Network coding can be considered as a key enabler to achieve high throughput at low energy requirements in the 5G and beyond networks. Enabling the intermediate nodes to code and transmit the packets, network coding improves the resiliency against packet losses, but also introduce several security challenges in a non-trusted environment. A malicious intermediate user can pollute the information flow and such pollution attacks can significantly reduce the efficiency of the network if goes undetected. Integrity schemes with homomorphic properties are proposed to detect pollution attacks at the earliest. This paper proposes a bandwidth efficient, SDN-based integrity scheme suitable for the small cell environment. The proposed approach uses the secure control channel with the central controller for all security signalling and allows the participating nodes to process the packets verifying the integrity of received packets without any additional overhead on the communication channel. The proposed scheme is analyzed for the security against pollution attack, bandwidth efficiency, and scalability against the increasing number of users and varying coding parameters.