Why the delivered speed of WiFi (FTTH) is generally lower than the Promised/ Advertised speed?

The difference between the promised (advertised) speed and the actual delivered speed by Internet Service Providers (ISPs) is often influenced by several factors, and the use of optical splitters in FTTH networks is one of those factors. Here are some reasons why the promised and delivered speeds can differ:

1. **Network Congestion:** Network congestion occurs when many users in a particular area or on a network segment are simultaneously using the internet. During peak usage times, the available bandwidth is shared among all users, leading to a decrease in individual connection speeds.

2. **Signal Loss:** As optical signals travel through fiber-optic cables, they can experience some signal loss due to factors like distance and the quality of the fiber. This can affect the delivered speed at the end-user's location.

3. **Splitter Ratios:** The use of optical splitters, as explained earlier, divides the available bandwidth among multiple subscribers. The ratio chosen by the ISP can impact the delivered speed to individual subscribers. If a higher split ratio is used, each subscriber gets a smaller portion of the overall bandwidth.

4. **Service Plan:** Subscribers often choose different service plans with varying speed tiers. The advertised speed represents the maximum potential speed for a given plan. Actual speeds may vary based on the plan selected.

5. **Quality of Equipment:** The quality of networking equipment, including the FAPs, ONTs (Optical Network Terminals), and customer premises equipment, can affect the delivered speed. High-quality equipment tends to perform better.

6. **Distance to Central Office or Data Center:** The distance between a subscriber's location and the central office or data center where the internet connection originates can impact speed. Longer distances may result in lower speeds due to signal attenuation.

7. **Network Design and Management:** The overall design and management of the network by the ISP play a crucial role in ensuring consistent and reliable speeds. Well-designed networks with adequate capacity are less likely to experience significant speed drops.

Use of Optical splitter is one of the commonly found reasons:

Optical splitters in a Fiber to the Home (FTTH) network divide the optical signal and distribute it to multiple subscribers. While they enable multiple connections from a single fiber, they do divide the available bandwidth or speed among those connections. This division of speed is a trade-off that allows service providers to efficiently serve multiple customers using a single optical fiber.

Here's how it works:

1. **Original Speed:** Let's say the optical signal coming into the FAP provides a certain amount of bandwidth, for example, 1 Gbps (gigabit per second).

2. **Splitting:** If a splitter with a 1:4 ratio is used, it will divide the optical signal into four equal parts. Each of these parts would have a maximum potential speed of 1/4 of the original, which is 250 Mbps (megabits per second).

3. **Subscriber Connections:** Each subscriber connected to one of the splitter's output ports will have access to this divided bandwidth, in this case, up to 250 Mbps. The actual speed experienced by a subscriber will depend on various factors, including network congestion and the service plan they've subscribed to.

So, while optical splitters allow for cost-effective and efficient sharing of a single optical fiber among multiple subscribers, they do divide the available speed. However, the divided speed is still typically much faster than what is available with traditional copper-based broadband technologies, and it allows for high-speed internet access for multiple households or businesses sharing the same fiber infrastructure.