An Efficient Indoor Navigation Scheme Using RFID-based Delay Tolerant Network Hao Ji,Lei Xie,Yafeng Yin,Sanglu Lu State Key Laboratory for Novel Software Technology,Nanjing University,Nanjing,China Email:jiqiusheng@dislab.nju.edu.cn,Ixie@nju.edu.cn,yyf@dislab.nju.edu.cn,sanglu@nju.edu.cn Abstract-As a supporting technology for most pervasive important problem is how to locate and navigate to a specified applications,indoor localization and navigation has attracted mobile user.For example,when a baby or a dog is lost in extensive attention in recent years.Conventional solutions mainly a shopping mall,how to quickly locate and navigate to the leverage techniques like WiFi,cellular network ete.to effectively locate the user for indoor localization and navigation.In this mobile target?Obviously,the mobile target can only passively paper,we investigate into the problem of indoor navigation by leave some traces in the environment through the equipped using the RFID-based delay tolerant network.Being different NFC or bluetooth modules.It cannot actively propagate its cur- from the previous work,we aim to efficiently locate and navigate rent position directly to the searchers.Besides,time-efficiency to a specified mobile user who is continuously moving within the indoor environment.We respectively propose a framework is very critical to the searchers,since the less time to use,the to schedule the tasks and manage the resources in the network more opportunities to find the target. and a navigation algorithm to locate and navigate to the moving Therefore,it is essential to devise a time-efficient navigation target.Experiment results show that our solution can efficiently scheme by using the RFID-based delay tolerant network.In reduce the average searching time for indoor navigation. this paper,we first propose a framework to schedule the I.INTRODUCTION tasks and manage the resources in this network.Furthermore, As the rapid proliferation of pervasive applications in indoor we propose a navigation algorithm to locate and navigate to the moving target.The main contributions of this paper are environment,a lot of location-based services and context- summarized as follows: aware services are put forward,in which location is viewed as one of the most significant factors.For most applications, We propose a framework leveraging RFID-based de- it is required to provide an accurate location for the specified lay tolerant network for localization and navigation.By objects.However,the current mature technology like global sufficiently leveraging the "store-and-forward"properties position system (GPS)can only be used in the outdoor of the delay tolerant network,our solution provides an environment for localization,several issues like the multi-path effective mechanism for navigation using "crowdsourc- effect and severe path loss make the indoor localization a lot ing"capabilities.By effectively scheduling the tasks and more complicated than the outdoor situation.Therefore,a lot managing the limited resources in the tags,the system can of research works have focused on localization and navigation provide navigation services for a large number of users. schemes for indoor environment [1-7].Most of the solutions We propose a time-efficient scheme to locate and navigate are rather complicated and fairly expensive. to a mobile target who is continuously moving.According Recent technological advances have enabled the develop- to the latest obtained spots of appearance,our solution ment of low-cost,low-power devices [8-9].RFID,as a novel navigates the searcher to the most possible region of the technology for automatic identification,provides us with a target,which achieves a good performance in terms of new opportunity for indoor localization and navigation.For the time-efficiency. example,the low-cost RFID tags can be widely deployed II.RELATED WORK inside the indoor environment and act as landmarks for lo- calization.Since current smart phones can be equipped with Many research works use RFID technology for indoor localization [10-13].LANDMARC [10]is a tag localization near field communication (NFC)or bluetooth modules,which can effectively communicate with the active/passive tags,the prototype in indoor environment.By utilizing extra fixed location reference tags to help location calibration,it can mobile users can actively interrogate the surrounding tags with increase location accuracy without deploying large numbers tiny devices like smart phones and leave messages or traces to the tags.In this way,the RFID-based infrastructure forms a of RFID readers.Zhu et al.propose an fault-tolerant RFID delay tolerant network.As the scanning range of RFID system reader localization approach to solve the problem of frequent is usually no more than 5m,the system can effectively locate occurred RFID faults [13].Moreover,they also propose the index to measure the quality of a localization result. the users by limiting the positioning error to at most 5m. Escort [14]is an office environment localization and navi- In conventional indoor applications,the users are contin- uously moving within the indoor environment.Then,one gation system which uses client/server architecture.The client running on the user-carried mobile phones periodically mea- Corresponding Author:Dr.Lei Xie,Ixie@nju.edu.cn sures the value of accelerometer and compass of the user'sAn Efficient Indoor Navigation Scheme Using RFID-based Delay Tolerant Network Hao Ji, Lei Xie, Yafeng Yin, Sanglu Lu State Key Laboratory for Novel Software Technology, Nanjing University, Nanjing, China Email: jiqiusheng@dislab.nju.edu.cn, lxie@nju.edu.cn, yyf@dislab.nju.edu.cn, sanglu@nju.edu.cn Abstract—As a supporting technology for most pervasive applications, indoor localization and navigation has attracted extensive attention in recent years. Conventional solutions mainly leverage techniques like WiFi, cellular network etc. to effectively locate the user for indoor localization and navigation. In this paper, we investigate into the problem of indoor navigation by using the RFID-based delay tolerant network. Being different from the previous work, we aim to efficiently locate and navigate to a specified mobile user who is continuously moving within the indoor environment. We respectively propose a framework to schedule the tasks and manage the resources in the network and a navigation algorithm to locate and navigate to the moving target. Experiment results show that our solution can efficiently reduce the average searching time for indoor navigation. I. INTRODUCTION As the rapid proliferation of pervasive applications in indoor environment, a lot of location-based services and context￾aware services are put forward, in which location is viewed as one of the most significant factors. For most applications, it is required to provide an accurate location for the specified objects. However, the current mature technology like global position system (GPS) can only be used in the outdoor environment for localization, several issues like the multi-path effect and severe path loss make the indoor localization a lot more complicated than the outdoor situation. Therefore, a lot of research works have focused on localization and navigation schemes for indoor environment [1-7]. Most of the solutions are rather complicated and fairly expensive. Recent technological advances have enabled the develop￾ment of low-cost, low-power devices [8-9]. RFID, as a novel technology for automatic identification, provides us with a new opportunity for indoor localization and navigation. For example, the low-cost RFID tags can be widely deployed inside the indoor environment and act as landmarks for lo￾calization. Since current smart phones can be equipped with near field communication (NFC) or bluetooth modules, which can effectively communicate with the active/passive tags, the mobile users can actively interrogate the surrounding tags with tiny devices like smart phones and leave messages or traces to the tags. In this way, the RFID-based infrastructure forms a delay tolerant network. As the scanning range of RFID system is usually no more than 5m, the system can effectively locate the users by limiting the positioning error to at most 5m. In conventional indoor applications, the users are contin￾uously moving within the indoor environment. Then, one Corresponding Author: Dr. Lei Xie, lxie@nju.edu.cn important problem is how to locate and navigate to a specified mobile user. For example, when a baby or a dog is lost in a shopping mall, how to quickly locate and navigate to the mobile target? Obviously, the mobile target can only passively leave some traces in the environment through the equipped NFC or bluetooth modules. It cannot actively propagate its cur￾rent position directly to the searchers. Besides, time-efficiency is very critical to the searchers, since the less time to use, the more opportunities to find the target. Therefore, it is essential to devise a time-efficient navigation scheme by using the RFID-based delay tolerant network. In this paper, we first propose a framework to schedule the tasks and manage the resources in this network. Furthermore, we propose a navigation algorithm to locate and navigate to the moving target. The main contributions of this paper are summarized as follows: • We propose a framework leveraging RFID-based de￾lay tolerant network for localization and navigation. By sufficiently leveraging the “store-and-forward” properties of the delay tolerant network, our solution provides an effective mechanism for navigation using “crowdsourc￾ing” capabilities. By effectively scheduling the tasks and managing the limited resources in the tags, the system can provide navigation services for a large number of users. • We propose a time-efficient scheme to locate and navigate to a mobile target who is continuously moving. According to the latest obtained spots of appearance, our solution navigates the searcher to the most possible region of the target, which achieves a good performance in terms of the time-efficiency. II. RELATED WORK Many research works use RFID technology for indoor localization [10-13]. LANDMARC [10] is a tag localization prototype in indoor environment. By utilizing extra fixed location reference tags to help location calibration, it can increase location accuracy without deploying large numbers of RFID readers. Zhu et al. propose an fault-tolerant RFID reader localization approach to solve the problem of frequent occurred RFID faults [13]. Moreover, they also propose the index to measure the quality of a localization result. Escort [14] is an office environment localization and navi￾gation system which uses client/server architecture. The client running on the user-carried mobile phones periodically mea￾sures the value of accelerometer and compass of the user’s