Royal Institute of Technology Dept. of Signals, Sensors and Systems Performance and Implementation Aspects of Wireless Indoor Communication Systems with Local Centralization Stefan Pettersson Royal Institute of Technology Dept. of Signals, Sensors and Systems 12/2/2018

Presentation Outline Introduction Thesis Scope Models and Definitions Wireless Indoor Communication Radio Resource Management Local Centralization - The Bunch Concept Thesis Scope System Performance System Coexistence Implementation Aspects Models and Definitions Simulation Indoor Scenario Results Conclusions 12/2/2018

Wireless Indoor Communication High Speed Internet Access Different services Large User Concentration Dense infrastructure High co-channel interference Multiple Systems Coexistence Radio Resource Management 12/2/2018

Radio Resource Management Base Station Strongest Lowest power Channel Random Quality based Fixed Distributed Centralized Can be: Transmitter Power Constant received Quality based 12/2/2018

Local Centralization The Bunch Concept Intra-Bunch Centralized Synchronized “Cheap” signaling Inter-Bunch Distributed Unsynchronized “Expensive” signaling CU Central Unit RAU Remote Antenna Unit Local Centralization - Low Complexity 12/2/2018

The Link Gain Matrix Every RAU transmits its ID on a unique beacon channel 12/2/2018

Intra-Bunch RRM RAU Selection: Lowest path loss (strongest) Channel Selection: Sorting methods Feasibility Check: Power Control: 12/2/2018

Thesis Scope - Efficient RRM Capabilities for Coexistence High Performance Low Tx-Power Low Complexity Error Insensitivity Interference Avoidance Possible to Implement 12/2/2018

Improving System Performance Channel Selection Strategies Random Least-Interfered Most-Interfered Lowest-Number Beamforming Sectoring Downtilting Sort the available channels, use the first feasible one Adjust the antenna pattern to reduce co-channel interference 12/2/2018

Improving System Performance cont. - Downtilting The antenna patterns are focused and directed downward HPB is the Half Power Beamwidth 12/2/2018

Improving System Performance cont. - Sectoring Reduced co-channel interference Trunking loss No frequency reuse between sectors 12/2/2018

Coexistence One bunch covering all three floors One bunch covering one floor 12/2/2018

Implementation Aspects Computational Complexity Sector Direction Offset RAU Location Offset 12/2/2018

Performance Measures and Definitions Snapshot simulations in the downlink Performance measures: assignment failure rate, nu - The fraction of users that did not get a feasible channel or got a channel that had to low quality flops per allocation attempt - The number of floating point operations needed for an allocation (Matlab) distribution of the transmitter powers Relative traffic load = users/channel/cell Capacity is the load where nu equals 2% 12/2/2018

Indoor Scenario - Building Layout Three floors with equal number of RAUs The RAUs are placed at the ceiling level 12/2/2018

Indoor Scenario cont. - Floor Layout Meters The Remote Antenna Units are placed in the center of every second office 12/2/2018

Capacity Comparison for FCA, Distributed, and Bunch Systems Assignment failure rate Relative traffic load 12/2/2018

Capacity with Downtilting Assignment failure rate Relative traffic load Error on p. 40! 12/2/2018

Results of Sectoring The gain from reduced interference is larger than the trunking loss for small number of sectors FCA and distributed systems gain more than our centralized system More sectors result in lower transmitter powers thus improving the coexisting capability of the bunch system 12/2/2018

Capability of Coexistence - Capacity Comparison Assignment failure rate Relative traffic load 12/2/2018

Reducing Complexity Using Multiple Bunches Three bunches cover one floor each The assignment failure rate is maintained at two percent 12/2/2018

Improving Capacity with Sectoring Using Random Channel Selection Three bunches cover one floor each The assignment failure rate is maintained at two percent 12/2/2018

RAU Installation Sensitivity Very small effects of sector rotation offset Large shadow fading reduces the offset impact Small effects of RAU location offset User distribution and floor layout 12/2/2018

Conclusions The studied bunch system outperforms FCA and distributed systems Sector antennas increase the system capacity and greatly reduce the transmitter powers Local centralization reduces the complexity but also the capacity The capacity loss with multiple bunches can be regained with sectoring The bunch system is insensitive to RAU implementation errors 12/2/2018

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Numerical Analysis Snapshot simulations in downlink Lp [dB] = 37+30log(R)+18.3n((n+2)/(n+1) - 0.46) Log-normal shadow fading with 12 dB std. dev. PC dynamic range is 30 dB Orthogonal channels All channels are available at every RAU No mobility n = Tx-Rx distance in # of floors 12/2/2018

Antenna Pattern - Downtilting Half Power Beamwidth,  HPB: The gain has dropped to half of its center value 320 - 220 = 100 degrees 310 - 230 = 80 degrees Front-to-Back Ratio, FBR: The gain ratio between the front and back lobe is set to 15 dB 12/2/2018

Antenna Pattern - Sectoring Constant antenna gain in front and back lobes The number of available channels are split equally between the sectors Front-to-Back ratio is 15 dB One sector pattern out of four in a four-sector scenario. 12/2/2018

Capacity with Sector Antennas - One Bunch, One Floor Assignment failure rate Relative traffic load 12/2/2018

Tx-Power Distribution with Sectoring - One Bunch, One Floor Probability Transmitter-Power [dBm] 12/2/2018

CDF of SIR with Multiple Bunches Probability SIR [dB] 12/2/2018

FCA Reuse Pattern Cluster size 4 20 40 60 80 100 10 30 50 Meters 20 40 60 80 100 10 30 50 Meters Floor-1 1 2 3 4 Floor-2 Cluster size 4 12/2/2018

Sector Direction Offset - No Fading, One Sector Random direction offset within 350 degrees 12/2/2018

RAU Location Offset The RAUs are randomly located within a 7 by 7 meter square 12/2/2018

RAU Location Offset in an Office BxyUni = 2+2i 12/2/2018

Sector Rotation Offset - FCA without Fading Assignment failure rate Relative traffic load 12/2/2018

Complexity Comparison - Single Bunch Flops per allocation attempt Relative traffic load 12/2/2018

Channel Selection Using External Interference Assignment failure rate Relative traffic load 12/2/2018