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Submission Guidelines:
All submissions are to be submitted through turn-it-in. Drop-boxes linked to turn-it-in will be
set up in the Unit of Study Moodle account. Assignments not submitted through these dropboxes will not be considered.
Submissions must be made by the due date and time.
The turn-it-in similarity score will be used in determining the level if any of plagiarism. Turn-it-in
will check conference web-sites, Journal articles, the Web and your own class member
submissions for plagiarism. You can see your turn-it-in similarity score when you submit your
assignment to the appropriate drop-box. If this is a concern you will have a chance to change
your assignment and re-submit. However, re-submission is only allowed prior to the submission
due date and time. After the due date and time have elapsed you cannot make re-submissions
and you will have to live with the similarity score as there will be no chance for changing. Thus,
plan early and submit early to take advantage of this feature. You can make multiple
submissions, but please remember we only see the last submission, and the date and time you
submitted will be taken from that submission.
Your document should be a single word or pdf document containing your report.
Designing a High speed Wireless Data Link
Line of Sight Link Budget Analysis
Several major factors that can impact the performance of a radio system are
• Available/permitted output power,
• Bandwidth,
• Receiver sensitivity,
• Antenna gains
• Environmental conditions
In this case study, the students will be required to calculate the link budget for a LOS Wireless link. Read
through the following to understand some of the aspects and elements that need to be considered
when calculating a Link Budget.
Received Power
If the estimated/calculated received power is sufficiently large (relative to receiver sensitivity), the link
budget is sufficient for sending data.
Received Power (dBm) = Transmitted Power (dBm) + Gains (dB) − Losses (dB)
Gains(dB)=Transmit Antenna gain+ Receiver Antenna Gain
Receiver sensitivity is the lowest power level at which the receiver can detect an RF signal and
demodulate data.
Link Margin/Fade Margin
The amount by which the received power exceeds receiver sensitivity is called the link margin/fade
margin.
In wireless systems, multipath propagation results in multiple copies of a signal to arrive at different
signal phases at the receiver. If these signals add up destructively, the resulting signal power can be
lower by a factor of 100 or 1000 (20 or 30 dB). The signal level relative to the noise declines making
signal detection at the receiver more difficult. It is therefore highly recommended to keep a link margin
of 30 dB when designing a wireless system.
Link Margin=Received Power-Receiver sensitivity
Losses
In a line-of-sight wireless system, losses are mainly due to free-space path loss (FSPL). Other losses are
due to antenna cabling and connectors. Generally, 0.25dB loss per connector and 0.25dB loss for every
3-ft of antenna cable should be included in the link budget calculations. However, for the sake of
simplicity, you can neglect these losses for your calculations.
( ) = 10 10 (
4

)
2
In dB’s the path loss when the distance (d is in km) and the frequency (f is in MHz) can be simplified as
follows:
( ) = 20 10( ) + 20 10( ) − 147.55
————————————————————————————————————————————–
(a) Calculate the FSPL in dB for a distance of 5Km and 10 Km for two different frequencies 2.4GHz,
5.8GHz and construct a table as follows:
FSPL(dB)
Distance(Km) 2.4GHz 5.8GHz
5
10
(b) For the information given below, calculate the link budget analysis for the wireless system,
which will involve calculating the following:
• Received Power
• Link Margin
Distance: 10 km
Frequency: 2.4 GHz
Link Type: Point-to-Point, Line-of-Sight
Tx power: +23dBm
Antenna gain is 24dBi
Assume negligible loss for cabling and connectors
Receiver Sensitivity: -72dBm
Assume that we are using the same antennas at the transmitter and the receiver side, the link
budget calculations will be the same as the link budget in both directions is expected to be
symmetrical. In cases where 2 types of antenna systems with different transmit power are used,
we must perform two link budget analysis, one in each direction.
(c) For the calculated Link Margin at 5Km what can you say about the availability/reliability of the
link based on the following Table which shows the relationship between the available link
margin and link availability as a percentage of time.
Time Availability (Percentage) Link/Fade Margin
90 8
99 18
99.9 28
99.99 38
99.999 48
case_study.pdf

Unformatted Attachment Preview

MITS5003 Wireless Networks & Communication 2019SS
Case Study
Submission Due Date: 20/01/2020 before 5 pm
Submission Guidelines:
All submissions are to be submitted through turn-it-in. Drop-boxes linked to turn-it-in will be
set up in the Unit of Study Moodle account. Assignments not submitted through these dropboxes will not be considered.
Submissions must be made by the due date and time.
The turn-it-in similarity score will be used in determining the level if any of plagiarism. Turn-it-in
will check conference web-sites, Journal articles, the Web and your own class member
submissions for plagiarism. You can see your turn-it-in similarity score when you submit your
assignment to the appropriate drop-box. If this is a concern you will have a chance to change
your assignment and re-submit. However, re-submission is only allowed prior to the submission
due date and time. After the due date and time have elapsed you cannot make re-submissions
and you will have to live with the similarity score as there will be no chance for changing. Thus,
plan early and submit early to take advantage of this feature. You can make multiple
submissions, but please remember we only see the last submission, and the date and time you
submitted will be taken from that submission.
Your document should be a single word or pdf document containing your report.
Designing a High speed Wireless Data Link
Line of Sight Link Budget Analysis
Several major factors that can impact the performance of a radio system are





Available/permitted output power,
Bandwidth,
Receiver sensitivity,
Antenna gains
Environmental conditions
In this case study, the students will be required to calculate the link budget for a LOS Wireless link. Read
through the following to understand some of the aspects and elements that need to be considered
when calculating a Link Budget.
Received Power
If the estimated/calculated received power is sufficiently large (relative to receiver sensitivity), the link
budget is sufficient for sending data.
Received Power (dBm) = Transmitted Power (dBm) + Gains (dB) − Losses (dB)
Gains(dB)=Transmit Antenna gain+ Receiver Antenna Gain
Receiver sensitivity is the lowest power level at which the receiver can detect an RF signal and
demodulate data.
Link Margin/Fade Margin
The amount by which the received power exceeds receiver sensitivity is called the link margin/fade
margin.
In wireless systems, multipath propagation results in multiple copies of a signal to arrive at different
signal phases at the receiver. If these signals add up destructively, the resulting signal power can be
lower by a factor of 100 or 1000 (20 or 30 dB). The signal level relative to the noise declines making
signal detection at the receiver more difficult. It is therefore highly recommended to keep a link margin
of 30 dB when designing a wireless system.
Link Margin=Received Power-Receiver sensitivity
Losses
In a line-of-sight wireless system, losses are mainly due to free-space path loss (FSPL). Other losses are
due to antenna cabling and connectors. Generally, 0.25dB loss per connector and 0.25dB loss for every
3-ft of antenna cable should be included in the link budget calculations. However, for the sake of
simplicity, you can neglect these losses for your calculations.
( ) = 10 10 (
4 2
)

In dB’s the path loss when the distance (d is in km) and the frequency (f is in MHz) can be simplified as
follows:
( ) = 20 10 ( ) + 20 10 ( ) − 147.55
————————————————————————————————————————————-(a) Calculate the FSPL in dB for a distance of 5Km and 10 Km for two different frequencies 2.4GHz,
5.8GHz and construct a table as follows:
FSPL(dB)
Distance(Km)
5
10
2.4GHz
5.8GHz
(b) For the information given below, calculate the link budget analysis for the wireless system,
which will involve calculating the following:
• Received Power
• Link Margin
Distance: 10 km
Frequency: 2.4 GHz
Link Type: Point-to-Point, Line-of-Sight
Tx power: +23dBm
Antenna gain is 24dBi
Assume negligible loss for cabling and connectors
Receiver Sensitivity: -72dBm
Assume that we are using the same antennas at the transmitter and the receiver side, the link
budget calculations will be the same as the link budget in both directions is expected to be
symmetrical. In cases where 2 types of antenna systems with different transmit power are used,
we must perform two link budget analysis, one in each direction.
(c) For the calculated Link Margin at 5Km what can you say about the availability/reliability of the
link based on the following Table which shows the relationship between the available link
margin and link availability as a percentage of time.
Time Availability (Percentage)
90
99
99.9
99.99
99.999
Link/Fade Margin
8
18
28
38
48

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