Yuanxin Ouyang

An Improved RFID-Based Locating Algorithm by Eliminating Diversity of Active Tags for Indoor Environment

The location awareness is a crucial foundation for perceptions of the surroundings in the smart environment. Radio frequency identification (RFID), as one of the most promising technologies, plays a more important role in the indoor location awareness. This paper surveys current RFID-based locating research and discusses the problem that is brought by the tags diversity derived from different manufacturer types and different used-time of built-in battery. We present the algorithm named RFDiffFreeLoc to improve the location precision by eliminating the dissimilarity among tags. In the stimulation experiments, we analyze the impact of noise on performance and contrast our algorithm with the existing LANDMARC algorithm. The simulation performances show that our algorithm is feasible via two metrics: the mean error and cumulative error distribution. The results indicate that RFDiffFreeLoc significantly increases the locating accuracy: when the space between the reference tags is 1 m, the mean error drops 0.076–0.344 m according to various noise conditions. Furthermore, a prototype system named RFHome is deployed for validating the algorithm in the actual home environment. The practical experimental results demonstrate that our algorithm is more effective than previous LANDMARC algorithm.

A Scalable RFID-Based System for Location-Aware Services

Location-awareness is a crucial trait of the mobile computing applications. The RFID is not only a feasible, novel, and cost-effective candidate for the indoor location sensing but also considered as the bridge which can merge physical world with hyperspace. Our study focuses on a location-aware computing architecture which provides the scalable location-based services for tracking nearly all daily objects by utilizing the RFID tags. The paper presents a hierarchical structure to organize the position areas based on tracking zone of interest (TZOI). Because the context is vital for mobile computing and can enable the revolution in computing model, a method of managing the location-centric context record is brought forward. We further propose an approach to aware the objects intentions and requirements which are varying over location by tracing and matching these records. An original application experimenting on the baggage handling in the airport also demonstrates the location awareness, e.g., when the baggage has been automatically sorted and arrives the correct place, one SMS is delivered to the owners mobile phone to remind him.

TCP congestion control for wireless datacenters

TCP is a low cost and easy-to-use transport layer protocol widely used in datacenter based applications and web services. Many TCP congestion control algorithms have been proposed to improve the performance of TCP in datacenter networks. However, the emerging wireless technologies in datacenter networks create new problems for TCP congestion control. On the one hand, TCP algorithms must suit the special application patterns (such as incast and Partition/ Aggregate) of the datacenters. On the other hand, TCP must perform well within the random packet losses caused by unreliable wireless links. Although there are many datacenter/wireless oriented TCP algorithms for either datacenter or wireless networks, designing a TCP algorithm that can meet both “datacenter” and “wireless” requirements of wireless datacenters still remains a great challenge. In this paper, a novel congestion control algorithm is proposed to improve the performance of TCP over wireless datacenter environments. The proposed approach combines an ACK-based wireless network bandwidth estimate with an ECN-based datacenter TCP congestion control that can perform well in both the datacenter environments and wireless links. The simulated experiments validate the performance of our proposed approach.

Case study of human computer interaction based on RFID and context-awareness in ubiquitous computing environments

Context-awareness becomes the key technology in the human computer interaction of ubiquitous computing. The paper discusses the characteristic, significance as well as function of the context, and the properties of the human computer interaction in the ubiquitous environments where the physical space fuses with the information space. These characteristics bring new requirements, that is, mobility, tractability, predictably and personality. To satisfy the demands, we present a method to realize context-awareness and the wireless interaction by using the pervasive RFID tags to track the context and using Bluetooth as the contact-less communication measure. We also construct a prototype system composed of RFID tags, BTEnableReaders and Bluetooth-enable mobile terminals. One case of application scenario is given and the experimental results show that the performance and robustness of the device are suitable for ubiquitous applications and the interaction is experienced more positively by users than the conventional method. The devices we design also can be extended to other application areas such as wearable computing, health care, disable help, and road navigation.

Research on lightweight RFID Reader Protocol

Radio frequency identification (RFID) is a kind of widely used contactless automatic recognition technology. Large-scale deployment of RFID readers and tags provides a very good hardware foundation for ubiquitous computing. A typical RFID system is usually composed of four parts: tag, RFID reader, RFID middleware and application system. To make the RFID reader integration uniform and effective, and meet the low calculation requirement of low-cost readers, a lightweight RFID reader protocol is presented. Considering the EPC standard has become a virtual standard of RFID system due to its rapid development, to meet the demand of EPC reader protocol standard (RPS), the presented protocol is specified in three layers, respectively the reader layer, the messaging layer and the transport layer. Differ from EPC RPS, in which different Messaging/Transport Bindings provide for different kinds of transport, the Messaging Layer and the Transport Layer are no longer designed to be working in pairs. Fieldbus technologies (especially PROFIBUS) are used for reference in the implementation of the transport layer.

On Design of Mobile Agent Based Location Service for Geographic Routing

On the impact of the node mobility, location service approaches based on the node location management incur high protocol overhead and low validity of location information. Therefore, a mobile location agent (MLA) algorithm is introduced to optimize location service. For each node, a location agent will be used to perform the location update and query by location service to decrease the protocol overhead. The location agent will assist the packet routing to the destination, which will upgrade the validity of location information caching in the network and improve the performance of geographic routing. When analyzing routing according to the location agent, we show a new method traversing all local closest nodes around a void location agent region to obtain the location information of the destination node. We select representative location service protocols and perform MLA algorithm. Simulation experimental results show that MLA algorithm can significantly reduce the protocol overhead of location service and improve the packet delivery ratio of geographic routing effectively.

Routing Optimized Video Transmission over Mobile Ad Hoc Networks

In mobile ad hoc networks, the communication node always produces a great deal of routing control packets while performing the route discovery and maintenance, which seriously impacts the real-time video transmission quality. Therefore, we propose a new routing control packets limited forwarding (RCPLF) algorithm that can reduce the routing overhead of on-demand routing protocol. In our algorithm, the route discovery is limited within a reasonable region, so that the number of routing control packets can be reduced and the bandwidth occupied by them can be saved effectively. Thus RCPLF algorithm is beneficial to improve the real-time video transmission quality. The simulation experiments have been carried out to measure the performance. In addition, any routing protocol using flooding based route discovery can use this algorithm to optimize video transmission performance.

A Web 2.0 Based Computer Knowledge Learning Platform

Traditional Web-based online learning systems usually focus on the dispatch of knowledge, and lack of ways for students to get involved. Introduction to Computer Basics (ICB) is one of the first professional courses for freshmen majored in computer science, as well as information technology. To make the learning platform of ICB more helpful, a Web 2.0 based computer knowledge learning platform is presented, which changes the focus from course content to the students¿ participation. Web 2.0 elements including personal and group spaces, wiki cyclopedia, interest mining and personalized recommendation, and RSS resource subscription are integrated. The platform has been put into use already, and got satisfaction from both teachers and students.

A precise approach to tracking dim-small targets using spectral fingerprint features

A precise method for accurately tracking dim-small targets, based on spectral fingerprint is proposed where traditional full color tracking seems impossible. A fingerprint model is presented to adequately extract spectral features. By creating a multidimensional feature space and extending the limited RGB information to the hyperspectral information, the improved precise tracking model based on a nonparametric kernel density estimator is built using the probability histogram of spectral features. A layered particle filter algorithm for spectral tracking is presented to avoid the object jumping abruptly. Finally, experiments are conducted that show that the tracking algorithm with spectral fingerprint features is accurate, fast, and robust. It meets the needs of dim-small target tracking adequately.

RFIDPROBUS: A universal RFID reader communication protocol

To make the RFID reader integration uniform and effective, a universal RFID reader communication protocol named RFIDPROBUS is presented. This protocol can be applied to the RFID middleware or application, the collection nodes and the central control system. It is lightweight and can be easily deployed and expanded. To meet the demand of EPC Reader Protocol Standard, RFIDPROBUS is specified in three layers. The Reader Layer defines the content and abstract syntax format of the exchange information between readers and the host, as well as the operations performed by the readers. The Messaging Layer defines the medium data format by Backus-Naur Form. The Transport Layer offers basic transportation service for the upper layer.