EDGE-PRIORITIZED CHANNEL- AND
TRAFFIC-AWARE UPLINK CARRIER
AGGREGATION IN LTE-ADVANCED SYSTEMS
AUTHORS
R. SIVARAJ, A. PANDE, K. ZENG, K. GOVINDAN,
P. MOHAPATRA
PRESENTER
R. SIVARAJ,
Ph.D student in CS,
UC DAVIS, CA, USA
Email: rsivaraj AT ucdavis DOT edu
http://spirit.cs.ucdavis.edu
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AGENDA OF THE PRESENTATION
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INTRODUCTION
ISSUES IN EXISTING LITERATURE
PROBLEM STATEMENT
KEY CONTRIBUTIONS
WHY UPLINK?
SYSTEM MODEL
CARRIER AGGREGATION
SCHEDULING
PERFORMANCE EVALUATION
DISCUSSION
CONCLUSION
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INTRODUCTION TO LONG TERM
EVOLUTION
90
1.4 MHz CC
2600 MHz
5 MHz CC
2025 MHz
20 MHz CC
1900 MHz
15 MHz CC
1525 MHz
10 MHz CC
800 MHz
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INTRODUCTION TO LTE-ADVANCED
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LTE RELEASE 10 (4G CELLULAR NETWORK – EVOLVED FROM OFDMA LTE)
PROVISIONING NEXT-GEN TELECOMMUNICATION SERVICES
PEAK DATA RATES:
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DOWNLINK (Low Mobility): 1 Gbps
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UPLINK (Low Mobility): 500 Mbps
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DOWNLINK (High Mobility): 100 Mbps
PEAK BANDWIDTH: 100 MHz
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AGGREGATION OF UPTO 5 COMPONENT CARRIERS
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SCALABLE LTE BANDWIDTHS RANGING FROM 1.4 MHz to 20 MHz
PHYSICAL RESOURCE BLOCKS (PRB)
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CONSTITUENT OF 12 SUB-CARRIERS (EACH 18 kHz) – MINIMUM RESOURCE
ALLOCATION UNIT FOR ANY UE
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DOWNLINK: CONTIGUOUS/DIS-CONTIGUOUS SUB-CARRIERS FOR A SINGLE PRB
(CHANNEL)
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UPLINK: CONTIGUOUS SUB-CARRIERS FOR A SINGLE PRB (RECOMMENDED)
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CARRIER AGGREGATION
SESSION ADMISSION CONTROL
L3 – CC ASSIGNMENT
L2 – PACKET
SCHEDULING
L2 – PACKET
SCHEDULING
L2 – PACKET
SCHEDULING
LINK ADAPTATION
LINK ADAPTATION
LINK ADAPTATION
HARQ
HARQ
HARQ
MAC
MAC
MAC
CC
CC
CC
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ISSUES IN EXISTING LITERATURE
Am in here for a
video conferencing
Same number
of resources for
both ?
Send an email to my
boss applying for leave
Now I wanna
surf Facebook
Video gaming with
my friends for the
next half-hour
Ah !!!! Jus wanna
surf Facebook
I wanna stream
a HD video
A VoIP call to
my manager
Center/Close to center UEs
contribute to less UL traffic
Edge
UEs contribute
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UE GROUPING
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Grouping of UEs based on spatial correlation – Similar channel conditions and
radio characteristics
CQI
CQI
CQI
CQI
CQI
CQI
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KEY CONTRIBUTIONS OF THE PAPER
PROBLEM STATEMENT:
How to optimally provision next-generation telecommunication services
in LTE-Advanced uplink ?
APPROACH:
 Prioritization of cell-edge UE groups for channel- and Traffic-aware
Carrier Aggregation
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Effectively accommodates log-normal shadowing, channel fading and
propagation losses which adversely impact edge throughput
Efficient representation of under-represented weak terminals
Profile-based Proportional Fair Packet Scheduling
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Resolves contention of resources using inter- and intra-group scheduling on a
time-domain and frequency-domain basis
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MOTIVATION - WHY UPLINK ?
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HIGHER UPLINK TRAFFIC WITH THE EVOLUTION OF WEB 2.0
UPLINK COULD POSSIBLY EXCEED DOWNLINK IN 2020 (CISCO
ESTIMATES)
MOBILE TERMINALS – MORE POWER-LIMITED THAN THE eNodeB
RADIO CHANNEL CHARACTERISTICS (LIKE PATH LOSS) INFLUENCE
UE TRANSMISSION POWER
FREQUENCY DIVERSITY AND AMC : NOT EFFECTIVELY-UTILIZED IN
THE UPLINK
MOTIVATION FOR SUBSCRIBERS TO CONTRIBUTE TO UPLINK
TRAFFIC FROM THEIR HAND-HELD DEVICES
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MOTIVATION - WHY CHANNELAWARE AND EDGE ?
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41% INCREASE IN THROUGHPUT OVER CHANNEL-BLIND ASSIGNMENT
57% INCREASE IN EDGE UE THROUGHPUT
PATH LOSS-BASED ASSIGNMENT FOR CHANNEL AWARENESS
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SYSTEM MODEL
QCI
CALCULATE
AMBR
QCI
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NON-ADJACENT INTER-BAND CARRIER AGGREGATION (800 MHz, 1525 MHz, 1800 MHz,
2025 MHz, 2600 MHz)
FOR ANY UE, ASSIGNABLE CC SET CONTAINS CCs WHOSE PATH LOSS IS LESS THAN A
PRE-DEFINED THRESHOLD
ASSIGN RESOURCES ONLY FROM ASSIGNABLE CCs TO UE GROUPS
UEs FROM EACH GROUP SEND QCI TO eNB (TRAFFIC SUBSCRIPTION)
DETERMINATION OF AMBR REQUIREMENTS FOR EACH GROUP
EQUAL POWER ALLOCATION ON ALL FREQUENCY BANDS WITH SINR, CQI AND
SPECTRAL EFFICIENCY COMPUTATIONS:
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DISTRIBUTION OF ASSIGNABLE
CCs TO UEs
CC1
UE1
CC2
UE2
CC3
UE3
CC4
UE4
CC5
UE5
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N
CARRIER AGGREGATION – THE OBJECTIVE
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AGGREGATING THE CCs AND ASSIGNING THEIR PRBs TO THE GROUPS
Theoretical Formulation: NP-Hard Generalized Assignment Problem:
CC1
CC2
CCi
βij
G1
W1
G2
W2
Gj
Wj
…
CCn
ITEMS
…
…
Gm
Wm
BINS
pij
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SOLUTION : SUBSET OF ITEMS (AGGREGATED CARRIER U) TO BE ASSIGNED
TO THE BINS
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FEASIBLE SOLUTION: SOLUTION WITH MAXIMUM PROFIT (ACHIEVED
UPLINK THROUGHPUT)
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HEURISTICS
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PRIORITIZING THE SPATIAL GROUPS
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: = SET OF ASSIGNABLE CCs FOR UE r IN GROUP Gi
i:= SET OF ASSIGNABLE CCs FOR GROUP Gi
PRIORITY METRIC :=
800
G1
1525
G2
1800
Gj
2025
…
2600
Gm
MGi
LEAST PRIORITIZATION OF CELL-CENTER UEs IN RESOURCE
ALLOCATION – COULD STILL GUARANTEE ALLOCATION OF GOOD
CCs
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PROOF OF CORRECTNESS – THE
INTUITION
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ASSIGNABLE RESOURCES FOR GROUP Gi : A B C
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ASSIGNABLE RESOURCES FOR GROUP Gj : A B C D E
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ASSUME Gj GETS A HIGHER PRIORITY THAN Gi (by contradiction):
 A,B,C COULD BE ASSIGNED TO Gj (worst case traffic requirement)
 ASSIGNABLE RESOURCES FOR Gi – EXHAUSTED (SHOULD BE
SCHEDULED IN THE NEXT TIME SLOT)
IF Gi GETS A HIGHER PRIORITY THAN Gj
 A,B,C COULD BE ASSIGNED TO Gi (worst case traffic requirement)
 D,E COULD STILL BE ASSIGNED TO Gj
HIGHER ADVERSE IMPACT FOR THE FORMER CASE – NOT A NEARLY
OPTIMAL SOLUTION
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PRB ASSIGNMENT
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GOAL
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To allocate the best set of contiguous channels to the UE groups
To minimize resource contention and dependency on scheduling
Already assigned resource/CC – considered for re-assignment to another
group only while lack of choice for the other group
FORMULATION:
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Sum of estimated bandwidths of UEs of group Gi
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yij := Fraction of the total number of PRBs in CC j allocated to Gi
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βij := Available bandwidth in CC j for group Gi
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PRB ASSIGNMENT
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Traffic requirement for any group Gi :
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Estimate the SINR, CQI and MCS – Spectral Efficiency values for all the PRBs
across each assignable CC for a given UE transmission power and path loss model
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Spectral Efficiency is given by:
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Channel allocation follows Maximum Throughput algorithm using the computed
MCS levels
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SCHEDULING
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TO RESOLVE CONTENTION AMONGST THE UE GROUPS AND
INDIVIDUAL UEs
PHASE I : TIME DOMAIN-BASED INTER-GROUP PFPS
COMMON RESOURCES
t2
G1
t1
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PROFILE-BASED TD METRIC:
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SERVICE PRIORITIZATION
G2
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SCHEDULING
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INTRA-GROUP FREQUENCY-DOMAIN PFPS:
UE1
UE3
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UE with maximum FD metric :
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Total number of PRB combinations:
UE2
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SIMULATION DETAILS
1.
2.
3.
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NS3 LENA – LTE/EPC NETWORK SIMULATOR
FULLY-IMPLEMENTED LTE UPLINK PHY AND MAC FUNCTIONALITIES
FEATURES INCLUDE MODELING THE AMC, PATH LOSS MEASUREMENTS,
CHANNEL-STATE INFORMATION FEEDBACK
CELL SIZE 1 km
NON-ADJACENT FREQUENCY BANDS = 10 (5 CCs CHOSEN FOR CA)
FREQUENCY BANDS : 800, 1525, 1800, 2025, 2600 MHz
CONSTANT POSITION MOBILITY MODEL FOR eNB, CONSTANT VELOCITY
MOBILITY MODEL FOR Ues
UNIFORM UE DISTRIBUTION ACROSS THE CELL
MAXIMUM 10 UEs PER CELL, (MAX. 5 HIGH-END TRAFFIC APPLICATIONS PER
UE), GBR TRAFFIC APPLICATIONS
JAKES FADING MODEL, LOG NORMAL SHADOWING, 23 dBM UE
TRANSMISSION POWER, 43 dBM eNB TRANSMISSION POWER, -120 dBM
THRESHOLD PATH LOSS, -174 dBM/Hz NOISE SPECTRAL DENSITY
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TRAFFIC DETAILS
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RESULTS
CC ASSIGNMENT (IMPR 33%, 15%)
INTER- AND INTRA-GROUP PFPS
(IMPR 15%, 21%)
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RESULTS
CC ASSIGNMENT IN UNIFORM SCENARIO
CC ASSIGNMENT (EDGE UEs)
(IMPR. 64%, 54%)
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RESULTS
INTER- AND INTRA-GROUP PFPS
(EDGE UEs IMPR. 62%)
UNIFORM CC ASSIGNMENT (EDGE
UEs IMPR. 10%)
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RESULTS
CDF OF LTE-A UPLINK
THROUGHPUT (IMPR. 20%, SD
14%)
ACHIEVED GBR (91.7%, 87.4%)
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DISCUSSIONLUSIONS
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IMPACT ON POWER OPTIMIZATION :
 ESTIMATED TRANSMISSION POWER FOR UE ON ANY CC:
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LOW VALUES OF M AND PL FROM OUR PROPOSED MECHANISMS –
MINIMIZES POWER CONSUMPTION
REST OF THE PARAMETERS ARE CC-SPECIFIC OPEN-LOOP AND
CLOSED-LOOP VALUES
NOT APPLICABLE TO HIGH-SPEED MOBILE UEs – NO DISTINCT CELLCENTER AND CELL-EDGE UEs, IRRELEVANT FEEDBACK
REQUIRES COORDINATION AMIDST MULTIPLE, NEIGHBORING eNBs
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CONCLUSIONS
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CHANNEL- AND TRAFFIC-AWARENESS IN RESOURCE ALLOCATION FOR
LTE-ADVANCED SYSTEMS
FOCUS ON UPLINK CARRIER AGGREGATION – CC ASSIGNMENT AND
PFPS
MOTIVATION FOR GROUPING OF UEs
CC ASSIGNMENT – PROBLEM THEORETICALLY-MODELLED AS NP-HARD
GENERALIZED ASSIGNMENT PROBLEM
PROPOSAL OF EDGE-PRIORITIZED CC ASSIGNMENT
PROPOSAL OF TIME-DOMAIN INTER-GROUP AND FREQUENCY-DOMAIN
INTRA-GROUP PFPS
PERFORMANCE EVALUATION – 33% IMPR IN CC ASSIGNMENT AND 15%
IMPROVEMENT IN SCHEDULING MECHANISMS
DOWNLINK LTE-ADVANCED MULTICAST, HIGH-SPEED SCENARIO –
ENVISIONED FOR FUTURE WORK
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QUERIES??
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THANK YOU
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