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Understanding Erlang and Grade of Service (GoS) in Telecommunications

telecommunication network engineering grade service erlang traffic management

Grade of Service (GoS) and Erlang are crucial concepts in telecommunications and network engineering. They help us understand and measure how well a network or system performs, especially when dealing with voice and data traffic. Let’s break them down:

What is Grade of Service (GoS)?

Think of GoS as a report card for your network’s quality. It tells you the probability that a user will be unable to connect – maybe a call gets blocked, or a connection attempt fails – because the network is too busy or unavailable.

  • GoS is usually expressed as a percentage or a decimal between 0 and 1.
  • 0 means perfect service – no blocking at all!
  • 1 means complete blockage – no service is available.
  • Therefore, a lower GoS value means better service quality, and a higher GoS means worse service quality.

What is Erlang (E)?

Erlang is a unit that measures how much traffic or load is on a telecommunications network or system over a specific period. It essentially tells you how busy the resources are.

  • Erlangs represent the average rate of resource usage over time. For instance, the number of concurrent calls or the amount of data being transmitted.
  • One Erlang means one continuous hour of resource usage.
  • For example, if a phone line is used for 30 minutes, that’s 0.5 Erlangs of traffic.

By tracking traffic in Erlangs and aiming for specific GoS values, network managers can make sure their networks provide the level of service people expect while using resources efficiently and preventing congestion.

Erlang and GoS Calculator Example

Inputs

Outputs

Let’s say you have the following:

INPUTS:

  • Total calls made (offered) during the busiest hour: 1400
  • Number of calls lost: 7
  • Average call duration: 4 minutes

OUTPUTS:

  • Erlang = 93.3
  • Grade of Service = 0.005

Erlang and Grade of Service Formulas

Both Erlang and GoS are used in telephony to measure telephone traffic and assess its performance.

The following formulas are used in Erlang and Grade of Service calculations:

Erlang and Grade of Service Calculator equation

Note: “Busy hour” implies that the value of T (time) is equal to 60 minutes.

Conclusion

In short, Erlang and Grade of Service calculators and formulas are essential for planning, optimizing, and managing telecom and network systems. They help network professionals provide reliable, high-quality services while using resources wisely and keeping costs under control.