This paper presents dynamic spectrum sharing protocol, in which operators lease or borrow their spectrum depending on traffic load condition over unit time. To achieve this, a spectrum sharing rule is proposed, which guides the operator when to lease or borrow spectrum with respect to current traffic load condition. The spectrum sharing rule presented here depends on both user arrival rate and service rate which contribute to the traffic load experienced by the operator over a unit time. Further, we analyze the impact of presented spectrum sharing rules on the multi-operator system in terms of probability of blocking. © 2018 IEEE.