(keitai-l) Re: Camera phones - USB & WPAN

From: Ken Chang <kench_at_hotmail.com>
Date: 07/25/02
Message-ID: <F73Fha6xkOhS1UeJVNt00016386@hotmail.com>
Benjamin,

(1)
let's do two things first, (A) separate the physical/data-link,
network, and application layers, and then (B) find out what're
the core problems that Bluetooth will solve.

I'd like to see everything network: from the first Macintosh
17 years ago talking with a printer in AppleTalk, to the new
iSCSI standard.  you can use WLAN to connect to peripherals
like printer or NAS harddrive, and you can link a network card
via USB (or maybe 1394?), so network is not a major factor.

applications are not directly related.  you can turn on aircon
by sending an SMS, doesn't have to be Bluetooth.  any Internet
connected appliances can be controlled over cellular, WLAN, or
an RJ-45 jack in the armrest.

I think the problem is, with applications in mind, what'll be
the bandwidth, interference, capacity, security, and price
requirements for a WPAN design.

(2)
for example, 200 people packed in a railroad car and enjoying
music/video using Bluetooth, or 200 students typing on their
Bluetooth keyboard in a classroom?  how will the 79 frequencies
and 8 MAC addresses provide the capacity?  will the low power
radio with frequency hopping be enough for robust and fast
response radio links?

(please tell me how if Bluetooth can solve the problem.)

one problem with WPAN is that the traffic is way higher than
WWAN on a per node basis.  this is easy to understand if you
compare the traffic over your Internet connection, to/from
your peripherals, and on the system bus.

while less than 10% of people are actually active on their
mobile phones (maybe 1% for wireless messaging), the majority
of people will have live traffic circulating their WPAN.

one will have to be brave to design a system like this, ...
especially if he travels frequently and physically by air.

cheers,

Ken


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Received on Thu Jul 25 13:34:51 2002