GSM interfaces

What are the interfaces between thee following?a.) BTS and MS b.) BTS and BSC c.) BSS and MSC d.) TRAU and BSC e.) BSC and PCU

a.) BTS and MS

- Base station subsystem is a segment of cellular telephone network that is responsible for setting signals and traffic between mobile phone sets and network switching subsystems.
- Transcoding of speech channels are carried out by BSS. BSS allocates radio channels to mobile phones, paging, transmission and reception over the air interface and many other tasks that are pertaining to the radio network.

b.) BTS and BSC

- Base Station Controller provides the intelligence behind the BTSs. A BSC conrolls hundreds of BTSs.
- Allocation of radio channels, receiving measurements from the mobile phones are some of the major task handlings by BSC.
- BSC controls BTS to BTS.
- BSC acts as a concentrator in which many different low capacity connections to BTSs will become reduced to few numbers of connections towards the mobile switching center.
- BSC provides the required data to operation support subsystem(OSS) and also to the performance measuring centers
- BTS supports the key features like, frequency hopping, sectorization, and GPRS.
- The expansion and upgradation in the field are the features emphasized during its design.
- The power output of BTS is up to 80W.

c.) BSS and MSC

- BSS will send the called number to MSC(Mobile Switching Center)
- MSC checks the VLR and queries BSS for allocation of resources for the cell
- Then MSC routes the call to GMSC
- Switching nodes for base station controls is done by MSC

d.) TRAU and BSC

- TRAU (Transcoder and Rate Adaptation Unit) is an entity to perform a transcoding function for speech channels and RA(Rate Adaptation) for various data channels.
- BSC and TRAU does not demand specific environmental conditions to perform operations.
- With this the operator has an option for placing any one or both units at a central location.
- BSC supports various BSC-BTS configurations like star, multidrop and loop, and star configurations towards TRAU
- TRAU is a stand alone unit which could be located close to a MSC(Mobile Switching Center), which enables the optimum utilization of 16 kbit/s channel sub multiplexing and saves line costs.

e.) BSC and PCU

- The Packet Control Unit is an adaptor / handler unit which enables GPRS and EDGE functionality within Radio Access Network.
- The BSC from the GSM network is connected with packet core by PCU
- Motorola PCU is based on certain industry standards like Compact PCI and is highly scalable.