Aiming at the problem that resource allocation among multiple cognitive radio systems has high complexity in TD-LTE

a two-step resource allocation method is adopted

which allocates subcarriers in the first step and power in the second step

and in power allocation

an auction-based limited steps power allocation algorithm is proposed.This algorithm divides interference threshold of primary system（PS） into several parts

then auction each part among multiple cognitive radio（CR） systems one by one

power allocation is achieved in limited steps.The experiment results show that the new algorithm not only has low complexity

but also has near optimal performance.