Context Information for Fast Cell Discovery in mm-wave 5G Networks

The exploitation of the mm-wave bands is one of the most promising solutions for 5G mobile radio networks. However, the use of mm-wave technologies in cellular networks is not straightforward due to mm-wave harsh propagation conditions that limit access availability. In order to overcome this obstacle, hybrid network architectures are being considered where mm-wave small cells can exploit an overlay coverage layer based on legacy technology. The additional mm-wave layer can also take advantage of a functional split between control and user plane, that allows to delegate most of the signaling functions to legacy base stations and to gather context information from users for resource optimization. However, mm-wave technology requires high gain antenna systems to compensate for high path loss and limited power, e.g., through the use of multiple antennas for high directivity. Directional transmissions must be also used for the cell discovery and synchronization process, and this can lead to a non-negligible delay due to the need to scan the cell area with multiple transmissions at different directions. In this paper, we propose to exploit the context information related to user position, provided by the separated control plane, to improve the cell discovery procedure and minimize delay. We investigate the fundamental trade-offs of the cell discovery process with directional antennas and the effects of the context information accuracy on its performance. Numerical results are provided to validate our observations.Comment: 6 pages, 8 figures, in Proceedings of European Wireless 201

Fast Cell Discovery in mm-wave 5G Networks with Context Information

The exploitation of mm-wave bands is one of the key-enabler for 5G mobile radio networks. However, the introduction of mm-wave technologies in cellular networks is not straightforward due to harsh propagation conditions that limit the mm-wave access availability. Mm-wave technologies require high-gain antenna systems to compensate for high path loss and limited power. As a consequence, directional transmissions must be used for cell discovery and synchronization processes: this can lead to a non-negligible access delay caused by the exploration of the cell area with multiple transmissions along different directions. The integration of mm-wave technologies and conventional wireless access networks with the objective of speeding up the cell search process requires new 5G network architectural solutions. Such architectures introduce a functional split between C-plane and U-plane, thereby guaranteeing the availability of a reliable signaling channel through conventional wireless technologies that provides the opportunity to collect useful context information from the network edge. In this article, we leverage the context information related to user positions to improve the directional cell discovery process. We investigate fundamental trade-offs of this process and the effects of the context information accuracy on the overall system performance. We also cope with obstacle obstructions in the cell area and propose an approach based on a geo-located context database where information gathered over time is stored to guide future searches. Analytic models and numerical results are provided to validate proposed strategies.Comment: 14 pages, submitted to IEEE Transaction on Mobile Computin

PARFAIT:Privacy-preserving, secure, and low-delay service access in fog-enabled IoT ecosystems

Traditional fog-enabled IoT ecosystems always assume fully-trusted and secure fog nodes, offering computational capabilities and storage space closer to constrained IoT devices. However, such security-related assumptions can easily fall when considering the exposure of fog nodes’ location, the heterogeneity of device providers, and the ease of misuse and misconfigurations by end-users, to name a few. As a result, compromised fog nodes can stealthily steal sensitive information, such as the devices’ location, path, and private personal attributes. This paper presents PARFAIT, a privacy-preserving, secure, and low-delay framework for securely accessing services in fog-enabled IoT ecosystems. PARFAITguarantees low-delay authentication and authorization to local fog nodes, protecting the identity and the attributes possessed by the IoT devices. Moreover, PARFAITuses rolling ephemeral identities, providing unlinkability among access requests, thus preventing the tracking of mobile IoT devices by multiple compromised fog nodes. We performed several experimental tests on a reference proof-of-concept to show the viability of PARFAIT. Specifically, adopting an elliptic curve with a group size of 512 bits, PARFAITallows the access to a single protected resource in only 0.274 s, and such a delay rises to only 0.359 s with 10 consecutive requests (66.8% less than the quickest competing approach).</p

GABA_A-mediated synaptic activity in rat hippocampal neurones <i>in vitro</i> and its modulation by other neurotransmitters and second messengers.

The patch-clamp technique (whole-cell and outside-out configurations) has been used to characterize spontaneous ɣ-aminobutyric acid A (GABAA) receptor mediated currents in pyramidal cells of thin hippocampal slices obtained from neonatal rats. In early postnatal life, GABA is the main excitatory neurotransmitter on hippocampal pyramidal cells. The frequency distribution histogram of spontaneous GABAergic currents could be fitted by a single exponential function revealing the random nature of these events. The present results demonstrate that in tetrodotoxin (TTX) solution spontaneous GABAA receptor mediated miniature postsynaptic currents (mPSCs) were present. At -70 mV the first peak in the current amplitude distribution was 16 ± 6 pA (n =13). This value was similar to that found for GABAergic currents (14 ± 6 pA) elicited by low intensity extracellular stimulation, suggesting that this effect was due to the release of elementary units of GABA. In outside-out patches, GABA activated single-channel events of 24 and 35 pS conductance. Assuming that a postsynaptic current of 15 pA corresponds to a single quantum of GABA, one could calculate that one quantal current represents the simultaneous opening of 6 to 9 GABAA receptor channels in the postsynaptic cell. The metabotropic Glutamate Receptor (mGluR) agonist, 1 -aminocyclopentane-1,3-dicarboxylic acid (t-ACPD), induced an increase in frequency but not in amplitude of spontaneously occurring GABAergic currents; this potentiating effect was blocked by the Protein Kinase A (PKA) antagonist Rp-adenosine 3', 5'-cyclic monophosphotioate triethylamine (Rp-cAMPS), suggesting that glutamate, acting on mGluRs, is able to increase GABA release through the metabolic pathway which involves PKA. The potentiating effect of t-ACPD was not observed in TTX solution indicating that the site of action of the mGluR agonist is probably located at the somatodendritic level and not on the nerve terminals ofGABAergic intemeurones. In the presence of forskolin, which increases intracellular cyclic AMP (cAMP) levels, a rise in frequency but not in amplitude of miniature GABAA receptor mediated currents was observed, an effect that was prevented by the selective PKA antagonist Rp-cAMPS. These experiments suggest that presynaptic mGluRs localized on GABAergic interneurones may facilitate the activity of these cells and their release of GABA through cAMP-dependent PKA. Moreover, PKA may interfere directly with the mechanism of GABA release as demonstrated by its action on miniature events. The present results provide new evidence that the release of a major neurotransmitter such as GABA is up-regulated by another neurotransmitter namely Glutamate, thus demonstrating an important reinforcement of excitatory signals during an early stage of brain development