Sony Ericsson P990i - Manual (Page 53)

White Paper P990i
53 January 2006
Preliminary version - P1F
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• Continuity of active circuit switched services
when moving within UMTS Radio Access Net-
work, within GSM/GPRS and between UMTS
Radio Access Network and GSM/GPRS cover-
age areas.
• Continuity of active and packet switched ses-
sions when moving within UMTS Radio Access
Network, within GSM/GPRS and between
UMTS Radio Access Network and GSM/GPRS
coverage areas.
General operational considerations
Mechanisms defined to support service continuity
between different radio systems or radio access
modes should effectively cope with a number of
coverage scenarios:
• Limited coverage in a “sea” of coverage pro-
vided by another radio system or radio access
mode.
• Selective operation at a geographical boundary,
with extensive UMTS Radio Access Network
coverage on one side, and extensive coverage
from another radio system on the other side.
• Geographically colocated areas of UMTS Radio
Access Network coverage and another radio
system.
Performance requirements
Temporary degradation of service caused by
handover
During intra-UMTS Radio Access Network hando-
ver or handover from UMTS Radio Access Network
to GSM/GPRS, degradation of service should be
no greater than during intra-GSM/GPRS handover.
The duration of the discontinuity experienced by
packet switched and circuit switched real time
services should be shorter than that in the hando-
ver of voice calls over GSM/GPRS.
Requirements on multiple bearer services
handover from UMTS radio access network to
GSM/GPRS
Consideration must be given to services that may
involve multiple bearer services (and simultaneous
sessions). The mapping between UMTS Radio
Access Network bearer services and GSM/GPRS
bearer services depends on many factors such as
data rate, delay constraints, error rate etc. In the
event that certain UMTS Radio Access Network
bearer services cannot be handed over to GSM/
GPRS, the handover of some of the bearers to
maintain the service should not be precluded.
In the case where a user equipped with a dual
mode terminal is in UMTS Radio Access Network
coverage, and has multiple PDP contexts activated
(for instance to support multimedia), then it is pref-
erable to handover one PDP context, rather than
dropping all of them.
As a first priority only the PDP contexts which have
an associated QoS that can be supported by the
GSM/GPRS should be candidates for handover.
If there are still multiple PDP contexts as “handover
candidates”, then the operator should choose
which PDP is maintained. When roaming, the serv-
ing network should make this decision. The opera-
tor may choose to either:
• Drop all of the PDP contexts.
• Choose one based upon criteria such as dura-
tion, amount of traffic transferred, etc.
Handover in P990i
This phone is compliant with the 3GPP R99
December 2002 release.
GSM to UMTS
The product supports circuit switched voice
handover from GSM to UMTS.
UMTS to GSM/GPRS
The product supports packet switched data
handover and circuit switched voice handover from
UMTS to GSM/GPRS.