Common Access Control Class

Value range: Check box,  including level 0 forbidden,lever 1 forbidden,…till level 9 forbidden 

Content: One of the parameters of random access control information. i.e. 0~9 bits of “AC”. It is used for load control of ordinary subscribers,  to permit or forbid the network access of some common level users. “1” stands for forbidden and “0” for permitted.

Recommendation: 000000000

In some special cases and areas, the operator expects to prohibit all or part of MS from sending access requests or paging response. For example, emergency status occurs or a serious fault occurs to a GSM PLMN. Therefore, GSM specification 0211 requires to assign an access level for each common GSM subscriber. The common access level is divided into levels 0~9, which are stored in the SIM cards of MS, and has nothing to do with access priority.

Some cells with extremely heavy traffic may be congested during busy hour, resulting in a large number of RACH collisions, AGCH flow overload, Abis interface flow overload, etc. GSM specifications provide a variety of ways for dealing with the overload and congestion, but most of them will lower the availability of equipment resources. The network operator can set the access control parameter (C0-C9) properly to control the traffic inside the cell. For example, when the cell suffers traffic overload or congestion, Ci can be set as 0 to prohibit MS with this access level from accessing this cell (change of Ci will not affect MS in dedicated mode), thus reducing the traffic of the cell. To solve this problem, values of C0-C9 in the cell can be changed periodically. For example, at intervals of five minutes, alternatively allow the access of MS with odd access levels and those with even access levels.

For example, 1000000000 indicates to allow the access of subscribers with the levels other than 0. During installation and commission of BTS or during maintenance test for some cells, they all can be set to “1” to prohibit the access of subscribers.