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Unlike the fixed power grid cooperative networks, which are mainly based on the reception reliability parameter while choosing the best relay, the wireless-powered cooperative communication network (WPCCN) and in addition to the reception reliability the transmission requirement consideration is important for relay selection schemes. Hence, enabling efficient transmission techniques that address high attenuation of radio frequency (RF) signals according to the distance without increasing the total transmission power is an open issue worth studying. In this relation, a multiantennas power beacon (PB) that assists wireless-powered cooperative communication network (PB-WPCCN) is studied in this paper. The communication between source and destination is achieved with the aid of multiple relays, where both the source and the multiple relays need to harvest energy from the PB in the first place to enable their transmission functionalities. A novel relay selection scheme is proposed, named as two-round relay selection (2-RRS), where a group of relays that successfully decode the source information is selected in the first round selection. In the second round, the optimal relay is selected to forward the recorded information to the destination. The proposed 2-RRS scheme is compared with two existing relay selection schemes, i.e., partial relay selection (PRS) and opportunistic relay selection (ORS). The analytical closed-form expressions of outage probability and average system throughput are derived and validated by numerical simulation. The comparison results between different relay selection schemes show: (I) The superiority of the proposed 2-RRS scheme as it achieves around 17% better throughput compared to the conventional ORS scheme and 40% better than the PRS scheme, particularly when PB transmit power is 10 dB; (II) The proposed 2-RRS scheme guarantees the lowest outage probability, especially when the PB is equipped with multiantennas and performs beamforming technique; (III) The optimal localisation of the PB between the source and N relays depends on the adopted relay selection scheme; (IV) The exhaustive search of the maximum system throughput value shows that the proposed 2-RRS scheme required shorter energy harvesting time compared to other schemes. The increase in energy harvesting time and number of relays do not necessarily reflect positively on the system throughput performance; hence tradeoffs should be taken into consideration.

To move towards next generation of green communications, we study a power beacon (PB) assisted wireless powered cooperative communication network (PB-WPCCN). We propose a new system model with a source and a number of candidate relays that are not directly connected to the power grid. System harvests energy from RF broadcast signals radiated from PB, and works cooperatively to successful deliver information to the target device through relay network. System executes this process in two stages relay selection decode then forward, namely, (2SRS-DF). First of all, select a group of relay candidates who can successfully decode the received signal from the source. Secondly, choose the best relay with the capability to forward the decoded message to the destination from the group which successfully decodes the source signal in the first stage. The closed-form expression for the average outage probability and the throughput of the proposed system is derived and presented. We validate the theoretical results by numerical simulations. The impact of position and number of relay terminals along with time allocation parameters are also studied.

The production of durum wheat in Algeria is hardly sufficient for the growing demand for this product. Dependent on climatic hazards, the national average yields which hardly exceed 10 q ha-1, are mainly due to a lack of mastery of production techniques such as fertilization, plant protection, supplemental irrigation, etc. The aim of the undertaken experimentation was to constitute a nitrogen fertilization strategy for durum wheat that fit the region of the plains of Constantine in Algeria. Based on the form of fertilizer, the method, and the time of application, the experimentation profited from good soil and good climatic conditions.  For that, we established an experimental device including various methods of contribution: ground and foliar nitrogen fertilizers, split or fully applied at-planting. The analysis of growth parameters and yield components showed that any nitrogen input results in improvements whatever its form or modality. Moreover, the method with a single application of nitrogen fertilizer at-planting on the ground was most efficient for the whole of the studied parameters, except the length of the ear where we observed the best result with foliar supply.