Temporal Management of RFID Data
Fusheng Wang Peiya Liu
Integrated Data Systems Department
Siemens Corporate Research
755 College Road East, Princeton, NJ 08540, USA
{fusheng.wang, peiya.liu}@siemens.com
Abstract
RFID technology can be used to significantly im-
prove the efficiency of business processes by pro-
viding the capability of automatic identification
and data capture. This technology poses many
new challenges on current data management sys-
tems. RFID data are time-dependent, dynamically
changing, in large volumes, and carry implicit se-
mantics. RFID data management systems need
to effectively support such large scale temporal
data created by RFID applications. These sys-
tems need to have an explicit temporal data model
for RFID data to support tracking and monitor-
ing queries. In addition, they need to have an
automatic method to transform the primitive ob-
servations from RFID readers into derived data
used in RFID-enabled applications. In this pa-
per, we present an integrated RFID data manage-
ment system – Siemens RFID Middleware – based
on an expressive temporal data model for RFID
data. Our system enables semantic RFID data
filtering and automatic data transformation based
on declarative rules, provides powerful query sup-
port of RFID object tracking and monitoring, and
can be adapted to different RFID-enabled applica-
tions.
1 Introduction
1.1 Background
RFID (radio frequency identification) technology uses
radio-frequency waves to transfer data between readers and
movable tagged objects, thus it is possible to create a physi-
cally linked world in which every object is numbered, iden-
tified, cataloged, and tracked. RFID is automatic and fast,
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and does not require line of sight or contact between read-
ers (or sensors) and tagged objects. With the significant
advantages of RFID technology, RFID is being gradually
adopted and deployed in a wide area of applications, in-
cluding supply chain management [1, 2, 3, 4, 5], retail [6],
anti-counterfeiting [7], security [8], and healthcare. For ex-
ample, Siemens Business Services launched a pilot project
to track patients with RFID bracelets during hospital ad-
missions [9].
Through the automatic data collection, RFID technol-
ogy can achieve greater visibility and product velocity
across supply chains, more efficient inventory manage-
ment, easier product tracking and monitoring, reduced
product counterfeiting and theft, and much reduced labor
cost. On the other hand, there is a chasm between the phys-
ical world and the interpreted world through sensor obser-
vations. These observations need to be automatically in-
terpreted and semantically transformed into business logic
data, before they can be integrated into business applica-
tions, such as ERP and WMS.
1.2 Characteristics of RFID Data and Problem State-
ments
Despite the diversity of RFID applications, RFID data
share common fundamental characteristics, which have to
be fully considered in RFID data management systems.
Temporal and dynamic
. RFID applications dynamically
generate observations and the data carry state changes.
All sensor observations are associated with the timestamps
when the readings are made; objects’ locations change
along the time; the containment relationships change along
the time, and all EPC [10] related transactions are also as-
sociated with time. (EPC – Electronic Product Code – is
an identification scheme for universally identifying physi-
cal objects, defined by standard committees [10].) It is es-
sential to model all such information in an expressive data
model suitable for application level interactions, including
tracking, monitoring, and application integration [11, 12].
Implicit semantics and inaccuracy of data
. In an RFID
system, a reader observation comprises of the reader EPC,
the observed EPC value of an RFID tag, and the timestamp
when the observation occurs. These data carry implicit in-
formation, such as changes of states and business processes
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