Abstract: A modem apparatus is configured to provide wireless network access in accordance with an Orthogonal Frequency Division Multiplexing communications scheme. The apparatus comprises a hardware subsystem comprising baseband processing components (302), Radio Frequency processing components (304) and a digital interface. The Radio Frequency processing components (304) comprise a converter component arranged to convert between time and frequency domains in accordance with the Orthogonal Frequency Division Multiplexing communications scheme; a subcarrier processing component operably coupled to the converter component, the subcarrier processing component being arranged to implement conversion between a collapsed space of subcarriers and an expanded space of subcarriers in accordance with resource assignment data; a cyclic prefix processing component responsive to control information. The baseband processing components (302) comprise a channel estimation component.