- The maximum data rate supported by a GSM system is 9.6 kbps.- However there are extensions to GSM standard to improve throughput.- GPRS is one of the extended GSM service.- The extended standards of GSM allows theoretical data rates on the order of 114 Kbit/s, but with throughput closer to 40Kbit/s in practice.
- The services offered by GSM are ISDN compatible- GSM allows synchronous data and asynchronous data to be transported as bearer service, one of the telecommunication services offered by GSM, and forms ISDN terminal- The data could be either transparent service or nontransparent service- Telephony is one of the services offered by GSM, which an emergency and the service provider is notified by dialing 3 digits- By using appropriate fax adaptor, G3 fax service is supported- One of the features of GSM is Short Messaging Service- Certain services, namely supplementary services are provided on top of teleservices or bearer services by GSM, such as, caller identification, call forwarding, multiparty conversations, barring outgoing calls and call waiting.
- Short form of Global System for Mobile Communications, is a wireless network system- A standard for digital cellular mobile communications- International roaming arrangements are enabled among mobile network operators, by providing the subscribers to use their personal mobile phones anywhere in the world.- GSM is considered as second generation mobile, as signaling and speech channels are digital- The carriers can be replaced without replacing mobile phones.- The ubiquity of GSM implementations is also enabling the switching between network operators, who can choose equipment from many GSM equipment vendors.- GSM pioneered low cost SMS implementation- The GSM standard includes a worldwide emergency telephone number feature.
Softer handoff- Softer handover is a significant soft handover in which the added and removed links belong to the same node- Macro diversity with maximum ratio combining could be performed in the same node- The movement of handoff, when a user can be served in another cell more efficiently (less power emission, less interference), is the most obvious cause for better performance.
Soft handoff- Soft handoff is a feature in which a cellular phone is simultaneously connected to two or more cellular phones during a single call- It is he overlapping of repeater coverage ones, which enables every cell phone set is always well within the range of a specific repeater.- More than one repeater can send and receive signals to transmit signals to and from mobiles.- All repeaters are used with the same frequency channel for each mobile phone set.- Practically no dead zones and as result, the connections seldom interrupted or dropped.
Sync. Channel- A base station transmits a Sync-Channel that spreads with Walsh code 32.- The frame of synch channel is 80/3ms long with frame boundary is aligned to the pilot.- Sync channel transmits a single message continually, called Sync Channel Message.- The Sync Channel Message contains network information, including the PN offset that is used by the Base Station sector.- The length and content of the message is dependent on the P_REV.- The message transmission rate is 32 bits / frame.- The message is encoded to 128 symbols- The message yielding rate is 1200 bits / s.
Pilot Channel- A forward link channel which is a base to mobile that modulates only by the pilot PN. It spreads common codes to all signals transmitted from a given base station.- Several critical important functions are provided by the pilot channel for forward links in IS-95 systems- The pilot channel modulation facilitates the process of time synchronized replica generation at the receiver of the PN spreading sequences. These are utilized at the transmitter for modulating the synchronization, paging and traffic channels. These are transmitted from the same base station.
