FTTH Solution

What is FTTH?

FTTH (Fibre To The Home) means the fibre runs all the way to the subscriber’s home or office, and every service is carried as light. At the customer end an optical network terminal converts that light back into Ethernet ports, telephone ports and Wi-Fi. It is the deepest access layer in the FTTx family — fibre to the cabinet stops at the street, FTTH does not.

The technology underneath is the PON (Passive Optical Network). “Passive” is the important word: between the exchange and the subscriber there is no powered equipment at all. Splitting is done by optical splitters that need no electricity, no cabinet, no cooling and no battery. That single property is what makes FTTH cheaper to run than copper, and it is why the network stays up during a power cut.

The PON architecture: three building blocks

A PON has exactly three parts. Once you can place a device in one of these three boxes, the rest of the network follows.

Why one fibre carries three services

PON separates the directions by colour, so a single strand serves everyone at once:

• Downstream, 1490 nm — the OLT broadcasts to every ONU on the port; each ONU reads only the frames addressed to it.
• Upstream, 1310 nm — all ONUs share the same fibre and transmit in time slots assigned by the OLT (TDMA), so bursts never collide.
• 1550 nm, optional — a separate overlay for CATV video. Three wavelengths share one strand without interfering.

The equipment behind each block

1. OLT: size the ports, then the uplink

An OLT is normally a rack-mounted chassis with line cards. It uplinks to the metro network over GE or 10GE and each PON port feeds tens to hundreds of ONUs through splitters. Three specifications decide the model:

• PON port count — derived from the number of subscribers to be covered, divided by the ONUs you plan to put on one port.
• Uplink capacity — 10GE is the practical minimum for a new build; 1GE fills up faster than expected.
• Multicast and management — IPTV needs efficient multicast replication, and a thin management system makes every later fault expensive.

Our GPON OLT range is compact: the QT7001 with one PON port and the QT7002 with two, both carrying 1×10GE plus 4×GE uplinks for smaller and mid-size builds. The full list sits under GPON OLT.

2. ODN: the splitter is the only active decision

A typical ODN chain runs: feeder cable → optical distribution frame (ODF) → splitter → distribution cable → fibre access terminal → drop cable → ONT. Only the split ratio is a real design choice; everything else is packaging.

The core component is a PLC (planar lightwave circuit) splitter. The larger the ratio, the fewer OLT ports you need, but the less bandwidth each subscriber gets and the shorter the reach:

Connectors are normally SC/APC — the green angled ferrule — because the angled contact keeps back reflection away from the 1490 nm downstream. Match the whole ODN to APC and do not mix in UPC patch leads.

The field hardware that goes with this stage: rack-mount and pull-out ODFs at the frame end, self-supporting outdoor drop cable or indoor drop cable into the building, airplane-head SC/APC fast connectors for termination in the field, and fibre terminal boxes plus splice closures for the joints. Bulk cable is under Fiber Optic Cable, and mounting hardware under Cable Hardware & Metal Parts.

3. ONU / ONT: pick the port mix, not the highest model

The terminal is where the service becomes usable, so its ports define what the subscriber can buy:

• GE / FE Ethernet — PC, router, IPTV set-top box.
• POTS (RJ11) — a conventional handset carried as VoIP.
• Wi-Fi 2.4 GHz / 5 GHz — phones, laptops, tablets.
• USB or CATV coax — attached storage, or an RF video feed.

Ordering a 4GE + Wi-Fi unit for a single-PC subscriber wastes money on every unit in the project. The two ends of the range make the point: the SG5000 is a single-port 1GE ONT for a basic line, while the SG8161 gives 4GE, POTS, CATV, Wi-Fi 5 and two USB ports for a full-service subscriber. Everything in between is under ONU / ONT.

4. Management, uplink and power

The last group is not part of the PON itself but decides how it is operated:

• EMS — remote provisioning, bulk configuration, alarms and fault location. Without it every truck roll is manual.
• Aggregation and routing — BAS, aggregation switches and routers for authentication, accounting and traffic concentration. See Network Equipment.
• Optical transceivers — the SFP modules that populate the uplink ports. See SFP.
• Power and resilience — PoE switches for access points and cameras (PoE Switch, up to the KU-9048G-6F+ 48-port unit), plus UPS and battery backup at the exchange (UPS & Battery).

For longer metro spans and CWDM/DWDM transport, see DWDM / OTN Solution.

A complete FTTH topology

Figure 2 shows the chain end to end: the internet edge and the EMS connect to the OLT (the figure illustrates an 8 to 64 port unit), the trunk fibre reaches an optical splitter, and fibre then fans out to six different ONT configurations.

One strand therefore carries four services at once: broadband, VoIP, multicast IPTV and Wi-Fi.

Five parameters to check before deployment

Most FTTH projects that fail do not fail on equipment quality. They fail because one of these five numbers was never written down.

Measure the receive level at every ONU after installation. A value between −8 and −25 dBm is a pass; a value at the edge means the ODN has a bad splice, a tight bend or a dirty connector, and it will fail in the first rainy season. A handheld PON power meter reading 1310 / 1490 / 1550 nm covers all three wavelengths in one pass, and an OTDR tells you where the loss actually is.

Why operators choose FTTH

Where FTTH is deployed

• Operator FTTH rollouts and copper-to-fibre upgrades
• New cabling for residential estates, apartment blocks and villa developments
• Industrial parks, office buildings and dedicated enterprise lines
• Rural and township universal-service coverage
• Safe-city CCTV backhaul and smart-community networks

Selection and deployment advice

1. Count ports before choosing an OLT. Subscribers divided by ONUs per port gives the port count; keep 10GE on the uplink regardless.
2. Keep the split plan moderate. 1:16 or 1:32 for dense areas, 1:8 where subscribers are spread out, and never more than two stages.
3. Match the ONT to the service, not to the catalogue. 1GE for internet only; add POTS or 4GE only when the subscriber actually buys voice or IPTV.
4. Measure optical power at every ONU. −8 to −25 dBm is the acceptance window; record it per address.
5. Deploy the EMS from day one. Remote provisioning and fault location remove most of the field labour.

Start with these

The parts of a typical first build, in the order they are installed.