Energy efficient communication in wireless networks

Energy-efficient communication is studied for large wireless ad hoc networks using multihop communications or cooperative beamforming. A game-theoretic analysis is used to study the effects of receiver choice and transmit power on the energy efficiency of multihop networks in which the nodes communicate using Direct-Sequence Code Division Multiple Access (DS-CDMA). Non-cooperative power control games are proposed in which each user seeks to choose transmit powers and receivers to maximize the number of bits is successfully transmits per unit of energy consumed. The unique Nash equilibrium of this game is studied and compared to socially optimal solutions. Optimal transmit powers are derived for energy-efficient, low-overhead cooperative beamforming in ad hoc networks. Collaborating nodes retransmit local signals to faraway destinations, multiplying the received analog waveform by a complex weight chosen (in a distributed fashion) to maximize the received SNR. The improvement in SNR is explicitly derived for a large number of cooperating nodes. Game theory is used to study the interactions between clusters of collaborating nodes and the resulting unique Nash equilibrium is analyzed. Finally, practical considerations limiting the scaling of multihop networks are studied. Bounds on the energy consumed by multihop networks are used to study optimal network design criteria.