The Authentication, Authorization and Accounting (AAA) servers

By engineer, on October 11th, 2009

The two terms of wireless or mobile internet services related to how subscriber will be permitted to access internet and how they will be charged are Authentication and Accounting functions. One more function that still important is Authorization process but at this time I will leave the last function. We can say that Public Data Serving Node (PDSN) does not do the entire of data processing but it will send requests to another network element. The functions related to the Authentication, Authorization and Accounting, PDSN will send requests to the Authentication, Authorization and Accounting (AAA) servers which complied with CDMA platform. Different platform will have different requirement to each three functions above such as which parameter will be forwarded from accounting server to PDSN according to the subscriber identity whether IMSI or DN

1. Authentication Function

Before subscriber is allowed to browse to internet or download content of Value Added Service (VAS), Authentication Server will check the parameter sent by subscriber whether valid or not. The parameters that will be checked could be username and password, domain and International Mobile Station Identity (IMSI). Each subscriber whether they make a dial session through modem attached to the computer/laptop or mobile phone/handset will send certainty parameters to the PDSN before they permit to browse to internet. Authentication Server will authenticate these parameters and once it matches subscriber will be allowed to go to the next level and one or more parameters are not match than subscriber will be rejected. Authentication Server could be done by its PDSN or dedicated server. To have more authentication parameters, usually telecommunication companies will install dedicated Authentication Server. It also could be combined with the authorization and accounting functions.

2. Accounting function

Accounting is charging function. It relates to the balance deduction and how subscriber will be charged, what kind of charging mechanism will be applied. Telecommunication companies which have various charging of wireless or mobile internet service, usually will have dedicated charging gateway to create many charging policies. Actually charging function can be done by PDSN itself but it is very simple and can not adopt various charging rules. The charging rules could how duration based, volume based, hybrid charging (combination between duration and volume bases) free tariff for certainty period, free charging for mount bytes, free accessing to certainty address e.g. free for chatting at Yahoo Messenger etc. Accounting server is how they will charge the subscriber. Therefore they maintain the connection to the Intelligent Network (IN) as the telecommunication infrastructure where subscriber balance is placed. Accounting server will check the current balance for prepaid subscriber and reserve the balance before it permit to browse to internet or download some contents of Value Added Service (VAS)