Cel-Fi RS3 Installer, Atlanta + Southeast US

What Cel-Fi RS3 is, in one paragraph

Cel-Fi RS3 is Nextivity's small-commercial cellular booster — the middle child of the Cel-Fi product line. It sits between the Cel-Fi GO G41 single-zone booster and the QUATRA active distributed antenna system. A typical RS3 deployment consists of a donor antenna mounted on the roof or an exterior wall, a low-loss coax run down to the head-end RS3 booster, and a passive coax DAS distributing the boosted signal through four to six indoor antennas across the floor plate. Single-carrier per unit, locked to AT&T, Verizon, T-Mobile, or FirstNet. Same IntelliBoost digital regeneration architecture as the rest of the Cel-Fi line, which is why RS3 hits up to 100 dB of system gain without raising the noise floor.

The building size sweet spot

JBT specifies RS3 most often for buildings in the 10,000 to 25,000 sq ft range — single-tenant office buildings, two-story medical clinics, retail flagships, and smaller distribution warehouses. Below 10,000 sq ft on a single floor, Cel-Fi GO G41 covers the space at a lower cost. Above 25,000 sq ft, the passive coax DAS link budget starts to cost too many decibels through cable, couplers, and splitters; we move to Cel-Fi QUATRA with its active Cat6 / fiber backhaul to keep the per-antenna output strong.

The other dimension that matters is the donor signal strength outside the building. RS3 needs a usable downlink at the donor-antenna location. If the donor RSRP is below approximately -110 dBm, the booster doesn't have enough signal to work with regardless of model. JBT measures the donor signal at proposed antenna locations during the site survey and moves the donor antenna if necessary to find a workable RSRP.

Why RS3 specifically (vs. the rest of the Cel-Fi family)

The three reasons we land on RS3 instead of GO G41 or QUATRA:

• More indoor antenna ports than GO G41. GO G41 supports up to four indoor antennas on a default coax run; RS3's head-end is engineered for a designed passive DAS with up to six indoor antennas through couplers and splitters, sized for the floor plate rather than a default.
• Higher head-end output than GO G41. RS3 has higher transmit power at the head end, which gives the engineered DAS more headroom for coupler and splitter loss. The result is even per-antenna output across the building.
• Lower cost than QUATRA. A QUATRA active DAS requires Cat6 / fiber pathway and Network Unit power at each Coverage Unit. For buildings where the passive coax DAS link budget works, RS3 covers the building at a notably lower install cost — usually 40-60% less than the equivalent QUATRA.

RS3 isn't a default booster. It's specifically the right answer when the building is bigger than a single-zone GO can cover, but small enough that the active DAS overhead of QUATRA isn't earned. Most of JBT's RS3 installs land in mid-sized professional service offices, urgent-care clinics, retail flagships, and pre-cast warehouses around 15,000–22,000 sq ft.

Engineering the passive coax DAS

The variable that makes or breaks an RS3 deployment is the passive DAS link budget. Every component between the RS3 head-end and the most distant indoor antenna costs decibels: coax cable loss per 100 ft, 2-way and 3-way splitter loss, hybrid coupler loss, connector loss. JBT engineers the DAS as a designed system rather than running coax to wherever's convenient. The deliverable is a coax topology drawing showing every antenna location, every component between the head-end and that antenna, and the predicted dBm output at each antenna port.

The standard JBT RS3 DAS uses:

• LMR-400 or 1/2-inch superflex jumpers from head-end to first splitter
• Low-PIM hybrid couplers (typically -150 dBc PIM) to feed multiple antennas from a single feed
• Low-PIM 2-way and 3-way splitters in the engineered DAS topology
• Plenum-rated coax (CMP) wherever the cable runs above ceiling tiles
• Low-PIM omnidirectional ceiling antennas (typically with 3-5 dBi gain) on the indoor side

Every component has documented loss, every link is sized in the design spreadsheet, and the predicted dBm at each indoor antenna is on the heat-map drawing the customer signs off on.

What a JBT RS3 deployment looks like

Our typical RS3 project lands in four phases over a 4-6 week cadence:

1. Site survey + design. A field tech measures donor signal RSRP / RSRQ outside the building at proposed donor-antenna locations and walks the interior to map dead zones. We propose a head-end location, four to six indoor antenna locations, the coax pathway, and the carrier(s) to cover. Output: a one-page design summary and a coverage commitment.
2. Engineered design package. Heat-map prediction, coax topology drawing, bill of materials, link-budget spreadsheet, and the per-carrier dBm coverage map. Customer signs off; JBT orders hardware.
3. Installation. Roof or wall donor-antenna mount, coax pull down to the head-end, RS3 head-end installation in a telecom closet or server room, indoor antenna mounting on the engineered DAS plan, and final coax termination + PIM test.
4. Commissioning + carrier activation. RS3 paired to the Nextivity WAVE portal, per-carrier registration filed (AT&T, Verizon, T-Mobile, or FirstNet), and JBT walks the building doing live RSRP measurements at every indoor antenna to validate the predicted coverage. System left running and monitored.

Multi-carrier RS3 deployments

A single RS3 unit covers exactly one carrier. For customers who need multi-carrier coverage (which is most commercial customers), JBT stacks RS3 head-ends and shares the passive DAS through engineered hybrid couplers. Each RS3 gets its own donor antenna or shares a multi-carrier donor antenna depending on the geometry; the indoor DAS feeds all carriers through the same antenna locations using the hybrid coupler infrastructure. The carrier-specific link budget gets engineered per carrier so the indoor signal stays inside the compliance window for each.

Multi-carrier RS3 adds cost — each carrier needs its own head-end and registration — but it shares the most expensive line item: the indoor passive DAS. For three-carrier coverage of an Atlanta office, JBT typically delivers the install at roughly 2.0-2.4× the single-carrier cost rather than 3×.

PIM testing and why JBT does it

Passive intermodulation (PIM) is the silent killer of passive DAS performance. Any non-linear junction in the coax pathway — a corroded connector, a poorly-torqued N-type, a kinked coax run — generates intermodulation products that fall back into the carrier's uplink band and reduce the uplink signal-to-noise ratio. The system might pass a downlink RSRP test but fail to hold a usable uplink for users on the floor. JBT runs a PIM sweep on every RS3 passive DAS at commissioning using a calibrated PIM analyzer, documents the worst-case PIM measurement, and fixes anything above the -150 dBc threshold before declaring the install complete. The PIM test report is part of the project close-out package.

WAVE monitoring and ongoing support

Every RS3 JBT commissions comes online inside the Nextivity WAVE cloud portal. WAVE gives JBT remote visibility into uplink and downlink signal levels, current gain, oscillation alarms, and dropped-call counters. JBT support agreements bundle WAVE monitoring with annual signal-level audits and prioritized dispatch — when telemetry shows the donor signal has degraded or the head-end is approaching gain limit, we proactively dispatch before the customer feels it.

Donor signal optimization for RS3

The donor signal is the foundation of every RS3 install — if the booster doesn't have a usable downlink to work from, no amount of indoor DAS engineering can rescue the system. JBT's site survey measures donor RSRP / RSRQ on the target carrier at every viable donor-antenna location around the building exterior — roof corners, parapet edges, exterior walls — and chooses the location with the strongest RSRP and the cleanest RSRQ. We aim a directional Yagi or panel donor antenna at the nearest macro cell tower whenever practical (which usually delivers 8-15 dB of additional donor signal over an omnidirectional antenna) and document the bearing in the as-built drawings so future service calls don't lose the alignment.

For the harder donor-signal cases — buildings in cellular dead zones, single-story buildings surrounded by taller buildings, basements with no roof access — JBT can deploy an elevated donor antenna on a sleeved mast or a roof-mount tower for several feet of additional height. The donor-side antenna gain plus the IntelliBoost regeneration gives RS3 a meaningful operating window even on marginal donor signal that a passive booster could not work with.

Atlanta service area

JBT installs Cel-Fi RS3 across the Atlanta metro (Downtown, Midtown, Buckhead, Sandy Springs, Alpharetta, Roswell, Marietta, Smyrna, Dunwoody, Decatur, Kennesaw, Duluth, Lawrenceville) and the broader Southeast US — Georgia, Alabama, Tennessee, South Carolina, North Carolina, and Florida. For the broader Cel-Fi commercial cellular product strategy, see our Cel-Fi installer overview, and for the underlying DAS service practice, see the DAS / in-building cellular service page.

RS3 is a commercial cellular service — not public-safety BDA. For nationwide SHIELD ERCES work, see our SHIELD ERCES installer page.

Frequently asked questions

Call (770) 637-2094 to scope a Cel-Fi RS3 small-commercial cellular booster install in Atlanta or anywhere in the Southeast US, or see the DAS / in-building cellular service page for the broader JBT DAS practice.