Contention based resource allocation in 6G

Reliable and Low Latency Communications is one of the several use cases targeted by 5G NR. Considering this, 5G has standardized a Grant-Free transmission method in the form of Configured Grant for dedicated and reliable low latency access. Configured Grant is highly suitable for deterministic traffic but can be a spectrally inefficient for sporadically transmitting users. On the other hand, contention or shared pool-based approaches could provide spectrally efficient grant-free access for group of sporadically transmitting users. However, users can select the same resource in the pool, and collisions can happen causing a degradation in reliability. In this thesis work, we aim to study a useful sensing design for users sending over a grant-free channel how future 6th generation networks will enable shared resources framework for allocating resources. The sensory process can help in assisting users in eliminating collisions and cutting delay. Preliminary results have shown, for certain traffic type, the sensing methods can outperform existing scheduling methods, namely dynamic and configured grant in terms of performance. This is supported by my mathematical and graphical results and thus can be considered a viable candidate for scheduling methods expansion in 6G to serve versatile traffic

Nonlinear Photocarrier Dynamics and the Role of Shallow Traps in Mixed-Halide Mixed-Cation Hybrid Perovskites

We examine the role of surface passivation on carrier trapping and nonlinear recombination dynamics in hybrid metal-halide perovskites by means of excitation correlation photoluminescence (ECPL) spectroscopy. We find that carrier trapping occurs on subnanosecond timescales in both control (unpassivated) and passivated samples, which is consistent within a shallow-trap model. However, the impact of passivation has a direct effect on both shallow and deep traps. Our results reveal that the effect of passivation of deep traps is responsible for the increase of the carrier lifetimes, while the passivation of shallow traps reduces the excitation density required for shallow-trap saturation. Our work demonstrates how ECPL provides details about the passivation of shallow traps beyond those available via conventional time-resolved photoluminescence techniques.</p