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corDECT. Wireless Access System DONE BY ANISHA BABY NO:4. INTRODUCTION.
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corDECT Wireless Access System DONE BY ANISHA BABY NO:4
INTRODUCTION • corDECT is a new wireless local loop system. • Eliminate the physical connections between telephone exchanges and subscribers. • Based on the DECT(Digital Enhanced Cordless Technologies) standard.
It offers high quality voice and data transmission. • Easier to implement ,support large number of subscribers. • Provides simultaneous voice & internet access.
Disadvantages of wired local loop • High cost. • More faults occur. • Rapid deployment is difficult • It is expensive. These disadvantages can be solved by using corDECT wireless local loop.
Advantages of corDECT • Provides cost effective solution to local loop problems. • Easy expansion of the network . • Provides high quality voice and data and FAX capability. • Good speech quality . • Provides simultaneous voice and internet access.
The main parts of the system are • DECT Interface Unit(DIU) • Compact Base Station(CBS) • Wallset(WS) • Handset(HS)
DECT Interface Unit • Performs system control. • This can cater up to 20 base stations. • It carries signal and power feed for the base stations even up to 3kms.
Compact Base Station • This is the radio fixed part of the DECT wireless local loop. • Mounted on a tower top which can cater up to 50 subscribers. • Provides 12 simultaneous speech channels.
Wallset • It is a wireless fixed terminal adaptor . Handset • It is a portable telephone providing voice service to a user. It consist of two more parts • BSD-connects 4 CBS to DIU • RBS-extend the CBS coverage to 25kms.
Divides its 20MHz bandwidth in to 10 frequency bands. • Each time slot is divided in to 24 channels. • So that up to 12 simultaneous calls can be handled.
DECT Protocol Stack • Four protocol layers. • Physical (PHL) Layer • Specifies the division of 10ms frames. • Monitors quality of signal. • Medium Access Control(MAC) Layer • Handles handover(bearer handover) of a connection .
Data Link Control(DLC) Layer • Provides connection oriented and connectionless service. • Handles handover(connection handover). • Network(NWK) Layer • Call control. • Registration & Authentication.
Architecture & Implementation • Micro-cellular system support high speed data,voice telephony etc. Features are • Frequency is selected using Dynamic Channel Selection(DCS). • Roaming anywhere . • Authentication & Encryption. • Handover from channel to channel.
The DIU(exchange) consist of • OMC(Operation & Maintenance control ) • SWITCH(Voice/Data Path Switching Subsystem) • BIM(Base Station Interface Modules) OMC • performs call processing . • Runs the DECT NWK layer. • System operation, maintenance ,billing .
SWITCH • Switching voice between subscribers. • Runs a part of the DECT DLC layer. BIM • CBSs are connected to the DIU at the BIM • Supports two CBS.
The portable runs the entire DECT protocol stack. • Inter-Working Unit(IWU) performs billing,registration etc.
Call Scenario • Sequence of events at the DECT DLC & DECT NWK layer. • Portable A sends request to portable B. • OMC checks whether A is a valid user. • B establishes the connection. • After sometime release the connection.
CONCLUSION • It offers relatively low cost & rapid installation of telecom services in areas of even high subscriber density. • Good for highly dense urban areas. • Use telephone &internet on the same line simultaneously.