peanut
2012-03-11, 10:03 PM
The idea of access class was introduced into the standard to regulate or limit access to the network in case of exceptional circumstances. The idea has been introduced in GSM and was taken up in an identical manner in the UMTS specifications.
Network subscribers are all divided randomly into ten access classes (numbred 0 to 9), described as ordinary or public. In addition, certain subscribers may also belong to one or more special classes, depending on the nature of their activity. The standard defines five special classes ( numbered 11 to 15), as follows:
class 11: reserved for the network operator;
class 12: security services (poice, surveillance, etc.);
class13: public services (electricity distribution,etc.);
class 14: reserved for the emergency services;
class 15: reserved for the staff of the network operator (allocated, for example, to-on-site maintenance technicians).
Access class 10 corresponds to emergency calls,i.e. calls to special numbers, 999 in the UK, 911 in North America, and 112 in Europe.
The network transmits continuously, on the BCCH, the access classes authorised to access the channel. Thus when a mobile wants to access the network (whether at the request of the user or on receipt of a paging message), it will compare the access class or classes allocated to the user and stored in the SIM/USIM card, with the classes authorised by the network.
Operators thus have a very simple means of limiting new calls to their networks. By successively forbidding public access classes (each of wich represents 10% of the population of subscribers), they can go as far as completely forbidding access to their networks.This type of access control can be very relevant in the case of traffic congestion or in the case of natural disaster, in order to reserve communication ressources for emergency calls and the emergency services.
To prioritize users there is a special service called: Enhanced Multi-Level Precedence and Pre-emption service (eMLPP)
for more information about access classes, refer to "Access Control", 3GPP TS 22.011.
Network subscribers are all divided randomly into ten access classes (numbred 0 to 9), described as ordinary or public. In addition, certain subscribers may also belong to one or more special classes, depending on the nature of their activity. The standard defines five special classes ( numbered 11 to 15), as follows:
class 11: reserved for the network operator;
class 12: security services (poice, surveillance, etc.);
class13: public services (electricity distribution,etc.);
class 14: reserved for the emergency services;
class 15: reserved for the staff of the network operator (allocated, for example, to-on-site maintenance technicians).
Access class 10 corresponds to emergency calls,i.e. calls to special numbers, 999 in the UK, 911 in North America, and 112 in Europe.
The network transmits continuously, on the BCCH, the access classes authorised to access the channel. Thus when a mobile wants to access the network (whether at the request of the user or on receipt of a paging message), it will compare the access class or classes allocated to the user and stored in the SIM/USIM card, with the classes authorised by the network.
Operators thus have a very simple means of limiting new calls to their networks. By successively forbidding public access classes (each of wich represents 10% of the population of subscribers), they can go as far as completely forbidding access to their networks.This type of access control can be very relevant in the case of traffic congestion or in the case of natural disaster, in order to reserve communication ressources for emergency calls and the emergency services.
To prioritize users there is a special service called: Enhanced Multi-Level Precedence and Pre-emption service (eMLPP)
for more information about access classes, refer to "Access Control", 3GPP TS 22.011.