Analog On-Tag Hashing: Towards Selective Reading as Hash Primitives in Gen2 RFID Systems
Analog On-Tag Hashing: Towards Selective Reading as Hash Primitives in Gen2 RFID Systems
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DOI：
10.1145/3117811.3117835
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发表时间：
2017-07
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影响因子：
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通讯作者：
Lei Yang;Qiongzheng Lin;Chunhui Duan;Zhenlin An
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作者：
Lei Yang;Qiongzheng Lin;Chunhui Duan;Zhenlin An
由于当前系统的性能差距，数十亿商用现货（COTS） RFID标签的部署引起了研究界的广泛关注。特别是，支持哈希的协议（HEP）是过去十年中研究得最彻底的主题之一。hep设计用于广泛的显著应用（例如，缺失检测），而无需收集所有标签。hep假设每个标签都包含一个哈希函数，这样标签就可以选择一个随机但可预测的时隙，以显示其存在的1位存在信号来应答。然而，哈希函数在现实中从未在COTS标签中实现，这使得hep成为十年不可触及的海市蜃楼。本工作设计并实现了一组用于COTS gen2兼容RFID系统的模拟标签上哈希原语（称为Tash），将先前的hep从理论推向实践。特别地，我们设计了三种类型的哈希原语，即tash函数、tash表函数和tash算子。所有这些哈希原语都是通过选择性读取实现的，这是Gen2协议中指定的基本和强制功能，无需任何硬件修改和制造。我们进一步将我们的哈希原语应用于两个典型的HEP应用程序（即基数估计和缺失检测），以显示Tash的可行性和有效性。我们的原型（由一个ImpinJ阅读器和3000个Alien标签组成）的结果表明，新设计降低了60%的空中通信开销。tash操作符还可以将开销降低29.7%。
Deployment of billions of Commercial Off-The-Shelf (COTS) RFID tags has drawn much of the attention of the research community because of the performance gaps of current systems. In particular, hash-enabled protocol (HEP) is one of the most thoroughly studied topics in the past decade. HEPs are designed for a wide spectrum of notable applications (e.g., missing detection) without need to collect all tags. HEPs assume that each tag contains a hash function, such that a tag can select a random but predicable time slot to reply with a one-bit presence signal that shows its existence. However, the hash function has never been implemented in COTS tags in reality, which makes HEPs a 10-year untouchable mirage. This work designs and implements a group of analog on-tag hash primitives (called Tash) for COTS Gen2-compatible RFID systems, which moves prior HEPs forward from theory to practice. In particular, we design three types of hash primitives, namely, tash function, tash table function and tash operator. All of these hash primitives are implemented through selective reading, which is a fundamental and mandatory functionality specified in Gen2 protocol, without any hardware modification and fabrication. We further apply our hash primitives in two typical HEP applications (i.e., cardinality estimation and missing detection) to show the feasibility and effectiveness of Tash. Results from our prototype, which is composed of one ImpinJ reader and 3,000 Alien tags, demonstrate that the new design lowers 60% of the communication overhead in the air. The tash operator can additionally introduce an overhead drop of 29.7%.