Assignment on Multiplexing, Error and Flow Control, and Network Design

Assignment
Name:
Subject
Date Of Submission

PART I
a)
Total Bits = 4 + 6 + 4 + 2 = 16bits
Time = 2s
According to Blaufer,
Bits (b) = rate (r) * time (t)
16 bits = r * 2s
r = 16 bits/2s
Data rate r = 8bits/s
b) encoding techniques .
Amplitude shift keying (ASK): digital data i can be defined as a variation of
amplitudes in the a carrier wave . Two unlike amplitudes of transporter signal signify
'0' or '1' (Sanghi). A unique pattern of binary digits that represent digital data are
allocated to each of the finite number of amplitudes is used. Every bid encoded equal
number of amplitudes
Frequency shift keying (FSK): different digits are defined by a change in frequency,
while the amplitude of the carrier remains the same . Two unlike occurrences
approaching carrier frequency represent '0' ,''1'.
Phase shift keying (PSK): This phase is changed to show data signals. The state of a
bit is determined relative to that of the bit preceding it, in accordance with data being
transmitted. (Sanghi).
c)
i) The status string in binary
Acceleration - 5m/s2 = 0101
Ultrasound – 48cm = 0.48m = 0.01111
Motors – full = 1111
Battery – 75% = 10
Status signal: 0101 0.01111 1111 10
ii) Status string on ASK, FSK, PSK
64 3 6F 64 65 20 41 53 43 49 49
d) =10001111001101

e)Error and Flow Control
Error Control:
Hamming Code
It is a method that utilizes redundant bits which are included with the original data. The bits
are ordered in a manner to allow for detection of a corrupt bit since unlike indecent bits yield
different fault results. Once identified, the receiver reverses its value and corrects the error.
Flow Control:
A Simplex Stop-and-Wait Protocol
The Sender sends data and waits for the response from Receiver.
If the Channel has errors there will be no acknowledgement from the receiver because it did
not receive the correct data. This will disable the sender from sending the next data hence the
communication will end.
Sliding Window Protocol
Here, both communicating parties use buffer of the same size, eliminating the necessity to
wait for the sender to transmit the next data, it just sends one after the other without having to
wait of the receiver’s acknowledgment.

Part II: Multiplexing and multiple access
TDM
In Time-division multiplexing, multiple data streams with different frequencies are
transmitted on the single link by separating the signal into many segments, so that each signal
materializes on the line for little time as possible in an alternating manner. Single data are
collected together at equally time streams. Therefore, these signals being transmitted appear
as if they are moving concurrently as sub-channels in one message channel, but in reality they
are taking a different path.
 At the transmitter, several signals are transmitted simultaneously over a time sharing
basis. Each signal utilizes all the frequencies in its allocated time slot, for the duration
of the transmission.
 At the receiver, the sampler has to be synchronized with the incoming waveform to
reassemble the data streams.
There are two types of TDM:
1. Synchronous TDM (STDM)
STDM uses the following procedure:
1. All devices are given chances to transmit data on the data link.
2. Individually device are given equally time to transfer or move data on the link that is
available. The total speed of various input lines does not exceed the capacity of path.
The speed of the input links do not exceed the path or data link.
3. Individually device positions its information on the part when its time reaches; taking
turns in a fixed order and fixed time (interleaving).
4. Interleaving is done byte by byte.
5. The time slot remains empty for devices that do not have data to transmit.