A conventional mobile communication system is a circuit based system that enables a base station to transmit a control signal to a user terminal using a downlink-dedicated channel. However, it is difficult to apply a conventional method for transmitting a control signal using the dedicated channel to a long term evolution (LTE) system that is a packet based system introduced for providing various packet services. Currently, the related standardization processes of the LTE system have been in progress.
Unlike the circuit based system that fixedly allocates radio resources to a terminal, a plurality of terminals share radio resources for transmitting packet service data in mobile communication systems for providing a packet service. Accordingly, the packet based mobile communication system needs a method for providing uplink control information to a plurality of terminals in order to enable each of the terminals to distinguish allocated radio resources from the other and to access the allocated radio resources at a scheduling time. Also, a long term evolution (LTE) system for providing a pure packet service requires a method for forming uplink control information to variably and flexibly use the radio resources of a physical layer and a method for transmitting the uplink control information.
To fulfill such requirements, there have been many researches for developing a method for dividing radio resources into local allocated radio resource and distributed allocated radio resource in order to allocate and manage radio resources adaptively to a wireless environment. In order to effectively allocate the two types of radio resources, there have been also many researches in progress for developing a method for transmitting control information through a control channel shared by a plurality of terminals rather than a Wideband Code Division Multiple Access (WCDMA) scheme and transmitting the predetermined part of the control information through radio resources allocated to each of terminals.
That is, there is a demand for developing a method for effectively forming uplink control information using a downlink from a base station to a terminal and transmitting the uplink control information with minimum radio resource occupied in packet based mobile communication systems developed based on a 3rd generation partnership project (3GPP) system so as to improve the utilization of limited radio resources.