Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Distributed Antenna Systems
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# Environmental and Service Conditions {toc}
−## DAS equipment shall be rated for the temperature, humidity, and airflow conditions of its installed location. {note}
+## DAS equipment shall be rated for the temperature, humidity, and airflow conditions of its installed location.
−## Head-end and remote-unit electronics are commonly located in telecommunications rooms, electrical rooms, or above accessible ceilings. Donor antennas and roof-mounted equipment are exposed to weather and solar load. Antennas and cabling installed in HVAC plenums must carry the appropriate plenum fire rating. The design shall confirm each device's rated environmental envelope against its actual location before submittal. {note}
+## Head-end and remote-unit electronics are commonly located in telecommunications rooms, electrical rooms, or above accessible ceilings. Donor antennas and roof-mounted equipment are exposed to weather and solar load. Antennas and cabling installed in HVAC plenums must carry the appropriate plenum fire rating. The design shall confirm each device's rated environmental envelope against its actual location before submittal.
```datasheet
…4 unchanged lines
max: 50
step: 5
−setpoints: [0, 40]
+setpoints: [-5, 0, 40, 50]
```
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# System Architecture {toc}
−## The DAS architecture shall be selected to match building size, floor-plate geometry, signal-source strategy, and budget. {note}
+## The DAS architecture shall be selected to match building size, floor-plate geometry, signal-source strategy, and budget.
−## Passive DAS distributes signal entirely over coaxial cable from a head-end amplifier and suits buildings up to roughly 100,000 sq ft. Active fiber-fed DAS converts the signal to optical, distributes it over fiber to remote radio units, and suits buildings above 200,000 sq ft or multi-building campuses where coaxial loss budgets cannot close. Hybrid DAS runs an active fiber backbone to zone distribution units and then passive coaxial within each zone, balancing cost and reach for mid-rise buildings of roughly 100,000 to 500,000 sq ft. Digital DAS transports baseband over fiber (CPRI/eCPRI) to digital remote units and suits high-capacity venues and 5G NR deployments. {note}
−
```datasheet
label: DAS architecture
…7 unchanged lines
```
+## Passive DAS distributes signal entirely over coaxial cable from a head-end amplifier and suits buildings up to roughly 100,000 sq ft. Active fiber-fed DAS converts the signal to optical, distributes it over fiber to remote radio units, and suits buildings above 200,000 sq ft or multi-building campuses where coaxial loss budgets cannot close. Hybrid DAS runs an active fiber backbone to zone distribution units and then passive coaxial within each zone, balancing cost and reach for mid-rise buildings of roughly 100,000 to 500,000 sq ft. Digital DAS transports baseband over fiber (CPRI/eCPRI) to digital remote units and suits high-capacity venues and 5G NR deployments. {note}
+
## Signal Source {toc}
−### The signal source shall be selected per carrier and shall be confirmed compatible with the chosen architecture. {note}
+### The signal source shall be selected per carrier and shall be confirmed compatible with the chosen architecture.
−### An off-air donor antenna captures the existing macro-network signal and is the lowest-cost source but depends on adequate outdoor signal and clear line-of-sight to the serving tower. A carrier-provided base station (BTS) delivers dedicated capacity independent of the macro network but requires carrier hardware, backhaul, and floor space. A small-cell head-end per carrier is the dominant 5G NR source and feeds passive or active distribution. The source choice drives capacity, latency, and the carrier-coordination path. {note}
−
```datasheet
label: Signal source type
…6 unchanged lines
```
+### An off-air donor antenna captures the existing macro-network signal and is the lowest-cost source but depends on adequate outdoor signal and clear line-of-sight to the serving tower. A carrier-provided base station (BTS) delivers dedicated capacity independent of the macro network but requires carrier hardware, backhaul, and floor space. A small-cell head-end per carrier is the dominant 5G NR source and feeds passive or active distribution. The source choice drives capacity, latency, and the carrier-coordination path. {note}
+
### The donor antenna shall be installed with unobstructed line-of-sight to the serving macro cell.
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## Neutral-Host Configuration {toc}
−### A neutral-host (multi-carrier) design shall share one distribution backbone among all served carriers, with each carrier providing its own signal source combined at the head-end. {note}
+### A neutral-host (multi-carrier) design shall share one distribution backbone among all served carriers, with each carrier providing its own signal source combined at the head-end.
−### Neutral-host shared infrastructure is the dominant procurement model for new commercial construction: the building owner or a neutral-host operator deploys a single passive or active backbone, and each licensed carrier connects its own base station or small cell. Single-carrier dedicated systems are increasingly rare outside carrier-owned venues. The combining network at the head-end must accommodate the composite power and band set of every served carrier without intermodulation. {note}
−
```datasheet
label: Carrier service model
…5 unchanged lines
```
+### Neutral-host shared infrastructure is the dominant procurement model for new commercial construction: the building owner or a neutral-host operator deploys a single passive or active backbone, and each licensed carrier connects its own base station or small cell. Single-carrier dedicated systems are increasingly rare outside carrier-owned venues. The combining network at the head-end must accommodate the composite power and band set of every served carrier without intermodulation. {note}
+
+### The number of licensed carriers served shall be specified, and the head-end combining network shall accommodate their composite power and band set without intermodulation.
+
```datasheet
label: Number of licensed carriers served
…3 unchanged lines
max: 4
step: 1
−setpoints: [3, 4]
+setpoints: [1, 3, 4]
```
# Frequency Bands and RF Performance {toc}
−## The supported band set shall cover every frequency the served carriers and tenants require, confirmed before design. {note}
+## The supported band set shall cover every frequency the served carriers and tenants require, confirmed before design.
−## Under-specifying bands is a common and costly error: a system built for only 700 MHz and 1900 MHz cannot serve a tenant who later needs AWS-3 or 5G NR C-Band, and adding bands after installation means replacing remote units and antennas. The 80% band set for large commercial and institutional buildings is 700 MHz (Band 12/13/17), 850 MHz (Band 5), AWS 1700/2100 MHz (Band 4/66), PCS 1900 MHz (Band 2/25), and 2500 MHz (Band 41), with 5G NR n77 (3.7 GHz C-Band) added where carriers require. {note}
−
```datasheet
label: Supported frequency bands
…19 unchanged lines
```
+## Under-specifying bands is a common and costly error: a system built for only 700 MHz and 1900 MHz cannot serve a tenant who later needs AWS-3 or 5G NR C-Band, and adding bands after installation means replacing remote units and antennas. The common band set for large commercial and institutional buildings is 700 MHz (Band 12/13/17), 850 MHz (Band 5), AWS 1700/2100 MHz (Band 4/66), PCS 1900 MHz (Band 2/25), and 2500 MHz (Band 41), with 5G NR n77 (3.7 GHz C-Band) added where carriers require. {note}
+
## Signal-Level Targets {toc}
−### The design shall meet the specified in-building downlink signal target in general areas, with a defined edge-of-coverage minimum. {note}
+### The design shall meet the specified in-building downlink signal target in general areas, with a defined edge-of-coverage minimum.
−### The downlink target is expressed as RSRP for LTE and NR. A common general-area design target is -85 dBm; the 80%-case default specified here is -90 dBm, with -105 dBm as the absolute edge-of-coverage minimum. The uplink link budget must close at the device transmit limit so that handsets at coverage edge can reach the source, typically requiring received uplink 10 to 15 dB above the noise floor at the base station. {note}
−
```datasheet
label: Downlink design target (RSRP, general areas)
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max: -75
step: 5
−setpoints: [-90, -85]
+setpoints: [-90, -85, -75]
```
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max: -90
step: 5
−setpoints: [-105, -100]
+setpoints: [-110, -105, -100, -90]
```
+### The downlink target is expressed as RSRP for LTE and NR. A common general-area design target is -85 dBm; the default specified here is -90 dBm, with -105 dBm as the absolute edge-of-coverage minimum. The uplink link budget must close at the device transmit limit so that handsets at coverage edge can reach the source, typically requiring received uplink 10 to 15 dB above the noise floor at the base station. {note}
+
### The system shall close the uplink link budget so that a device transmitting at its maximum power at the coverage edge is received above the source noise floor.
## Output Power and Gain {toc}
−### Composite output power per remote unit and per amplifier shall be set within the specified envelope and within the device's rated linear range. {note}
+### Composite output power per remote unit and per amplifier shall be set within the specified envelope and within the device's rated linear range.
−### Composite output power per active remote unit typically ranges from +20 dBm to +37 dBm (100 mW to 5 W) depending on zone size; a passive bi-directional amplifier head-end typically delivers a total composite output of +23 dBm to +33 dBm. Operating an amplifier beyond its rated composite power degrades the noise figure and generates intermodulation that interferes with both the DAS and the macro network. Gain shall be set so the link budget closes without exceeding the linear range. {note}
+### Composite output power per active remote unit typically ranges from +20 dBm to +37 dBm (100 mW to 5 W) depending on zone size; a passive bi-directional amplifier head-end typically delivers a total composite output of +23 dBm to +33 dBm. Operating an amplifier beyond its rated composite power degrades the noise figure and generates intermodulation that interferes with both the DAS and the macro network. Gain shall be set so the link budget closes without exceeding the linear range.
```datasheet
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max: 37
step: 1
−setpoints: [20, 33]
+setpoints: [17, 20, 33, 37]
```
…5 unchanged lines
max: 9
step: 0.5
−setpoints: [5, 6]
+setpoints: [3, 5, 6]
```
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## Coaxial Distribution {toc}
−### Passive coaxial distribution shall use 50 Ω plenum-rated cable sized to the run length and signal budget. {note}
+### Passive coaxial distribution shall use 50 Ω plenum-rated cable sized to the run length and signal budget.
−### Trunk runs use 50 Ω flexible coaxial cable with a nominal 0.4 in OD; drops of 30 ft or less may use 50 Ω flexible coaxial cable with a nominal 0.2 in OD. Passive trunk runs longer than approximately 150 ft exceed the loss budget and starve the downstream antennas of signal, which then forces additional amplifiers that were not in the original design. The design shall verify every passive run against the loss budget rather than assuming a fixed maximum. {note}
+### Trunk runs use 50 Ω flexible coaxial cable with a nominal 0.4 in OD; drops of 30 ft or less may use 50 Ω flexible coaxial cable with a nominal 0.2 in OD. Passive trunk runs longer than approximately 150 ft exceed the loss budget and starve the downstream antennas of signal, which then forces additional amplifiers that were not in the original design. The design shall verify every passive run against the loss budget rather than assuming a fixed maximum.
```datasheet
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max: 200
step: 10
−setpoints: [120, 150]
+setpoints: [120, 150, 200]
```
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## Fiber Distribution {toc}
−### Active and digital DAS shall distribute over fiber sized to the run distance. {note}
+### Active and digital DAS shall distribute over fiber sized to the run distance.
−### Intra-building runs of 300 m or less may use OM3 or OM4 multimode fiber (50/125 µm); runs longer than 300 m or between buildings shall use OS2 single-mode fiber. Fiber backbone pathways from the telecommunications room to the head-end are frequently a scope gap between the low-voltage and IT contractors; the demarcation shall be stated explicitly in relation to [[sync/structured-cabling]]. {note}
+### Intra-building runs of 300 m or less may use OM3 or OM4 multimode fiber (50/125 µm); runs longer than 300 m or between buildings shall use OS2 single-mode fiber. Fiber backbone pathways from the telecommunications room to the head-end are frequently a scope gap between the low-voltage and IT contractors; the demarcation shall be stated explicitly in relation to [[sync/structured-cabling]].
```datasheet
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## Antenna type, density, and placement shall be selected to achieve the signal target across each floor plate. {note}
−## Omnidirectional ceiling-mount patch antennas suit open floor plates; directional panel antennas suit corridors, perimeters, and long narrow spaces. On open plates an omnidirectional antenna covers roughly 2,500 to 5,000 sq ft, falling to 1,000 to 2,500 sq ft where cubicle partitions or concrete construction attenuate signal. The 80%-case planning density is one antenna per 3,000 sq ft; the coverage prediction governs the final count and placement. {note}
+## Omnidirectional ceiling-mount patch antennas suit open floor plates; directional panel antennas suit corridors, perimeters, and long narrow spaces. On open plates an omnidirectional antenna covers roughly 2,500 to 5,000 sq ft, falling to 1,000 to 2,500 sq ft where cubicle partitions or concrete construction attenuate signal. The typical planning density is one antenna per 3,000 sq ft; the coverage prediction governs the final count and placement. {note}
+## The primary antenna type shall be specified, selected to suit the coverage geometry of the floor plate it serves.
+
```datasheet
label: Primary antenna type
…5 unchanged lines
```
+## The planning antenna density for open floor plates shall be specified, established by the coverage prediction for the actual construction and partition conditions.
+
```datasheet
label: Planning antenna density (open floor plate)
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### Antenna locations are shown on the drawings and shall be field-coordinated with ceiling-mounted MEP, lighting, and fire-protection devices. [[drawing: antenna location plan]]
−### Antennas serving 4×4 MIMO or beamformed 5G NR shall be MIMO-capable; single-port legacy antennas shall not be used for MIMO bands. {note}
+### Antennas serving 4×4 MIMO or beamformed 5G NR shall be MIMO-capable; single-port legacy antennas shall not be used for MIMO bands.
−### Legacy DAS antennas are single-port and cannot carry 4×4 MIMO or beamforming, which 5G NR massive-MIMO sources require. Specifying single-port antennas on a system intended to carry 5G NR silently caps the system at SISO performance. Where any supported band uses MIMO, the remote units and antennas shall be MIMO-capable end to end. {note}
+### Legacy DAS antennas are single-port and cannot carry 4×4 MIMO or beamforming, which 5G NR massive-MIMO sources require. Specifying single-port antennas on a system intended to carry 5G NR silently caps the system at SISO performance. Where any supported band uses MIMO, the remote units and antennas shall be MIMO-capable end to end.
# Power and Backup {toc}
−## The head-end and active remote units shall be served by dedicated, labeled, UPS-backed power. {note}
+## The head-end and active remote units shall be served by dedicated, labeled, UPS-backed power.
−## Each head-end requires a dedicated 120 V circuit; a 20 A circuit is the minimum and a 30 A circuit is typical for multi-carrier active head-ends. The breaker shall be labeled "DAS HEAD-END - DO NOT DE-ENERGIZE." UPS backup runtime is a minimum of 2 hours at full load for commercial-cellular-only systems and a minimum of 4 hours for any system carrying a public-safety overlay, with NEC Article 700/701 applying where the overlay is a legally required system. {note}
−
```datasheet
label: Head-end dedicated circuit rating
…12 unchanged lines
max: 8
step: 1
−setpoints: [2, 4]
+setpoints: [2, 4, 8]
```
+## Each head-end requires a dedicated 120 V circuit; a 20 A circuit is the minimum and a 30 A circuit is typical for multi-carrier active head-ends. The breaker shall be labeled "DAS HEAD-END - DO NOT DE-ENERGIZE." UPS backup runtime is a minimum of 2 hours at full load for commercial-cellular-only systems and a minimum of 4 hours for any system carrying a public-safety overlay, with NEC Article 700/701 applying where the overlay is a legally required system. {note}
+
### The head-end breaker shall be labeled "DAS HEAD-END - DO NOT DE-ENERGIZE" at the serving panel.
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# Network Management {toc}
−## The system shall include a network management system (NMS) with remote monitoring and alarm integration. {note}
+## The system shall include a network management system (NMS) with remote monitoring and alarm integration.
−## Without remote monitoring, post-installation failures of a remote unit, fiber link, or amplifier go undetected until users complain. The NMS shall report device status and alarms over SNMP or the manufacturer's native protocol and shall forward critical alarms to the building management system. Alarm points shall include amplifier fault, oscillation, fiber-link loss, and loss of signal source. {note}
+## Without remote monitoring, post-installation failures of a remote unit, fiber link, or amplifier go undetected until users complain. The NMS shall report device status and alarms over SNMP or the manufacturer's native protocol and shall forward critical alarms to the building management system. Alarm points shall include amplifier fault, oscillation, fiber-link loss, and loss of signal source.
### The system shall provide an NMS that monitors every active device and reports faults over SNMP or a manufacturer-native protocol.
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# Testing and Commissioning {toc}
−## The system shall be commissioned by grid-test signal measurement and accepted only against documented signal targets. {note}
+## The system shall be commissioned by grid-test signal measurement and accepted only against documented signal targets.
## Without a defined grid-test protocol and acceptance criteria there is no contractual basis for system performance. The commissioning method follows the IFC 510 / NFPA 72 grid approach: each floor is divided into a measurement grid of at least 20 points, and every point must meet the minimum downlink signal threshold for every supported band. Critical areas - stairwells, elevators, and parking - are tested as 99% compliance zones. Each rebroadcast carrier additionally performs its own acceptance testing before the system is placed in service. {note}
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# Delivery, Storage, and Handling {toc}
−## Equipment shall be delivered, stored, and handled to protect electronics and connectors from damage and contamination. {note}
+## Equipment shall be delivered, stored, and handled to protect electronics and connectors from damage and contamination.
## Head-end and remote-unit electronics shall be kept in their original packaging, in a dry conditioned space, until installation. Coaxial cable ends and fiber connectors shall be capped to keep dust and moisture out, and fiber shall not be bent below its minimum bend radius at any point during pulling or storage. {note}
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# Warranty {toc}
−## The Contractor shall provide a manufacturer warranty on equipment and a separate workmanship warranty on the installation. {note}
+## The Contractor shall provide a manufacturer warranty on equipment and a separate workmanship warranty on the installation.
−## The manufacturer warranty covers the head-end, remote units, and active distribution electronics for the specified term; the workmanship warranty covers cabling, terminations, and installation labor. Because firmware and carrier configurations evolve, the warranty period and any included firmware updates shall be stated explicitly. {note}
+## The manufacturer warranty covers the head-end, remote units, and active distribution electronics for the specified term; the workmanship warranty covers cabling, terminations, and installation labor. Because firmware and carrier configurations evolve, the warranty period and any included firmware updates shall be stated explicitly.
### The Contractor shall provide a manufacturer equipment warranty of not less than the period selected below from the date of final acceptance.
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# Spare Parts {toc}
−## The Contractor shall furnish spare components sufficient to restore service after a single device failure. {note}
+## The Contractor shall furnish spare components sufficient to restore service after a single device failure.
## At a minimum the owner should receive one spare of each active remote-unit type and a stock of antennas, connectors, and patch cords proportional to the installed quantity, so that a failed device can be replaced without waiting on procurement. Carrier-furnished base-station hardware is excluded from this spare-parts requirement. {note}
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max: 10
step: 1
−setpoints: [5, 5]
+setpoints: [2, 5, 10]
```
### The Contractor shall furnish spare connectors and patch cords proportional to the installed quantity.