Kaputa - Blockchain, Non-Fungible Token and Model Card Integrated 5G/6G Network Slice Broker and Marketplace

5G network slicing enables IoT networks to connect billions of heterogeneous objects providing high quality of service, high network capacity, and enhanced system throughput. It opens a new marketplace opportunity for cloud providers and network operators to sell portions of their networks to address specific customer needs in 5G applications. However, there are numerous open challenges to providing end-to-end slices due to complex business and engineering requirements from service and resource providers. To address these challenges, in this paper, we propose "Kaputa", a blockchain-enabled network slice broker and NFTenabled network slice marketplace. Here, different stakeholders such as cloud providers, network operators, RAN providers, and transport network providers can collaborate to rent their resources. Kaputa orchestrates the network slices with the help of blockchain smart contracts. The orchestrated network slices will be encoded as NFT tokens and published in the Kaputa NFT marketplace. Customers can purchase the network slices from the marketplace based on their 5G application requirements via paying crypto/fiat currency. The revenue will be distributed among different providers. The data provenance information of the network slices is encoded into Model Cards and stored in the blockchain ledger. A prototype of Kaputa has been implemented with FreedomFi and OpenAirInterface 5G core. To the best of our knowledge, this is the very first research that tries to represent 5G/6G network slices as NFTs. This design methodology provides enhanced transparency and auditability to the network slice orchestration process while providing an open platform to share and trade network slices in the marketplace.