Background and Outline
RFID tag systems are expected to be widely
used as one of the fundamental tools of
the ubiquitous network society in the future.
Compared to the bands (below 135kHz, 13.56
MHz and 2.45GHz) that have been used until
now for RFID tag systems, the tag system
using the 950MHz band offers communications
over longer distances. Concerning high-power
passive tag systems using the 950MHz band,
a system was institutionalized in April
2005, in accordance with a partial report
by the Information and Communications Council
in December 2004.
Subsequently, and with a view to more efficient
use of the 950 MHz RFID tag systems, investigations
have continued and the MIC received on October
12, 2005, a partial report from the Information
and Communications Council concerning technical
conditions for more efficient high-power
passive tag systems and for low-power passive
tag systems using the 950MHz band.
Promotion of the penetration of RFID tag
systems is now expected to get under way.
Outline of Partial
Report
Technical conditions
for more efficient high-power passive tag
systems using the 950MHz band
- As to the passive tag systems that are
not equipped with commoditizing technologies,
there is the fear of (1) interference between
reader/writers (R/W) using the same frequency
band, and (2) interference on the tag side
from the multiple R/W frequencies. In order
to avoid and reduce these effects, carrier
sense functions and transmission time controls
will be introduced as commoditizing technologies.
- In order to implement carrier sense,
the 952MHz to 954MHz band is split into
200 kHz-wide single radio channels. However,
in order to respond to increases in transmission
speed too, bundled use of single radio channels
has also been made possible (see graph 1).
- Concerning transmission times, the estimated
time for reading approximately 200 tags
at once is set at 4 seconds. And idle time
is set at 50ms which is adequate time needed
for vacating channels.
Graph 1 Channel allocation
for high-power types 
Technical conditions for low-power passive
tag systems using the 950MHz band
- As to low-power passive tag systems using
the 950MHz band, it is assumed that they
are utilized in a wide variety of fields
where handy-type bar code readers are used,
such as retail stores and behind the scenes
at large supermarkets, and factory lines,
and that used by the general public of a
terminal that would be combined with a mobile
phone. Taking these into consideration,
tests have been carried out at transmission
distances of about 50cm.
- Strength of transmission power and spurious
area discharge were investigated in order
to avoid interference to personal digital
cellular (PDC) and IMT-2000 (in the future)
using neighboring frequency bands, and the
frequency bands have been set 1MHz wider
than for the high-power type at 952MHz to
955MHz (3MHz) and antenna power at the 10mW
level of specified low-power radio stations
which require no licenses.
- In order to introduce commoditizing technologies
using carrier sense, as is the case for
the high-power type, the 952MHz to 955MHz
has been split into 200 kHz-wide single
radio channels. However, in view of possible
applications, the number of channels that
can be used simultaneously has been set
at one (see graph 2).
- Also, from the point of view of giving
preference to the high-power type transmission
where greater responsiveness is required
over the low-power type, the transmission
speed has been set at 1 second, with the
idle time at 100ms.
Graph 2 Channel allocation
for low-power types
(n: In numbers 1 to 9, italics indicate
new technical requirements)
Topics
for Ongoing Investigation
Active tag
system using the 433MHz band
Investigation of shared use with amateur
radios that use the same frequency band
is needed. At present, investigations are
ongoing, taking into consideration the results
of on-site testing.
Low-power active radio
system using the 950MHz band
Concerning the low-power radio system which
is expected to be used in the 950MHz band
in the future, technical investigations
on shared use with passive tag systems are
needed, taking international trends into
consideration.
