An opportunistic spectrum access scheme, reciprocal access scheme, based on non-random access protocol for heterogeneous networks is proposed. A case is considered, in which the users of these two heterogeneous reciprocal networks have cognitive functions, and they can access each other dynamically. Users’ behavior is modeled by a continuous-time Markov model. Moreover, probabilities of blocked and forced termination of users in the two heterogeneous cognitive networks are derived as the performance metrics. In addition, throughput of users is evaluated. Performance of the reciprocal access scheme is compared with the traditional non-shared access scheme. The results show that the system performance can benefit from the
proposed scheme.