Change Request NFC Forum Technical Committee

Change Request
NFC Forum Technical Committee

/ Title: / Correction and improvement on definition of EGT for the NFC-B Listen mode
To: / Technical Committee
Document to be changed: / TC-DEV-MS-00067R000-NFCForum-TS-DigitalProtocol-1_1_draft_13[1] CR.doc
Submitting Companies: / Inside Secure
Contact Details: / Olivier Carron <>
Date: / 3 April 2013
Replaces: / 29 October 2012
Classification: / Major

Reason for Change

In the current specification, the description of the Extra Guard Time for the NFC-B Listen mode is not precise enough and its implementation may lead to communication error following the loss of the phase reference Ø0.

This change request proposes to correct and improve the statements.

IPR

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Recommendation

The detailed description should be incorporated into the specification accordingly.

Detailed Description of Proposed Change

5.1.4 Pattern Synchronization

Patterns are grouped in a pattern group that are 10 bit durations long. The separation between two pattern groups is defined as the Extra Guard Time (EGT).

Requirements 37: NFC-B Pattern Group Separation

Poll and Listen Mode /
1.1.1.1 The time between two consecutive pattern groups sent by the NFC Forum Device in Poll Mode to the NFC Forum Device in Listen Mode MUST be EGTB,POLL. Refer to Appendix A.2 for the value of EGTPOLL.
1.1.1.2 The time between two consecutive pattern groups sent by the NFC Forum Device in Listen Mode to the NFC Forum Device in Poll Mode MUST be EGTB,LISTEN. The Listen Device SHALL ensure that the established phase reference Ø0 is still valid at the end of the EGT so that the next phase transition still occurs at nominal positions of rising or falling edges of the subcarrier. The EGTLISTEN SHALL then be a multiple of 16/fc. Refer to Appendix A.2 for the value of EGTB,LISTEN

The separation between two patterns within a pattern group occurs according to the following requirements.

Requirements 38: NFC-B Pattern Boundaries

Poll Mode / Listen Mode /
1.1.1.3 For Poll®Listen communication, pattern boundaries within a pattern group MUST occur between n bd ± 8/fC where n is the number of pattern boundaries after the start pattern falling edge (1 £ n £ 9). / 1.1.1.4 For Listen®Poll communication, pattern boundaries within a pattern group MUST only occur at nominal positions of rising or falling edges of the subcarrier: n bd ± 16/fC.