Mobile communication networks experience a tremendous growth. According to the vision of Wireless World Research Forum (WWRF), there will be 7 trillion wireless devices serving 7 billion people by the year 2017. Ubiquitous access to information anywhere, anytime and anyhow at low cost is one of the essential features of future mobile communication networks, which will interconnect a heterogeneity of various systems and be much more dynamic and flexible in terms of changes in access technology, topology, services, etc. Moreover, there will be a need to match resources supply with application demands as these demands are expected to fluctuate over time. This makes an adequate service placement in such networks of a major importance. In this paper we survey the existing service placement mechanisms and present a qualitative comparison of existing mechanisms. Moreover we also highlight the short comings of existing approaches so that the new approaches can remove the short comings of exis...