Topics I need to study more

Physical Layer
CRC (data link error checking)
Physical layer stuff here

Shannon's Law (maximum theoritical capacity if channel in bit/s)

C = B_{C} l o g_{2} (1 + \frac{P_{r}}{N_{0} + B_{c}})

$B_{C}$ is the bandwith of the channel (Hz)
$P_{r}$ is the signal power as seen by receiver (W)
$N_{0}$ is the white noise, noise power per unit bandwith (W/Hz)
$N_{0} B_{c}$ is the noise power within the bandwith, as seen by receiver (W)

Free space loss, ideal isotropic antenna

\frac{P_{t}}{P_{r}} = \frac{(4 π d)^{2}}{λ ²} = \frac{(4 π f d)^{2}}{c^{2}} λ f = c

$P_{t}$ is the signal power at transmitting antenna
$P_{r}$ is the signal power at the receiving antenna
$λ$ is the carrier wavelength
$d$ is the propagation distance between antennas
$c$ is the speed of light ( $3 \times 10^{8}$ m/s)