Laboratory 3: Intra e-UTRAN Handover

Aims:
This part of the lab is designed to provide studen
ts with an overview of handover scenarios within
LTE EUTRAN. It is based on the intra e-UTRAN handov
er test performed in a Telstra’s LTE FDD
network travelling on a train from Redfern to Peter
sham. Nemo Handy has been used as test equipment
and the recorded log files have been further proces
sed using Nemo Analyze. The recorded data in Excel
sheet is provided for students to study the handove
r events and present them in a graphical form.
Outline:
Section 1 – Introduction to Relevant Theory
1.1 LTE Mobility Management
1.2 Handover
1.3 3GPP Defined Handover for LTE
1.4 Handover Decision in Intra e-UTRAN
1.4.1 RSRP
1.4.2 RSRQ
1.5 Reselection
Section 2 – Measurement Explanation and Example
2.1 System Description
2.2 Measurement Data
Section 3 – Lab Exercise
Task 1: Coverage and Quality
Task 2: Handover Event
Task 3: Ping-pong Handover
Appendix A – Example: handover Scenario
42890 4G Mobile Technologies
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P a g e
Section 1: Introduction to Relevant Theory
1.1 LTE Mobility Management
LTE handles the mobility of UE in two general state
s; RRC Connected and RRC Idle state. When the UE
is in RRC Idle state cell reselection occurs for th
e mobility of UE whereas when it is in RRC Connecte
d
state handover procedures handle the mobility.
Fig 1: EMM and ECM States
1.2 Handover
In RRC Connected mode, mobile devices are usually f
ully synchronized with the network in the uplink
and downlink directions and can therefore transmit
and receive data at any time. While the device is i
n
this state, a user data tunnel is established betwe
en the SGW and eNB and another tunnel between SGW
and PDN GW. Data can transmit in both directions an
d at the same time UE is continuously monitoring
the signal quality of serving and neighboring cells
which it reports to the network in pre defined tim
e
interval. On the basis of measurement report, netwo
rk triggers the handover to move UE to the better c
ell.
In LTE, handover is controlled autonomously by each
eNodeB which also decides the interval for
measurement reporting either periodically or event
triggering. The reason for distributing the intelli
gence
among base stations in LTE is to reduce the connect
ion setup time and to speed up the handover
procedure. Thus, eNodeB itself is responsible to se
nd the measurement report parameters to the mobile
device once the RRC connection is established and w
ith the RRC configuration message when handed
over to new cell.