The 5G New Radio (NR) standard for wireless communications supports the millimetre-wave (mmWave) spectrum to yield unprecedented improvement of the access network capacity. However, intermittent blockages in the mmWave signal may degrade the system performance and lead to the under-utilisation of the allocated resources. To circumvent this problem, the transmission slot-time shall be adjusted according to the blockage condition, avoiding the resource under-utilisation. In this paper, we propose that the 5G NR flexible numerology should be applied to adapt the slot-time in order to mitigate the blockage effects. We validate this claim by analysing the expected data rate of a mmWave system, under a range of blockage scenarios. We show that different blockage scenarios may require different numerologies to produce best performance, and that the correct choice of numerology may improve this performance by as much as hundreds of Mbps. Our results carry insights important for the design of blockage-aware scheduling mechanisms for 5G.
The literature on blockage mitigation in mmWave communication is mostly focused on techniques that rely on spatial macro-diversity. Such techniques allow the transmitter to find an alternative physical path for the mmWave signal when the primary LOS path fails due to a blockage event. The main techniques considered are: (i) : usage of surfaces made of materials that reflect the mmWave signal to cover an obstructed spot through a NLOS path @cite_17 @cite_28 ; (ii) : forwarding the transmission to a relay node that has a LOS path with the UE @cite_19 @cite_18 ; (iii) : moving the AP location during the transmission to a position where there is a LOS path @cite_24 ; (iv) : associating the UE with multiple AP , so the UE can have a LOS path served by a backup AP @cite_9 @cite_2 .
@cite_18 @cite_28 @cite_9 @cite_24 @cite_19 @cite_2 @cite_17
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60 GHz millimeter-wave networks have emerged as a potential candidate for designing the next generation of multi-gigabit WLANs. Since the 60 GHz links suffer from frequent outages due to blockages caused by human mobility, deploying 60 GHz WLANs that can provide robust coverage in presence of blockages is a challenging problem. In this paper, we study blockage-aware coverage and deployment of 60 GHz WLANs. We first show that the reflection profile of an indoor environment can be sensed using a few measurements. A novel coverage metric (angular spread coverage) which captures the number of available paths and their spatial diversity is proposed. Additionally, it is shown that using relays can extend the coverage of the AP at a lower cost and provide added spatial diversity in the available paths. We propose a heuristic algorithm that determines the AP and relay locations while maximizing the angular spread coverage metric for the clients. Our testbed-based evaluation shows that for five different rooms, our proposed deployment can guarantee an average connectivity of 91.7 , 83.9 , and 74.1 of client locations in the presence of 1, 3 and 5 concurrent human blockages respectively, substantially increasing the robustness of 60 GHz links against blockages. Device to device (D2D) relaying and multi-beam reflection are two effective approaches to deal with the blockage problem in millimeter-wave (mmWave) communication, each with its own limitations when serving a large number of user equipments (UE). A combination of D2D relaying and multibeam reflection is expected to enhance the performance, but the selection of UEs to be served by each approache remains a challenge. In this paper, we consider adaptive mode selection between D2D relaying and multi-beam reflection in a time division duplex (TDD) mmWave network. We formulate a joint mode selection and resource sharing problem with the objective of maximizing the sum logarithm rate, and propose a two-stage solution algorithm. In the first stage, we derive the optimal resource sharing solution under the case that all UEs are served by D2D relaying. In the second stage, an adaptive algorithm is proposed to determine the set of UEs that switch from D2D relaying to multi-beam reflection. Simulation results demonstrate that the proposed scheme achieves considerable performance gain compared to several benchmark schemes. Multi-connectivity is emerging as promising solution to provide reliable communications and seamless connectivity at the millimeter-wave frequency range. Due to the obstacles that cause frequent interruptions at such high frequency range, connectivity to multiple cells can drastically increase the network performance in terms of throughput and reliability by coordination among the network elements. In this paper, we propose an algorithm for the link scheduling optimization that maximizes the network throughput for multi-connectivity in millimeter-wave cellular networks. The considered approach exploits a centralized architecture, fast link switching, proactive context preparation and data forwarding between millimeter-wave access points and the users. The proposed algorithm is able to numerically approach the global optimum and to quantify the potential gain of multi-connectivity in millimeter-wave cellular networks. Unmanned aerial vehicles (UAVs) are widely used in military due to the hostile environment and safety concern. To tackle the challenges on UAV communications, millimeter wave (MMwave) communication has been considered as a potential solution for both security and high throughput capability. However, insufficient research has been carried out for MMwave communications on drone, and no widely recognized channel model is available. In this paper, the blockage effect of MMwave communications, due to the drone propeller, is studied using hardware testbed. A scheme is proposed to predict the fast but periodic blockage and mitigates the throughput loss in such a ‘heartbeat’ channel. Millimeter-wave (mmWave) communications is one of the most promising candidate technologies for next generation cellular networks due to the global bandwidth shortage for mobile broadband access. The susceptibility of millimeter waveform propagation to blockages, however, may largely restrict the coverage of mmWave signals. To overcome blockages, we propose to leverage two-hop device-to-device (D2D) relaying. Using stochastic geometry, we develop a coverage probability model for the downlink of a relay- assisted mmWave cellular network using dominant interferer analysis, which accounts for both beamforming gains and blockages. Theoretical analysis and simulation results show that the downlink coverage of a mmWave cellular network can be improved by using two-hop D2D relay transmissions. Network softwarization is a major paradigm shift, which enables programmable and flexible system operation in challenging use cases. In the fifth-generation (5G) mobile networks, the more advanced scenarios envision transfer of high-rate mission-critical traffic. Achieving end-to-end reliability of these stringent sessions requires support from multiple radio access technologies and calls for dynamic orchestration of resources across both radio access and core network segments. Emerging 5G systems can already offer network slicing, multi-connectivity, and end-to-end quality provisioning mechanisms for critical data transfers within a single software-controlled network. Whereas these individual enablers are already in active development, a holistic perspective on how to construct a unified, service-ready system as well as understand the implications of critical traffic on serving other user sessions is not yet available. Against this background, this paper first introduces a softwarized 5G architecture for end-to-end reliability of the mission-critical traffic. Then, a mathematical framework is contributed to model the process of critical session transfers in a softwarized 5G access network, and the corresponding impact on other user sessions is quantified. Finally, a prototype hardware implementation is completed to investigate the practical effects of supporting mission-critical data in a softwarized 5G core network, as well as substantiate the key system design choices. Milimeter-wave links can provide GBit s data rates but are highly susceptible to blockage. In case a direct line-of-sight communication path becomes blocked, communication via a reﬂected path may allow to maintain connectivity. A common approach is to switch to such an alternative path whenever the ﬁrst path becomes blocked. However, this requires detecting the blockage and then reconﬁguring the transceiver to use the new path which incurs latency. For trafﬁc with strict latency or reliability requirements, or in highly dynamic environments where path switching would be frequent, using both paths concurrently can be more beneﬁcial. In this paper, we consider using multiple paths and dividing the transmission power over those paths, instead of path switching. We propose an algorithm to allocate power among the different mmWave communication paths to overcome link blockage under randomly distributed obstacles. The power allocation algorithm is based on analysis of the blockage probabilities of the direct and reﬂected paths using geometric probability, to statistically maximize the overall capacity of the path between two nodes. We evaluate the performance of the proposed algorithm via simulation for various wireless environments.