In order to enhance simultaneously the association robustness of mobile users and spectrum efficiency (SE) of systems, by integrating the decoupled uplink (UL)/downlink (DL) association (DUDA) and cross‐tier dual connectivity (DC), the orthogonal multiple access (OMA)‐mode and non‐OMA (NOMA)‐mode design schemes are investigated over a three‐tier heterogeneous network (HetNet) accompanying with the proposition of a conditional association analysis method. The scheme exploits effectively the DC requirement of NOMA. Additionally, in the proposed conditional association design and analysis method, the decoupling UL association designs are conducted only under a given DL association condition. Owing to low complexity, this method shows that it is very easy to achieve the possible decoupling UL DC designs and the corresponding condition association probabilities. Then, the conditional coverage probabilities and SEs of the OMA‐mode and NOMA‐mode HetNets are derived by specially considering DUDA and coupled UL/DL association strategies. The proposed conditional design framework can be easily extended to multi‐tier HetNets and is helpful to select feasible DL candidate from all possible DL associations so that the resulting UL associations are optimal. Besides this, the cross‐tier DC design ensures the effective exploitation of the whole network resources because different tiers have different serving levels.

We propose and implement an innovative remote attestation framework called DR@FT for efficiently measuring a target system based on an information flow-based integrity model. With this model, the high integrity processes of a system are first measured and verified, and these processes are then protected from accesses initiated by low integrity processes. Toward dynamic systems with frequently changed system states, our framework verifies the latest state changes of a target system instead of considering the entire system information. Our attestation evaluation adopts a graph-based method to represent integrity violations, and the graph-based policy analysis is further augmented with a ranked violation graph to support high semantic reasoning of attestation results. As a result, DR@FT provides efficient and effective attestation of a system's integrity status, and offers intuitive reasoning of attestation results for security administrators. Our experimental results demonstrate the feasibility and practicality of DR@FT.

Determining whether a given policy meets a site's high-level security goals can be difficult, due to the low-level nature and complexity of the policy language, and the multiple policy violation patterns. In this paper, we propose a visualization-based policy analysis framework that enables system administrators to visually query and visualize SELinux security policies and to easily identify the policy violations. We propose and formalize both a semantic substrate and adjacency matrix visualization techniques for policy visualization. Furthermore, we propose a visual query language for expressing policy queries in a visual form. Our framework is targeted towards enabling the average administrator by providing an intuitive cognitive sense about the policy, policy queries and policy violations. We also describe our implementation of a visualization-based policy analysis tool that provides the functionalities discussed in our framework.