Building Distributed Antenna Systems Presented by; Hedley Boyd-Moss

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.

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)

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

Building Distributed Antenna Systems Frequency Spectrum overview DAB 206MHz GSM 850-1800MHz PMR 150-174 & 400-520MHz GPRS/2G 850-1800MHz 5G ? GRN 400-520MHz UMTS/3G 850-2100MHz FM 88-108MHz LTE/4G 700-3500MHz AM 0.5-1.6MHz WiFi 2.4GHz WiFi 5.8GHz 1 2 3 4 5 6 Frequency GHz

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

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

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

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.

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

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

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

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

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.

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

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

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

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)

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

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