The document explains various encoding techniques used in computer networks to transmit data between nodes over links, including NRZ, NRZI, Manchester, and 4B/5B schemes. It discusses the advantages and drawbacks of each encoding method and outlines the concepts of links (point-to-point and multipoint) and nodes. Additionally, it highlights the importance of clock recovery in ensuring accurate data transmission.

1. TRINITY INSTITUTE OF PROFESSIONAL
STUDIESSector – 9, DwarkaInstitutional Area, New Delhi-75
Affiliated G.G.S.IP.U, Delhi
Advance Computer
networks(20311)
Submitted By :Submitted By :
Natasha ManiktahlaNatasha Maniktahla
(Assistant Professor)(Assistant Professor)

2. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
ENCODING TECHNIQUES
The first step in turning nodes and links into usable
building blocks is to understand how to connect
them in such a way that bits can be transmitted from
one node to another over physical links are called
encoding techniques.

3. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
Encoding Schemes:
 NRZ
 Clock Recovery
NRZI
Manchester
 4B/5B

4. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
NRZ (Non Return To Zero):
In this values are mapped to data value 1 onto high
signal and data value 0 onto low signal and is called
NRZ scheme.
Drawback: Problem with NRZ is that a sequence of
several consecutive.
1’s: signal stay high on link 0’s: signal stay low on link.

5. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
Baseline Wander:
Receiver keeps an average of signal and uses this
average to distinguish between low & high signal.
Low than 0: low signal.
High than 1: high signal

6. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
Clock Recovery:
Frequent transitions from high to low & vice
versa. Clock recovery
uses two techniques:
Encoding
Decoding
Where every clock cycle sender transmits a bit &
receiver receives a bit. If receiver’s clock is
slightly faster or slower than sender’s clock, it
does not correctly decode the signal.

7. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
NRZI (Non Return To Zero
Inverted):
Non return to zero inverted where the sender make a
transition from current signal to encode as 1 and stays
at current signal to encode as 0. This shows the
problem of consecutive 1’s but does nothing with
consecutive 0’s

8. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
Manchester:
In Manchester, encoding results in 0, being encoded as
low to high and 1 being encoding as high to low, where
0’s & result is transition to signal clock can be
effectively recovered at receiver.
Drawback: It doubles the rate at which signal transition
made a link. The rate at which signal changes is called
Baud Rate.

9. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
4B/5B Encoding:
The concept of 4B/5B is to insert extra bits into bit
stream so as to break up long sequences of 0’s or 1’s.
Here 4 bits of actual data are encoded in 5 bit code that
is then transmitted to the receiver hence the name is
4B/5B.

10. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
LINKS & NODES
Link: A link is the physical communication pathway that
transfers data from one device to another.
Types of links:
1.Point-to-point: A point to point link provides a
dedicated link between two devices. The entire
capacity of the channel is reserved for transmission
between those two devices. For example, telephone
calls etc.

11. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, DwarkaInstitutional Area, New Delhi-75
LINKS & NODES
2.Multipoint: Multipoint link is the one in which more
than two specific devices share a single link. In a
multipoint link, the capacity of the channel is shared,
either spatially or temporally.
3.Node: In a network, a node is a connection point or
an end point for data transmissions. In general, a node
has programmed or engineered capability to recognize
and process or forward transmissions to other nodes.

12. 10/30/15