1. Building Distributed Antenna Systems
Presented by;
Hedley Boyd-Moss

2. Building Distributed Antenna Systems
What is a DAS?
A designed and intended RF signal coverage delivery system within an RF shielded area.
Used to provide extended RF coverage for services such as AM, FM DAB, PMR. GRN, Cellular and WiFi rebroadcast.

3. Building Distributed Antenna Systems
What are the fundamental service differences?
Cellular
WiFi
GRN
PMR
AM, FM & DAB
User
Public &
Commerce
Emergency services
Utilities & Commerce
Public
Application
Paid Service
Public & Paid Service
Public Safety
Services
Public Service
Revenue generation
High
None
Medium
None / low
GRN – Government Radio Network (Police, Fire, Ambulance)
PMR – Public Mobile Radio (including utility services such as Water. Electricity and Gas)

4. Building Distributed Antenna Systems
Generally, ubiquitous coverage for all services
Cellular (mobile)
Drivers:
More content, higher resolution, faster and less latency 5G
LTE/4G
Speed, Content & Bandwidth
UMTS/3G
GPRS/2G
GSM
1990
2000
2010
2020
Time

5. Building Distributed Antenna Systems
Frequency Spectrum overview
DAB
206MHz
GSM
MHz
PMR
& MHz
GPRS/2G
MHz
5G ?
GRN
MHz
UMTS/3G
MHz FM
88-108MHz
LTE/4G
MHz AM
MHz
WiFi
2.4GHz
WiFi
5.8GHz 1 2 3 4 5 6
Frequency GHz

6. Building Distributed Antenna Systems
FM, PMR and GRN Analogue to Digital Migration
FM Voice Radio Services migration to DAB
More data / less
frequency spectrum
PMR and GRN migration from Analogue to Digital.
FM 25KHz to FM 12.5KHz channel spacing
DMR/MOTOTRBO
APCO
P25P1
P25P2
iDAS - iCOM
NXDN
NEXEDGE - Kenwood
TETRA

7. Building Distributed Antenna Systems
DAS Block Diagram
Source
LAN/
WAN
Coupler / Combiner
POI
(Point of Interface)
Services
WiFi
RF Signal Delivery System
CELLULAR
BTS
GRN
PMR FM
Off Air AM

8. Building Distributed Antenna Systems
DAS Types (general)
Passive
Coaxial cable fed antenna or antennas via passive splitters or couplers
Coaxial cable fed into leaky / radiating coaxial cable
Coaxial cable fed into a mix of leaky / radiating & coaxial cable to antenna’s
Active
Fibre Fed Head End to RF Remote BDA’s
Head End BDA to Bi-Directional Line Amplifiers
Fibre or Ethernet Connected Remote IP based Radio Terminals (WiFi)
Hybrid
A mix of both Active and Passive components and feeder systems

9. Building Distributed Antenna Systems
DAS Rebroadcast / Repeater Amplifier Types
Active repeaters - Channelised or Broad Band?
Either amplifier type is generally applicable to both UL and DL in the same DAS system.
A Channelised active repeater, amplifies only the channel of interest.
Although more costly, is used for links back to the donor or coverage extension into both RF shielded and non-shielded areas
A Broad Band active repeater amplifies a window of frequency spectrum in which the frequency of interest is amplified.
The Broad Band repeater is simpler and less costly, the use of it however is regulated by ACMA as it may cause interference to other users.

10. Building Distributed Antenna Systems
Important DAS design metrics
Input of relevant coverage modelling data (building materials)
Post building construction RF signal survey
Accurate building floor plans indicating risers and cable trays/ducts.
UL & DL link budget balancing
Narrow input UL & DL signal margins
Minimal DAS induced RF noise
Minimise possible external on-frequency interference in either DL or UL

11. Building Distributed Antenna Systems
Important DAS design metrics
Ensure AC mains and or DC power capacity required is available
Plan DC Battery Back-up capacity, direct or via UPS
External Donor facing antenna to DAS RF isolation
Compliance to building cable codes, fire walls , and use of Low Smoke, Low Halogen fire retardant coaxial, Ethernet and or fibre optic cables where applicable.
Regulatory compliance, ACMA. Mobile Carriers Forum
Hosted network operators design and build requirement & DAS system test and pass requirements

12. Building Distributed Antenna Systems
Important DAS design metrics
Provision of building earth and bonding facilities where necessary
External antenna coaxial, AC mains and data line lighting surge protection
Safe RF radiation exposure limits
Future proofing wherever possible for frequency migration and technology evolution
Consider maintenance and testing access to components and terminated cable ends, placing them where possible for easy access.
Component pre-acceptance for visual aesthetics, size and colour where applicable

13. Building Distributed Antenna Systems
Important DAS design metrics
Output Power / Frequency / Coverage Balancing.
Coaxial cable OD’s, bending radius, installation access.
The thicker the coaxial cable (OD);
- the lower the RF transmission loss for a given frequency
- the larger the bending radius
- the higher the material cost p/m
- the more difficult to work with

14. Building Distributed Antenna Systems
DAS records and cable / component labelling
Complete accurate “as-built” cable drawings
Identify concealed component / cable positions (photographic record)
Indicate mains or DC circuit breaker positons and labelling
Location of equipment circuit breakers and labelling
Cleary identify test points and location of historical measurement records at time of commissioning
Physically identity cable type when radiating / leaky feeder at intervals and ends
On acceptance, record post DAS build RF level measurement positions or walk test routes as a bench mark.

15. Building Distributed Antenna Systems
Typical DAS Passive Components
Wilkinson power divider / splitter (low/medium power)
Air Cavity power divider / splitter (high power)

16. Building Distributed Antenna Systems
Typical DAS Passive Components
3-Port Directional Coupler
4-Port Hybrid Coupler

17. Building Distributed Antenna Systems
Typical DAS Passive Components
Resistive load
Coaxial Cable Load

18. Building Distributed Antenna Systems
DAS Service Disrupters
Component PIP (Peak Instantaneous Power) breakdown
PIM (Passive Inter-Modulation) RF generation
High VSWR / Low Return Loss on components or coaxial cables
Post construction physical damage to cables and components
Sub-standard cable connector preparation and termination
Un-calibrated or faulty test and measurement equipment
Loose terminations onto component connectors (not torqued)

19. Building Distributed Antenna Systems
DAS Service Disrupters
Excessive construction dust in equipment rooms
Sub-standard optical fibre splicing
Dirty / dusty / oily optical interface surfaces
Sub-standard RJ45 Termination connector crimp
Overtightened cable hangers / fasteners
Unidentifiable cables, components
Installing any cables to run over sharp edges
Using the wrong tools for the job

20. Building Distributed Antenna Systems
THANK YOU