Date: Mon, 15 May 2000 21:53:59 +0100 (BST) From: Duncan Barclay <dmlb@ragnet.demon.co.uk> To: "Karsten W. Rohrbach" <karsten@rohrbach.de> Cc: roger@FreeBSD.ORG, bsd-nomads@clave.gr.jp, mobile@FreeBSD.ORG, Roger Hardiman <roger@cs.strath.ac.uk>, Borje Josefsson <bj@dc.luth.se>, Panagiotis Astithas <past@netmode.ntua.gr> Subject: Re: Nokia Card Phone 2.0 PCMCIA GSM phone, need help Message-ID: <XFMail.000515215359.dmlb@computer.my.domain> In-Reply-To: <20000515165854.B93503@rohrbach.de>
next in thread | previous in thread | raw e-mail | index | archive | help
On 15-May-00 Karsten W. Rohrbach wrote:
> Panagiotis Astithas(past@netmode.ntua.gr)@Mon, May 15, 2000 at 11:43:08AM
> +0300:
>> On Mon, May 15, 2000 at 08:00:49AM +0200, Borje Josefsson wrote:
>> > The only thing is that the card phone seems to default to connect at 9600
>> > bps. Does anybody know the right AT commands to enable 28k or 44k?
>>
>> I don't think the GSM protocol can do more than 9600 bps. Maybe 14400 under
>> special conditions (GSM+ or something like that).
> correct me if i'm wrong but there's a thing called hscsd which appears
> to be some kind of gsm channel bundling to achieve 56kbps connections
> /k
GSM has three or four evolving paths for data and higher bit rates. They
fit together as a matrix so there are a few.
Firstly there is
HSCSD High speed circuit switched data.
circuit switched connections (like normal GSM) for data but is
Multislot (see below).
GPRS General packet radio service.
connection orientated/packet switched data transfer, can use
Multislot.
Multislot "channel bundling" but not really
Uses more than one slot per frame of eight slots. Different
classes use up to 8Tx and 8Rx slots. Class 10 is most common to
give 5 Rx and 2 Tx slots (I think). There are good reasons
why 8Tx+8Rx will never be seen in consumer handsets - you
need two receivers and seperate transmitter it will be a brick.
As multislot concatenates the 156bit slots there is the option
to recode the error correction so that more of the n*156bits
are used for data. E.g. 1 slot data will be 9600Bd, but
two slot will be >19200Bd.
EDGE Enhanced data rates for GSM evolution (seriously)
EDGE changes the modulation to use 8PSK and not GMSK. This
triples the rate data rate, so a slot contains 468bits at
156baud. It will be used for EGPRS.
GPRS will be available this summer - infact most networks support it
already but handsets don't (it requires big changes to software that
is bigger than the FreeBSD kernel and some changes to the radio (I do
this at work)).
EDGE will be available in small clusters in a couple of years. This
requires massive changes to the basestations and handsets. Many
handset manufacturers aren't yet considering it - too busy with GPRS.
Basestation manufacturers are in development, but production is a
way off (we do this at work).
HSCSD is unknown. Most people think that GPRS is the most useful as it
is like the internet (e.g. mappings for IP over GPRS exists
as part of the GSM specfication).
Duncan
---
________________________________________________________________________
Duncan Barclay | God smiles upon the little children,
dmlb@ragnet.demon.co.uk | the alcoholics, and the permanently stoned.
________________________________________________________________________
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-mobile" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.000515215359.dmlb>