A context-aware system is one that gracefully adapts to user

environment changes, rendering its applications/services more personalized.

Location has been long considered as the most important context

and numerous Location Based Services have been introduced. Proximity

detection is considered as a high level proactive location based function

that detects proximity between two mobile users. This function is needed

in diverse applications such as dating services, gaming and child tracking.

This paper presents Direction-based Dynamic Shifted Circle (DDSC)

approach which takes users direction as context in providing an efficient

proximity detection technique. Simulation experiments proved that DDSC

outperforms similar algorithms that have been introduced in literature

previously, in terms of the number of messages exchanged.