Transcript PPT Presentation

Enhanced Uplink Carrier Aggregation for
LTE-Advanced Femtocells
VTC Fall: September 6th 2011
Authors:
Luis G. Uzeda Garcia et. al.
Soc Classification level
1
© Nokia Siemens Networks
Presentation / Author / Date
Outline
• Motivation : Problem Definition
• Preliminaries: UL FPC and ACCS
• Proposed Solution
• Simulation Assumptions & Results
• Conclusions
Soc Classification level
2
© Nokia Siemens Networks
Presentation / Author / Date
Motivation: Problem Definition
UL Carrier Aggregation in Macro Cells:
– Possible to schedule UEs on multiple CCs
– Problem: single or multiple CCs?
– Answer: distinguish between power limited
and non-power limited UEs
UL Carrier Aggregation in Femto Cells:
– Problem: single or multiple?
– Fact: power limited UEs are unlikely
– Poor answer: always multiple CCs
– Better answer: consider CA for ICIC
Hua Wang, et al., “Uplink Component Carrier Selection for LTE-Advanced Systems with Carrier
Aggregation,” in IEEE ICC, June 2011
Soc Classification level
3
© Nokia Siemens Networks
Preliminaries: UL Fractional power control
Not considered in this study
Power control formula [TS 36.213]:
P[dBm] = min{ Pmax, P0 + α*L + 10*log10M + Δmcs + f(Δi) }
Power control in uplink aims at:
– Controlling inter-cell interference
– Prolonging UE battery life time
– Achieving lower receiver dynamic
range
Thinking multi-cell:
– Uncoordinated femtocell deployments
– Close Subscriber Groups
– Severe inter-cell interference
– Introduce UL FPC information into the
CC selection procedure
Soc Classification level
4
© Nokia Siemens Networks
UL “interfered zones” may
differ from UE to UE
Preliminaries: ACCS in a nutshell
Autonomous Component Carrier Selection (ACCS) is a self-organizing
and fully distributed interference management concept on a CC level.
ACCS Framework
Femto is
powered on
Select Base
CC
Evaluation based
on BIM entries
BIM relies on DL
measurements!
Nice DL simulation
results!
Soc Classification level
5
© Nokia Siemens Networks
Presentation / Author / Date
What about the
UL?
Traffic
Increases
Select
Supplementary CCs
Proposed Solution (1/2)
Apply ACCS
• ACCS Assumptions
• BIMs: predict C/I experienced whenever
Cell-Specific
UE1
UE1
UE2
UE2
UE3
UE3
Equivalent
FAP CC-set
Soc Classification level
6
© Nokia Siemens Networks
Presentation / Author / Date
UE-Specific
U
two cells (serving and interferer) use the
same CC at the same time with equal
transmit Power Spectral Densities
• UL {1} → {2} ≈ DL{1} ← {2}
• UL {1} ← {2} ≈ DL{1} → {2}
Expected Outcomes
U
Equivalent
FAP CC-set
Proposed Solution (2/2)
“Fixing” BIMs
•
UE (i) is the UE, among the ones served by
HeNB {1}, with the largest path loss towards
it, in this example UE [B]. This UE is
potentially the worst victim of incoming UL
interference.
•
UE (j) is the UE responsible for cell’s {1} , i.e.
cell’s {2} . This is the UE served by HeNB {2}
that potentially is the worst source of UL
interference towards HeNB {1} – in this
example UE [C].
•
UE (k) in (5) is the one responsible for cell’s
{1} , i.e. the worst source of outgoing uplink
interference towards HeNB {2}. In this case,
it is UE [B] as well (k=i), but this is not
necessarily always true. Either way, this has
no impact in terms of signaling since UEs
(i,k) are served by the same evaluating cell.
•
Finally, UE (l) is analogous to UE (i), in that,
it is the UE with the largest path loss towards
its serving cell {2} and hence the worst
potential victim of outgoing interference, in
our example: UE [D].
Soc Classification level
7
© Nokia Siemens Networks
Presentation / Author / Date
Cell-Specific
UL{S }{n}  DL{S }{n}  ( Li , L j )  ( PSDi , PSD j )
UL{S }{n}  DL{S }{n}  ( Lk , Ll )  ( PSDk , PSDl )
UE-Specific
UL {n}  DL{S }{n}  ( L , L j )  ( PSD , PSD j )
UL {n}  DL {n}  ( L , Ll )  ( PSD , PSDl )
Simulation Assumptions
Dual Stripe scenario:
10 m
10 m
Deployment Assumptions
10 m
• Topology:
– Three floors (up to 120 Femtos)
– Deployment ratio 75%
• Closed Subscriber Group (CSG)
•
•
•
•
No co-channel Macro layer
Antenna configuration: 2x2
Path loss model from R4-091422
Wall penetration loss: 5/10 dB
(inner/outer) walls
• Uniform distribution of 1 UE and 3UEs
per residence (always indoors)
• Simple full buffer traffic
• Equal resource packet scheduling
Soc Classification level
8
© Nokia Siemens Networks
Presentation / Author / Date
10 m
10 m
ACCS Assumptions
• 5 Component Carriers
• Minimum required SINR for primary CC
and secondary CC equals 15 and 8 dB,
respectively
UL FPC Assumptions
P0 =[-50] dBm
α = [0.2 0.4, 0.6, 0.8,1.0 ]
PTX min = -40 dBm
PTX max = 23 dBm
Key Performance Indicators
• UL SINR
• CC usage/cell and CC usage/UE
• Average UL Cell TP
– Aggregated throughput from all UEs connected to a single cell [Mbps]
• UL Outage User TP
– 5%-percentile of UE throughput [Mbps]
• Normalized (relative) versions of the two variables:
– Baseline performance: Unmodified ACCS
Soc Classification level
9
© Nokia Siemens Networks
Presentation / Author / Date
Simulation Results: 1 UE/cell
UL SINR: Original ACCS versus proposed
method. The 0% to 10% outage region is
highlighted. The correction is much more
relevant for low values of α as the imbalance
between DL and UL estimations increases.
The share of UEs who have access to at
least 2 CCs increases when compared to
the original case. That combined with the
SINR improvement led to the significant
relative gains in outage throughput
UL {n}  DL{S }{n}  ( L , L j ).(1   )
Imbalance:
SINR Comparison
1
CC Usage per Cell Comparison
0.35
=0.2 Original
0.9
=0.4 Original
0.8
=0.8 Original
=0.6 Original
0.3
 =0.2
 =0.4
 =0.6
 =0.8
0.25
Original
=0.2 Proposed
=0.4 Proposed
=0.6 Proposed
0.6
0.5
Relative Frequency
Empirical CDF
0.7
=0.8 Proposed
0.1
0.4
0.3 0.05
0.2
0.15
0.1
0.2
0.1
0
-20
0.05
0
6
-15
8
-10
10
-5
12
14
0
5
10
Average UL SINR [dB]
Soc Classification level
10
© Nokia Siemens Networks
15
20
Presentation / Author / Date
25
30
0
1
2
3
4
Total # of deployed CCs/cell
5
Perfomance Results: 1 UE/cell and 3 UEs/cell
The potential of the proposed scheme,
especially in terms of UL 5% outage
throughput where relative gains of up to
52% are seen with respect to the
original non-FPC-aware ACCS concept.
UE specific with 3UEs/cell: the effective
CC usage per cell is the set union of the
CC usage of its served UEs. Cells reuse
CCs more aggressively when compared
to UEs.
Proposed versus Original
Multi UEs/cell
60
0.4
50
CCs/UE:  =0.6
0.35
0.3
40
Relative Frequency
Relative Performance (%)
CCs/cell:  =0.6
Average Cell TP
5% Outage UE TP
30
20
0.25
0.2
0.15
0.1
10
0.05
0
-5
0.2
0.4
0.6
Value of  (UL FPC)
Soc Classification level
11
© Nokia Siemens Networks
Presentation / Author / Date
0.8
0
1
2
3
Total # of deployed CCs
4
5
Final Remarks and Conclusions
• ACCS provides a fully distributed (scalable) and self-adjusting
frequency re-use mechanism for the UL as well.
• Enhanced Uplink Component Carrier Selection Scheme
boosts UL performance further.
• User Specific Uplink Component Carrier Selection allows a
“virtual” and controlled reuse-1, thus solving the UL CA
problem in Femtocells.
• Actively tweaking FPC parameters using the proposed
framework are suggested for future studies.
Soc Classification level
12
© Nokia Siemens Networks
Presentation / Author / Date
Thank You!
Questions?
[email protected]
Soc Classification level
13
© Nokia Siemens Networks
Appendix with additional slides
Soc Classification level
14
© Nokia Siemens Networks
Presentation / Author / Date
Perfomance Results: ACCS UL @ 75%
ACCS seems to capture the benefits from the ‘best’ frequency reuse cases in
terms of both KPIs. Results inline with DL ones.
All results are normalized with respect to plain
frequency re-use with no power control.
Soc Classification level
15
© Nokia Siemens Networks
Presentation / Author / Date
Performance Summary
Deployment
Configuration
Ratio
25%
75%
Average cell
capacity
Outage capacity
1/1 {-60; 0.6}
-5%
+25%
1/3 {NO PC}
-43%
+116%
ACCS {-60; 1}
+18%
+235%
1/1 {-60; 0.6}
-8%
+69%
1/3 {-60; 0.8}
-7%
+332%
ACCS {-60; 0.8}
+26%
+416%
P0 ≈ -60 dBm and high α values [0.6 , 0.8]
seem to be the most promising settings.
Soc Classification level
16
© Nokia Siemens Networks