A geolocation based channel access scheme is proposed for a discrete Fourier transform modulated filter-bank based underlay cognitive radio transceiver operating in the industrial, scientific, and medical (ISM) band. The scheme is based on a time-division duplexing (TDD) link quality assessment in which the channel state information (CSI) is acquired considering both fast fading and path loss. The achievable link quality of the secondary user is assessed by estimating a range of average bit-error rate (BER) values for different primary user geolocation estimates. The scheme considers both third-party interferences as well as mutual interference between primary and secondary user links based on a chance-constrained programming. The achievable BER ranges are simulated for different scenarios of the primary user geolocations.