Channel hopping

In television terminology channel hopping may be used as an alternative phrase for Channel surfing.

Channel hopping is a slang term used by Britons making short trips across the English Channel. It is most commonly used for trips to France, often for the purposes of a booze cruise, but may also apply to trips to other countries such as The Netherlands or Belgium.

Although it commonly denotes a short trip (or short distance) by ferry or Channel Tunnel, such as Dover to Calais, the growth of cheap air travel by airlines such as Ryanair and EasyJet over the past decade has expanded channel hopping to include flights of less than two hours which can take the British traveller to many locations in Western Europe at low prices.

In telecommunication

In telecommunication context, channel hopping is a method to send radio signals in wideband systems. The signals are transmitted by choosing a different carrier frequency among many available sub-carriers. A pseudorandom sequence known to both transmitter and receiver is used so the intended receiver can listen to the correct channel. This is used in OFDM (Orthogonal frequency-division multiplexing).

A latin square can be used to describe the hopping pattern. Assume we want to design a hopping patterns which repeat every N_c OFDM symbol time, where N_c is prime. The periodic hopping pattern of the N_c sub-carriers can be represented by a square matrix (latin square) of dimension N_c with entries from the set of virtual channels, namely 0, 1,..., N_c-1. The row of the hopping matrix corresponds to a sub-carrier and each column represents an OFDM symbol time. Therefore, the (i, j) entry of the matrix correspondes to the virtual channel number the i^th sub-carrier is taken on by, at OFDM symbol time j.

This article is related to Frequency-hopping spread spectrum.