In this reported work, the blockage probability for the 60GHz radio links is analysed in typical indoor environments with random human activities. With up to Q random distributed human bodies, the average blockage possibility is calculated in the sense of statistics for the radio links between the user devices and the ceiling-mounted access point (AP) in a typical wireless LAN architecture. Also, the blockage impact to the effective channel capacity is quantified as a reduction related to the blockage probability. Numerical simulations show that the blockage probability increases almost linearly as the user devices are moving towards the edge of the service area, and the increasing rate is largely affected by the height of the AP and the human density.Introduction: Recently, high-speed communication in indoor environments using the 60GHz millimetre-wave band has attracted much attention from both industry and academic societies owing to attractive features such as ultra-high transmission rate, high-level security and unlicensed operation [1]. However, the radio transmission essentially relies on the line of sight (LOS) path between the transceivers, which is very sensitive to blockage impact by human activity. Since the human body shadowing effect is almost inevitable in indoor applications, such as 60GHz wireless LAN (WLAN), extensive research efforts have been made to characterise the shadowing impacts via simulation and measurement campaigns. Collonge et al.[2] presented several propagation measurements in a realistic indoor environment with natural human activity for a 60GHz channel, and identified the unavailability rate (UR) of the channel as the portion of time when the LOS path is blocked. In a typical office environment, the authors in [3] revealed that the loss of propagation-path visibility of the 60GHz radio links is affected by the human density and service area. Also, Wang et al. in [4] characterised the human body shadowing attenuation by excluding the blocked signal power at the receiver, and quantified the link stability by the distribution of the duration when the attenuation level exceeds a certain threshold. However, in a dynamic obstruction environment, it is seldom mentioned to analytically evaluate the probability that a 60GHz radio link might be blocked in a statistical way, which largely affects the performance of the emerging applications in 60GHz band, e.g. the wireless streaming of uncompressed high-definition (HD) TV.In this Letter, an analysis framework of the blockage probability is proposed for 60GHz radio links in a typical indoor environment with random human activity. Different from [2] and [3], a wireless LAN with a star topology is considered in a general indoor scenario. The access point (AP) is ceiling-mounted at the centre of a service area, in which the user devices (DEVs) are randomly distributed and communicate with the AP via LOS paths. From the probabilistic distribution of the human bodies and the incurred shadow area, the possibility of a singlehop radio link being ...

Developments in wireless communications and wearable devices have facilitated the emergence of a network of tiny sensors embedded in, on or around human body called Wireless Body Area Network (WBAN). Over the last decade, WBAN has increasingly been playing a vital role in modern medical systems because of its potential to revolutionize healthcare delivery. The data collected by the sensors contain sensitive information and are transmitted via wireless channels. However, the openness of these channels makes WBAN vulnerable to attacks by unauthorized users. Therefore, secure authentication and data encryption schemes in WBAN are essential. The resource constraint nature of the sensors makes traditional cryptographic schemes unsuitable. Consequently, authentication schemes based on channel characteristics are proposed, which are more suitable with fewer requirements. However, existing approaches do not consider mutual authentication as well as passive/active attacks. Motivated by these limitations, we propose in this paper, a mutual authentication and data encryption scheme based on signal propagation characteristics and enhanced butterfly algorithm. To validate the effectiveness of our scheme, we conducted an extensive real-world experiment involving 5 volunteers in indoor and outdoor areas, under distinct scenarios. We further conducted security and performance analyses to validate the effectiveness of our scheme in terms of resources and its resilience to various attacks. The results of the experiments and the analyses show that our scheme could mutually identify legitimate users and protect user data against active/passive eavesdropping attacks with minimal overhead.INDEX TERMS Authentication, active attack, passive attack, signal propagation characteristic, wireless body area network (WBAN).

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract