Technical comparative analysis of FTTR and FTTH

I. Architecture definition and deployment differences

FTTH refers to the situation where the fiber optic line terminal is located at the entrance interface of the user's residence. The network architecture is as follows: the operator's office equipment (OLT) is connected to a single optical network terminal (ONT/optical modem) at the user end via an optical distribution network (ODN). After the optical signal completes the optoelectronic conversion at the ONT, it distributes data to indoor devices through Ethernet cables or wireless LAN technology.

FTTR refers to extending fiber optics further into every major functional room within a user's residence. Its architecture is as follows: a main optical network unit is placed at the entry point, which is directly connected to the subordinate optical network units in each room through lightweight optical cables laid indoors in a star topology. Each subordinate unit independently provides local network access.

The core difference lies in the location and quantity of signal conversion points: FTTH involves centralized conversion at a single point, while FTTR involves distributed conversion at multiple points.

II. Physical Layer and Performance Comparison

transmission medium

FTTH: Optical signal transmission ends at the ONT, and thereafter relies on Cat 5e/Class 6 network cables or Wi-Fi RF signals.

FTTR: Optical signals are transmitted directly to each room through a tight-buffered fiber optic cable (G.657 A2/B3 type) with a diameter of approximately 2mm, maintaining optical transmission throughout the entire process.

Bandwidth and attenuation:

FTTH: Indoor network cables have a bandwidth limit (such as Category 5e cables supporting 1Gbps within 100 meters). Wi-Fi signals experience significant attenuation after passing through walls, resulting in both rate and latency degradation.

FTTR: Single-mode fiber exhibits extremely low transmission loss (<0.4 dB/km) within the 1310/1550nm window, resulting in almost negligible attenuation for indoor short-distance transmission. Each room can independently provide access capabilities equivalent to the bandwidth provided to the household from the unit.

Coverage and roaming:

FTTH: Relying on a single or wireless router for coverage, there are areas with weak signal strength. Switching between multiple wireless access points typically occurs in the hundreds of milliseconds, which may lead to service interruptions.

FTTR: Each room is equipped with an independent wireless access point (slave unit) to achieve full coverage at the physical layer. Under the control of the master unit, it supports IEEE 802.11k/v/r protocols, enabling seamless roaming of devices between multiple access points in milliseconds.

III. Installation and Deployment Requirements

Wiring requirements:

FTTH: Only one incoming fiber is required to be pre-buried to the home information box during the construction period.

FTTR: During the construction or renovation period, a single-core optical cable needs to be pre-buried or exposed from the home information box to each target room.

Device configuration:

FTTH: One standard ONT.

FTTR: A master optical gateway and multiple slave optical gateways need to be configured, with the number of devices proportional to the number of room locations.

Construction complexity:

FTTH: mature technology, standardized construction.

FTTR involves indoor fiber optic termination (welding or cold splicing) and optical link adjustment and testing, which requires higher construction craftsmanship.

IV. Applicable Scenarios and Cost Analysis

Applicable scenarios:

FTTH: suitable for small and medium-sized apartments, where the network demand primarily focuses on Internet access and standard definition video streaming.

FTTR: It is suitable for large-area, multi-partitioned residences (such as villas and large-scale apartments), as well as scenarios with stringent requirements for network latency and bandwidth stability (such as 8K streaming media, cloud gaming, real-time remote collaboration, and high-density smart home).

Cost structure:

Initial investment: Due to the increased number of devices and dedicated cabling, the initial cost of FTTR is significantly higher than that of FTTH.

Operation and maintenance costs: The FTTR system is more complex, with an increased number of potential maintenance points.

Upgrade cost: FTTR's fiber optic infrastructure possesses the capability to evolve towards future technologies (such as 50G-PON), potentially reducing replacement costs in the long run.

V. Technological evolution and selection suggestions

FTTR is a natural extension of FTTH at the user side, aiming to address bandwidth bottlenecks and coverage issues in the "last ten meters" of indoor areas. Selection should be based on objective evaluation:

Demand assessment: Measure the actual speed and latency of the existing network at various key points to determine whether they constitute business bottlenecks.

House type assessment: Analyze the degree of obstruction posed by the building structure to wireless signals.

Budget evaluation: Weighing one-time investment against long-term experience and potential upgrade costs.

For newly constructed residences, it is recommended to consider embedding fiber optic cables into each room during the design phase to reserve space for future upgrades. For renovations of existing residences, it is necessary to assess the feasibility of laying fiber optic cables openly or utilizing existing conduits.

VI. Summary

FTTH completes broadband access from the operator's network to users' residences. FTTR further extends high-quality optical connections to every functional area within the residence, eliminating issues of uneven indoor bandwidth allocation and coverage blind spots at the physical layer through architectural changes. Its essence is to trade higher initial deployment complexity and cost for a full-space, stable, and high-performance network access experience, primarily targeting specific scenarios and users with stringent requirements for network performance.

Cooperation with ZG TECH in FTTH/FTTR solutions

At ZG, we specialize in delivering cutting-edge FTTH/FTTR solutions to cater to your diverse connectivity needs. As technology evolves rapidly, we remain committed to staying at the forefront of network solutions, ensuring you are equipped with the most advanced and reliable fiber optic network. Let's join forces to build the cornerstone of a future-proof network.