Participatory sensing is a crowd-sourcing technique for exploring interesting aspects of the world ranging from personal to community. Recently participatory sensing has attracted considerable attention of research community with a number of open issues and challenges. Motivating people to participate in sensing the phenomena around and report those to dedicated servers is the key factor for the success of this system.
Different incentive mechanisms have been proposed to increase the participation rate of users in this context. This paper presents a brief survey of these techniques identifying their respective limitations and finally reports the issues yet to be addressed to develop an widely acceptable incentive model.