In this paper, we propose a novel energy-efficient route-discovery scheme with transmission power control (TPC) for ad hoc networks. The proposed scheme is very simple and improves energy efficiency without any information about neighbor nodes. In the proposed scheme, when a node receives a route request (RREQ), the node calculates the routing-level backoff time as being inversely proportional to the received power of the RREQ. After the route discovery, source and intermediate nodes transmit packets by the power-controlled medium access control (MAC) protocol. In addition, we propose an extended version of the proposed scheme for discrete power control devices. Simulation results demonstrate the proposed schemes can discover more energy efficient routes than the conventional schemes.

In this paper, we describe the implementation of the proposed single user type CDMA adaptive interference canceller (AIC) with RAKE structure in the developed testbed for the base station, and evaluate its performance in the multiuser and multipath fading environment. Laboratory experiment demonstrates that the AIC receiver is much more near-far resistant than the conventional matched filter (MF) receiver in the multiuser case. When the power of the other users is 6 dB larger than that of the desired user, the AIC receiver can achieve the BER of 10-3 at C/PG = 33. 3 % in the 2-path fading channel, while the MF receiver cannot achieve the BER at C/PG of more than 20. 8%. Furthermore, we evaluate the effect of transmission power reduction in the transmitter with transmission power control (TPC). The experimental result shows that the required transmission power can be greatly reduced by 3. 0 dB and 9. 2 dB with the AIC receiver at C/PG = 29. 2 % and 33. 3%, respectively.

In this paper, we briefly describe the proposed radio access scheme based on CDMA/FDD for next-generation mobile radio systems, and evaluate its performance through laboratory and field experiments on transmission power control (TPC) and diversity, which are the key technologies to achieve efficient CDMA systems. The design of the practical TPC method is discussed, and a robust method is presented for operation in low signal to interference power ratio (SIR). Laboratory experiments demonstrate that space and path diversity effectively improve the TPC performance in the Doppler frequency range of 40 to 80 Hz, and reduces the required Eb/N0 to achieve the BER of 10-3. The necessary diversity order for multipath fading mitigation in all the Doppler frequency range is also investigated. Through the field experiments in urban area of Tokyo using a developed system at 0. 96 Mcps, a low required Eb/N0 of 2. 8 dB can be obtained because of the effectiveness of the diversity.