Rate Maximization of Decode-and-Forward Relaying Systems with RF Energy Harvesting

We consider a three-node decode-and-forward (DF) half-duplex relaying system, where the source first harvests RF energy from the relay, and then uses this energy to transmit information to the destination via the relay. We assume that the information transfer and wireless power transfer phases alternate over time in the same frequency band, and their time fraction (TF) may change or be fixed from one transmission epoch (fading state) to the next. For this system, we maximize the achievable average data rate. Thereby, we propose two schemes: (1) jointly optimal power and TF allocation, and (2) optimal power allocation with fixed TF. Due to the small amounts of harvested power at the source, the two schemes achieve similar information rates, but yield significant performance gains compared to a benchmark system with fixed power and fixed TF allocation.

Seasonal changes in broodstock spawning performance and egg quality in ballan wrasse (Labrus bergylta)

Sea lice continue to be one of the largest issues for the salmon farming industry and the use of ballan wrasse (Labrus bergylta) as a biological control is considered to be one of the most sustainable solutions in development. Broodstock management has proved challenging in the initial phases due to the significant lack of understanding of basic reproductive physiology and behaviour in the species. The aim of the study was to monitor captive breeding populations throughout a spawning season to examine timing and duration of spawning,quantify egg production, and look at seasonal changes in egg quality parameters as well as investigate the parental contribution to spawning events. A clear spawning rhythm was shown with 3-5 spawning periods inclusive of spawning windows lasting 1-9 days followed by inter spawning intervals of 8-12 days. Fertilization rate remained consistently high (> 87.5%) over the spawning season and did not differ significantly between spawning populations. Hatch rate was variable (0-97.5 %), but peaked in the middle of the spawning season. Meanoocyte diameter and gum layer thickness decreased slightly over the spawning season with no significant differences between spawning populations. Fatty acid (FA) profile of eggs remained consistent throughout the season and with the exception of high levels of ARA (3.8 ± 0.5 % of total FA) the FA profile was similar to that observed in other marine fish species. Parental contribution analysis showed 3 out of 6 spawning events to be single paired mating while the remaining 3 had contributions from multiple parents. Furthermore, the proposed multiple batch spawning nature of this species was confirmed with proof of a single femalecontributing to two separate spawning events. Overall this work represents the first comprehensive data set of spawning activity of captive ballan wrasse, and as such and will be helpful in formulating sustainable broodstock management plans for the species.