In this paper, a cognitive radio network (CRN) model is presented. In this model, the control of the CRN is distributed among the frequency spectrum considered for transmission using cognitive pilot channels (CPCs). This control is performed by using frequency-division and time-division multiplexing techniques. Frequency-division is used to divide the spectrum into predetermined frequency slots in which cognitive radio users (CRUs) communicate. Then, the frequency slots are divided into sub-frequency slots, some of which are defined as CPC and used by the CRUs to communicate with a central cognitive base station (CCBS) and to determine availability in a frequency slot. Time-division is used to determine if a primary user (PU) has accessed the channel used by CRUs. Using this time-division approach, presence of PUs is detected. We have designed a CRN able to work with today's available technologies and CRU devices that use different frequency bands of operation. Results of the performance of the network will be presented in terms of the number of CRU and the time these CRUs use the CPCs for control.

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In this paper, a method for energy reduction in a centralized cognitive radio network (CRN) is presented. The basic model of the CRN provides signaling through cognitive pilot channels (CPCs) distributed in every available channel or frequency slot. The control is performed by using frequencydivision and time-division multiplexing techniques. This control, as expected, permits the utilization of the CRN by heterogeneous cognitive radio user (CRU) devices. We had designed a CRN able to work with today's available technologies and CRU devices that use different frequency bands of operation. However, in terms of energy, this control can be very inefficient due to the fact that at specific periods of time, the network might be completely used. Results of the performance of the network will be compared to a basic CRN model in which CPCs are used for control in every available channel.