What is Network Identity Parameter CGI in GSM
In GSM, the Network Identity Parameter CGI (Cell Global Identity) is a code that uniquely identifies a specific cell in a mobile network. It comprises the Mobile Country Code (MCC), Mobile Network Code (MNC), Location Area Code (LAC), and Cell Identity (CI). The CGI helps in identifying and differentiating cells within a GSM network, facilitating efficient communication between mobile devices and the network infrastructure.
What is Network Identity Parameter CGI in GSM
Network identity parameters mainly include cell global identity (CGI) and base station identity code (BSIC).
CGI=MCC+MNC+LAC+CI
Once MS receives SYS INFO, it decodes the CGI information, and decides whether it can stay in the cell according to the MCC and MNC indicated by CGI. At the same time, it judges whether the current location area is changed, so as to decide whether to execute location update. During the location update process, MS will report the new LAI to the network, so that the network can know the LA in which MS is currently located.
As a global cellular mobile communication system, GSM conducts strict coding for each GSM network in every country, and even every location area, BTS, and cell, so as to ensure that each cell corresponds to a unique number all over the world.
The adoption of this coding scheme can achieve the following objectives:
1. Ensure that MS can correctly identify the current network, so that MS can accurately select the network expected by subscribers and operators.
2. Ensure that the network can know the real-time position of MS, so that the network can connect various service requests to the MS.
3. Ensure that the MS can report correct neighbor cells’ information to the network during conversation, so that network can perform handover when necessary to keep continuous conversation for the mobile subscribers.
The Cell Global Identity (CGI) in GSM is a unique identifier for every cell in the network. It helps mobile devices and the network recognize and manage individual cells, especially for tasks like handover, location updates, and paging.
CGI Components
CGI is made up of four main parts:
- MCC (Mobile Country Code) – Identifies the country (e.g., 262 for Germany).
- MNC (Mobile Network Code) – Identifies the operator within the country (e.g., 01 for Telekom Deutschland).
- LAC (Location Area Code) – Identifies a group of cells (a location area) served by the network.
- CI (Cell Identity) – Identifies the specific cell within the location area.
Format
CGI = MCC + MNC + LAC + CI
Each cell broadcasts its CGI regularly, allowing mobile stations to know exactly which cell they are connected to and report it to the network when required (e.g., during location updates). This identity is critical for routing calls and messages to the correct location of the mobile device.