1. IBTUF VIII – AUSTIN, TX Distributed Antenna Systems for Large Venues
Presented by:
Prabhu Maragathavannan
Principal Engineer- CAR/TN Region January 15, 2014

2. Agenda DAS Zones –Capacity Vs System Performance
DAS Zones Vs Sectors
User Throughput expectations
3D Model and inclined surfaces
Performance based capacity solution
Case study : BOA Stadium
Jumbled PN Issue
Delay settings
Significance of Delay settings
Cause and Effects
Parameters to be adjusted
UL attenuation settings for different equipment
Noise Figure Calculation
UL attenuation settings examples
Path imbalance
Balancing Tool

3. DAS Zones- Capacity Vs System Performance

4. DAS Zones- Capacity Vs System Performance
Capacity planning based on market share, technology split, simultaneous users, active connected users and target throughput etc
“X” Number of sectors requested
How do sectors translate to System Performance in stadiums and arenas?

5. DAS Zones- Capacity Vs System Performance
Example: 4 sector configuration
Sector Boundaries

6. DAS Zones- Capacity Vs System Performance
User experience in the bowl will be different based on where they are seated
Users in this area get great Throughput due to higher modulation
User gets poor Throughput in the sector boundaries due to bad SINR
More Sectors create more Boundaries with poor SINR

7. DAS Zones- Capacity Vs System Performance
Two aspects of the design
Capacity planning based on market share, technology split, simultaneous users, active connected users and target throughput etc
Performance based capacity planning using Target SINR and Noise Figure calculations
Consider Noise rise due to loading which will affect SINR
SINR of 10 dB in an empty stadium may be even 2 dB based on the amount of loading. Need to include the “noise rise due to loading” into calculations
Number of remotes per sector to be considered for noise figure
Even if enough power is available, try to have additional remotes to create zones for future. We cannot suddenly create additional sectors if we don’t have those in place
Both of these factors go hand in hand and there is a tradeoff between the two at a point and might have to grow vertically at this point

8. DAS Zones- Capacity Vs System Performance
If there are multiple levels, make sure inclination is defined properly and all sectors are transmitting when generating SINR plots

9. DAS Zones- Capacity Vs System Performance
We can see the different tiers of the stadium with the antenna locations on the 3D view in this example clearly showing the slope and inclination well defined for propagation modeling

10. DAS Zones- Capacity Vs System Performance
The predictions should be based on the inclined surfaces also inside the bowl. The more accurate the slope and the angle directions are, the prediction results will be more close to actual scenario

11. Case Study: BOA Stadium

12. BOA Case study: Voice PN Dominance

13. BOA Case Study: EVDO PN Dominance

14. BOA Case Study: EVDO PN dominance after delay compensation
This zone was down during testing

15. Delay Settings

16. Delay Settings
The eNode B is responsible for maintaining the uplink timing synchronization for the users.
In LTE, timing adjustment is performed using the timing-advance(TA) command, which is transmitted either as part of a random-access response or as a MAC control element
When the TA command is transmitted as part of the random access response, a 11-bit TA command with possible values of TA=0,1,2,…1282 is used which provides timing adjustment from 0 to 667 uS
When the UE is already synchronized, only fine timing adjustment is necessary and is done on MAC control message

17. Delay Settings
Delay compensation is an underrated concept and could cause performance issues
DAS Systems have an inherent delay, especially the ones with long fiber runs
They have to be balanced for the sectors and then compensated at the BTS/eNode B
Unbalanced delays = PN Offset for CDMA as BTS are time synchronized- will cause JUMBLED PN issues (EVDO seems to be more sensitive than voice)
Will affect LTE significantly as each TA granularity is around 0.52us
New delay compensation parameter GPSAntDel for Motorola equipment (CDMA) and has been successfully implemented at several venues
Should be kept in mind while moving zones around and assigning to sectors with different delays

18. Delay settings
Fiber lengths for multiple remotes to the same sector should be balanced for delay

19. LTE Delay Compensation
LTE (Ericsson example)

20. Motorola Delay compensation
Motorola parameter for delay compensation (4812)
Delay compensation in nano seconds
Please note this has to be set at a frame level unlike LTE

21. Motorola Delay compensation
Delay compensation for UBS frames
Delay compensation in nano seconds
Note the difference for UBS frames

22. UL attenuation settings for different equipment

23. Why is Noise Figure important ?
Where Fn and Gn are the noise factor and available power gain, respectively, of the n-th stage. Note that both magnitudes are expressed as ratios, not in decibels.
The overall noise figure of a radio receiver is primarily established by the noise figure of its first amplifying stage. Subsequent stages have a diminishing effect on signal to noise ratio. For this reason, the first stage amplifier in a receiver is often called the Low Noise Amplifier(LNA).

24. UL Attenuation Settings (Solid Equipment)
Attenuation at the remote should be 0

25. UL Attenuation Settings (Solid Equipment)
Setting at the conditioners are ok

26. UL Attenuation Settings (MA Equipment)
Setting at the conditioners are ok

27. UL Attenuation UL Attenuation
In neutral host systems try to keep UL atten on the DIU trays to have control
Active trays like iPOI are great option but make sure it is not locked by the other carrier for neutral host scenarios

28. Path Imbalance

29. Path Imbalance
An unbalanced path will allow individual UE’s to generate inter-cell interference at cell edges which could cause higher receive noise floors.
Rises in reverse link noise floors at eNodeB receivers will slow uplink throughput considerably, well before the downlink is affected
Tool to calculate required UL attenuation

30. Thank You!