This paper focuses on the highest step of our NoC design flow, which addresses the efficient deployment of real applications over an ad hoc NoC. At this level we propose a methodology and a tool to decide the NoC parameters and to generate the path coding within network interfaces for guarantied and best effort communications. The originality of our approach is based on two points. First our tool includes a derivation technique to obtain NoC communication constraints (latency, bandwidth) from application designer knowledge (application throughput). Secondly, the decision tool explores a 3D graph (t,x,y) for path allocation while taking into account mutual exclusion and global latency for FIFO minimisation under time constraints. This paper illustrates the first point. Two real applications: smart camera and multiprocessor turbo-decoder are presented to illustrate the design flow.