Kanglian Zhao

Human Localization Using Multi-Source Heterogeneous Data in Indoor Environments

A human localization system using multi-source heterogeneous data in indoor environments is proposed in this paper. The system can be easily constructed with already deployed Wi-Fi and camera infrastructures and is able to make use of received signal strength samples, surveillance images, and room map information to achieve a comparable performance. In a corridor scenario, we optimize propagation model (PM) parameters with crowdsourcing data from only several locations and establish a data table of optimized parameters for trilateration localization. These crowdsourcing data are also used to correct trilateration localization results, through which localization performance can be greatly improved. In a room scenario, we locate a human object with a panoramic camera and room map. We first detect the human object on the observed image and search a pixel location that represents the object’s location best. Then, the pixel location on the image is mapped to the room map using an artificial neural network. By this method, localization accuracy of sub-meter level can be obtained. We perform the proposed system in our experimental environment, and the experimental results show that our localization system not only requires no extensive time and labor cost, but also outperforms fingerprinting and PM localization systems.

Application Layer Channel Coding for Space DTN

Space communications have the characteristics of long link delays, frequent link disruptions and high error rates. With reliable Licklider Transmission Protocol (LTP) or Transmission Control Protocol (TCP), automatic repeat request (ARQ) is applied to enable reliable data delivery in delay/disruption tolerant networking (DTN). However, ARQ is inefficient for space communications especially in links with long round trip time (RTT). In this paper, an application layer Reed-Solomon (ALRS) channel coding scheme is proposed, which is further combined with ARQ to guarantee reliable transmission in DTN architecture. The proposed ALRS coding scheme is implemented in open source ION-DTN software and its performance is evaluated on a dedicated testbed. The results of the experiments show that this scheme in DTN can be speed up in most scenarios compared with ARQ-only scheme. With coding in application layer, the scheme is also more compatible with the overlay characteristic of DTN.

How Quick Is QUIC in Satellite Networks

Quick UDP Internet protocol (QUIC) was proposed by Google in 2012 as a reliable protocol on top of UDP. Compared with the widely used TCP for HTTP protocol, it is a new multiplexed and secure transport optimized for HTTP/2 semantics. The improvements of QUIC in terrestrial networks have been proved by previous researches, but few works have been done yet to evaluate the performance of QUIC via satellite links. In this paper, for the first time we evaluate the performance of QUIC, in comparison with HTTP/2 and HTTPS, via GEO satellite Internet access emulated on a dedicated testbed. The results of the experiments and our analysis confirm that QUIC does help reduce the overall page retrieval time in satellite networks. It is noted that QUIC outperforms HTTPS and HTTP/2 especially when the propagation delays are long and the packet loss rates are high, which is normal for GEO mobile satellite communications.

A Full-Protocol-Stack Testbed for Space Network Protocol Emulation

With the rapid development of space networks, new space communications protocols are emerging, for which emulation is an essential step during design and test. In this paper, we propose a lab-based testbed, in which software and hardware tools are utilized together to emulate full network protocol stack. A software protocol gateway is implemented to preform protocol conversion like IP over CCSDS in Data Link Layer. A specified hardware, Cortex CRT-Q is adopted for accurate emulation of space links, which connects upper layers with Physical Layer. Thus, our testbed benefit from both the fidelity provided by hardware and flexibility brought by software.

Spatial Crowdsourcing-Based Sensor Node Localization in Internet of Things Environment

With the development of mobile computing, sensor technology and wireless communications, Internet of Things (IoT) has been one of the research hotspots in recent years. Because sensor node localization plays an important role in IoT, we propose a spatial crowdsourcing-based sensor node localization method in this paper. Based on the concept of spatial crowdsourcing, anchor nodes are assigned to new locations according to node location relationship for localization performance improvement. Then, unknown nodes are upgraded to be anchor nodes. Finally, localization coordinates are calculated with DV-Hop method. Simulation results prove that our proposed localization method outperforms DV-Hop method.

Design and Implemention of an Emulation Node for Space Network Protocol Testing

This paper proposed a scheme to design and implement an embedded emulation node, which provided an approach to emulate a precision network environment for the measurement of network protocols in the space information network. The design scheme employed the Beaglebone black (BBB) board which owns the approximate hardware performance as a satellite has, ported the real-time operating system RTEMS to BBB board, and then loaded the ION-DTN on it. We established the RTEMS development environment on BBB board, and then designed and implemented the network adapter driver associated with BBB board for RTEMS. The emulation results show that the designed emulation node is stable and reliable. With the DTN protocol stack working properly on emulation node, the function and performance of the designed emulation node can meet the requirements of space network protocol tests.

Performance Evaluation of DTN Routing Protocols in Vehicular Network Environment

Compared with the traditional Internet architecture, Delay/Disruption Tolerant Networking (DTN) has a bundle layer between the application layer and transport layer and is able to tolerate delays and disruptions. In this paper, we simulate typical DTN routing protocols and configure a vehicular network environment to evaluate the protocol performance. We compare the performance evaluation indicators that include delivery ratio, overhead ratio, average delay, and average buffer time with different node numbers and buffer sizes. We finish the simulation using Opportunistic Network Environment (ONE) simulator and the DTN routing protocols are evaluated according to the simulation results.

Licklider Transmission Protocol for GEO-Relayed Space Networks

As one of the most important convergence layer (CL) protocol for delay/disruption-tolerant networking (DTN), Licklider transmission protocol (LTP) has recently been proposed for deep space communications, but it has rarely been considered for near earth applications. In this paper, LTP is adopted instead of TCP as CL with Bundle protocol (BP) for future application in GEO-relayed space networks (GRSN). Experiments are conducted on our computer based testbed in emulation of the basic scenarios during data transmission from LEO satellite to a ground station in GRSN. The results show that in transmission efficiency BP with LTPCL outperforms other protocols, such as BP with TCPCL, direct terrestrial TCP (TCP Cubic) and TCP variants (TCP Hybla) for space segments in most scenarios. It could be envisioned that DTN with LTPCL for space segment is currently the best choice for future GEO-relayed space internetworking.

Utility-Based Delay Tolerant Networking Routing Protocol in VANET

Because traditional Internet architecture is not suitable for hash network environments like sparse distribution and intermittent connection of nodes, Delay Tolerant Networking (DTN) is proposed to address the delays and disruptions. In this paper, we propose a utility-based DTN routing protocol in Vehicular Ad Hoc Network (VANET). Through considering node distance, node speed, node direction angle, and node activity, the utility of node is defined and is computed to select node for forwarding messages. We simulate the proposed DTN routing protocol and six typical DTN routing protocols in a VANET environment. The simulation results show that our proposed utility-based DTN routing protocol is able to achieve a comparable performance.