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Broadband Network Architecture – Access Network Models

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Broadband Network – There are many broadband services Service Providers offer to their customers today. As a network engineer, you need to know the most common services and their advantages, disadvantages, design characteristics, and so on.

To have a great understanding of SP Networks, you can check my SP Workshop and also my new published “Service Provider Networks Design and Perspective” Book. The Book covers the SP network in great detail.

In this post, I will introduce these services and if I can see interest from the readers, I will explain the design aspects and deployment models of each one of them.

Note: I am going to explain broadband services in this post, not baseband, we are in 2022 right!

 

Access network infrastructure connects the backbone network to the customers.

 

There are two groups of broadband access technologies. Fixed broadband technologies and Mobile Broadband technologies.

You can find many Mobile Broadband articles on the website.

Figure 1: Access Network Technologies and the associated infrastructures

I will explain these technologies and then I will cover how physical locations can be connected in Fixed Broadband and Mobile Broadband infrastructure.

Fixed Broadband Technologies

Fixed broadband refers to those technologies where the end-user must remain at the same location to use the broadband service.

The access network is associated with the specific physical location.

Fixed broadband can be provided by wireline, wireless, or satellite technologies.

Wireline Fixed Broadband

Wireline fixed broadband service can be received in many ways as well.

1. DSL Fixed Wireline Broadband

Traditional xDSL (ADSL, VDSL, etc.) service is one way of having fixed wireline broadband service. Today in many continents most common access network technology is DSL.

 

dsl deployment

Figure 2: DSL deployment and the components

 

In DSL access, the traditional copper line of the telephone network is equipped with digital subscriber line technology.

DSLAM is used at the Service Provider network and the customer modem connection is terminated at the DSLAM.

2. Cable Fixed Wireline Broadband

The second fixed wireline broadband access technology is Cable Broadband. Broadband service is received through cable access by upgrading traditional cable television networks.

Customers can receive both broadband Internet service as well as TV service over the same cable.

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Figure 3: Cable Broadband simplified architecture

3. Fiber Fixed Wireline Broadband

The third and last fixed broadband access technology is Fiber. You probably heard FTTx before. There are many deployment options for FTTX access for sure.

You may have heard FTTH (Fiber to the home), FTTP (Fiber to the Premise), FTTB (Fiber to the Building), and so on.

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Figure 4: Different FTTx Deployment Options

Fiber access infrastructure is different from DSL and Cable in many ways.

With Fiber to the Home, from the fiber termination device of the Service Provider up to the modem in the customer’s home, the entire access network is fiber. This is the fastest option customer can get.

As you might know, finer has much less attenuation and loss compared to copper and coaxial cable.

Much higher data rates can be achievable through fiber. (In theory, you can send 300.000km/s over fiber, because the limit is the speed of light).

Between the customer and the street cabinet can be copper-based and DSLAM can be located on the street.

DSLAM to the fiber termination device which is located at the Service Provider Telephone Exchange (In the U.S it is generally called CO (Central Office) ) can be fiber.

This is another way of deploying FTTx service and called Fiber to the Premises/Cabinet or Curb.

In the above figure, the third deployment model which is Fiber to the Building is shown.

In this deployment option, fiber is brought up to the building and between DSLAM and the customer modem, the connection is copper-based.

Wireless Fixed Broadband

The most common technology for fixed wireless is WiMAX (Worldwide Interoperability for Microwave Access).

Microwave access is much cheaper compare to fiber access for wireless access operators.

Fiber access infrastructure can be leased from the fiber infrastructure providers by the wireless operator (This is very common among the Mobile Service Providers) or the wireless operators can deploy their own fiber infrastructure.

In both methods, capital expenditure is higher compared to wireless-based access systems.

Thus, today’s most common wireless backhaul is deployed via microwave as you can see from the below picture as well.

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Figure 5: Fixed Wireless Network

With WiMAX, access speed can reach up to 1Gbps and the customer connection speeds depend on the distance from the wireless base station.

Satellite Fixed Broadband

Satellite connections are generally used in rural areas where there are no other access network options available.

By the way, when you work in the Network Operator or Service Provider environment, especially if you are doing any kind of capacity planning work (Transport, Access, or IP network), you always hear urban, sub-urban, metro, and rural areas.

These are related to the number of people per square kilometer.

If the area is so crowded (Generally 4000 people/ sq km) it is called metro, after metro, urban, then sub-urban, least crowded places are called rural areas.

Satellite connection has much higher latency compared to other fixed broadband access technologies.

Speed increases by reducing latency, increasing bandwidth doesn’t mean faster connection.

This is another long discussion probably we should make.

When people increase their bandwidth, they tend to say we have a faster connection. That’s completely wrong.

When you have a shortcut (so lower latency ) you have a faster connection.

satellite connection

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Figure 6: Satellite Communication

Last but not least, satellite connection is almost always more expensive for the same speed, compared to other fixed broadband access technologies.

Mobile Broadband

Mobile broadband refers to those technologies where the end-user can use the broadband service while on the move and from any physical location.

These technologies provide different service speeds to the customers and the Service Provider access and the backbone infrastructure is designed in a completely different way.