Many to one/one to many Types of multiplexing Telephone system Chapter 8 Multiplexing Many to one/one to many Types of multiplexing Telephone system
Multiplexing vs. No Multiplexing
Multiplexing Synchronous Asynchronous Frequency -Division Multiplexing (FDM) Time-Division Multiplexing(TDM) Synchronous Asynchronous
FDM
FDM, Time Domain
Multiplexing, Frequency Domain
Demultiplexing, Time Domain
Demultiplexing, Frequency Domain
TDM
Synchronous TDM Allocates exactly the same time slot to each device at all times, whether or not a device has anything to transmit.
TDM, Multiplexing
TDM, Demultiplexing
Framing Bits
Data Rate Bit Stuffing: Add extra bits to a stream of data such that the devices data rates are integer multiple of each other.
Asynchronous TDM (Statistical TDM)
Frames and Addresses a. Only three lines sending data
Frames and Addresses Asynchronous TDM supports the same number of input lines with a lower capacity link. The total speed of the input lines can exceed the capacity of the path.
b. Only four lines sending data
Frames and Addresses c. All five lines sending data
Multiplexing and Inverse Multiplexing
Telephone Network
services Analog services Digital services
Analog services Switched Leased
Analog Switched Service (PSTN
Analog Leased Service
Analog Hierarchy
Digital services Switched/56 DDS DS
Why Digital? Less sensitive to noise. Inexpensive. Better quality.
Switched/56 Service Digital Service Unit (DSU): Changes the data rate to 56 Kbps and encodes it into the format used by the service provider. Support bandwidth on demand.
Digital Data Service (DDS) The digital version of the analog leased line. Subscriber can choose among 5 data rates: 2.4, 4.8, 9.6,19.2, or 56 Kbps.
Digital Signal Service (DS) Hierarchy`
T Lines DS-1, DS-2, … are services, T lines are the lines for transmission digital data, voice, etc. Service Line Rate (Mbps) Voice Channels DS-1 T-1 1.544 24 DS-2 T-2 6.312 96 DS-3 T-3 44.736 672 DS-4 T-4 274.176 4032
T-1 Line
T-1 Frame
Fractional T-1 Line
E Lines European version of T lines. Line Rate (Mbps) Voice Channels 2.048 30 E-2 8.448 120 E-3 34.368 480 E-4 139.264 1920