Defining Spatial Security Outage Probability for Exposure Region Based Beamforming

With increasing number of antennae in base stations, there is considerable interest in using beamfomining to improve physical layer security, by creating an `exposure region' that enhances the received signal quality for a legitimate user and reduces the possibility of leaking information to a randomly located passive eavesdropper. The paper formalises this concept by proposing a novel definition for the security level of such a legitimate transmission, called the `Spatial Secrecy Outage Probability' (SSOP). By performing a theoretical and numerical analysis, it is shown how the antenna array parameters can affect the SSOP and its analytic upper bound. Whilst this approach may be applied to any array type and any fading channel model, it is shown here how the security performance of a uniform linear array varies in a Rician fading channel by examining the analytic SSOP upper bound.Comment: Submitted to the IEEE Transactions on Wireless Communication

Effort-aware just-in-time defect identification in practice: A case study at Alibaba

National Research Foundation (NRF) Singapore under its AI Singapore Programm

Security optimisation of exposure region-based beamforming with a uniform circular array

This paper investigates the impact of a uniform circular array (UCA) in the context of wireless security via exposure region-based beamforming. An improvement is demonstrated for the security metric proposed in our previous paper, namely, the spatial secrecy outage probability (SSOP), by optimizing the configuration of the UCA. Our previous paper focused on formalizing the SSOP concept and exploring its applicability using a uniform linear array example. This paper proposes the UCA as a superior candidate because it is more robust against the effects of mutual coupling. The UCA's SSOP configuration is explored and a special expression is derived from the general expression for the first time, and a closed-form upper bound is then generated to facilitate analysis. By carefully designing the UCA structure particularly the radius, an SSOP optimization algorithm is derived and explored for mutual coupling. It is shown that the information leakage to eavesdroppers is reduced while the legitimate user's received signal quality is enhanced due to the use of beamforming

A clock-based dynamic logic for the verification of CCSL specifications in synchronous systems

International audienceThe Clock Constraint Specification Language (CCSL) is a clock-based specification language for real-time embedded systems. With logical clocks defined as first-class citizens, CCSL provides a natural way for describing clock constraints in synchronous systems — a classical model of concurrency for real-time embedded systems. In this paper, we propose a clock-based dynamic logic called CCSL Dynamic Logic (CDL) for the verification of CCSL specifications in synchronous systems. It extends the first-order dynamic logic with a synchronous execution mechanism in its program model and with CCSL primitives as terms in its logical formulae. We build a sound and relatively complete proof system for CDL to support the verification. Compared with previous approaches for verifying CCSL specifications, which are based on model checking and SMT checking techniques, our approach, which is based on theorem-proving, offers a unified verification framework in which both bounded and unbounded CCSL specifications can be verified. Technically, with the proof system of CDL, a complex CDL formula can be semi-automatically transformed into a set of quantifier-free, arithmetical first-order logic (QF-AFOL) formulae which can be checked by an SMT solver in an efficient way. As a case study, we analyze a simple synchronous system throughout the paper to illustrate how CDL works. We analyze and prove the soundness and completeness of the proof system for CDL. Currently, CDL is partially mechanized in Coq

Evaluations on Compressibility Factor Calculation Methods for High-Pressure H2S-Containing Natural Gases

The compressibility factor is an essential parameter for natural gas exploitation and processing. The method based on the equation of state (EoS) represents the most popular method for compressibility factor calculations. In this paper, the accuracy of compressibility factor calculations for two traditional cubic-EoSs (Soave-Redlich-Kwong (SRK) EoS, the Peng–Robinson(PR) EoS), the Benedict–Webb–Rubin-Starling (BWRs) EoS, and the Cubic-Plus-Association (CPA) EoS are evaluated based on experimental data for high-pressure H2S-containing natural gases. A total of 234 sets of experimental compressibility factors are applied to validate the above four EoSs, which cover pressures from 70MPa to 131MPa. Results show that for the high-pressure and low H2S content natural gas (35MPa≤P<70MPa, H2S<0.3%), the BWRS EoS yields the best results among the above four EoSs. The average relative deviation (ARD) between the experimental results and the calculated values is 1.07%. For high-pressure and high H2S content natural gas (35MPa≤P<70MPa, H2S≥0.3%), the CPA EoS yields the best results with an ARD of 1.01%. For ultra-high-pressure natural gas (P≥70MPa) without H2S, the BWRS EoS gives the best results with an ARD of 0.32% and the maximum relative deviation is 1.50%

Timed Automata Semantics of Spatio-Temporal Consistency Language STeC

International audienceIntelligent Transportation Systems (ITS) are a class of quickly evolving modern safety-critical embedded systems. Dealing with their growing complexity demands a high-level formal modeling language along with adequate verification techniques. STeC has recently been introduced as a process algebra that deals natively with both spatial and temporal properties. Even though STeC has the right expressive power, it does not provide a direct tooled support for verification. We propose to encode STeC specifications as Timed Automata to provide such a support and we illustrate our transformation strategy on a simple example

A verification framework for spatio-temporal consistency language with CCSL as a specification language

International audienceThe Spatio-Temporal Consistency Language (STeC) is a high-level modeling language that deals natively with spatio-temporal behaviour, i.e., behaviour relating to certain locations and time. Such restriction by both locations and time is of first importance for some types of real-time systems. CCSL is a formal specification language based on logical clocks. It is used to describe some crucial safety properties for real-time systems, due to its powerful expressiveness of logical and chronometric time constraints. We consider a novel verification framework combining STeC and CCSL, with the advantages of addressing spatio-temporal consistency of system behaviour and easily expressing some crucial time constraints. We propose a theory combining these two languages and a method verifying CCSL properties in STeC models. We adopt UPPAAL as the model checking tool and give a simple example to illustrate how to carry out verification in our framework

A dynamic logic for verification of synchronous models based on theorem proving

International audienceSynchronous model is a type of formal models for modelling and specifying reactive systems. It has a great advantage over other real-time models that its modelling paradigm supports a deterministic concurrent behaviour of systems. Various approaches have been utilized for verification of synchronous models based on different techniques, such as model checking, SAT/SMT sovling, term rewriting, type inference and so on. In this paper, we propose a verification approach for synchronous models based on compositional reasoning and term rewriting. Specifically, we initially propose a variation of dynamic logic, called synchronous dynamic logic (SDL). SDL extends the regular program model of first-order dynamic logic (FODL) with necessary primitives to capture the notion of synchrony and synchronous communication between parallel programs, and enriches FODL formulas with temporal dynamic logical formulas to specify safety properties — a type of properties mainlyconcerned in reactive systems. To rightly capture the synchronous communications, we define a constructive semantics for the program model of SDL. We build a sound and relatively complete proof system for SDL. Compared to previous verification approaches, SDL provides a divide and conquer way to analyze and verify synchronous models based on compositional reasoning of the syntactic structure of the programs of SDL. To illustrate the usefulness of SDL, we apply SDL to specify and verify a small example in the synchronous model SyncChart, which shows the otential of SDL to be used in practice