This paper is proposing some models for optimizing the Device-to-Device (D2D) communication in the context of congested environments, by using spectrum sensing. Different levels of decentralization - in computational intelligence, signal processing, power management and a greater percentage of open-source software - are discussed in a business-oriented perspective. A network of low power, inexpensive SDR devices is presented in solutions for implementing the partner discovery and spectrum selection as part of D2D communication in radio-congested urban environments. These practical solutions cover not only cost-effective SDR receivers but also local intelligence, with a spectacular add-on: mobility.