LOS Link Budget Analysis for High-Speed Wireless Data Link Design

This assignment provides a detailed solution for a wireless data link design problem, focusing on Line of Sight (LOS) link budget analysis. It includes calculations for Free Space Path Loss (FSPL) at different distances (5km and 10km) and frequencies (2.4GHz and 5.8GHz). The solution also covers the calculation of received power and link margin, incorporating transmitter power, antenna gains, and losses. Furthermore, it discusses the relationship between link margin and link availability, assessing the reliability of the wireless link based on a provided table. The analysis demonstrates how factors like receiver sensitivity and fade margin impact the overall performance and efficiency of the wireless communication system. Desklib provides this solved assignment to help students understand the concepts of wireless communication and link budget analysis, and offers additional resources like past papers and solved assignments.

(a) Calculate the FSPL in dB for a distance of 5Km and 10 Km for two different
frequencies 5.8GHz, 2.4GHz :
We know that,
FPSL ( dB )=20 log10 ( d )+ 20 log10 ( f ) +32.45
For, d = 5 km and f = 2.4 GHz, FPSL ( dB ) =20 log10 ( 5 ) + 20 log10 ( 2.4 ) +32.45
= 54.03
For, d = 5 km and f = 5.8 GHz, FPSL ( dB )=20 log10 (5 )+ 20 log10 ( 5.8 ) +32.45
= 61.69
For, d = 10 km and f = 2.4 GHz, FPSL ( dB ) =20 log10 ( 10 ) + 20 log10 ( 2.4 ) + 32.45
= 60.05
For, d = 10 km and f = 5.8 GHz, FPSL ( dB )=20 log10 (10 )+ 20 log10 ( 5.8 ) +32.45
= 67.72
The table has been constructed as follow:
FPSL (dB)
Distance (km) 2.4 GHz 5.8 GHz
5 54.03 61.69
10 60.05 67.72
(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
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.
We know that,
Gains (dB) =Transmit Antenna gain + Receiver Antenna Gain = 24+24 = 48 dB
Now,
Received Power (dBm) = Transmitted Power (dBm) + Gains (dB) − Losses (dB)
= 23 + 48 – 0 = 71 dBm
Link Margin = Received Power - Receiver sensitivity
Link Margin = 71 – (-72) = 143 dB

(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
We know that, Link Margin is basically the amounts by which the power received by the
receiver goes beyond the receiver sensitivity. For the given distance 5 km and the frequency
5.8 GHz, the calculated free space path loss is 61.69 dB. Now the receiver sensitivity is
specified as -72 dBm. That means the exceed amount is of about 143 dB. So the signal can be
received at the receiver antenna with a strength of 81.31 dB.
Now as we know that the time availability and the Fade margin actually define the efficiency
of the signal transmission. For the given distance, Fade margin is directly proportional to the
link availability. Link availability is the percentage of time that the link is available and
active. As the fade margin increases, the availability time of the link is also increases which
reflect a better transmission process. In the provided table also, it can be seen that with the
increasing value of link margin the link availability time is also increasing respectively.