Joint Content and Radio Access for the Internet of Things: A Smart-Contract-Based Trusted Framework

Access control plays a fundamental role in securing the Internet of Things (IoT) systems. Recently, blockchain-enabled secure and trusted access control has attracted remarkable attention since it alleviates the centralization concern in traditional frameworks. However, existing designs only deal with access request validation problems whereas overlooks content delivery issues. Considering that radio resources are increasingly stretched with the rapid growth of IoT devices in the 5G era, this may give rise to unacceptably high latencies of legal requests in peak hours. This article addresses this limitation by presenting JCRA, a Joint Content and Radio Access control framework for IoT applications. JCRA deploys access point contracts (APCs) and device contracts (DCs) to manage radio access points (APs) and IoT devices, respectively. The atom access contract (AAC) is responsible for conducting access control according to access policies in DCs as well as radio resource states in APCs. To enable flexible radio resource management that often involves solving optimization models in AAC, we introduce a task offloading scheme, which recruits specialized executor nodes to complete the computation-heavy part off-chain. A Proof-of-Solution-Quality rule is proposed for executor solution validation which ensures the off-chain calculation is trusted. We implement a prototype of JCRA to demonstrate its feasibility. The costs and performance of JCRA are also evaluated in detail.