What is Link Budget ?

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What is Link Budget?

A link budget is accounting of all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide, fiber, etc.) to the receiver in a telecommunication system. It accounts for the attenuation of the transmitted signal due to propagation, as well as the antenna gains, feed line and miscellaneous losses. Randomly varying channel gains such as fading are taken into account by adding some margin depending on the anticipated severity of its effects. The amount of margin required can be reduced by the use of mitigating techniques such as antenna diversity or frequency hopping.

A simple (General) link budget equation looks like this:
Received Power (dB) = Transmitted Power (dB) + Gains (dB) − Losses (dB)

The link budget is an important value that enables engineers to design systems based on the required sensitivity of a receiver at a particular distance.
The free space path loss is the loss in signal strength of a signal as it travels through free space. This value is usually calculated by discounting any obstacles or reflections that might occur. IEEE defines it as "The loss between two isotropic radiators in free space, expressed as a power ratio."
It is a value that is dependent on the distance, frequency and the gains in the system. The link budget calculation requires you to know the Free Space Path Loss.

Free Space Path Loss
The free space path loss is the loss in signal strength of a signal as it travels through free space. This value is usually calculated by discounting any obstacles or reflections that might occur in its path. IEEE defines it as "The loss between two isotropic radiators in free space, expressed as a power ratio." Enter the Frequency, Distance and System gains to calculate the Free Space Path Loss. It is expressed in dB.

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