With the development of cognitive radio technologies, dynamic spectrum sharing has become a promising approach to increasing the efficiency of spectrum use. This paper describes dynamic resource renting and offering mechanism for dynamic spectrum sharing in a multi cell context for OFDMA systems. A credit token based mechanism using auctioning is proposed in support of dynamic spectrum sharing between cells. The implementation of mechanism proposed is discussed from the perspective of current IEEE 802.22 standard activities. The mechanism proposed provides the incentive to sharing resources with the advantages of being real time, dynamic and self governance based policy so as to adapt the space time varying spectrum use between cells.