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SON for Future Networks
FUTURE NETWORKS 2014
Technische Universität Braunschweig 25. September 2014
Multi-Layer LTE / Wi-Fi Access Network Selection
Yu Wang+, Daniela Laselva*, István Z. Kovács*, Per-Henrik Michaelsen*, Relja Djapicφ, Pieter Willemen^, Kathleen Spaeyx, Bart Sasx, Dries Naudts^, Andreas Bergström+
+Ericsson Research, Stockholm, Sweden; *Nokia, Aalborg, Denmark; φTNO, Delft, Netherlands; ^iMinds/Ghent University, Ghent, Belgium, x iMinds/University of Antwerp, Antwerp, Belgium
SEMAFOUR Vision
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Decision Support System
SERVICE PROVIDER
NETWORK OPERATOR
HETEROGENEOUS NETWORK
General Network-‐Oriented ObjecGves
Network Status related to General Network-‐Oriented ObjecGves
Integrated SON Management
Physical Network Resources
Physical Network Resources
Physical Network Resources
Policy-‐Based SON Management Mon
itorin
g &
Diagno
sis
OperaGonal SON CoordinaGon
MulG-‐RAT / MulG-‐layer SON
WLAN Mgmt.
2G / 3G SON
LTE SON
UNIFIED SELF-MANAGEMENT SYSTEM
§ Why SON for LTE/WiFi Access Network Selection?
§ Objective
§ SON function design for the Access Network Selection
§ SON function evaluation
§ SON function implementation
§ Summary and Future Work
Outline
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§ Operators are using Wi-Fi for offloading – “Carrier grade Wi-Fi”
§ Great interests in integrating cellular and Wi-Fi networks – WiFi Alliance: Hotspot 2.0 Release 1/2 – 3GPP: IP session continuity, ANDSF, Radio interworking
§ One key technology component: access network selection – Today behaviour: “Wi-Fi If Coverage”.
§ SON for access network selection – SON: proved working in related areas, e.g. load balancing – A good candidate to address the LTE/Wi-Fi access network selection in
dynamic radio and traffic environments
Why SON for LTE/WiFi Access Network Selection?
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§ Objective: Access network selection between multi-layer LTE and Wi-Fi in dense urban deployments to improve user experience and network efficiency
– SON for LTE load control – SON for Inter-RAT LTE/Wi-Fi load control – QoS-oriented access network selection, e.g. based on a per user
throughput metric
Objective
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Average Load
Target
SON for LTE load control
Average Load
Target
SON for Inter-RAT LTE/Wi-Fi load control
Average Load
Target
Objective: LTE Load Control Objective: Inter-RAT Load Control
No
No
LTE load and WiFi load monitoring
LTE load is high
WiFi load is high?
Steer traffic to WiFi
LTE load is low
Steer traffic to LTE
Yes
Yes
No
No
No
No
LTE load and WiFi load monitoring
LTE load is high
WiFi load is high
Steer traffic to WiFi
LTE load is low
WiFi load is low
Steer traffic to LTE
Steer traffic to LTE
Steer traffic to WiFi
Yes
Yes
Yes
Yes
SON Function Design for the Access Network Selection
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LTE load and WiFi load monitoring
Steer traffic to WiFi
Steer traffic to LTE
Steer traffic to LTE
Steer traffic to WiFi
Yes
Yes
Yes
Yes
No
No
No
No
SON for LTE load control
SON for Inter-RAT load control
WiFi load is high
LTE load is low
WiFi load is low
LTE load is high
?
?
Monitoring KPIs
Control Parameters
* When both LTE and WiFi load is high or low, no action will be taken
&WiFi AP LTE Micro
&WiFi AP
SON Function Design – Control Parameters
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LTE Macro LTE Micro
RSS Threshold RSS Minimum Macro/Micro boundary
Macro
Micro
WiFi
LTE Macro
RSRP Threshold High RSS Minimum Macro/Micro boundary
RSRP Threshold Low
Macro
Micro
WiFi
WiFi RSS Threshold LTE RSRP High & RSRP Low Thresholds
To steer more traffic to WiFi – Decrease WiFi RSS Threshold – Decrease RSRP High Threshold
Increase RSRP Low Threshold
§ LTE load – Average raw percentage of physical resource blocks (PRBs) utilization – Average fraction of required PRBs in a cell to serve connected UEs
with a certain minimum bit rate
§ Wi-Fi load – Average percentage of channel busy time of a Wi-Fi AP – The channel is considered as busy if there is at least one active
connection associated to the AP and the AP or a UE is transmitting
§ How fast the SON functions can change configuration parameters which determine access network selection of UEs
§ Observation & Adjustment period (0.5 – 2 seconds) § Control parameter step size (0.5 – 5 dB)
SON Function Design – Monitoring KPIs
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SON Function Evaluation - Scenario
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LTE Macro LTE Micro & WiFi User location Deployment: LTE macro layer: [email protected], 46dBm LTE micro layer: [email protected] 33dBm 6dB range extension WiFi 802.11n: [email protected]/5GHz, 20dBm
Traffic hot zone area
§ Realistic dense urban environments § Dense WiFi deployment § Outdoor & Indoor
Outdoor Hot Zone
§ Evaluation domain:
SON Function Evaluation - Overview
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LTE Load Control Inter-RAT Load Control
RSS Threshold RSRP Thresholds
Indoor Outdoor
Static Users Mobile Users
Objective
Control Parameter
Environment
Mobility
§ Presented in this presentation: – LTE Load Control + RSRP Thresholds + Outdoor + Static Users – Inter-RAT Load Control + RSS Threshold + Outdoor + Static Users
§ RSRP Threshold Low (macros) and RSRP Threshold High (micros) are properly adjusted to meet the objective, i.e. keep LTE cell load within target range (60-80%)
SON Function Evaluation – LTE Load Control
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10
20
30
40
50
60
70
80
90
100
Cell l
oad
(%)
LTE Macro Co-located LTE Micro / Wi-Fi AP
-110
-100
-90
-80
-70
-60
-50
-40
RSRP
Thr
(dBm
)
Cell LoadRSRP Thr HighRSRP Thr Low
Outdoor Hot Zone scenario without UE mobility
High load in macro#3 due to limited offloading possibilities
§ The SON configuration results in 50% offload to Wi-Fi while good Wi-Fi throughput is achieved, i.e. 5th-ile throughput of 2.6 Mbps
§ Overall good performance is achieved, avg UE throughput=19.1 Mbps – vs. Baseline “Wi-Fi if coverage” with mean UE throughput = 10.5 Mbps
§ Micro performance lower than macro due to presence of cell-edge UEs
SON Function Evaluation – LTE Load Control cont’
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Outdoor Hot Zone scenario without UE mobility
§ RSS Thresholds are properly adjusted to meet the objective, i.e. balance the load between LTE and Wi-Fi
SON Function Evaluation – Inter-RAT Load Control
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20
40
60
80
100
Cell
load
-80-75-70-65-60-55-50-45-40
RSS
thre
shol
d (d
Bm)
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20
40
60
80
100
Cell
load
-80-75-70-65-60-55-50-45-40
RSS
thre
shol
d (d
Bm)
Fixed Threshold = -65 dBm
SON function
Wi-Fi Load
LTE Load
RSS Threshold
§ Convergence and stabilization of the RSS threshold
SON Function Evaluation – Inter-RAT Load Control cont’
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20 40 60 80 100 1200
20
40
60
80
100
Load
(%)
-80-75-70-65-60-55-50-45-40
RS
S th
resh
old
(dB
m)
Time (sec)
RSS thresholdWLAN AP loadLTE cell load
§ The proposed SON functions are intended to be implemented in a distributed manner
– Control parameters are updated every few seconds
§ Implementation of the access network selection rules – Executed in terminals assisted by the network: Control parameter thresholds
are sent to terminals via broadcasted or dedicated signalling channels being standardized in 3GPP (RAN2 R12)
– Controlled by the network: Control parameters are monitored at a network node and the node controls the access network selection
§ Information exchange between LTE and WiFi – Standardization of such an interface is being discussed in 3GPP (RAN3 SI) – Proprietary interfaces – Terminals as relays
SON Function Implementation
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§ SON functions for LTE and Wi-Fi access network selection have been designed, evaluated and demonstrated in realistic dense urban scenarios
§ The effectiveness of the SON functions was proved with controlled load levels and improved user throughput
§ We found the performance of the SON functions were most sensitive to the control parameter updating pace, i.e. the step size and period
§ Next step: QoS-oriented access network selection, e.g. based on a per user throughput metric
Summary and Future Work
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DEMONSTRATOR on Multi-Layer LTE / Wi-Fi Access Network Selection Presented in Room SN22.2 during the next break!
POSTERS on the SEMAFOUR use cases
Presented during the next break in Room SN22.2
Don’t miss!
18 SEMAFOUR - Workshop on SON for Future Networks, 25. September 2014
Thank you for your attention
www.fp7-semafour.eu
19 SEMAFOUR - Workshop on SON for Future Networks, 25. September 2014