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| 2. |
- Zhang, Zhi, et al.
(författare)
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A low delay multiple reader passive RFID system using orthogonal TH-PPM IR-UWB
- 2010
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Ingår i: Proceedings - International Conference on Computer Communications and Networks, ICCCN. - Zurich.
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Konferensbidrag (refereegranskat)abstract
- Current passive RFID systems face the challenges to locate mobile objects in real time in indoor environments, including the realization of low delay as well as effective cooperation among readers and accurate ranging ability in the physical layer. In order to overcome these challenges, this paper presents a low delay multi-reader passive RFID system using ultra high frequency (UHF) radio as the forward link from readers to tags and orthogonal time hopping pulse-position modulation (TH-PPM) impulse ultra-wideband radio (IR-UWB) over the dynamic framed slotted ALOHA algorithm as the backward link from tags to readers. The asymmetric radio links overlap parts of the forward and backward transmission and avoid reader-tag collisions. Readers cooperate via network synchronization by a server and a contention-based update strategy to acknowledge tags. An optimal system configured with 4 readers using 16 orthogonal TH sequences is suggested and operates 3 times faster than the theoretical potential of EPC Class-1 Generation-2 protocol with the listen-before-talk scheme.
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| 3. |
- Zhang, Zhi, et al.
(författare)
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Code division multiple access/pulse position modulation ultra-wideband radio frequency identification for Internet of Things : concept and analysis
- 2012
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Ingår i: International Journal of Communication Systems. - : Wiley. - 1074-5351 .- 1099-1131. ; 25:9, s. 1103-1121
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency identification (RFID) is a compelling technology for Internet of Things (IoT). Ultra-wideband (UWB) technology is one promising wireless technique for future RFID, especially for high-throughput sensing applications. On-off keying UWB RFID system provides high pulse rate but suffers severe collisions that limit the system throughput. This paper proposes to utilize low pulse rate code division multiple access/pulse position modulation UWB in the tag-to-reader link to provide multiple tag access capability and build a high-throughput RFID system for IoT. We analyze asynchronous matched filter receiver and decorrelating receiver for multi-tag detection and design an effective medium access control scheme to optimize the network throughput. We propose an effective dynamic frame size adjustment algorithm on the basis of theoretical analysis and determine the preferable length of Gold codes. With a similar data rate, the throughput of the proposed system using the decorrelating receiver is 8.6 times higher than that of the electronic product code class 1 generation 2 system. Only using 1/10 pulse rate and 1/15 data rate, the proposed system outperforms the on-off keying UWB RFID system 1.4 times in terms of throughput.
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| 4. |
- Zhang, Zhi, et al.
(författare)
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COSMO : CO-simulation with MATLAB and OMNeT++ for indoor wireless networks
- 2010
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Ingår i: 2010 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE GLOBECOM 2010. - 9781424456383
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Konferensbidrag (refereegranskat)abstract
- Simulations are widely used to design and evaluate new protocols and applications of indoor wireless networks. However, the available network simulation tools face the challenges of providing accurate indoor channel models, three-dimensional (3-D) models, model portability, and effective validation. In order to overcome these challenges, this paper presents a new CO-Simulation framework based on MATLAB and OMNeT++ (COSMO) to rapidly build credible simulations for indoor wireless networks. A hierarchical ad hoc passive RFID network for indoor tag locating is described as a case study, demonstrating the significance and efficiency of COSMO compared with other network simulators. COSMO surpasses other network simulators in terms of workload and validity.
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| 5. |
- Zhang, Zhi, et al.
(författare)
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Item-Level Indoor Localization With Passive UHF RFID Based on Tag Interaction Analysis
- 2013
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 61:4, s. 2122-2135
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Tidskriftsartikel (refereegranskat)abstract
- Radio-frequency identification (RFID) with a received signal strength indicator (RSSI) is a low-cost and low-complexity approach for item-level indoor localization. Although RSSI-based algorithms suffer from multipath effect and other environmental factors, reference tags and RSSI changes can be utilized to further improve the localization accuracy. However, the current algorithms lack deep analysis of the influence of tag interaction on localization accuracy and faces the challenge of simultaneously locating multiple close targets. In this paper, we propose an analysis method about how tag interaction affects a tag antenna radiation pattern and an RSSI change. The tag interaction analysis guides us to improve the design of RSSI-based localization algorithms. We take the k-nearest neighbor (k-NN) algorithm and the Simplex algorithm as two examples. The experimental results show that the revised k-NN and the revised Simplex algorithms are robust to different numbers, spacing, and materials of target objects, and they are superior to other RFID localization schemes, considering cost, capability of simultaneous localization of multiple targets, and location estimation errors.
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| 6. |
- Zhang, Zhi, et al.
(författare)
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Two-layered wireless sensor networks for warehouses and supermarkets
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The rapid development of wireless sensor network and RFID technologies offers a wide range of novel applications and services. In this paper, we present a two-layered wireless network for warehouses and supermarkets to monitor goods storage and sale, and assist for quality management and market analysis. The hierarchical architecture uses IEEE 802.15.4a impulse ultra-wideband radio (IR-UWB) communication protocol between slave sensor nodes and master sensor nodes, and IEEE 802.11b/g between master sensor nodes and server. The performance of our proposal is evaluated based on the widely used OMNeT++ simulation environment. Simulation results are presented and discussed according to different sampling rates and traffic loads for specific scenarios requirements. © 2009 IEEE.
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| 7. |
- Zhang, Zhi, et al.
(författare)
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Wireless sensor networks for logistics and retail
- 2009
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Ingår i: INSS2009 - 6th International Conference on Networked Sensing Systems. - Pittsburgh, PA. - 9781424463145 ; , s. 98-101
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Internet of Things technologies makes it possible to trace when and where the excellent food or wine is spoiled or loses perfect taste in logistics and retail. This paper describes a system using a two-layered wireless sensor network to monitor the supply chain from manufacturer to consumer, including the network topology, application software on server, and sensor node hardware. It employs GSM/GPRS as the high layer network and semi impulse ultra-wideband radio (IR-UWB) for the low layer communication. We propose GSM Cell-ID location technology for tracking the goods transportation, and time-of-arrival method for local positioning. Finally, the first version of the system implementation and future work are presented. ©2009 IEEE.
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