5G and 5G-Advanced cellular networks are vulnerable to local outages resulting from disasters or targeted attacks. This fragility stems from the reliance on the central core network involved for most 5G connectivity use cases. Crisis-struck areas isolated from the cellular core network form islands , where crisis response is hindered by the unavailability of recovery-relevant services, such as emergency calls, cell broadcasts, messengers, and news apps. Our concept of island-ready, resilient-by-design 6G communication networks envisions local cellular connectivity allowing users to connect to local application servers, which is currently impossible. In our conceptualization, we follow an all-society approach, as realizing island connectivity requires the cooperation of multiple actors, including users, operators, developers, providers, and authorities. We evaluate the island readiness of 5G and 5G-Advanced systems and outline the open challenges stakeholders must address for full island readiness, such as decentralizing the 6G core network and designing local-first application architectures.

Using smartphone apps during crises is well-established, proving critical for efficient crisis response. However, such apps become futile without an Internet connection, which is a common issue during crises. The ongoing 6G standardization explores the capability to provide local cellular connectivity for areas cut off from the Internet in crises. This paper introduces to the HCI community the concept of cellular island connectivity in isolated areas, promising a seamless transition from normal operation to island operation with local-only cellular connectivity. It presents findings from a survey (N = 857) among adult smartphone users from major German cities regarding their smartphone usage preferences in this model. Results show a shift in app demand, with users favoring general-purpose apps over dedicated crisis apps in specific scenarios. We prioritize smartphone services based on their criticality, distinguishing between apps essential for crisis response and those supporting routines. Our findings provide operators, developers, and authorities insights into making user-centric design decisions for implementing island-ready 6G communication.

While designed to locate lost items, Bluetooth trackers are increasingly exploited for malign purposes, such as unwanted location tracking. This study probes deeper into this issue, focusing on the widespread use of these devices for stalking. Following a dual approach, we analyzed user data from a widely used tracking detection app (over 200,000 active installations) and conducted a comprehensive online survey (N=5,253). Our data analysis reveals a significant prevalence of trackers from major brands such as Apple, Tile, and Samsung. The user data also shows that the app sends about 1,400 alarms daily for unwanted tracking. Survey insights reveal that 44.28% of stalking victims had been subjected to location tracking, with cars emerging as the most common hideout for misused trackers, followed by backpacks and purses. These findings underscore the urgency for more robust solutions. Despite ongoing efforts by manufacturers and researchers, the misuse of Bluetooth trackers remains a significant concern. We advocate for developing more effective tracking detection mechanisms integrated into smartphones by default and creating supportive measures for individuals without smartphone access.

Modern smartphones support FIDO2 passwordless authentication using either external security keys or internal biometric authentication, but it is unclear whether users appreciate and accept these new forms of web authentication for their own accounts. We present the first lab study (N=87) comparing platform and roaming authentication on smartphones, determining the practical strengths and weaknesses of FIDO2 as perceived by users in a mobile scenario. Most participants were willing to adopt passwordless authentication during our in-person user study, but closer analysis shows that participants prioritize usability, security, and availability differently depending on the account type. We identify remaining adoption barriers that prevent FIDO2 from succeeding password authentication, such as missing support for contemporary usage patterns, including account delegation and usage on multiple clients.