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LTE Mobility
Prepared for LTE seminar (2007-12-06) by EAB/TBU Gunnar Mildh
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Ericsson Internal LTE Mobility 2007-12-172
Content of presentation
Background, Requirements and Solutions for
Intra-LTE mobility
Inter-RAT mobility with GERAN/UTRAN
Inter-RAT mobility with CDMA2000
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Intra-LTE mobility
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Ericsson Internal LTE Mobility 2007-12-174
Service requirements on intra-LTE mobility
Not so strong compared to other requirements such as
user plane latency (< 10 ms), capacity, …
–3GPP TR 25.913 only states that the service interruption
should be less or equal than GSM CS
Looking at possible services today it is difficult to find
some services with strong requirements
–Voice works with < 200 ms
–TCP should probably cope with 100 ms interruption as long
as there are not packet losses
–Play out buffers for streaming would probably be much
larger than 200 ms
Requirements for future services are unknown
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Ericsson Internal LTE Mobility 2007-12-175
Radio requirements
The characteristics of the LTE radio system will lead to
quite tough requirements on the intra-LTE mobility
solution
–No soft handover
–Reuse 1 (potential for strong interference at street corners
etc.)
–Problems seen today when using hard handover in HSPA
This leads to a risk that UE is looses connection to
serving cell before handover is completed (illustrated
on next slide)
–UE experiences a radio link failure, leading to longer
service interruption
