Transmission scheduling for broadcasting with two energy‐harvesting switching transmitters

Abstract

To minimise transmission completion time in energy-harvesting rechargeable communication systems, various transmission scheduling schemes have been proposed. However, they did not consider the issue where a transmitter may fail before completing the transmission. To resolve this issue, transmission scheduling for broadcasting with energy-harvesting switching transmitters is studied. The broadcasting communication system consists of two transmitters and two users. The transmitters harvest energy independently and work alternately. The transmission scheduling problem is formulated as minimising the transmission completion time, under the energy causality constraint, the data transmission constraint, and the transmitter switching constraint. Transmitter switching is addressed by proving that a transmitter should not stop transmission before switching to the other transmitter and the switching threshold should be zero. Then, an optimal transmission policy is proposed based on earlier works on rate region and the transmitter switching mechanism. The proposed optimal transmission policy can achieve a larger rate region than several kinds of suboptimal transmission policies.

Power allocation and transmitter switching for broadcasting with multiple energy harvesting transmitters

“…To reduce control overhead and to save energy, the number of switches should be as least as possible. Following our previous work in [1,32], we propose a transmitter switching policy to choose the suitable transmitter to send data with the principle of less number of switches. It should be emphasized that the turn of the working transmitters does not affect the transmission completion time.…”

“…The energy causality means that at any given time, the total amount of consumed energy must be no more than the total amount of harvested energy. Following our previous work in [1], we treat all the transmitters as a whole transmitter (we only care about the amount of bits sent to the receivers while the bits sent by which transmitter do not matter) and find out the optimal total transmission power that achieves the maximum departure region [2] for a given deadline (the dual problem of transmission completion time minimization). Then, we rebuild the optimal power allocation policy [2] in our system setup.…”

“…Recently, energy harvesting or rechargeable sensor networks emerge as a new paradigm of sensor networks, in which the nodes can harvest energy from nature [1][2][3]. Before this, sensor network nodes are powered by batteries with limited energy storage, which are hard to recharge or replace.…”

“…To make the transmitter switching effective and decrease the switching overhead, a well-designed policy is essential to choosing the suitable transmitter to work. Motivated by the above fact and lying on the earlier works [1,2,32], power allocation and transmitter switching for broadcasting in a communication system with multiple energy harvesting transmitters and multiple receivers are studied in this paper. Our target is to minimize the transmission completion time and to reduce the number of switches under the energy causality constraint.…”

“…2) A new power allocation policy is proposed which performs close to the optimal one but is simpler. 3) A new transmitter switching policy is proposed for the communication system with multiple energy harvesting transmitters and multiple receivers, which is more complex than the communication systems we studied before [1,32].…”