1. 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

2. 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

3. 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

4. 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

5. 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

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

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

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

9. 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

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

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

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

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

14. 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

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

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

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

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

19. 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

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

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

22. 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

23. 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

24. 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

25. 12/2/2018

26. Numerical Analysis Snapshot simulations in downlink
Lp [dB] = 37+30log(R)+18.3n((n+2)/(n+1) )
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

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

28. 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

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

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

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

32. FCA Reuse Pattern Cluster size 4 20 40 60 80 100 10 30 50 Meters20 40 60 80
100 10 30 50
Meters
Floor-1 1 2 3 4
Floor-2
Cluster size 4
12/2/2018

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

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

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

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

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

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