WOLA processing: A useful tool for windowed waveforms in 5G with relaxed synchronicity

International audienc

Fast convergence joint optimization of PAPR reduction and digital predistortion in the next-generation broadcasting systems

Abstract The vast majority of designs on peak-to-average power ratio (PAPR) reduction and PA linearization schemes in broadcasting systems can be found in literature dealing with both of them in a separate manner on problem formulation, optimization objectives, and implementation issues without considering their mutual influence. Their overall performance might be suboptimal even if each of them has been optimized independently due to possible conflicts as both techniques are interdependent. This paper proposes an adding signal method that jointly achieves PAPR reduction and PA linearization simultaneously, and no extra processing is required at the receiver. The simulation results show that the proposed scheme offers a good performance/complexity trade-off requiring fewer iterations than recent methods

Effects of mixing tree species and water availability on soil organic carbon stocks are depth dependent in a temperate podzol

Mixing tree species is a forest management strategy put forward to increase and stabilize primary productivity. Yet, little is known about soil organic carbon (SOC) storage in mixed species forests, particularly under water shortage. In this study, we used a tree diversity experiment in southwestern France to assess the interactive effects of water availability (via irrigation) and mixing tree species (monocultures of pine (Pinus pinaster) and birch (Betula pendula) versus mixed plots of pine-birch and pine-birch-oak (Quercus robur)) on SOC stocks in the forest floor and across five mineral soil layers (0-5, 5-15, 15-30, 30-60 and 60-90 cm deep). We found that SOC stocks were negatively affected by irrigation in the forest floor due to an increase in decomposition rates. However, SOC stocks were positively influenced by both the mixing of tree species and irrigation in the mineral soil, particularly at the 15-30-cm soil depth. This is because root niche partitioning in mixed plots and an increase in tree biomass in irrigated plots may have resulted in greater organic matter inputs through rhizodeposition and the incorporation of microbially-derived compounds. These preliminary results indicate that SOC dynamics and its response to biotic and abiotic factors are strongly dependent on soil depth. Our data further highlight that the positive effect of mixing trees on SOC stocks was higher in irrigated plots, thereby contradicting the idea that tree mixture effects are expected to be greater when environmental conditions are harsher. We conclude that mixing tree species can increase SOC stocks in the short term in temperate forests, even if the exact mechanisms remain to be identified.Diversité et Productivité des forêTs impactées par le Changement ClimatiqueCARbone, Traits fonctionnels associés, et leur Optimisatio

Associational resistance to a pest insect fades with time

Tree diversity is one of the drivers of forest resistance to herbivores. Most of the current understanding of the diversity resistance relationship comes primarily from short-term studies. Knowing whether tree diversity effects on herbivores are maintained over time is important for perennial ecosystems like forests. We addressed the temporal dynamics of the diversity resistance relationship by conducting a 6-year survey of pine attacks by the pine processionary moth Thaumetopoea pityocampa (PPM) in a tree diversity experiment where we could disentangle tree composition from host density effects. During the first years after planting the trees, PPM attacks on maritime pine Pinus pinaster were reduced in the presence of birch Betula pendula, a fast-growing non-host tree (i.e. associational resistance). This effect was maintained but faded with time as the pines eventually grew taller than neighbouring birches. The number of repeated attacks on individual pine trees also decreased in mixed pine-birch stands. Pine density had a positive effect on stand colonisation by PPM and a negative effect on the proportion of trees that were attacked. Pines were less likely to be repeatedly attacked as pine density increased, with attacks being spread over a larger number of host trees. Collectively, these results unravel the independent contribution of tree species composition and host density to tree resistance to herbivores. Both processes had directional changes over time. These results indicate that the resistance of planted forests to herbivores can be improved by carefully choosing the composition of mixed forests and the timing of species planting