Penghematan Daya pada Sistem Komunikasi Kooperatif Two-Way dengan Pengaturan Rasio Data Rate

Currently, many communication technologies use wireless media because it can provide seamless connectivity and mobile access. In the implementation, wireless communication system faces many challenges, one of them is fading. The effect of fading on a wireless channel will also add power consumption on mobile devices and can reduce the information signal power. However, fading can be overcome by using a cooperative communication system which is a method that utilizes antenna from other users (relays) with the principle of diversity, so the performance of wireless communication system can be improved. This paper proposes power saving on two-way cooperative communication system based on data rate ratio. The method of setting the value of this data rate ratio aims to minimize power consumption in a two-way cooperative communication system, i.e., a full-duplex communication system with quantized and forward (QF) relay protocol. To obtain a minimum power consumption, the ratio of the data rate must be set on the assumption that the value of the transmit power of each source and the relay is equal. The result shows that the system performance is improved, the system SNR value becomes lower, and the power is more efficient by adjusting the ratio of data rate compared to the conventional system without power control

Low-complexity energy-efficient resource allocation for delay-tolerant two-way orthogonal frequency-division multiplexing relays

Energy-efficient wireless communication is important for wireless devices with a limited battery life and cannot be recharged. In this study, a bit allocation algorithm to minimise the total energy consumption for transmitting a bit successfully is proposed for a two-way orthogonal frequency-division multiplexing relay system, whilst considering the constraints of quality-of-service and total transmit power. Unlike existing bit allocation schemes, which maximise the energy efficiency (EE) by measuring ‘bits-per-Joule’ with fixed bidirectional total bit rates constraint and no power limitation, their scheme adapts the bidirectional total bit rates and their allocation on each subcarrier with a total transmit power constraint. To do so, they propose an idea to decompose the optimisation problem. The problem is solved in two general steps. The first step allocates the bit rates on each subcarrier when the total bit rate of each user is fixed. In the second step, the Lagrangian multipliers are used as the optimisation variants, and the dimension of the variant optimisation is reduced from 2N to 2, where N is the number of subcarriers. They also prove that the optimal point is on the bounds of the feasible region, thus the optimal solution could be searched through the bounds