White paper
Sony Ericsson P1
53
May 2007
Positioning
The basic cost efficient positioning method
available in 3G networks relies on measuring
round-trip time. In 3G it is called Cell-ID + TA
(Timing in Advance).
Time difference measurement, involving several
base stations, can be used to obtain a more
accurate position.
Positioning methods are already used to support
location-based information services such as
©
YellowPages, restaurant guides, traffic
information, directions and friend finder
applications. Typically, SMS or voice messages,
has been used as delivery mechanism. Java™ and
MMS messages will add new possibilities to deliver
attractive location-based applications.
GPRS
The introduction of GPRS was a big step in the
evolution of the GSM networks for enhancing the
capabilities of data communication. Data traffic has
increased (over both wired and wireless networks),
with the growth in demand for Internet access and
services paralleling that of mobile communications.
We can now see that the demand for high-speed
Internet access is the key driver for coming
generations of wireless multimedia and
entertainment services, and GPRS is important as
a stepping stone when we enter the 3G network
era. GPRS has allowed innovative services to be
created and granted access to new and previously
inaccessible market segments, which will be
further developed with 3G.
GPRS is able to take advantage of the global
coverage of existing GSM networks. Applications
developed for GPRS have been deployed on a
large scale and have thus reaped the associated
benefits.
With GPRS, Sony Ericsson P1 sends data in
“packets” at a very high speed. The phone remains
connected to the network at all times, using
transmission capacity only when data is sent or
received. Instead of occupying an entire voice
channel for the duration of a data session, Sony
Ericsson P1 sends and receives data in small
packets, as needed, much like IP on the Internet.
Thanks to this, the phone is always online, using
transmission capacity only when data is sent or
received. Sony Ericsson P1 is compatible with
GPRS R99. The GSM system limits the ability to
use all eight time slots, so Sony Ericsson P1 uses
up to four time slots for receiving data, and up to
one slot for transmitting.
Information about the identity of the phone and the
characteristics of the connection are described in
the PDP (Packet Data Protocol) context. This
information is stored both in the phone and in the
mobile network, so that each phone is identified
and “visible” to the system.
Using GPRS with Sony Ericsson P1 has many
advantages:
• Constant connection – Keep an open connec-
tion to an email system or the company net-
work, staying online to receive and send
messages at all times. All connection settings
can be managed by using the data connections
feature.
• High speed – Gain access automatically to
increased band-width when downloading large
files, images etc.
• Cost efficient – Use transmission capacity only
when needed, thus reducing costs.
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