Impact of Base Station Antenna Azimuth Beamwidth on …€¦ · · 2017-11-22Impact of Base...

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

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!

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• Directional panel antenna / linear array

• ±45 polarization for diversity

• 65 azimuth beamwidth

• 4 - 15 elevation beamwidth

Antenna Characteristics for 3-sector Networks

COMMUNICATION


• 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


• 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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SPR and Azimuth Beamwidth

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65 Beamwidth 45 Beamwidth 33 Beamwidth

SPR = 5% SPR = 1% SPR = 0.5%

COMMUNICATION


• 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


• 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

COMMUNICATION


Network Map

Simulation Region

Focus Area

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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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Antenna Patterns

• Identical elevation patterns used in each simulation

• 4 elevation downtilt, 6.8 elevation beamwidth

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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


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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LTE Simulation Coverage Plot – 200 m

85° Beamwidth Antenna

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LTE Simulation Results

Peak RLC Throughput (DL)

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Traffic Load (DL)

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Connection Success Rate

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Total number of Users

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LTE Simulation Results –200 m

Bearer DL Modulation, Coverage Area and PDSCH C/(I+N)

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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


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

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UMTS Simulation Results –200 m

UMTS CQI

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UMTS CQI

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Results Summary

85, 45 and 33 Results as % Change from 65 Data

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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

Impact of Base Station Antenna Azimuth Beamwidth on …€¦ · · 2017-11-22Impact of Base...

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