This paper sheds the light on coexistence and sharing between high altitude platform system (HAPS) and Fixed Services (FS) as a recently critical issue due to the spectrum shortage. International Telecommunications Union Radiocommunications sector (ITU-R) allocated the 5850-7075 MHz band for the operation of HAPS along with existing FS services. Therefore, coexistence and sharing requirements like separation distance and frequency separation coordination must be achieved in terms of both co-channel and adjacent channel frequencies. The interference analysis mode based on the spectrum emission mask (SEM) is applied in the mentioned band to extract the required frequency separation to protect adjacent channel interference. Also interference to noise ratio (INR) as standard interference criteria is utilized.