Base Station Subsystem (BSS)

 Base Station Subsystem (BSS):

The Base Station Subsystem comprises of two parts:

1. Base Transceiver Station (BTS)
2. Base Station Controller (BSC)

The Base Station Subsystem consists of many BSCs that connect to a single MSC. Each BSC controls up to several hundred Base Transceiver Stations (BTSs). 

Some of the BTSs can be colocated at the BSC and the others can be remotely distributed. They are connected to the BSCs by dedicated leased lines or microwave links.

The interface that connects BTS to BSC is called the Abis interface. carries the traffic and maintenance data.

Must Read>> Abis Interface

1. Base Transceiver Station (BTS)

The Base Transceiver Station (BTS) has radio transceivers that define a cell and are capable of handling the radio-link protocols with the Mobile Station (MS).

The functions of Base Transceiver Station (BTS) are:

• Handling radio link protocols.

• Providing full-duplex communication to the Mobile Station (MS).

Must Read>> Mobile Station

• Interleaving and deinterleaving. The BTS comprises the Transcoder Rate Adapter Unit (TRAU). In LE this unit, the GSM-specific speech encoding and decoding is done. Also, the rate adaption function of data is done.

2. Base Station Controller (BSC)

The Base Station Controller manages the radio resources for one or more BTSs. It controls up to several hundred BTSs. They are connected to a single MSC.

The functions of the Base Station Controller are:

• to control Base Transceiver Station (BTS).

• radio resource management.

• handoff management and control.

Mobile handoffs between two BTSs that are controlled by a BSC are handled by the same BSC. This reduces the burden of the Mobile Switching Center (MSC).

Must Read>> Mobile Switching Center (MSC)

BSC also handles radio-channel setup and frequency hopping.

The BSCs are physically connected through leased lines or microwave links to the MSC. The interface between the BSC and MSC is called an A interface.