In this paper, we present the design of the communication in a wireless sensor network. The resource limitations of a wireless sensor network, especially in terms of energy, require an integrated, and collaborative approach for the different layers of communication. In particular, energy-efficient solutions for medium access control, clusterbased routing, and multipath creation and exploitation are discussed. The proposed MAC protocol is autonomous, decentralized and designed to minimize power consumption. Scheduling of operations, e.g. for the MAC protocol, is naturally supported by a clustered structure of the network. The multipath on-demand routing algorithm improves the reliability of data routing. The approaches taken and presented are designed to work together and support each other.