NOTE This standard governs the design, supply, installation, and commissioning of in-building Distributed Antenna Systems (DAS) for commercial cellular wireless coverage. (1.1)

NOTE A DAS captures or generates licensed cellular signal and redistributes it through a building over coaxial cable, fiber, or both so that mobile devices achieve usable signal in areas the macro-cellular network cannot reach. The system comprises a head-end (signal source plus combining and amplification), a distribution network, and distributed antennas. This standard covers passive, active fiber-fed, hybrid, and digital DAS architectures, neutral-host designs serving multiple carriers, and the 4G LTE and 5G NR sub-6 GHz bands from 600 MHz through 3.7 GHz. (1.2)

NOTE DAS is warranted where the macro-cellular network alone cannot deliver the required in-building signal level. (1.3)

NOTE The typical triggers are building area above approximately 50,000 sq ft, RF-attenuating construction (cast-in-place concrete, metal-clad or low-emissivity glazing), underground or structured parking, and large-venue or arena occupancies. Coverage need is established by survey of the as-built or modeled macro signal, not assumed; a building that already meets the design target on every floor does not require a DAS. (1.4)

NOTE Cellular DAS and public-safety responder radio enhancement are distinct systems with separate regulatory frameworks, amplifiers, antennas, and approvals. (1.5)

NOTE Commercial cellular DAS operates under FCC Part 20 and requires carrier coordination agreements; public-safety responder radio enhancement (ERRCS / BDA) operates under FCC Part 90, is governed by IFC Section 510, NFPA 72 Chapter 24, and NFPA 1 Chapter 11, uses UL 2524-listed amplifiers, and is approved by the fire AHJ. The two systems frequently share physical pathways (conduit, cable tray, riser sleeves) but use separate amplifiers, antennas, and regulatory approvals. Public-safety responder coverage is specified under Public Safety Radio Systems and is outside this standard. (1.6)

NOTE Scope boundary with adjacent telecommunications standards: structured cabling, telecommunications rooms, grounding busbars, and public address are specified under their respective standards. (1.8)

NOTE Backbone and horizontal structured cabling, telecommunications room provisioning, and cable-tray pathways are specified under Structured Cabling; telecommunications grounding busbars (TMGB/TGB) are specified under Telecommunications Bonding; public address and paging distribution is specified under Public Address And Paging. Where this standard requires pathways, bonding, or fiber backbone, those elements are furnished under the referenced standards unless the Contract Documents assign them here. (1.9)

NOTE Carrier participation is a regulatory prerequisite, not a design preference, and shall be confirmed before infrastructure is procured. (4.1)

NOTE Under FCC Part 20, a commercial DAS that rebroadcasts a licensed carrier's signal requires that carrier's coordination agreement. Carrier base-station provisioning and neutral-host onboarding routinely take 6 to 18 months and sit on the project critical path. Specifying and installing distribution infrastructure without confirmed carrier participation produces a physically complete but non-functional system, which is among the most common and most expensive failures in DAS projects. (4.2)

NOTE Single-Source Responsibility (4.3)

NOTE Fragmented active components from multiple vendors risk interoperability gaps in firmware, network management, and warranty coverage. Passive components (coaxial cable, splitters, antennas) do not share firmware or management interfaces and may be sourced from any manufacturer meeting the specified electrical and frequency ratings. (4.4)

NOTE DAS equipment shall be rated for the temperature, humidity, and airflow conditions of its installed location. (5.1)

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. (5.2)

NOTE The DAS architecture shall be selected to match building size, floor-plate geometry, signal-source strategy, and budget. (6.1)

NOTE 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. (6.2)

NOTE The signal source shall be selected per carrier and shall be confirmed compatible with the chosen architecture. (6.3.1)

NOTE 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. (6.3.2)

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. (6.4.1)

NOTE 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. (6.4.2)

NOTE The supported band set shall cover every frequency the served carriers and tenants require, confirmed before design. (7.1)

NOTE 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. (7.2)

NOTE The design shall meet the specified in-building downlink signal target in general areas, with a defined edge-of-coverage minimum. (7.3.1)

NOTE 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. (7.3.2)

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. (7.4.1)

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. (7.4.2)

NOTE Passive coaxial distribution shall use 50 Ω plenum-rated cable sized to the run length and signal budget. (8.1.1)

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. (8.1.2)

NOTE Active and digital DAS shall distribute over fiber sized to the run distance. (8.2.1)

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 Structured Cabling. (8.2.2)

NOTE Antenna type, density, and placement shall be selected to achieve the signal target across each floor plate. (9.1)

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. (9.2)

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. (9.2.2)

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. (9.2.3)

NOTE The head-end and active remote units shall be served by dedicated, labeled, UPS-backed power. (10.1)

NOTE 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. (10.2)

NOTE DAS equipment shall be bonded to the telecommunications grounding system per ANSI/TIA-607-C. (11.1)

NOTE Head-end and remote-unit chassis shall be bonded to the telecommunications grounding busbar (TGB) or main busbar (TMGB) with conductors sized per ANSI/TIA-607-C. Inadequate or absent bonding produces ground-loop interference and can drive amplifier oscillation. The busbars themselves and the bonding backbone are furnished under Telecommunications Bonding; this standard requires only that DAS equipment connect to them. (11.2)

NOTE The system shall include a network management system (NMS) with remote monitoring and alarm integration. (12.1)

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. (12.2)

NOTE The system shall be commissioned by grid-test signal measurement and accepted only against documented signal targets. (13.1)

NOTE 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. (13.2)

NOTE Equipment shall be delivered, stored, and handled to protect electronics and connectors from damage and contamination. (14.1)

NOTE 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. (14.2)

NOTE The Contractor shall provide a manufacturer warranty on equipment and a separate workmanship warranty on the installation. (15.1)

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. (15.2)

NOTE The Contractor shall furnish spare components sufficient to restore service after a single device failure. (16.1)

NOTE 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. (16.2)