How data is transmitted is there in this slide :)

1. Data Transmission rate and
Bandwidth

2. Data transmission
• A very important consideration in data communication is how
fast data we can send, in bit per second, over a channel. Data
rate is depend upon three main factors
1. The bandwidth available
2. The signal we use
3. The level of noise
• Data can be analog or digital. The term analog data refers to
continues; the term digital data refers to information that has
discrete state.
• For example, the sound made by human voice is analogues
whereas the data stored in computer is digital.

3. Digital transmission
• Bit: number with value 0 or 1
– n bits: digital representation for 0, 1, … , 2n
– Byte or Octet, n = 8
– Computer word, n = 16, 32, or 64
• n bits allows enumeration of 2n possibilities
– n-bit field in a header
– n-bit representation of a voice sample
– Message consisting of n bits
• The number of bits required to represent a message is a
measure of its information content
– More bits → More content

4. Bit Rates of Digital Transmission
Systems
System Bit Rate Observations
Telephone
twisted pair
33.6-56 kbps 4 kHz telephone channel
Ethernet
twisted pair
10 Mbps, 100 Mbps 100 meters of unshielded twisted
copper wire pair
Cable modem 500 kbps-4 Mbps Shared CATV return channel
ADSL twisted
pair
64-640 kbps in, 1.536-
6.144 Mbps out
Coexists with analog telephone
signal
2.4 GHz radio 2-11 Mbps IEEE 802.11 wireless LAN
28 GHz radio 1.5-45 Mbps 5 km multipoint radio
Optical fiber 2.5-10 Gbps 1 wavelength
Optical fiber >1600 Gbps Many wavelengths

5. Analog Long-Distance Communications
• Each repeater attempts to restore analog signal to its original
form
• Restoration is imperfect
– Distortion is not completely eliminated
– Noise & interference is only partially removed
• Signal quality decreases with # of repeaters
• Communications is distance-limited
• Still used in analog cable TV systems
• Analogy: Copy a song using a cassette recorder
Source DestinationRepeater
Transmission segment
Repeater. . .

6. Analog vs. Digital Transmission
Analog transmission: all details must be reproduced accurately
Sent
Sent
Received
Received
Distortion
Attenuation
Digital transmission: only discrete levels need to be reproduced
Distortion
Attenuation

7. Bandwidth
• One characteristics that measures network
performance is Bandwidth. However this term can
be used in two different context bandwidth in hertz
and in bits per second.
• Bandwidth in hertz
• Bandwidth in bits per second

8. • Bandwidth in hertz is the range of frequencies contained in a
composite signal or the range of frequencies a channel can
pass. For example, we can say the bandwidth of a subscriber
telephone line is 4khz.
• Bandwidth in bits per second
the term bandwidth can also refer to the number of bits per
second that a channel, a link or even a network can transmit.
For example, one can say the bandwidth of fast internet
network (or the link in this network) is a maximum of 100
Mbps. This means that this network can send 100 Mbps.

9. Thank You!!!