Arif Otyakmaz, ComNets, RWTH Aachen University Half- and Full-Duplex FDD Operation in Cellular Multi-Hop…
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Arif Otyakmaz, ComNets, RWTH Aachen University
Half- and Full-Duplex FDD Operation in Cellular Multi-Hop
Mobile Radio Networks
Arif Otyakmaz, Rainer Schoenen
Department of Communication Networks RWTH Aachen University, Germany
FFV Workshop, 21.11.2008
1515thth FFV Workshop FFV Workshop
2Arif Otyakmaz, ComNets, RWTH Aachen University
OverviewOverviewOverview – Introduction – Duplex – System– Concept - Simulations - Conclusion
• Introduction and Motivation• Duplex Schemes in Mobile Radio
Networks• WINNER MAC frame structure• Concept for Relay Capable Combined
Full-/Half-Duplex FDD• Simulation Scenarios and Results• Conclusion
3Arif Otyakmaz, ComNets, RWTH Aachen University
Introduction and MotivationIntroduction and Motivation
• WRC 2007 frequency bands identified for IMT-Advanced systems
• ITU-R published invitation for submission of proposals for candidate IMT-Advanced systems
• Likely candidates (among others):– 3GPP LTE-Advanced (Release 10)– IEEE 802.16m (WiMAX)– IST WINNER and Celtic WINNER+ projects
• To provide scalability and adaptivity candidate systems– are based on OFDMA– support FDD and TDD– integrate “Decode-and-Forward” layer 2 relaying for
capacity enlargement and coverage extension
Overview – Introduction – Duplex – System– Concept - Simulations - Conclusion
4Arif Otyakmaz, ComNets, RWTH Aachen University
Duplex SchemesDuplex Schemes
• Time Division Duplex (TDD)– Able to adapt the DL and UL phases
according to the data service– Switching between DL and UL needs
guard times to avoid interference– Larger cells lead to larger guard times Practical for metropolitan area
environments• Frequency Division Duplex (FDD)
– No need for guard times due to different radio resources in DL and UL
– Not able to adapt to different data services like TDD
– Higher cost of manufacture Practical for wide area environments
• Half-duplex FDD (HFDD)– Cheaper alternative to full-duplex FDD
time
guard band
DL UL
DL
UL
guard time
frequency
TDD
FDD
time
guard band
DL
UL
frequency
HFDD
Overview – Introduction – Duplex – System– Concept - Simulations - Conclusion
5Arif Otyakmaz, ComNets, RWTH Aachen University
WINNER MAC Frame and RelayingWINNER MAC Frame and Relaying
“UT” “UT” “BS” “UT” “BS”“BS” “BS”
frame
“UT”
f
t
BS
UT
RN
RUT
hop1
hop2relay link
feeder link
• Relay Nodes (RN) change “task” on frame basis• “BS task” on 2nd hop: Supplying associated Remote User Terminals (RUT) on
resources assigned by the BS by means of so called “resource partitioning• “UT task” on 1st hop: “Fed” by supplying Base Station (BS)
Overview – Introduction – Duplex – System– Concept - Simulations - Conclusion
UL
DL
duplex guardband
frame0.6912 ms
preamble0.36 ms
1 super-frame = 1 preamble + 8 frames = 0.36 ms + 8 x 0.6912 ms = 5.8896 ms
f
t
chun
k
UL
Sync
h.
RA
CH
DL
Sync
h.
BC
HB
CH
BC
H
6Arif Otyakmaz, ComNets, RWTH Aachen University
Concept for Relay CapableConcept for Relay CapableCombined Full-/Half-Duplex FDDCombined Full-/Half-Duplex FDD
Map
Data
BS
UT Half-Duplex Group 1
RN
UL
DL
frequ
ency 2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
20 21 763 54framenumber / time
UL
DL
frequ
ency 2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
20 21 763 54framenumber / time
UL
DL
frequ
ency UT
UT
BS
BS
UT
UT
BS
BS
UT
UT
BS
BS
UT
UT
BS
BS0 21 763 54framenumber / time
UL
DL
frequ
ency 1
2
2
1
1
2
2
10 21 763 54framenumber / time
RemoteUT Half-Duplex Group 1
Overview – Introduction – Duplex – System– Concept - Simulations - Conclusion
7Arif Otyakmaz, ComNets, RWTH Aachen University
Single-Hop Scenario:Single-Hop Scenario:One BS, one FD-UT, one HD-UTOne BS, one FD-UT, one HD-UT
Overview – Introduction – Duplex – System– Concept - Simulations - Conclusion
FDUL FD HD
UL FD HD
Saturation of full-duplex and half-duplex UT
Frame N Frame N+1
Frame N Frame N+1
Full-Duplex UT below saturation
8Arif Otyakmaz, ComNets, RWTH Aachen University
Representative Multi-Hop ScenarioRepresentative Multi-Hop ScenarioOverview – Introduction – Duplex – System– Concept - Simulations - Conclusion
UT3
UT4
UT5
RUT6
RUT7
RUT8
BS1 RN2
hop1hop2
UT3
UT4
UT5
RUT6
RUT7
RUT8
SingleHop (SH)
FDFDD
MultiHop (MH)
HDFDDGroup 1
Group 2
Single-Hop Multi-Hop
Full-DuplexFDD
Half-DuplexFDD
Group 1
Group 2
9Arif Otyakmaz, ComNets, RWTH Aachen University
Resource Partitioning between BS and RNResource Partitioning between BS and RNOverview – Introduction – Duplex – System– Concept - Simulations - Conclusion
BS1
time
frequ
ency
DL
UL
BS UTTaskPhase
RN267%
BS1
BS1RN267%
BS1
BS1RN2
BS1
BS1RN2
BS1
BS1RN2
BS1
BS1RN2
BS1
...
...
frame 0 1 2 3 4 5 ...
...
UT3
UT4
UT5
RUT6
RUT7
RUT8
BS1 RN2
hop1hop2
DL
UL
“BS” “BS” “BS”“UT” “UT”“UT” RN “task”
10Arif Otyakmaz, ComNets, RWTH Aachen University
Uplink ThroughputUplink ThroughputOverview – Introduction – Duplex – System– Concept - Simulations - Conclusion
Offered total traffic [Mbit/s]
Thro
ughp
ut p
er s
tatio
n [b
it/s]
(* 1
07 )
UT3
UT4
UT5RUT6
RUT7RUT8
Offered total traffic [Mbit/s]
Thro
ughp
ut p
er s
tatio
n [b
it/s]
(* 1
07 )
UT3UT4
UT5
RUT6RUT7
RUT8
Stateless/memoryless scheduler:Round-Robin
Stateful scheduler:Proportional-Fair
UL th
roug
hput
per
stat
ion
[Mbi
t/s]
UL th
roug
hput
per
stat
ion
[Mbi
t/s]
Total offered UL cell traffic [Mbit/s] Total offered UL cell traffic [Mbit/s]
x10x10
11Arif Otyakmaz, ComNets, RWTH Aachen University
Proportional Fair: History Weight ParameterProportional Fair: History Weight ParameterOverview – Introduction – Duplex – System– Concept - Simulations - Conclusion
Offered total traffic [Mbit/s]
Thro
ughp
ut p
er s
tatio
n [b
it/s]
(* 1
07 )
Offered total traffic [Mbit/s] P
acke
t del
ay [s
]
UT3
UT4UT5
RUT6
RUT7RUT8
x10
Total offered UL cell traffic [Mbit/s]
UL th
roug
hput
per
stat
ion
[Mbi
t/s]
Total offered UL cell traffic [Mbit/s]UL
pac
ket d
elay
[s]
• Enlarging “history weight” parameter to 0.99 leads to fairness in terms of throughput between the different UT types
12Arif Otyakmaz, ComNets, RWTH Aachen University
ConclusionConclusionOverview – Introduction – Duplex – System– Concept - Simulations - Conclusion
• “Proof of Concept” for relay capable combined full-/half-duplex FDD
• A memoryless scheduler– leads to unfair capacity share between half- and full-duplex
UTs.– can lead to waste of / unused resources.– In multi-hop scenarios this unfairness intensifies.
• A stateful scheduler– guarantees scheduling fairness over multiple frames and so
solves before mentioned problems.– Scheduler strategy “Proportional-Fair” is sufficient.
• Multi-hop operation demands sophisticated coordination– Considering number of remote UTs already during scheduling
for first hop– Balance between “resource partitioning” for second hop and
scheduling for first hop• Cognitions directly applicable to LTE and WiMAX
13Arif Otyakmaz, ComNets, RWTH Aachen University
Thank you for your attention !
Arif Otyakmazaoz@comnets.rwth-aachen.de
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