What is Erlang and Grade of Service (GoS) ?

Grade of Service (GoS) and Erlang are terms commonly used in telecommunications and network engineering to describe and measure the performance and congestion of a network or system, particularly in the context of voice and data traffic.

Grade of Service (GoS): It is a metric that quantifies the quality of service provided by telecommunication network or system. It represents probability that a user will experience a blocked call or connection attempt due to network congestion or unavailability.

GoS is expressed typically as a percentage or decimal between 0 and 1. O represents no blocking (i.e. perfect service) and 1 represents complete blocking (no service available).
This means lower GoS value indicates better service quality and higher GoS indicates poor service quality.

Erlang (E) : It is a unit of measurement used to quantify the traffic intensity or load on a telecom network or system over specific period of time. Erlangs are used to represent the average rate of resource usage over time, such as number of concurrent calls or amount of data being transmitted.

The 1 Erlang refers to one continuous hour of resource usage.
For example, if phone line is occupied for 30 minutes, it represents 0.5 Erlangs of traffic.

By understanding traffic loads in Erlangs and setting target GoS values, they can ensure that networks provide the desired level of service quality while optimizing resource utilization and avoiding congestion

Erlang and GOS Calculator

Traffic calls offered in busy hour (input1) :

Traffic calls lost (input2) :

Average call duration in minutes (input3) :

Erlang (Output1) :

Grade of Service (Output2) :

INPUTS: Total traffic calls made(offered) in busy hour = 1400, Traffic calls lost = 7, Average call duration (minutes) = 4
OUTPUTS: Erlang = 93.3 , Grade of Service = 0.005

Erlang Formula and Grade of Service Formula

Both Erlang and GoS (Grade of Service) parameters are used in the telephony system for the measurement of telephone traffic with respect to how good it is performing. Following equation or formula is used for Erlang and Grade of Service calculator. Note : Busy hour gives value of T equal to 60

Erlang and Grade of Service Calculator equation

Conclusion : In summary, Erlang and Grade of Service calculators and formulas provide valuable tools for planning, optimizing, and managing telecommunications and network systems. They enable network professionals to deliver reliable and high quality services while efficiently utilizing resources and controlling costs.

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Erlang, GOS and switching links

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