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ACB (Access Class Barring)

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Introduction:

Access Class Barring (ACB) is a feature of the Global System for Mobile Communications (GSM) which allows mobile network operators to restrict access to their network based on certain criteria. The feature is particularly useful in controlling access to the network during periods of network congestion or when there is a need to prioritize certain classes of users.

In this article, we will explore Access Class Barring in detail, including its purpose, the types of barring, and the configuration parameters.

Purpose of ACB:

Access Class Barring is used to control access to the network during periods of network congestion, high traffic, or when there is a need to prioritize certain classes of users. By selectively barring certain users, network operators can ensure that critical services such as emergency services, and high-priority users such as law enforcement officials or VIPs are given priority access.

ACB is particularly useful in scenarios where there are a large number of mobile devices accessing the network, such as in crowded public areas or during large-scale events such as sports matches or music festivals.

Types of ACB:

There are two main types of ACB that can be implemented by mobile network operators. These are:

  1. Access Class Barring for Mobile Originating (ACB-MO): This type of ACB is used to restrict access to the network for mobile devices attempting to make outgoing calls. When ACB-MO is enabled, mobile devices attempting to make a call will be checked against a list of barred Access Classes. If the device is found to belong to a barred Access Class, the call will be blocked.
  2. Access Class Barring for Mobile Terminating (ACB-MT): This type of ACB is used to restrict access to the network for incoming calls to a mobile device. When ACB-MT is enabled, incoming calls to a mobile device will be checked against a list of barred Access Classes. If the calling device is found to belong to a barred Access Class, the call will be blocked.

Configuration Parameters:

ACB can be configured using a range of parameters. These include:

  1. Access Class: The Access Class is a parameter used to group mobile devices into specific categories. Each Access Class is assigned a number between 0 and 9, with 0 being the highest priority and 9 being the lowest priority. Mobile devices can be assigned to different Access Classes based on their level of priority.
  2. Barring Factor: The Barring Factor is a parameter used to determine the degree to which access to the network is restricted for a particular Access Class. The Barring Factor is assigned a value between 0 and 100, with 0 indicating no restriction and 100 indicating complete restriction.
  3. Time Period: The Time Period is a parameter used to specify the time during which ACB is enabled. Mobile network operators can configure ACB to be enabled during specific time periods, such as during peak traffic periods or during events.
  4. Cause Value: The Cause Value is a parameter used to specify the reason for Access Class Barring. Cause Values can be assigned to different Access Classes based on the type of service or user being barred.
  5. Retry Delay: The Retry Delay is a parameter used to specify the amount of time that must pass before a mobile device can attempt to access the network again after being barred. This parameter is used to prevent network congestion caused by multiple retries by barred devices.

Conclusion:

Access Class Barring is a powerful feature of the GSM network which allows mobile network operators to control access to their network based on certain criteria. By selectively barring certain users, network operators can ensure that critical services and high-priority users are given priority access during periods of network congestion or high traffic.

ACB can be configured using a range of parameters, including Access Class, Barring Factor, Time Period, Cause Value, and Retry Delay. These parameters allow network operators to fine-tune the operation of ACB and tailor it to their specific needs.

In addition to controlling network access, ACB can also be used to improve network performance and user experience. By restricting access to the network during peak traffic periods, network operators can prevent network congestion and ensure that all users have a reliable and high-quality service.

Overall, Access Class Barring is an important feature of the GSM network, and its effective use can be crucial in ensuring network stability, reliability, and quality of service. With the growing demand for mobile data and the increasing number of devices accessing the network, ACB is becoming an essential tool for mobile network operators to manage their networks effectively and meet the evolving needs of their users.