Mobile communications

摘要

Mobile communications apparatus (103) are arranged to transmit encoded speech in accordance with a first protocol and to transmit extended data in accordance with a second protocol. A wideband extension (601) is divided into time slots (TN0-TN7) which are substantially in phase with time slots for speech transmission. Signalling channels provided for speech are also used for establishing data calls within the extension. Extended data is conveyed by a process of orthogonal frequency division multiplexing is created (804). The multiplex is created by an inverse fast Fourier transform (903) and the transmission frequencies undergo a hopping sequence.