Joint spectrum access scheme for peak power control in Cognitive Radios

High Peak to Average Power Ratio (PAPR) is a parameter commonly associated to the multi-carrier signals like Orthogonal Frequency Division Multiplexing (OFDM). SoftWare Radio (SWR) is another example of multi-carrier signals and inherits high PAPR. Also, as SWR is an enabling technology for Cognitive Radio (CR) systems, therefore signals also demonstrate high power fluctuations in CR context. Upon opportunistic spectrum access in CR, the situation regarding PAPR becomes even grave as more carriers (secondary carriers) are added in an already large numbered multi-carrier signal (primary signal). This paper explores the PAPR variations on spectrum access in CR context. Also, the reduction of PAPR in CR is performed using a PAPR reduction method called Tone Reservation (TR). In TR, certain carriers of the data signal are reserved to create a peak reducing signal which on addition to the data signal reduces its peak power. These carriers are called peak reducing carriers (PRC). CR PAPR is reduced by presenting a joint spectrum access scheme which implies a part of secondary carriers as PRC to reduce CR PAPR.