BSS INTERFACES
There are four main interfaces are received and transmitted by the BSS is used for traffic and signaling information. These interfaces are the A Interface, A-ter interface, A-bis Interface, and Air Interface. A Interface connects the flow of information between the MSC / VLR with the TRC, A-ter interface between the TRC with BSC-BSC, A-bis interface to send information between the BSC and BTS, while the Air Interface operates between BTS and MS.
Basically there are two lines of relationship building interfaces, namely:
- 2 Mbps PCM (E1) interface. E1 physical channel is divided into 32 ts, respectively - each with a bit rate of 64 Kbps. This is the normal configuration on the GSM 900 and GSM 1800 networks
- 1.5 Mbps PCM (T1) interface. T1 physical channels are divided into 24 ts, respectively - each with a bit rate of 64 Kbps. This is the normal configuration on the GSM 1900.
A INTERFACE
A Interface provides two separate types of information, signaling and traffic between the MSC to the BSS. Track talk at transcodekan the TRC and the SS7 signaling that is connected directly to the TRC or on adifferent path to the BSC.
A Interface provides two separate types of information, signaling and traffic between the MSC to the BSS. Track talk at transcodekan the TRC and the SS7 signaling that is connected directly to the TRC or on adifferent path to the BSC.
A-TER INTERFACE
Is a path between the TRC and BSC. At the TRC talking point in transkodekan from 64 Kbit / s to 16 Kbps. 13 Kbps to track information and 3 kbps for in band signaling information.
A-BIS INTERFACE
Responsible for shipping traffic and signaling information between the BSC to the BTS. Transmission protocol used to transmit signaling information on the A-bis Interface is the link Access Protocol on the D Channel (LAPD).
DXU = Distribution Switch Unit TRU = Transceiver Unit |
INFORMATION A-BIS
- A-bis Interface serve transfer voice and signaling information between the BSC and RBS. Signaling between the BSC and the RBS 2000 cikup complex. There is signaling to DXU and TRU (Tranceivers units). Track talk at the TRC is encoded by a traumatic or BSC / TRC. Signaling information is handled in the BSC by TRH. Physical Layout of traffic and signaling to each TRU at A-bis interface depending on the format chosen to facilitate information transfers. There are three possible formats that can be selected for the transfer of information on the A-bis Interface:
- LAPD Unconcentrated - Signalling for each TRU sent at 64 Kbps channel form and accompanied by two 64 Kbps channels each carrying four submultiplexed voice / data channels 16 Kbps each
- LAPD Concentration-Recommended for all cells, but is devoted to TRU who has 3 or more (for a cell with 1-2 TRU per cell LAPD multiplexing the A-bus provides the most efficient transmission). With LAPD concentration, each PCM 2.25 TRU takes time slots. That could be raised to 13 TRU on E1, such as comparing the 10 TRU without this feature.
- LAPD Multiplexing - Recommended for all cells that use 1-2 TRU. LAPD multiplexing with each TRU need 2 PCM time slots. That could be raised to 15 TRU on a single lane 2 Mbit PCM, as compared to 10 TRU without this feature. With 2 TRU in a single cell, normally only 14 of the existing channel in the Air Interface that is used for traffic, and using 2 air time slots for the BCCH and SDCCH signaling. Raising the required transmission there are about 14 times 16 Kbps, ie 3.5 PCM time slots.
Remaining time slots used for signaling the LAPD to two TRU. Total 2 PCM time slots are used for 2 TRU. E1 network using time slot 0 at A-bis interface to provide a synchronization reference to the RBS. In the T1 network frame synchronization information content from a T1 line into RBS synchronization with the Network. In this system an internal synchronization source is indicated to the DXU which gives stable and reliable synchronization.
A-bis LAPD unconcentrated
