Mumbai University > Electronics and telecommunication engineering> Sem 7 > mobile communication

Marks: 10M

Year: May 2016

Solution:

• HSCSD is High Speed Circuit Switched Data; it is 2.5G GSM standard.
• It is a circuit switched technique that allows a single mobile subscriber to use consecutive user time slots in GSM standard, to obtain higher speed data access on the GSM network.
• It relaxes the error control coding algorithms originally specified in GSM standard for data transmissions.

• HSCSD is ideal for dedicated streaming internet access or real-time interactive web sessions.
• Increases available application data rate to 14.4 kbps.
• HSCSD is able to provide a raw transmission rate of up to 57.6 kbps to individual users by using up to four consecutive time slots.
• HSCSD bundles up to 8 GSM traffic channels into one high speed channel.
• HSCSD is a circuit switching technology, i.e. very suitable for constantly high data rates (e.g. telefax), but not for varying data rates (e.g. Internet browsing).

HSCSD is a feature enabling the co-allocation of multiple full rate traffic channels (TCH/F) into a HSCSD configuration. The aim of HSCSD is to provide a mixture of services with different air interface user rates by a single physical layer structure. The available capacity of a HSCSD configuration is several times the capacity of a TCH/F, leading to a significant enhancement in the air interface data transfer rate.

A new functionality is introduced at the network and MS to provide the functions of combining and splitting the data into separate data streams which will then be transferred via n channels at the radio interface, where n = 1, 2, 3, ... 8. Once split, the data streams shall be carried by the n full rate traffic channels, called HSCSD channels, as if they were independent of each other, for the purpose of data relay and radio interface L1 error control, until to the point in the network where they are combined. However, logically the n full rate traffic channels at the radio interface belong to the same HSCSD configuration, and therefore they shall be controlled as one radio link by the network for the purpose of cellular operations, e.g. handover. This requires a new functionality in BSS.