuming network's resources. On the contrary our proposed algorithm provides in-built security, without any additional overhead. To the best of our knowledge the proposed work is the first of its kind, providing ingrained security feature to the DTN. This work gives vantage point to the researchers in the field over other schemes proposed in the past.