The base station controller (基站控制器) is the connection point between the base transceiver station and the mobile switching center, and also provides the interface for exchanging information between the base transceiver station and the operation and maintenance center. A base station controller usually controls several base transceiver stations, and its main functions are to manage wireless channels, implement call and communication link establishment and dismantling, and control the handover of mobile stations within the control area. At present, there are mainly two types of base stations in China: GSM and CDMA.

BSC refers to the Base Station Controllerr (基站控制器).

It is the connection point between the base transceiver station and the mobile switching center, and also provides an interface for exchanging information between the Base Transceiver Station (基站收发台) and the Mobile Switching Center (移动交换控制台). A base station controller usually controls several base transceiver stations, and its main functions are to manage wireless channels, implement call and communication link establishment and dismantling, and control the handover of mobile stations within the control area.

It generally consists of the following modules:

AM/CM module: the center of voice exchange and information exchange.

BM module: complete call processing, signaling processing, wireless resource management, wireless link management and circuit maintenance functions.

TCSM module: complete the functions of multiplexing, demultiplexing and code conversion.

For specific information, please refer to the relevant knowledge of mobile communication.

Base Station Controller (基站控制台): The BSC controls a group of base stations, and its task is to manage the wireless network, that is, to manage the wireless cells and their wireless channels, the operation and maintenance of wireless equipment, the business process of the mobile station, and to provide communication between the base station and the MSC. interface. It is a feature of GSM to concentrate the functions related to wireless control to the BSC as much as possible to simplify the equipment of the base station. The list of its features is as follows:

1. Monitoring and management of wireless base stations, RBS resources are controlled by BSC, and BSC can also monitor the performance of RBS through internal software testing and loop testing on the voice channel. Ericsson's base stations monitor the TRX on the voice channel using in-house software testing and loop testing. If a failure is detected, the RBS will be reconfigured and the backup TRX will be activated, so that the original channel group remains unchanged.

2. For the management of radio resources, the BSC configures service and control channels for each cell. In order to be able to reconfigure accurately, the BSC collects various statistical data. Such as the number of lost calls, successful and unsuccessful handovers, traffic per cell, wireless environment, etc. Special logging functions can track all events of the call process, these functions can detect network failures and faulty equipment.

3. Handle the connection with the mobile station, be responsible for the establishment and release of the connection with the mobile station, assign a logical channel to each voice channel, during the call, the BSC monitors the connection, the mobile station and the transceiver measure the signal strength and voice quality, The measurement results are sent back to the BSC. The transmission power of the mobile station and the transceiver is determined by the BSC, and its purpose is to ensure a good connection quality and reduce the interference in the network to a minimum.

4. Positioning and handover, handover is controlled by the BSC, the positioning function continuously analyzes the quality of the voice connection, and thus can make a decision on whether to handover. Handover can be divided into intra-BSC handover, intra-MSC handover between BSCs, and MSC switch between. A special handover is called intra-cell handover. When the BSC finds that the voice quality of a connection is too low and a better cell cannot be found in the measurement results, the BSC switches the connection to another logical channel in the cell. Hope the call quality improves. Handover can also be used to balance the load between cells. If the traffic in one cell is too high, and the traffic in the adjacent cell is small and the signal quality is acceptable, part of the call will be forcibly switched to other cells. .

5. Paging management, BSC is responsible for distributing paging messages from MSC, in this aspect, it is actually a special transparent channel between MSC and MS.

6. Management of the transport network, the BSC configures, allocates and monitors the 64KBPS circuit with the RBS, it also directly controls the switching functions within the RBS. This switching function can effectively use 64K circuits.

7. Code conversion function, the voice coding of four full-rate GSM channels is multiplexed into one 64K channel and completed in the BSC, and one PCM time slot can transmit four voice connections. This function is realized by TRAU.

8. Speech coding.

9. BSS operation and maintenance, BSC is responsible for the operation and maintenance of the entire BSS. Such as system data management, software installation, equipment blocking and unblocking, alarm processing, test data collection, transceiver testing.