The Cognitive Radio Network (CRN) communication paradigm in 5G networks provides an effective infrastructure to enable different smart city applications like public safety applications. In future smart cities, dense deployment of wireless networks like Wi-Fi, WSN and MANET etc., can be integrated with 5G networks using CRN communication. CRN communication enables direct communication between nearby User Equipment using cellular or ad-hoc links, thereby improving the spectrum utilization, system throughput, and energy efficiency of the network. In this paper, we propose a Software Defined Cognitive Radio Network (SD-CRN) architecture where a centralized Software Defined Network (SDN) controller with cognitive ability communicates with the Cloud Head (CH) using in-band technology and the Cloud Head communicates with the User Equipment using Out-of-band technology. This architecture works in case of infrastructure damage and also helps to maintain communication between victims and first responders by forming mobile clouds with active devices having higher signal strength. Next, we propose Dynamic Hand Over Algorithm with Interference Cancellation (DHAIC) for providing adaptive handoff whenever link failure occurs. In addition, interference cancellation is further performed by this algorithm between each CRN group to cancel the interference caused by the devices during emergencies.