MLSE detector for beyond VHBR contactless air interface

Abstract

We investigate the problem of sequence detection in a non linear channel for a contactless air interface. The work presented in this study is based on the the VHBR (Very High BitRate) amendments of the ISO 14443 international standard. We focused more particularly on the part of the standard extension that defines the phase modulation (PSK) from the Proximity Coupling Device (PCD) to the Passive Inductive Coupled Card (PICC). We propose an efficient detector to overcome both Inter Symbol Interference (ISI) due to the high data rates, and system non linearities introduced by the differential detection at the receiver side. The proposed detector is an adaptation of the Viterbi algorithm for constraint-ternary alphabet. Our numerical results show that a rate of 13.56 Mbps can be achieved using a 15-states sequence detector.

Differentiating ASK Demodulator for Contactless Smart Cards Supporting VHBR

“…The reduction in the modulation index to 10%, as specified for Type B cards in the ISO/IEC 14443 standard, will exacerbate the problem. The emergent alternative is the use of PSK (phase shift keying) modulation [5]- [6]. However, PSK demodulators are complicated and require much more circuitry than ASK demodulators.…”