Sub-carrier allocation for control data in a communication system

摘要

Uplink and downlink scheduling information transmitted on a control channel to a mobile device requires varying content depending on the current state of the device. For instance an ACK/NACK message may or may not be required, resulting in different control channel sizes. The invention relates to fixing control channel sizes by transmitting ACK/NACK messages on a separate channel that is different from the control channel. A direct mapping function is preferably used to determine the sub-carriers to be used for the ACK/NACK messages from the uplink sub-carriers. This has particular relevance to a orthogonal frequency division multiply access (OFDMA) communication system.