Multiplexing and Spread Spectrum

 UNIT - 4 

Multiplexing and Spread Spectrum, frequency division multiplexing (FDM). Time division multiplexing (TDM): inverse multiplexing, wave-division multiplexing, FHSS AND DSSS multiplexing applications: the telephone system: Common carrier services and hierarchies, Analog services, Digital Services; DIGTAL SUBCRIBER LINE (DSL): ADSL, RADSL, HSDL, SDSL,VDSL

unit 4 

4.1 Multiplexing 

4.1.1 Frequency -Division Multiplexing (FDM)

multiplexing process 

demultiplexing process

the analog carrier system

4.1.2 wave length division multiplexing (WDM)

prisms in wdm and De Multiplexing

4.1.3 time division multiplexing TDM

• 1)Synchronous TDM

Inter Leaving 

Empty Slots

Data Rate Management

Multilevel Multiplexing

Multi Slot Allocation

Pulse Staffing

Frame Synchronization

Frame Synchronization Application

2) Statistical Time Division Multiplexing(STDM)

4.2 Sparead Spectrum

4.2.1. Frequency  Hopping Spread Spectrum (FHSS)

Freqency selection in FHSS

frequency hopping spread spectrum

frequency selection in fhss

4.2.2. Direct Sequence Spread Spectrum (DSSS)

DSSS Example

Services Provided by Telephone Networks

analog laser the service

analog switch De service 

800 service

wide area telephone service w a t s

900 service

analogue leased service

Digital Service

{ADSL is an adaptive Technology the system use the data rate based on the condition of the local loop}

Discrete multitone Technique(DMT)

HDSL : high-bit-rate digital subscriber line (HDSL)

ADSL Lite 

VDSL

upstream data and control

downstream data and control

customer side ADSL modem

ADSL modem

Telephone Company site DSLAM(digital subscriber line access multiplexer)

SDSL(symmetric digital subscriber line)

digital Data Services DDS

switched /56 Service Switched/56 Service

Digital SErvice unit (DSU)

Digital Data Service 

Digital Data Service(DDS)

9.3Digital Subscriber LINE

DSL

ADSL

using  existing local look