FTTA Fiber Cable & Patch Cord: From the BBU to the Antenna

FTTA (fiber to the antenna) cabling is the fiber infrastructure that connects a base station’s baseband equipment at the bottom of a tower to the radios at the top. An FTTA fiber cable — usually a hardened outdoor patch cord — carries the fronthaul link between the BBU/DU and the RRU, RRH, or AAU, replacing the heavy coaxial runs of earlier site designs. Because the connection lives outdoors for years, FTTA jumpers use sealed, ruggedized connector systems such as ODC.

The FTTA architecture in one picture

A modern macro site splits the base station into two physical parts:

• Bottom of tower / shelter: the baseband unit (BBU) — or, in 5G RAN splits, the DU (distributed unit) fed by a CU (centralized unit) deeper in the network.
• Top of tower / mast / rooftop: the radio — RRU (remote radio unit), RRH (remote radio head), or in 5G massive-MIMO designs the AAU (active antenna unit, radio and antenna in one housing).

The link between them is fronthaul. A single duplex pair of fronthaul cable does that work at a fraction of coax’s weight and wind load — and with no RF loss over distance. The protocols running over that fiber are CPRI (the long-standing 3G/4G fronthaul standard) and eCPRI (its packet-based evolution for 5G, which relaxes bandwidth requirements and allows Ethernet transport). The cable does not care which protocol it carries — the connector on the radio does.

Larger sites sometimes break the run at a tower-base junction box or closure: a multi-fiber feeder makes the long climb, and short hardened jumpers finish each leg to the radios. Every break point adds mated pairs to the loss budget — the connector rules in this guide apply at each of them.

A site typically also runs DC power up the same route, either as a separate power cable or as a hybrid (composite) cable combining fiber and power conductors in one jacket. The fiber jumpers in this guide handle the optical side; hybrid trunks are a separate bill of material.

The cables that do the work

An RRU fiber jumper is the workhorse of the stack: a short, factory-terminated FTTA cable assembly matched to the ports on each end. Jumper builds are tight-buffered round drop cable over an aramid strength member (the GYFJH class in most factory catalogs) — flexible enough for mast-top routing, tough enough for the pull; loose-tube constructions belong to the feeder and trunk layer, not to jumpers. The cable types below differ mainly in where each leg runs and which end is hardened.

BWNFiber builds the full jumper layer of this stack on the ODC fiber cable platform. The ODC-4C line covers four-fiber radio ports: ME FTTA patch cords, MP cable assemblies, FSS patch cords, and FSH outdoor cords. For non-ODC ports, we supply PDLC, NSN Boot, OptiTap, and armored CPRI variants for mixed-equipment sites.

FTTA connector types: the port decides

Radio vendors have shipped several hardened interface families across generations of RRU/RRH hardware. The jumper must match the port on your specific radio model — never the brand name, never the catalog photo.

ODC and Q-ODC are registered trademarks of HUBER+SUHNER; OptiTap is a trademark of Corning; FullAXS is a trademark of TE Connectivity. BWNFiber supplies ODC-compatible assemblies — always built against the radio’s port drawing, not a brand label. Outdoor connectors are built to performance categories such as IEC 61753-1, and the interface dimensions of the common families sit in the IEC 61754 series — which is why a third-party assembly can be built to mate correctly. RFQs also name AARC, RDC, and hardened MPO fan-outs; the rule does not change: match the port, not the brand. The full engineering comparison — mating behavior, ecosystem breadth, and how to choose — is in ODC vs ODVA vs FullAXS: FTTA connector types compared. Mixed-equipment sites join different families with custom hybrid assemblies.

Plug or socket? Check the gender before you order

Hardened radio ports come in two physical forms: plug (the protruding half) and socket (the recessed half). The jumper must carry the mating half at the radio end — and different manufacturers mark the same pair in opposite directions, so “male ODC” on one datasheet can be another vendor’s “female”. The resulting mismatch is one of the most common reasons FTTA jumpers come back. One photo of the port, taken square-on, resolves it before the order is cut. Variant letters in a series mark different end configurations — our ODC-2C line ships as ODC-2C ME, ODC-2C MP, ODC-2C FSS, and ODC-2C FSH — so confirm the exact plug/socket form against the drawing before ordering; the letters are not a substitute for the photo. If your BOM mixes radio generations, expect several genders and interface families on one site.

4G vs 5G: what changes for the cabling

More jumpers per site. On a 4G base station, a sector typically runs one duplex pair per RRU. On a 5G base station, capacity layers — multiple bands, dual carriers, massive-MIMO AAUs — multiply the radio count per site, and with it the jumper count. 4-fiber hardened connectors (ODC-4 class) consolidate pairs where the radio port allows.

eCPRI relaxes bandwidth, not distance. eCPRI cuts fronthaul bit rates versus CPRI, but the optical budget arithmetic is unchanged: connector pairs, splices, and fiber attenuation still sum against the transceiver budget. Tower runs of 50–150 m are routine for single-mode jumpers with margin to spare; the loss budget lives in the connections, not the glass. See our fiber loss budget guide.

Small cells move the problem, not remove it. Street furniture, poles, and indoor small cells still need hardened, compact connectivity — often the same interface families in compact Q-ODC-class housings, still factory-terminated.

Power planning diverges. Massive-MIMO AAUs draw more power than legacy RRUs; some sites adopt hybrid trunks, others upsize separate power runs. Decide before ordering jumpers, because the jumper route follows the power route.

How to select an FTTA cable: the short version

1. Identify every port. Radio model → interface family, gender, fiber count. Do this per radio type on the site BOM; one site can carry three interface families.
2. Count duplex links per port. One pair → 2-fiber build; two pairs → 4-fiber where the port supports it.
3. Choose fiber. OS2 single-mode (ISO/IEC 11801), bend-insensitive G.657.A1/A2, for essentially all tower fronthaul. Factory-terminated jumper builds standardize on G.657.A2 per ITU-T G.657 — it tolerates the tight mast-top routing that would eat a standard fiber’s loss budget, and stays compatible with G.652.D infrastructure. If the BOM also includes long feeder or hybrid trunk sections, those fiber units may be specified as G.652.D — confirm per link design.
4. Choose jacket. TPU for exposed tower runs (black, UV-stable); LSZH where the cable enters occupied space; armor where rodents or crush risk exist. Confirm the operating-temperature range against your climate — −40 to +70 °C is the outdoor norm, and desert or high-latitude sites can push past it at either end. See TPU vs LSZH for outdoor fiber.
5. Match ingress rating. IP67/IP68 mated at the outdoor end (per IEC 60529: IP67 = immersion to 1 m, IP68 = deeper/longer per manufacturer spec). IP65 hardware shows up in quotes — dust-tight and jet-proof, but not rated for immersion; for tower-top duty treat it as a compromise, not a spec. Caps go on anything unmated — an uncapped connector is the most expensive part of the whole site once water gets in. The full decision is in IP67 vs IP68 for fiber connectors.
6. Measure lengths per leg. Route length plus 3–5% service slack, measured on the as-built route rather than the site drawing; label both ends before the pull.
7. Require per-unit test records. IL/RL per assembly, against the link budget. As an acceptance floor, per-mated-pair insertion loss ≤ 0.3 dB and return loss ≥ 50 dB (SM UPC) sit in the range of IEC 61755 performance grades commonly specified for FTTA jumpers — but the real test is the sum against your transceiver budget, so ask for the report, not just the promise. On short jumpers this means light-source/power-meter IL and RL testing per assembly; OTDR earns its keep on feeder sections and fault location, not on a 100 m jumper.

The complete framework with RFQ checklist is in our ODC selection guide; installation practice is covered in how to install an ODC connector. If your BOM mixes radio generations or interface families, send the radio models or port photos with your site count — we map each line to an interface, a gender, and a build before quoting. Start the conversation →

FTTA ordering mistakes that cost a site visit

These are the failures tower crews keep seeing — each one turns a week of delivery into a second site visit:

1. Ordering by brand name instead of port. “A Nokia jumper” or “a Huawei jumper” is not a connector spec. The same vendor ships different interface families across radio generations.
2. Guessing the gender. Plug/socket mismatches cannot be adapted in the field. One port photo per radio type settles it (see above).
3. Buying indoor patch cords for tower work. Standard LC duplex jumpers have no environmental sealing and no strain relief for mast movement. They work in the shelter, nowhere else.
4. Ignoring the power plan. Jumpers ordered before the power routing is fixed end up too short, or routed through the wrong tray.
5. Field-terminating to save money. On-tower splicing or field polishing costs more in labor and re-visits than any factory-terminated jumper — and a field-polished connector has no test record to lean on when the link fails.
6. Skipping the dust caps during storage and pull. A contaminated end face fails inspection under IEC 61300-3-35 and adds loss you will chase around the site; a wet one corrodes. Cap both ends, and put the caps back after every inspection.
7. Pulling by the connector. Drag the cable, not the head; a hardened connector is rugged, not immortal. Keep the pull within the rated tensile load and the bend above the minimum radius — typical jumper class is a few hundred newtons and 10–20× the cable OD, but the datasheet governs. Torque the coupling nut to the manufacturer’s value, never “hand-tight plus a turn.”

What to send your FTTA cable supplier

A quotation that comes back right the first time starts with this list. Skip one item and the supplier has to guess — and the guess shows up in the price or the delivery:

1. Radio models (or port photos) per site type
2. Sectors and radios per site, number of sites
3. Interface family, gender, and fiber count per port
4. Route lengths per leg (radio ↔ junction ↔ BBU/DU), with slack policy
5. Jacket preference: TPU, LSZH, armored — and where each applies
6. Ingress requirement (IP67/IP68) and mating duty
7. Fiber: OS2 G.657.A2 default; state G.652.D for feeder sections if any
8. Acceptance: per-unit IL/RL records, test standard, and reporting format
9. Labeling and packing: sector/site numbering scheme printed on the jacket tags, matched on the carton labels and packing list for export shipments

Reading the reply is its own filter. A supplier who has done FTTA work asks for port photos or drawings before quoting, catches gender and fiber-count mismatches in your BOM, and treats per-unit IL/RL reports as standard paperwork — with the report format shown before production, not after. Complete lists come back with firm prices and lead times; vague ones come back padded on both.

For a first order or a new interface family, qualify a sample pair on the live radios before releasing site quantities — request the sample with the RFQ, along with the build datasheet and a sample test report. A two-day bench check beats a site-wide swap.

BWNFiber works from exactly this list: hardened jumpers across interface families, armored CPRI runs, custom lengths and labeling per sector, and per-unit test documentation. Regional practice differs here: North American tower-co sites mostly run separate power routing; self-built operator sites in the Middle East and Southeast Asia more often evaluate hybrid trunks. Fix the power plan first — the jumper plan follows it. Send your radio models and site count for a configured quotation.

Frequently asked questions

What is FTTA fiber cable?
FTTA (fiber to the antenna) cable is the fiber cabling connecting a base station’s baseband equipment (BBU/DU) to its tower-top radios (RRU/RRH/AAU). In practice it means hardened outdoor fiber patch cords — sealed connector systems like ODC on the radio end, standard LC/SC on the indoor end.

What cable is used for FTTA?
Factory-terminated outdoor jumpers: hardened 2- or 4-fiber patch cords (ODC, ODVA, FullAXS, PDLC, or NSN Boot depending on the radio port), OS2 G.657 single-mode fiber, TPU or LSZH jacket, ~5 mm OD. Armored LC patch cords serve protected duct runs; hybrid power+fiber trunks feed radios needing DC over the same route.

What is the difference between CPRI and eCPRI cable?
There is no physical “CPRI cable” or “eCPRI cable” — both protocols run over the same single-mode fiber jumpers. eCPRI is a packet-based fronthaul protocol that lowers bandwidth requirements; the cabling decision (connectors, fiber, jacket, length) is identical. The radio’s interface port, not the protocol, determines the connector.

How far can an FTTA fiber run?
Fronthaul links commonly span 50–150 m of tower and shelter routing; single-mode fiber with proper transceivers covers this with ample margin. The constraint is the connector loss budget, not distance — sum the mated pairs against the transceiver specification.

Do all RRUs use the same connector?
No. RRU/RRH hardware across vendors and generations uses several hardened families: ODC, Q-ODC, ODVA, FullAXS, PDLC, NSN Boot, and others. Identify the port from the radio’s datasheet per model — the same vendor ships different interfaces on different radios.

How do I identify the connector on my RRU?
Take a square-on photo of the port, then match it against the interface families in the table above (locking style, fiber count, and housing shape). The radio datasheet’s interface section confirms the family and gender. Do not order from the radio’s brand name — vendors use multiple families across models and generations.

What fiber count do I need per RRU?
One duplex link per radio port is the 4G default (2 fibers). Multi-band or dual-carrier radios may present 4-fiber ports; protection schemes add pairs. Count the duplex links on the port datasheet, then see ODC-2 vs ODC-4.

What insertion loss is acceptable for an FTTA jumper?
As an acceptance floor, per-mated-pair IL ≤ 0.3 dB and RL ≥ 50 dB (SM UPC) are in the range of IEC 61755 grades commonly specified for FTTA assemblies (North American specifications may cite Telcordia GR-326 instead — the acceptance logic is identical). The decisive check is the sum of all connections against your transceiver budget — so require per-unit IL/RL test records and compare them to the link design, not to a catalog number.

Can one cable carry both fiber and power to the radio?
Yes — hybrid (composite) FTTA trunks combine fiber units and copper power conductors in one jacket. The fiber breakout at each end still uses hardened jumpers. Hybrid versus separate power is a site-design decision driven by radio power draw and route constraints.

Should FTTA jumpers be single-mode or multimode?
Single-mode OS2, essentially without exception for tower fronthaul — bend-insensitive G.657.A1/A2 grades per ITU-T G.657 handle the tight routing at mast tops and enclosures. Multimode (OM3/OM4) belongs to data-center and short in-building links, not to fronthaul.

How are FTTA cables installed and maintained?
Factory-terminated jumpers arrive tested; field work is routing, pulling (with caps fitted, by the cable never the connector), mating to torque, and post-install power-meter verification. Maintenance is inspect-before-you-connect discipline — see our installation guide and cleaning & inspection guide.

Can BWNFiber supply a full site BOM?
Yes — hardened jumpers across interface families, armored CPRI runs, custom lengths and labeling per sector, with per-unit test reports. Send your radio models and site count for a configured quotation.

Plan your FTTA cabling

Send the radio models (or port photos), sectors per site, route lengths, and quantity. BWNFiber returns a per-site cabling plan — interface-matched jumpers, armored runs, labels, and per-unit test documentation. Start your RFQ →