The last decade has witnessed the convergence of three giant worlds: electronics, computer science and telecommunications. The next decade should follow this convergence in most of our activities with the generalization of sensor networks. In particular with the progress in medicine, people live longer and the aging of population will push the development of e-Health solutions based on Wireless Personal Area Networks (WPAN) and Wireless Body Area Networks (WBAN), as more and more people will prefer not to go to hospital, should it be for convenience or for cost reasons. The recent advances in wireless technology have helped the development of wireless body area networks (WBAN), where a set of communicating devices gathered in/around a human body can communicate in a ad-hoc way. These devices are connected to sensors which monitor movements and vital body parameters. The most critical point for BAN networks is the energy saving issue. The main target of our proposal is to develop original “green” low-power simple original solutions and to include some of them in a wireless multiprotocol gateway. The most effective way to save power is the cooperation between the nodes of the WBAN. Several original tasks will be developed towards this goal. An original channel estimator will be developed. It is a smoothing off-line low-complexity estimator that allows to really shorten the training sequence and thus prevents spoiling energy by transmitting less information. This algorithm is adaptive and allows the different links knowledge that will be chosen for cooperation. By allowing information processing in the intermediate nodes, Network Coding (NC) schemes, originally proposed for noiseless wired networks, have been proved to achieve network multicast capacity bounds. We will develop an efficient relay node selection based on the network power/energy constraint and we will perform optimal power allocation among nodes to achieve maximum rate with limited power constraint. The joint design of NC and channel code taking the overall network error correction ability into consideration, should lead to a high performance. The task of green cognition technology in wireless body area networks is also of utmost importance. On one hand, cognitive communication is known to be an effective technology for addressing WBAN-based applications across heterogeneous networks. On the other hand, cooperative transmission is known to enhance the transmission reliability and maintain low transmission power for WBAN. We will propose a novel network architecture for cognitive and cooperative transmission in WBANs. In particular, two schemes, Energy-aware Cooperative Transmission and Reliability-aware Cooperative Transmission, will be developed for different applications that have distinct energy consumption or reliability requirements. Finally, we aim not only at simulations but at integrating some of those algorithms in a real platform dedicated to low-energy BAN. In particular, to the best of our knowledge, neither off-line smoothing channel estimation, nor network coding was ever implemented on a real test-bed in France.