Telecom & Networking

Signals and data links: Shannon capacity, path loss, throughput, latency, subnets and Erlang traffic

Telecom & Networking formulas help you understand how information moves across cables, fiber, and wireless links—from the limits of channel capacity and data rate to path loss, latency, throughput, and subnet sizing. Whether you’re a student revising for exams or a professional designing networks and troubleshooting performance, these formulas are essential for predicting real-world communication behavior and making reliable engineering decisions.

Shannon Channel Capacity

C = B \log_2(1 + SNR)

Maximum error-free data rate of a channel given bandwidth and signal-to-noise ratio.

Nyquist Data Rate

NEWIntermediate

C = 2B \log_2 M

Maximum data rate for a noiseless channel with M signal levels.

Power Decibels

dB = 10 \log_{10}\frac{P_1}{P_2}

Ratio of two power levels expressed logarithmically.

Free-Space Path Loss

FSPL = 20\log_{10}d + 20\log_{10}f + 32.44

Signal attenuation over distance in free space (d in km, f in MHz).

Throughput

R = \frac{D}{t}

Actual data delivered per unit time.

Propagation Delay

NEWIntermediate

t = \frac{d}{v}

Time for a signal to travel a distance at propagation speed.

Bandwidth-Delay Product

BDP = B \times RTT

Amount of data 'in flight' on a link, setting the ideal window size.

Wavelength

\lambda = \frac{c}{f}

Physical length of one wave cycle for a given frequency.

Erlang Traffic Intensity

NEWIntermediate

A = \lambda h

Offered call traffic from call rate and average holding time.

Bit Rate from Baud

NEWIntermediate

R = B_r \times \log_2 M

Bit rate from symbol rate and bits carried per symbol.

Packet Transmission Time

t = \frac{L}{R}

Time to push a packet of L bits onto a link of rate R.

Usable Subnet Hosts

NEWIntermediate

H = 2^{(32-n)} - 2

Number of usable IPv4 addresses in a subnet with an n-bit prefix.

Queue Utilisation

\rho = \frac{\lambda}{\mu}

Fraction of a server's capacity being used by arriving traffic.

Signal-to-Noise Ratio (dB)

SNR_{dB} = 10\log_{10}\frac{S}{N}

Ratio of signal power to noise power in decibels.

Bit Error Rate

NEWIntermediate

BER = \frac{E}{N}

Fraction of transmitted bits received in error.

Download Time

t = \frac{S}{R}

Time to transfer a file of size S at rate R.

Antenna Gain (dBi)

NEWIntermediate

G_{dBi} = 10\log_{10} G

Directional gain of an antenna relative to an isotropic radiator, in decibels.