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1st-Generation UHF Standards for RFID

RFID is becoming as ubiquitous as printed bar codes. In fact, in many venues, optically scanned bar codes have been entirely replaced with embedded RFID tags. Clothing, high value electronics, packaged software, and even books have been using RFID (sometimes in the form of NFC - near field communications) for many years. Now, major retailers like Wal-Mart have made a commitment to making RFID ubiquitous. In the not-too-distant future, if you want to have your product sold by some of these retailers, you will be required to integrate RFID tags.

The magic price mark for RFID is a couple cents per tag. At that level, RFID can be added to every product and not represent more than a percent or two of the total cost.

This table summaries the protocols used in RID tags that operate in the 800/900 MHz band assigned for ISM (Industrial, Scientific & Medical) use.

  Key Parameters Auto-ID

Class 0


Class 1

ISO18000-6 A ISO 18000-6 B


Operating Frequency 902 MHz - 928 MHz 902 MHz - 928 MHz 860 MHz - 930 MHz 860 MHz - 930 MHz
Air Interface AM PWM AM PWM Pulse Interval ASK Manchester ASK
Bit Period NA: 25 µs/12.5 µs

EU: 62.5 µs

NA: 14.25 µs

EU: 66.67 µs

Data ‘0': 20 µs

Data ‘1': 40 µs

125 µs/25 µs
Data Rate NA: 40/80 kbps

EU: 16 kbps

NA: 70.18 kbps

EU: 15.00 kbps

33 kbps (1) 8/40 kbps

Duty Cycle


Data ‘1' low for 6 µs


Data ‘1' low for



Data ‘0' low for

10 µs


Manchester code

Modulation Depth

[Min, Max]

[20%, 100%] [30%, 100%] [27%, 100%] Nom 15%:

 [13%, 17%

Nom 99%:

 [90%, 100%]



Air Interface Passive Backscatter:


Passive Backscatter:

Pulse Interval AM

Passive Backscatter:

Bi-phase Space AM

Passive Backscatter:

Bi-phase Space AM

Bit Period NA: 25 µs/12.5 µs

EU: 62.5 µs

NA: 7.13 µs

EU: 33.33 µs

25 µs 25 µs
Data Rate NA: 40/80 kbps

EU: 16 kbps

NA: 140.35 kbps

EU: 30.00 kbps

40 kbps (1) 40 kbps (1)

Link Turnaround

Not Applicable (2) NA: 114 µs

EU: 534 µs

Shall not exceed 100 µs Shall not exceed 100 µs
General Reset Signal Duration 800 µs (CW) 64 µs (CW) 300 µs (CW) 400 µs (CW)
Collision Arbitration Deterministic binary

tree search

Deterministic/Slotted Adaptive Probabilistic binary

tree search (3)

Tag Read Speed Nom: 200 tags/sec

Max: 800 tags/sec

Not specified Nom: 100 tags/sec

(~10 ms/tag)

Nom: 100 tags/sec

(~10 ms/tag)

Tag Capacity Not limited by standard ~300 (4) ~300 (4) ~300 (4)
Memory Memory Type Read-only User programmable User programmable User programmable
Memory Organization EPC: 64/96 bits

Kill Code: 24 bits

Total: >=120 bits

EPC: 64/96 bits

Kill Code: 8 bits

Total: >=104 bits

Up to 256 blocks

w/256 bits/block (64 kBits)

Up to 256 blocks

w/8 bits/block (2 kBits)



Features Moderate

D0/ID1 + 24 bit kill



Reader broadcasts all or part of ID code.

Reader can request kill passcode.


Reader broadcasts

UID/SUID. Production set block lock bits. No kill command.


Reader broadcasts

UID/SUID. Production set block lock bits. No kill command.

(1) No mention of data rates specific to European operation. Reverse link is always 40 kbps.

(2) For Auto-ID class 0, the tag data response is always known a priori (i.e., nothing has to be computed based on the current bit).

(3) Probabilistic collision arbitration implies that tag selection speed will depend on the tag population size.

      This is a disadvantage.

(4) These standards are limited by the probabilistic nature of their collision arbitration protocols.

      Most of them assume a tag population of ~250 tags.

Source: RF Design, July 2005 , by Rob Glidden and John Schroeter. Click here for the full article.

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