Comments
www.researchandmarkets.com/reports/683104/multi_carrier_and_spread_spectrum_systems.pdf
Posted by crouse
A wireless network is divided geographically into a number of cells, each defined by a radio frequency (RF) radiation pattern from a respective base transceiver station (BTS) antenna. The BSC may be coupled to a mobile switching center (MSC) and a packet data serving node (PDSN). In typical circuit-switched wireless communication systems, the mobile switching center (MSC) connects the landline public switched telephone network (PSTN) system to the wireless communication system. The mobile switching center is typically split into a mobile switching center server and a media gateway, and incorporates the bearer independent call control (BICC). A mobile switching center includes a first database for storing location information and the call details of a mobile terminal. The MSC is also connected to a second database in which information about a subscriber registered in its mobile communication service is stored. The base stations route the communications to the MSC via a serving BSC. The MSC routes the communications to another subscribing wireless unit via a BSC/base station path or via the PSTN/Internet/other network to terminating destination. Between MSCs, circuit connections provide the handover mechanism that service calls as users roam from one service zone to another.
Posted by waqasahmad
There are different types of channel coding and modulation on the forward and reverse channels,coding involves speech data compression,error protection coding and adding channel codes.
forward link (base station to mobile)voice channel modulation process where audio signal is digitized to 64kbps.This is supplied to the voice coder(Vocoder). Error protection bits and repetition bits (discussed later) are then added. These bits are then interleaved(alternated in time)to avoid the effects of group errors due to redio signal distortion. The bots are the randomized by the PN code, primarily for voice privacy.The error protection coded date signal is then spread(multopled) by the orthogonal codes to create a high speed data signal of 1.228 million information bits per second.This information signal is spread again by the long PN code.later, data is sent to the modulator where it modulates the RF carrier for radio transmissio
Posted by hudson
-