Table 1. Existing work and key contributions.

Reference	Methodology	Key contribution	Advantage	Disadvantage	Future work
Kitchenham (2004)	Survey and case study	Investigated the potential of unmanned aerial vehicles in smart cities using blockchain.	Improved urban planning and emergency response and readiness.	Limited UAV battery life and coverage range	Develop energy-efficient UAVs
Keele (2007)	Experimental study	Used unmanned aerial vehicles (UAVs) to monitor traffic using a blockchain-based system.	Data on traffic in real time that is accurate and secure.	High initial setup cost for blockchain	Explore lightweight blockchain protocols
Euchi (2021)	Simulation and comparative analysis	Blockchain consensus techniques for UAV networks were compared and contrasted.	Greater capacity for business transactions within UAV networks.	Scalability issues with large UAV deployments	Investigate hybrid consensus for UAVs
Lagkas et al. (2018)	Analytical modeling	Blockchain was used to develop a model that might improve UAV flight paths.	Utilization of available resources in UAV operations in an effective manner.	Limited network bandwidth for UAV communication	Enhance communication protocols for UAVs
Pathak et al. (2020)	Field experiment and survey	Experiments were carried out in the real-world using UAVs equipped with blockchain technology.	Integrity improvements implemented in the data collected in urban surveys.	Regulatory challenges in drone deployment	Address legal and privacy concerns in UAVs
Sharma et al. (2020)	System prototype development	Constructed a working model of a system that integrates UAVs and blockchain.	Integrating UAVs smoothly into smart city initiatives.	Integration challenges with existing systems	Develop standardized APIs for UAV integration
Yigitcanlar et al. (2020)	Comparative study and user feedback	Analyzed the degree to which users were satisfied with blockchain-enabled UAV services.	Satisfaction and participation among the populace increase.	Limited standardization in UAV and blockchain technology	Establish industry standards for UAV services
Gupta et al. (2021)	Case study and stakeholder interviews	Investigated how stakeholders think regarding unmanned aerial vehicles using blockchain technology.	To learn more about how people feel about UAVs.	Limited public acceptance of UAV technology	Develop public awareness campaigns for UAVs
Mendoza, Rodriguez & Lhuillery (2018)	Data analysis and machine learning	For the analysis of UAV data, researchers made use of machine learning methods.	Smart city decision-making is enhanced by better data analysis.	Data privacy concerns related to UAV surveillance	Develop privacy-preserving data analytics for UAVs
Stankov et al. (2019)	Simulation and network optimization	Communication networks for unmanned aerial vehicles that are optimized utilizing blockchain.	Improved communication in terms of both speed and reliability.	Potential security vulnerabilities in blockchain	Implement advanced encryption techniques
Pamnani & Parvathi (2021)	Field testing and performance evaluation	Researchers conducted tests to see how well UAVs equipped with blockchain technology performed in actual city settings.	Monitoring in real time of metropolitan areas.	Limited scalability due to blockchain complexity	Explore scalable blockchain solutions for UAVs
Alam, Chamoli & Hasan (2022)	Comparative analysis and cost-benefit study	Using blockchain, researchers analyzed the efficiency of the costs associated with UAVs.	Reduced costs associated with processes while also improving efficiency.	High transaction fees and network congestion	Optimize blockchain parameters for cost efficiency