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Impact of Base Station Antenna
Azimuth Beamwidth on the
Performance of 3-Sector Site LTE
Deployments
Minya Gavrilovic
November 6th, 2014
COMMUNICATION
COMPONENTS INCExtending Wireless Coverage
Page 2
Why Sectorize RF Networks?
3 x omni antennas per site
• Site covers a single sector
• 1 × Tx antenna
• 2 × Rx antennas
• Rx antenna separation 12-20
3 x directional antennas per site
• 3 × Tx/Rx antennas – one per
sector
Capacity!
COMMUNICATION
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Page 3
• Directional panel antenna / linear array
• ±45 polarization for diversity
• 65 azimuth beamwidth
• 4 - 15 elevation beamwidth
Antenna Characteristics for 3-sector Networks
COMMUNICATION
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Page 4
• M x N MIMO
• 2×2, 4×2, 4×4, 8×8
• Azimuth beamforming
• Multiple beam antennas
• Splitting 3-sector sites into 6-sectors with split-beam / Bi-Sector type antennas
• Multi-beam antennas for very special, very high-capacity areas
• Elevation beamforming & sectorization
• Active antenna systems
• From macro to small cell…
Additional Methods in Increasing Capacity and Throughput
COMMUNICATION
COMPONENTS INCExtending Wireless Coverage
Page 5
• As LTE has become the de facto high-speed network of
choice, interference issues are on the rise
• Avoiding interference
• Interbeam cross-over points
• Interbeam over-laps
• Minimizing Sector Power Ratio
• Conventional single column antennas have few degrees of
freedom to shape the azimuth beam
• Carriers are starting to investigate use of narrower azimuth
beamwidths for 3-sector deployments
Azimuth Patterns and LTE
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COMMUNICATION
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Page 6
SPR and Azimuth Beamwidth
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65 Beamwidth 45 Beamwidth 33 Beamwidth
SPR = 5% SPR = 1% SPR = 0.5%
COMMUNICATION
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Page 7
• Investigate performance differences of base station antennas
of different azimuth beamwidths for 3-sector wireless network
• Focus on relatively dense cell site to site spacing
• Illustrate advantages vs. disadvantages in both LTE and
UMTS networks
• Assess impacts to performance and coverage area
• In particular, reduced coverage in 120 sectors by antennas of beamwidths
< 65
Goals of Investigation
COMMUNICATION
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Page 8
• Network of hexagonal cell, based on cell radii of:
• 200 m, 300 m, 500 m and 600 m
• Each cell site is assigned a fixed height of 30 m with standard azimuth pointing directions
0, 120 and 240
• Focus Area consists of 9 cell sites of 3-sectors
• Forsk ATOLL Planning Tool used for all simulations
• Different traffic models were created for each scenario
• Monte Carlo simulation generates subscribers that could be serviced for both LTE & UMTS technologies
• All simulations performed with clutter (rather than plain earth)
• Geographic area selected is suburban neighborhood of Toronto with moderate to low density trees
Simulation Network and Assumptions
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Page 9
Network Map
Simulation Region
Focus Area
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Page 10
Antennas Evaluated
• CCI multiband hexport antennas of 85, 65, 45 and 33 azimuth beamwidths considered
• High-band patterns at AWS Tx frequency, 2110 MHz, used for simulations
85 65 45 33
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Page 11
Antenna Patterns
• Identical elevation patterns used in each simulation
• 4 elevation downtilt, 6.8 elevation beamwidth
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Page 12
LTE Metrics and Terminology
PDSCH C/(I+N):
Carrier to Interference + Noise measured on the Physical Downlink Shared Channel.
Connection Success Rate (%):
Connection success rate is the ratio of connected users over the total number of users of that service in the cell.
Traffic Load DL (%):
Percentage of simulated downlink traffic in a sector compared to the maximum downlink traffic that can be supported by that sector in
a population saturated & interference dominated situation.
Total Users:
The number of users including the connected and delayed bearer users.
Bearer Modulation DL:
A combination of modulation and coding scheme supported by a given bearer on the DL.
Peak RLC Throughput:
The maximum RLC (Radio Link Control) channel throughput attainable using the highest bearer available at the user location in the
downlink.
Network Traffic Load:
Scaling factor of the traffic model set up in ATOLL used to vary number of users to create various scenarios.
COMMUNICATION
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Page 13
LTE Simulation Results Format
• LTE channel bandwidth used in simulation is 10 MHz
• Simulations carried out for Network Traffic Load = 0.1 to 3 in steps of 0.1
• 50 Monte Carlo simulations per Network Traffic Load
• Performance summary plots based on average performance over all Network Loads 0.1
to 3
• Results are presented per sector averaged over all sectors within the focus area
• Modulation, C/(I+N) and Coverage curves / plots provided only for Network Traffic Load =
1.0
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Page 14
LTE Simulation Coverage Plot – 200 m
85° Beamwidth Antenna
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Page 15
LTE Simulation Coverage Plot – 200 m
65° Beamwidth Antenna
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Page 16
LTE Simulation Coverage Plot – 200 m
45° Beamwidth Antenna
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Page 17
LTE Simulation Coverage Plot – 200 m
33° Beamwidth Antenna
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Page 18
LTE Simulation Results
Peak RLC Throughput (DL)
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Page 19
LTE Simulation Results
Traffic Load (DL)
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Page 20
LTE Simulation Results
Connection Success Rate
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Page 21
LTE Simulation Results
Total number of Users
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Page 22
LTE Simulation Results –200 m
Bearer DL Modulation, Coverage Area and PDSCH C/(I+N)
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Page 23
LTE Simulation Results –300 m
Bearer DL Modulation, Coverage Area and PDSCH C/(I+N)
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Page 24
LTE Simulation Results –500 m
Bearer DL Modulation, Coverage Area and PDSCH C/(I+N)
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Page 25
LTE Simulation Results –600 m
Bearer DL Modulation, Coverage Area and PDSCH C/(I+N)
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Page 26
UMTS Metrics and Terminology
CQI (Channel Quality Indicator):
A measure of the quality of the channel used by the User Equipment to measure the link quality based on C/I.
Average TCH Power (dBm):
The average power allocated to a traffic channel for supplying services.
COMMUNICATION
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Page 27
UMTS Simulation Results Format
• Simulations carried out for Network Traffic Load = 0.1 to 3 in steps of 0.1
• 50 Monte Carlo simulations per Network Traffic Load
• Only CQI plots are provided for Network Traffic Load = 1.0
COMMUNICATION
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Page 28
UMTS Simulation Results –200 m
UMTS CQI
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Page 29
UMTS Simulation Results –300 m
UMTS CQI
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Page 30
UMTS Simulation Results –500 m
UMTS CQI
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Page 31
UMTS Simulation Results –600 m
UMTS CQI
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Page 32
Results Summary
85, 45 and 33 Results as % Change from 65 Data
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Page 33
Conclusions and Future Work
• Antennas of narrower azimuth beamwidth:
• More suitable for smaller cells
• Improved throughput
• Reduced coverage
• LTE vs UMTS
• Advantages of narrower beamwidth is clearer in LTE than UMTS
• For UMTS, narrow beamwidth does not work well for larger cells
• Future work:
• Optimize network for different scenarios (downtilt, elevation beamwidth, gain)
• Compare differences between networks with flat earth and clutter
• Investigation with larger cell radii
• Higher number of sectors / site