Molecular communication (MC) has promising potential and a wide range of applications. However, odor-based communication which is common in nature, has not been sufficiently examined within the context of MC, yet. In this paper, we introduce a novel approach for implementing odor-based MC systems. We propose a new modulation scheme called Odor Perceptual Shift Keying (OPSK), which encodes information by shifting the perceptual values of odor molecules in pleasantness, intensity and edibility dimensions. We construct a system which transmits OPSK modulated signals between a transmitter and receiver. We conduct analyses on the system parameters to simulate performance metrics such as symbol error rate (SER) and symbol rate (SR). Our analyses indicate that OPSK has a potential for realizing odor-based MC systems. We find that under certain conditions, reliable odor-based MC systems can be implemented using OPSK across a variety of distance ranges from millimeters up to kilometers. Additionally, we introduce adaptive symbol transmission to our system for input symbol sequences featuring symbols that occur with unequal probabilities. We further demonstrate that the proposed algorithm at the transmitter side can achieve extended operation times.