Cordect

corDECT Wireless Access System DONE BY ANISHA BABY

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

Channel structure corDECT 20 MHz

24 Channels 12 forward channels

12 reverse channels

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. 5. Medium Access Control(MAC) Layer Handles handover(bearer handover) of a connection .

1. Data Link Control(DLC) Layer Provides connection oriented and connectionless service. Handles handover(connection handover). 3. 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 2. OMC(Operation & Maintenance control ) 3. SWITCH(Voice/Data Path Switching Subsystem) 5. 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.