What is Grade of service and blocking probability? What are delay systems in telecommunication networks?

What is Grade of service and blocking probability? What are delay systems in telecommunication networks?
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1 Answer

Answer :

Grade of service: In loss systems, the traffic carried by the network is generally lower than the actual traffic offered to the network by the subscribers. The overload traffic is rejected and hence it is not carried by the network. The amount of traffic rejected by the network is an index of the quality of the service offered by the network and is termed as grade of service (GOS) and is defined as the ratio of lost traffic to offered traffic. Offered traffic is the product of the average number of calls generated by the users and the average holding time per call. GOS is given by  

GOS = A-A0 / A0

 Where

 A= offered traffic

 A0 = carried traffic

 A-A0= lost traffic 

Blocking Probability: The blocking probability P is defined as the probability that all the servers in system are busy. When all the servers are busy, no further traffic can be carried by the system and the arriving subscribers’ traffic is blocked. At the first instance, it may appear that the blocking probability is the same measure as the GOS. The probability that all the servers are busy may well represent the fraction of the calls lost, which is what the GOS is all about.

Delay System: A class of telecommunication networks, such as data networks, places the call or message arrivals in a queue in the absence of resources, and services them as and when resources become available. Servicing is not taken up until the resources become available. Such systems are known as Delay Systems. Delay Systems are analyzed using queuing theory which is sometimes known as waiting line theory. Delay Systems in telecommunications include the following: 

• Message Switching

• Packet Switching

• Digit Receiver access

• Automatic Call distribution

• Call Processing  
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