Resources: June 2018

Broadband Strategy Development Building Blocks : Technical Aspects Overview

June 2018


The diagram below illustrates the flow of key elements that are generally considered in developing various elements of a National Broadband Strategy. As part of the development, the broadband definition, speed and penetration roadmap are key derivers in shaping the strategy.



The following figure illustrates an overview of the key drivers that are used as building blocks for addressing the first box of the foregoing diagram. We address some of them in this digest.


Broadband Definition/Speed Targets

The most challenging part of developing broadband policy is how to define the broadband and specify targets that maybe used to monitor its progress over a given time window.  

It should be recognised that the most appropriate targets should ideally relate to the experience of users and the availability of the necessary broadband services to support individual applications.  In reality, it is however very difficult to measure such targets and it is therefore more realistic to set an easily measured single metric such as delivery speeds.  The figure below shows examples of the target speed adopted in some countries national broadband strategy. 


Source: CASiTEL

Traffic Model - Applications Required Bit Rates

A traffic model is representative of the applications that are used on the demand side and their associated bit rate (in Mbps) required to support the supply side for an acceptable quality of service to the user. Application bit rates have been increasing due to the content becoming richer, in particular, video streaming is demanding more and more bandwidth due to higher resolution and quality of video (it should be noted that video compression techniques have been evolving aiming at reducing the data rate required for higher definition video content).


The figure below shows typical applications and their associated bit rates that are commonly used across the Internet.


Source: CASiTEL

Committed Information Rate (CIR)

Based on the peak to mean variation of data demand, it is customary to use Committed Information Rate (CIR) rather than a specific application bit rate requirement for the purpose of dimensioning an end-to-end broadband network.  The CIR is representative of what a user will experience as a minimum whilst using various applications.  Its value depends on the type of terminal a user uses and what mix of applications that user accesses.  As an example, the figure below shows three usage scenarios. The more stringent and data-hungry the applications mix is, the higher the CIR will be as a result.


Source: CASiTEL

Broadband Headline Speed


The CIR defines the minimum rate that a user will experience in a shared data pipe.  In practice, due to the mix of applications and their corresponding bit rate demands, as well as what the distance of a user is with respect to a radio access tower or a cabinet (fixed line), the actual speed experienced by the user will differ.

As a results, the broadband headline peak speed (instantaneous speed) is several times higher than the CIR as shown in the table below which is based on traffic simulation modelling (traffic mix of video (25%) and web browsing (75%) requiring application bit rates of 700Kbps and 150Kbps respectively).  It is seen that although the estimated CIR is about 287kbps, the actual rate experience (labelled “New Mean”) is about 2 times higher and 20% of users experience around 5 times higher than the estimated CIR.


Source: CASiTEL