Turkish Journal of Electrical Engineering and Computer Sciences




The frequent replacement requirement of UAVs for recharging outputs an extreme number of messaging for admission control of end-users. There are many studies that try to optimize the network capacity in an energy-efficient manner. However, they do not consider the security of data and control channels, which is the urgent requirement of 5G. Blockchain handles secure systems. However, the high numbered transactions in blockchain may cause bottlenecks while considering computational delay and throughput of end-user. In UAVs, a high percentage of battery is consumed for computational tasks instead of communication tasks. Therefore, to handle security by considering the computational needs, this paper proposes a novel two-layered blockchain-based admission control in UAV networks. It has two layers named as side-chain for UAVs and off-chain for end-users building in a decentralized manner. In the former one, the data bearer of end-users is protected by the side-chain of each transaction which is signed by admitted end-users and UAVs. Here, each transaction includes a unique transaction id, nonce value, IMSI of the user, RNTI of UAV, signed data, and hash value. In the latter one, the off-chain is built by signing admission contracts between users in a decentralized manner and the Merkle tree is constructed for the off-chain where the root hash is only stored in a side-chain. Then, the number of transactions that should be validated is extremely decreased. Moreover, PoS is used for the validation of transactions where the validator is selected randomly instead of the competition requirement as in PoW. A novel blockchain-based admission control algorithm isolates readmission control of end-users to 5G core-side during UAV replacement. According to performance evaluation, the proposed approach serves end-users by 64.2% better QoS than the conventional one during UAV replacement. Moreover, it keeps edge delay in acceptable range by using Merkle tree and PoS.


UAV networks, blockchain, 5G, admission control, Merkle tree

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