Spectrum-Sharing Transmission Capacity with Interference Cancellation

This paper analyzes large-scale networks that share the spectrum with interference cancellation (IC). The efficiency of spectrum sharing is determined primarily by interference, which in turn depends on the spatial densities, the interference cancellation method, and the spectrum sharing method, i.e., underlay or overlay. By assuming the Poisson distribution for transmitters, equal transmission power in the same system, and an interference-limited environment, this paper finds the performance gain from IC in terms of spectrum-sharing transmission capacity (S-TC), defined as the number of successful transmissions per unit area while guaranteeing the target outage probabilities of all coexisting systems. The effectiveness of IC is characterized by the coefficient of cancellation (CoC), and specific CoC values are derived for two simple IC scenarios, the strong interferer and the close interferer cancellation, with the assumption of having perfect information for channel states of interfering links and interferer locations. The sum S-TC optimal spatial densities of the two systems are given. Finally, CoC conditions to determine the superiority of an underlay or overlay method are presented. We verify that the underlay method could be preferred depending on the CoCs of coexisting systems; that is starkly different from the case without IC, in which the overlay method is always better.