(keitai-l) Re: Japan plans mobile phone pay plan

From: Dirk Rösler <lists2003_at_unicircuits.com>
Date: 10/29/03
Message-Id: <961FF940-09AB-11D8-9759-0030654492C6@unicircuits.com>
Just speculating...

Chances are it is getting responses from all cards first if they are 
compatible to a certain degree, later discarding invalid ones. If there 
is some challenge-response process going on, the gate may still wait 
for responses of the invalid cards, which they cannot answer correctly, 
thus creating a little delay. Plus I would guess that the medium does 
not allow very fast communication, so you may end up with 1 or 2 
seconds lag until all messages of all cards are communicated, timeouts 
etc., probably serially or even simplex.

Solutions would be to make your card scheme proprietary and not based 
on standards, so only your own cards will work with your readers (I 
believe Sony has made some changes to the standard, not the least to 
provide a "customer lock in" feature but I don't know details). Or 
better, deploy some sort of resolution protocol (e.g. only process data 
from first completed protocol exchange, ignore all other 
communications).

An interesting experiment would be to enter two or more valid cards for 
the system (this case Suica) and see which one is charged and if there 
is lag etc. But there will surely be a resolution protocol.

Otherwise make sure you only present only one card to the reader.

Dirk

On Wednesday, Oct 29, 2003, at 02:09 Asia/Tokyo, Ken Chang wrote:

> does anyone know when you have a number of IC cards within the range,
> how the technology will guarantee that the station communicate with
> and only with the wanted one?
>
> the JR gates sometimes have problem to access my Suica card, wasting
> me a second or two when I have other IC cards in the wallet.
>
>
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Received on Wed Oct 29 03:03:48 2003