Techniques are disclosed that allow for resource allocation during situations requiring co-existence in cognitive radios. Even under situations of bandwidth scarcity, the techniques allow various users to be guaranteed quality of service (QoS) by proper distribution and allocation of resources. The techniques allow wireless communication systems to operate in a normal mode and a co-existence mode. In the co-existence mode of operation, sub-frame creation, sharing and zone formation schemes are implemented that enable the existing underlying frame structure to remain intact and inter-operable with the legacy systems and at the same time, provide a guaranteed QoS. The zones effectively create partitions in space, time and frequency, which result in interference avoidance and allow various users in neighboring cells to communicate on the same frequencies.