Making sense of meaning:a survey on metrics for semantic and goal-oriented communication

Abstract Semantic communication (SemCom) aims to convey the meaning behind a transmitted message by transmitting only semantically-relevant information. This semantic-centric design helps to minimize power usage, bandwidth consumption, and transmission delay. SemCom and goal-oriented SemCom (or effectiveness-level SemCom) are therefore promising enablers of 6G and developing rapidly. Despite the surge in their swift development, the design, analysis, optimization, and realization of robust and intelligent SemCom as well as goal-oriented SemCom are fraught with many fundamental challenges. One of the challenges is that the lack of unified/universal metrics of SemCom and goal-oriented SemCom can stifle research progress on their respective algorithmic, theoretical, and implementation frontiers. Consequently, this survey paper documents the existing metrics– scattered in many references– of wireless SemCom, optical SemCom, quantum SemCom, and goal-oriented wireless SemCom. By doing so, this paper aims to inspire the design, analysis, and optimization of a wide variety of SemCom and goal-oriented SemCom systems. This article also stimulates the development of unified/universal performance assessment metrics of SemCom and goal-oriented SemCom, as the existing metrics are purely statistical and hardly applicable to reasoning-type tasks that constitute the heart of 6G and beyond

Secrecy analysis of a MIMO full-duplex active eavesdropper with channel estimation errors

Abstract In this paper, we investigate the secrecy performance of the multiple-input multiple-output (MIMO) wiretap channels in the presence of an active full-duplex eavesdropper with consideration of channel estimation error at the legitimate destination and eavesdropper. For this purpose, the probability density functions (PDFs) and cumulative density functions (CDFs) of the receive signal-to-interference-plus-noise ratio (SINR) at the destination and eavesdropper are given by conducting the singular value decomposition (SVD) on the estimated channel coefficient matrices. Consequently, the closed- form expressions for the probability of positive secrecy capacity and secrecy outage probability over Rayleigh fading channels are derived. Finally, the Monte-Carlo simulation results are presented to validate the accuracy of our theoretical analysis

Intercept probability analysis over the cascaded Fisher-Snedecor ℱ fading wiretap channels

Abstract In this paper, we have investigated the physical layer security over cascaded Fisher-Snedecor ℱ fading channels in the presence of randomly distributed eavesdroppers. To characterize the eavesdroppers’ intercept capability, both the conceptual k-th nearest and best eavesdroppers are introduced. The probability density function (PDF) of the k-th nearest and best eavesdropper is characterized. The probability of interception, is correspondingly regarded as the secrecy metric, and is further derived with closed-form expressions in terms of Fox’s H-function. For the purposes of providing more insights, the asymptotic behavior of the intercept probability is also provided. To explore the effects of the eavesdroppers’ density and the channel fading conditions on the secrecy performance, we have performed the Monte-Carlo simulation and compared our analytical results with the simulated ones. One can find that our analytical results are successfully verified by the simulation results