Sony Ericsson P990i - Manual (Page 54)

White Paper P990i
54 January 2006
Preliminary version - P1F
C
on
fiden
tial
Positioning
The basic cost efficient positioning method availa-
ble 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 accu-
rate position.
Positioning methods are already used to support
location-based information services such as
©
Yel-
lowPages, restaurant guides, traffic information,
directions and friend finder applications. Typically
SMS or voice has been used as delivery mecha-
nisms. Java™ and MMS 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 genera-
tions 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 cov-
erage of existing GSM networks. Applications
developed for GPRS have been deployed on a
large scale and have thus reaped the associated
benefits.
With GPRS, P990i sends data in “packets” at a
very high speed. The phone remains connected to
the network at all times, using transmission capac-
ity only when data is sent or received. Instead of
occupying an entire voice channel for the duration
of a data session, P990i 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. P990i is compatible with GPRS
R99.The GSM system limits the ability to use all
eight time slots, so P990i uses up to four time slots
for receiving data, and up to one slot for transmit-
ting.
Information about the identity of the phone and the
characteristics of the connection are described in
the PDP (Packet Data Protocol) context. This infor-
mation 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 P990i has many advantages:
• Constant connection
Keep an open connection to an email system or
the company network, 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.
• Email over GPRS
Remain connected to an email system while
reading and preparing messages, (which are
then sent at high speed).