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CPET/ECET 355CPET/ECET 3556. Multiplexing

Data Communications and NetworkingFall 2004

Professor Paul I-Hai LinElectrical and Computer Engineering TechnologyIndiana University-Purdue University Fort Wayne

www.ecet.ipfw.edu/~lin

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MultiplexingMultiplexing1. FDM – Frequency Division

Multiplexing2. WDM – Wave Division Multiplexing3. TDM – Time Division Multiplexing

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MultiplexingMultiplexing

From p. 149, Figure 6.1 of Data Communications and Networking, Forouzan, McGrawHill

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MultiplexingMultiplexing Categories of Multiplexing

From p. 150, Figure 6.2 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing FDM Definition – Carrier frequencies, Guard bands,

Analog signals Multiplexing Process Demultiplexing Process

From p. 151, Figure 6.3 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing Multiplexing Process Demultiplexing Process

From p. 151, Figure 6.4 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing Demultiplexing Process

From p. 152, Figure 6.5 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing Example 6-1

Assume that a voice channel occupies a bandwidth of 4 KHz. We need to combine three voice channels into a link with a bandwidth of 12 KHz, from 20 to 32 KHz. Show the configuration using the frequency domain without the use of guard bands.

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Frequency Division MultiplexingFrequency Division Multiplexing Example 6-1: Solution

From p. 152, Figure 6.6 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing Example 6-2: Five channels, each with a 100-

KHz bandwidth, are to be multiplexed together. What is the minimum bandwidth of the link if there is a need for a guard band of 10 KHz between the channels to prevent interference

From p. 153, Figure 6.7 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing Example 6-3: Four data channels (digital), each transmitting at 1

Mbps, use a satellite channel of 1 MHz. Design an appropriate configuration using FDM

From p. 154, Figure 6.8 of Data Communications and Networking, Forouzan, McGrawHill

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Frequency Division MultiplexingFrequency Division Multiplexing Analog Hierarchy

From p. 154, Figure 6.9 of Data Communications and Networking, Forouzan, McGrawHill

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Wave Division MultiplexingWave Division Multiplexing WDM – light signals

From p. 156, Figure 6.10 of Data Communications and Networking, Forouzan, McGrawHill

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Wave Division MultiplexingWave Division Multiplexing WDM – Combining/Splitting

From p. 156, Figure 6.11 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing TDM – Digital data Time Slots and Frames

From p. 157, Figure 6.12 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing Interleaving

From p. 159, Figure 6.14 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing

Example 5. Four 1-Kbps connections are multiplexed together. A unit is 1 bit. Find (1) the duration of 1 bit before multiplexing, (2) the transmission rate of the link, (3) the duration of a time slot, and (4) the duration of a frame?

Solution1. Before Multiplexing data rate = 1 Kbps

T = 1/Data rate = 1ms2. Link – Data rate = 4 x 1 Kbps = 4 Kbps

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Time Division MultiplexingTime Division Multiplexing

Example 5. Four 1-Kbps connections are multiplexed together. A unit is 1 bit. Find (1) the duration of 1 bit before multiplexing, (2) the transmission rate of the link, (3) the duration of a time slot, and (4) the duration of a frame?

Solution3. One time slot = 1/(Link data rate) =

1/4Kbps = 250 μs4. One frame = 4 time slots = 1 ms

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Time Division MultiplexingTime Division Multiplexing Example 6: Four channels are multiplexed using TDM. If each

channel sends 100 bytes/s and we multiplex 1 byte per channel:

Show the frame traveling on the link The size of the frame (4 bytes or 32-bits)

From p. 159, Figure 6.14 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division MultiplexingExample 6: Solution4 Channels, each channel – 100 bytes/sec1 Frame = 4 bytesFrame rate = 100 Frames/secFrame duration = 1/frame rate = 0.01 secLink bit rate = 100 Frames x 4 bytes/Frame

x 8-bit/byte = 3200 bps

The duration of a frame – 0.01 sec The frame rate – 100 Frames/sec The bit rate for the link – 3200 bps

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Time Division MultiplexingTime Division Multiplexing Example 7: A multiplexer combines four 100-Kbps

channels using a time slot of 2 bits. Show the output with four arbitrary inputs. What is the frame rate? What is the frame duration? What is the bit rate? What is the bit duration?

From p. 160, Figure 6.16 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing Synchronization:

– Mutiplexing/Demultiplexing– Framing bits

Bit Padding– Handling signals with different data rates

From p. 160, Figure 6.17 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing Digital Signal (DS) Service

From p. 162, Figure 6.18 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing T Lines

From p. 163, Table 6.1 of Data Communications and Networking, Forouzan, McGrawHill

Service Line Rate (Mbps)

Voice Channels

DS-1DS-1 T-1T-1 1.5441.544 2424

DS-2DS-2 T-2T-2 6.3126.312 9696

DS-3DS-3 T-3T-3 44.73644.736 672672

DS-4DS-4 T-4T-4 274.176274.176 40324032

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Time Division MultiplexingTime Division Multiplexing The T1 Frames

From p. 164 Fig. 6.19 of Data Communications and Networking, Forouzan, McGrawHill

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Time Division MultiplexingTime Division Multiplexing The T1 Frame Structure

– 8000 Frames/sec x 193bps for a frame = 1.544 Mbps

From p. 164 Fig. 6.19 of Data Communications and Networking, Forouzan, McGrawHill

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SummarySummary

Questions?