Filter
Top Products
White Paper V600
17 August 2005
Access Network and other radio systems such as
GSM/GPRS. As a principle, the requirements on
service continuity characteristics should be
according to the target network on which the serv-
ice is maintained.
Service continuity
Service continuity should support the following
scenarios:
• 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 co-located 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.