12. feb.2010 | christian müller distributed resource allocation in ofdma-based relay networks...
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12. Feb.2010 | Christian Müller
Distributed Resource Allocation in OFDMA-Based Relay Networks
Christian Müller
12. Feb. 2010 | Christian Müller
Outline
Motivation Relay Networks Scenarios and Problems Definitions Distributed Resource Allocation Summary
1
12. Feb. 2010 | Christian Müller
Outline
Motivation Relay Networks Scenarios and Problems Definitions Distributed Resource Allocation Summary
1
12. Feb. 2010 | Christian Müller
Coverage in Today‘s Cellular Networks
Base Station (BS)
User Equipment (UE)
wired backbone
Coverage Problem
2
12. Feb. 2010 | Christian Müller
Coverage in Relay Networks
Base Station (BS)
User Equipment (UE)
wired backbone
Coverage Problem
BS
UE
wired backbone
Improved Receive Power
Relay Station (RS)
2
12. Feb. 2010 | Christian Müller
Capacity in Today‘s Cellular Networks
wired backbone
Capacity Problem
3
12. Feb. 2010 | Christian Müller
Capacity in Relay Networks
wired backbone
Capacity Problem Frequency Reuse
wired backbone
3
12. Feb. 2010 | Christian Müller
Outline
Motivation Relay Networks Scenarios and Problems Definitions Distributed Resource Allocation Summary
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12. Feb. 2010 | Christian Müller
Considered Scenarios with Respect to Coverage and Capacity Problem
1st
2nd
3rd
5
RS • operating in half-duplex mode• decode, re-encode & forward
Orthogonal Medium Accessdownlink transmission
12. Feb. 2010 | Christian Müller
Considered Scenarios with Respect to Coverage and Capacity Problem
1st
2nd2nd
1st
2nd
3rd
5
Orthogonal Medium Accessdownlink transmission
Reuse Medium Accessdownlink transmission
RS • operating in half-duplex mode• decode, re-encode & forward
12. Feb. 2010 | Christian Müller
Resource Units
BS & RSs: time division OFDMA (Orthogonal Frequency Division
Multiple Access) set of predefined beams power modulation and coding schemes
6
time
frequency
slot
time-frequency unit
grid of beams
-150 -100 -50 0 50 100 150
0
-10
-30
-40
-50
-60
-20
direction in degrees
ante
nna
gai
n in
dB
resource block
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Resource Allocation Problem
7
user rates depend on allocation of all resource units
Huge Resource Allocation Problem• solution based on channel quality information• duration for solution limited by coherence time
• scenario• objective
12. Feb. 2010 | Christian Müller
Outline
Motivation Relay Networks Scenarios and Problems Definitions Distributed Resource Allocation Summary
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12. Feb. 2010 | Christian Müller
Novel ConceptsS
cen
ario
9
Orthogonal Medium Access
Reuse Medium Access
12. Feb. 2010 | Christian Müller
Novel ConceptsS
cen
ario
Distributed Concept for Orthogonal Medium Access
Distributed Concept for Reuse Medium Access
9
Orthogonal Medium Access
Reuse Medium Access
12. Feb. 2010 | Christian Müller
Novel Concepts
maximize sum of user rates subject to
minimum user rate
maximize minimum user rate
Trade-off performance vs. fairness
Sce
nar
io
Distributed Concept for Orthogonal Medium Access
Distributed Concept for Reuse Medium Access
9
Orthogonal Medium Access
Reuse Medium Access
12. Feb. 2010 | Christian Müller
Novel Concepts
exemplarily presentedcf. thesis
cf. thesis cf. thesis
9
maximize sum of user rates subject to
minimum user rate
maximize minimum user rate
Trade-off performance vs. fairness
Sce
nar
io
Orthogonal Medium Access
Reuse Medium Access
12. Feb. 2010 | Christian Müller
Distributed Concept for Reuse Medium Access
BS: design of grids of beams
RS: allocation of resource blocks
beams applied ontime-frequency unit
BS: allocation of resource blocks
bits per slot on RS-to-UE links
- uniformly allocated power- fixed number of allocated slots
Assumptions Flow of Subproblems
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12. Feb. 2010 | Christian Müller
Distributed Concept for Reuse Medium Access
BS: design of grids of beams
RS: allocation of resource blocks
beams applied ontime-frequency unit
BS: allocation of resource blocks
bits per slot on RS-to-UE links
- uniformly allocated power- fixed number of allocated slots
Assumptions Flow of Subproblems
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12. Feb. 2010 | Christian Müller
Design of Grids of Beams
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inter-beam interference
co-channel interference
unknown:– current positions of UEs– channel quality information
12. Feb. 2010 | Christian Müller
Design of Grids of Beams
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unknown:– current positions of UEs– channel quality information
non-adaptive solution:• each beam equally frequent• equal distance• randomly allocated to time- frequency unit
12. Feb. 2010 | Christian Müller
Design of Grids of Beams
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inter-beam interference
co-channel interference
RS1
RS2
unknown:– current positions of UEs– channel quality information
non-adaptive solution:• each beam equally frequent• equal distance• randomly allocated to time- frequency unit
known:+ positions of BS and RSs+ pathloss model+ beams+ user distribution
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Adaptive Design
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coverage areaof beam
metric for each combination of beams:
• determine interference based on pathloss model and antenna gain
• average value based on coverage area and user distribution
12. Feb. 2010 | Christian Müller
Adaptive Design
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coverage areaof beam
metric for each combination of beams:
• determine interference based on pathloss model and antenna gain
• average value based on coverage area and user distribution
use beams more often where receiving stations are expected
hot spot
12. Feb. 2010 | Christian Müller
Adaptive Design
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coverage areaof beam
metric for each combination of beams:
• determine interference based on pathloss model and antenna gain
• average value based on coverage area and user distribution
use beams more often where receiving stations are expected
allocate beams to time-frequency units sequentially → best fit
algorithm
hot spot
12. Feb. 2010 | Christian Müller
Distributed Concept for Reuse Medium Access
BS: design of grids of beams
RS: allocation of resource blocks
beams applied ontime-frequency unit
BS: allocation of resource blocks
bits per slot on RS-to-UE links
- uniformly allocated power- fixed number of allocated slots
Assumptions Flow of Subproblems
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Motivation of Assumptions
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co-channel interference
12. Feb. 2010 | Christian Müller
Motivation of Assumptions
Distributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
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12. Feb. 2010 | Christian Müller
Motivation of Assumptions
pilots of BSDistributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
1.pilot phase → Signal-to-Interference-plus-Noise Ratio (SINR) estimation
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12. Feb. 2010 | Christian Müller
Motivation of Assumptions
pilots of RSpilots of RS
Distributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
1.pilot phase → SINR estimation
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12. Feb. 2010 | Christian Müller
Motivation of Assumptions
Distributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
1.pilot phase → SINR estimation2.SINR feedback
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12. Feb. 2010 | Christian Müller
Motivation of Assumptions
Distributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
1.pilot phase → SINR estimation2.SINR feedback
14
12. Feb. 2010 | Christian Müller
Motivation of Assumptions
Distributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
1.pilot phase → SINR estimation2.SINR feedback3.allocation of resource blocks
SINR knowledge RS1 SINR knowledge RS2
SINR knowledge BS
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12. Feb. 2010 | Christian Müller
Motivation of Assumptions
Distributed Concept for Reuse Medium Access: • uniformly allocated power• fixed number of allocated slots• design of grids of beams
1.pilot phase → SINR estimation2.SINR feedback3.allocation of resource blocks4.data transmission
14
12. Feb. 2010 | Christian Müller
Distributed Concept for Reuse Medium Access
BS: design of grids of beams
RS: allocation of resource blocks
beams applied ontime-frequency unit
BS: allocation of resource blocks
bits per slot on RS-to-UE links
- uniformly allocated power- fixed number of allocated slots
Assumptions Flow of Subproblems
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Allocation of Resource Blocks
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Literature:• one problem across all links• requires knowledge of SINR
values in one point for- all resource blocks- all links
SINR values of resource blocks → bits per resource blocks
use SINR values locally→ distributed allocation
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Allocation of Resource Blocks Provided by RS
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• allocate resource blocks with objective max. min. user ratea) non-adaptiveb) adaptive
UE2
UE1 UE3
time
frequency time
frequency
1st beam:
2nd beam:
UE1
UE1
UE1
UE1
UE3
UE3
UE3
UE2
UE2
UE2
example with 2 beams:
12. Feb. 2010 | Christian Müller
Allocation of Resource Blocks Provided by RS
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• allocate resource blocks with objective max. min. user rate
a) non-adaptiveb) adaptive
• RSs know bits per slot for each RS-to-UE link
12. Feb. 2010 | Christian Müller
Allocation of Resource Blocks Provided by RS
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• allocate resource blocks with objective max. min. user rate
a) non-adaptiveb) adaptive
• RS knows bits per slot for each RS-to-UE link
• feedback to BS
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Allocation of Resource Blocks Provided by BS
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UE5UE4
RS1 RS2
2nd beam:
time
frequency
1st beam: RS1
RS1
UE4
UE5
RS2
time
frequency
UE4
RS2
RS2
RS1
RS1
• allocate resource blocks with objective max. min. weighted user rate
• UE weighted by 1, RS weighted by (number of UEs)-1
12. Feb. 2010 | Christian Müller
Allocation of Resource Blocks Provided by BS
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UE5UE4
RS1 RS2
• allocate resource blocks with objective max. min. weighted user rate
• UE weighted by 1, RS weighted by (number of UEs)-1
• RS is not allocated more than required
12. Feb. 2010 | Christian Müller
Evaluation Parameters
Parameter Value
size grids of beams 3
time-frequency units 64
number of resource blocks 192
number of slots 100
bits per symbol of modulation and coding schemes
0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8
main lobe direction 0°, 30°, 60°, …, 330°
channel model BS/RS to UE non-line of sight model
channel model BS to RS line of sight model
Coordinates in meter
Coo
rdin
ate
s in
met
er
BSRS
RS0
-100
-200
200
100
0-100-200 300100 200
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100
Performance Evaluation Design of Grids of Beams
20
all-adapt.BS: GoB, RB | RS: RBnon-adapt.
number of UEs5 10 15 20 25 30 35 40
0
120
80
60
40
20
aver
age
min
imum
use
r ra
te in
bits
/slo
t
GoB: design of grids of beams
RB: allocation of resource blocks
12. Feb. 2010 | Christian Müller
Performance Evaluation Allocation of Resource Blocks
21
all-adapt.BS: GoB, RB | RS: RBnon-adapt.
number of UEs5
010 15 20 25 30 35 40
120
100
80
60
40
20
aver
age
min
imum
use
r ra
te in
bits
/slo
t
GoB: design of grids of beams
RB: allocation of resource blocks
12. Feb. 2010 | Christian Müller
1
101
103
Signalling RS to BS
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per resource block:
- channel gain - phase - noise/interference assumption:
4 bits per value
all time-frequency units and best modulation and coding scheme used
number of UEs served by RS
100
102
104
105
num
ber
of
bits
/slo
t
2 3 4 5 6 7 8 9 10
Reference Central genius approach Distributed Concept For Reuse Medium Access
12. Feb. 2010 | Christian Müller
Outline
Motivation Relay Networks Scenarios and Problems Definitions Distributed Resource Allocation Summary
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12. Feb. 2010 | Christian Müller
Summary
formulation of resource allocation problems in relay networks aiming at fair user rate allocation & high sum rate allocation in scenarios without & with co-channel interference
concepts dividing problem in subproblems design grids of beams solved first in order to gain information about channels adaptive design of grids of beams according to user distribution and pathloss use information about channel locally and allocate resource blocks distributed
across BS and RSs low amount of signalling between RS and BS through bits/slot signalling
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12. Feb. 2010 | Christian Müller
Thank you.
12. Feb. 2010 | Christian Müller
Novel Adaptive Solutions
Maximize Sum of User Rates Subject to Minimum User Rate
Maximize Minimum User Rate
• noise• inter-beam interference
• noise• inter-beam interference • co-channel interference
Design of Grids of Beams
Allocation of Slots
BS: Allocation of Resource Blocks
Allocation of Slots
BS: Allocation of Resource Blocks
BS: Allocation of Power and Bits BS: Allocation of Power and Bits
RS: Allocation of Resource Blocks RS: Allocation of Resource Blocks
RS: Allocation of Power and Bits RS: Allocation of Power and Bits
BS: Allocation of Resource Blocks BS: Allocation of Resource Blocks
RS: Allocation of Resource Blocks RS: Allocation of Resource Blocks
Design of Grids of Beams
A
12. Feb. 2010 | Christian Müller
Motivation of Concepts
Design of Grids of Beams
Allocation of Resource Blocks,
Power and Bits
Allocation of Slots
Solution based on continuous number of bits depending on
SINR
Joint solutionbased on flexible number of
slots for single UE
Central solution
Joint concept for conventional network
Current information about co-channel interference
Solutions for combinational problems
Allocation of slots part of the concept for multiple
RSs and UEs
Use channel knowledge locally and define
distributed solution
Entire concept for relay networks
Pathloss model and user distribution
B