Wireless Network and Communication: Encoding, Error Control, Multiplexing, and Wi-Fi

WIRELESS NETWORK AND COMMUNICATION
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Part I: Encoding and error control
a) Calculate the data rate required for the robot to remote controller communication
Formulae for data rate is Number of bits passing through the network in bits per second.
Number of bits sent=Sum of individual bits
=4+6+4+2
=16
But that is in 2 seconds
therefore dividing by 2 to get in bits/second
=16/2
=8bps
b) Explain 3 types of suitable encoding techniques could be used to encode the
status string.
The robot design system could need an encoding scheme that is efficient in bandwidth utilization
and more effective for wireless transmission. The following will be more suitable for encoding the
bit strings.
1. NRZ-I(Non-Return to Zero Invert)
In NRZ-I signal encoding, we have to start from the start, all we have to do is to turn to the
opposite side if a one is found, otherwise, we don't have to do anything. If we get constantly zeros,
we have to stay on that side. This is illustrated in the diagram below,

2. Manchester encoding
It uses different curves to show whether it is a zero and another curve, the curves are shown below
zero
One
The ones are encoding with a high then lowered voltage while the zero is encoded with a high then
switched to a low voltage. This is illustrated in the example below,
3. Differential encoding
In D-man encoding, we make an inversion whenever we get one input from the high voltage to low
voltage and we make no inversion whenever we found a zero input. This is illustrated below

c)
i. Write the status string in binary for this instance
The status string is the array of the individual bits sent at the time instance.
First, converting all the values to binary notation gives the following output,
Accelerometer reading =5m/s2
Converting it to binary gives 0101 which is a 4-bit data output
Ultrasound detects an obstacle at 48cm. Converting this into binary notation yields the following
bits
110000 which is a 6-bit input
The motor status report is already in binary and it is 1111
The level of the battery is given at 75% which is equivalent to 0.75 decimal notation. Converting it
into binary, we get 0.11
The aggregated status stream is the array of the individual output data which is shown below
Status string = 0101+110000+1111+0.11
which concatenates to 0101110000111111
therefor the status string in binary is 0101110000111111
ii. Represent the status string on ASK, FSK, and PSK encoding techniques
i)ASK
In ASK, the amplitude of the carrier signal is modulated according to the value of the digital signal.
When a single bit is transmitted, Then a carrier signal is sent, if zero is transmitted then there will
be no carrier signal. In other words, the amplitude of the carrier signal will only be seen whenever
there is a one in the digital signal when zero is transmitted, there will be no carrier signal. That is
why ASK is also known as On-Off Keying.
Carrier wave is shown below