Spatial Reuse Research Articles

Distributed Wideband Sensing-Based Architecture for Unlicensed Massive IoT Communications

Providing Internet connectivity to a massive number of Internet-of-Things (IoT) objects over the unlicensed spectrum requires: 1) identifying a very large number of narrowband channels in a wideband spectrum and 2) aggressively reusing the available channels over space to accommodate the high density of IoT devices. To this end, we propose a sensing-based architecture that identifies spectral and spatial resources at a fine resolution. In particular, we first propose a sensing assignment scheduler, where each base station (BS) is assigned a subset of the spectrum to sense at a high resolution. We then propose a distributed sensing algorithm, where BSs locally process and share their sensing reports, so that each BS obtains occupancy information of the wideband spectrum at its location. Once the spatio-spectral resource blocks are identified, we further propose a distributed resource allocation algorithm that maintains high spatial reuse of spectral opportunities while limiting the intra-network and inter-network interference. Numerical simulations are presented to validate the effectiveness of the proposed distributed algorithms, comparing them to centralized and non-cooperative schemes. It is shown that our architecture identifies more spatio-spectral resources, with lower misdetection of incumbents. As a result, more IoT devices are connected with limited interference into incumbents.

Enabling a “Use-or-Share” Framework for PAL–GAA Sharing in CBRS Networks via Reinforcement Learning

By implementing reinforcement learning-aided listen-before-talk (LBT) schemes over a citizens broadband radio service (CBRS) network, we increase the spatial reuse at secondary nodes while minimizing the interference footprint on higher-tier nodes. The federal communications commission encourages “use-or-share” policies in the CBRS band across the priority access license (PAL)–general authorized access (GAA) priority tiers by opportunistically allowing the lower-priority GAA nodes to access unused higher-priority PAL spectrum. However, there is currently no mechanism to enable this cross-tier spectrum sharing. In this paper, we propose and evaluate LBT schemes that allow opportunistic access to PAL spectrum. We find that by allowing LBT in a two carrier, two eNB scenario, we see upward of 50% user perceived throughput (UPT) gains for both eNBs. Furthermore, we examine the use of ${Q}$ -learning to adapt the energy-detection threshold (EDT), combating problematic topologies, such as hidden and exposed nodes. With merely a 4% reduction in primary node UPT, we see up to 350% gains in average secondary node UPT when adapting the EDT of opportunistically transmitting nodes.

Proposal of a hierarchical topology and spatial reuse superframe for enhancing throughput of a cluster‐based WBAN

Proposal of a hierarchical topology and spatial reuse superframe for enhancing throughput of a cluster‐based WBAN

Congestion control vs. link failure: TCP behavior in mmWave connected vehicular networks

The millimeter-wave (mmWave) frequency band presents a viable communication platform for the exchange of large amount of data and communications of Connected Vehicular Networks (CVNs). Its ability to support multi-gigabit data rates and high spatial reuse is especially crucial because of the large volume of data produced by physical entity each second. However, its susceptibility the deafness problem, blockages, and beam misalignment is a major impediment, especially in highly mobile environment such as CVNs. Especially, CVNs are related to the life of human being, network reliability is one of the most important issue. To resolve this problem, recent studies on mmWaves have focused more on the PHY/MAC Layers, while fewer studies have examined the transport layer. In this paper, we examine the performance of TCP in mmWave based vehicular networks, focusing particularly on the effects of congestion and link failure. In addition, we highlight the problems of using conventional TCP in an mmWave CVNs and propose an real-time wireless TCP (RTW-TCP) implementation such mmWave environment. Finally, we compare the performance of the proposed RTW-TCP and conventional TCP. The simulation results show that the proposed scheme maximizes the total network resources by distinguishing link failure from network congestion in an mmWave CVNs.

Damysus: A Practical IEEE 802.11ax BSS Color Aware Rate Control Algorithm

Institute of Electrical and Electronics Engineers (IEEE) 802.11ax Spatial Reuse (SR) is a new feature in the IEEE 802.11 family, aiming at improving the spectrum efficiency and the network performance in dense deployments. The main and perhaps the only SR technique in that amendment is the Basic Service Set (BSS) Color. It aims at increasing the number of concurrent transmissions in a specific area, based on a newly defined Overlapping BSS/Preamble-Detection threshold. In this paper, we overview the latest developments introduced in the IEEE 802.11ax for the SR and propose a rate control algorithm developed to exploit the BSS Color scheme. Our proposed algorithm, Damysus is specifically designed to function in dense environments where other off-the-shelf algorithms show poor performance. Simulation results in various dense scenarios, show a clear performance improvement of up to 113% gain in throughput over the well known MinstrelHT algorithm.

3D Spatial Characteristics of C-V2X Communication Interference

In C-V2X (cellular vehicle-to-everything) communication networks, dense spatial reuse of the available radio spectrum is required to achieve efficient spectral usage. Spectrum reuse causes severe network interference where signals from many undesired transmitters are aggregated at a receiver. This paper investigates the 3D spatial characteristics of C-V2X communication interference in the angular domain. A 3D GIDM (Gaussian interference distribution model) is proposed, and the corresponding interference APD (angular power density) is given. Then, the closed-form expressions of some key spatial statistics of interference are derived based on the interference APD. Finally, the closed-form expressions of the probability density function and spatial correlation function of SIR (signal–to–interference ratio) are derived based on the 3D multipath APD model and spatial statistics of the Rice channel. Simulation analysis shows that 3D spatial angular directions have significant effect on these spatial statistics of interference and the spatial correlation function of SIR. The results provide useful insight on the analysis and design of the interference-limited networks.

Aportes a la Arqueología reduccional. El caso de Nuestra Señora de Ibitiracuá (Concepción de la Sierra, Misiones, Argentina)

A partir de los primeros trabajos arqueológicos que se vienen realizando en el casco histórico de la localidad de Concepción de la Sierra (provincia de Misiones, Argentina), antiguo emplazamiento de la reducción jesuítica-guaraní Nuestra Señora de Ibitiracuá, y el análisis preliminar de los materiales recuperados en distintos sondeos, se discuten los datos obtenidos en relación a antecedentes regionales para momentos pre y post-hispánicos. Se plantea el análisis de los atributos formales de las evidencias recuperadas en estas primeras intervenciones con el objetivo de identificar las características presentes en los materiales que se preservaron bajo la superficie, a pesar del alto dinamismo y disturbación del contexto arqueológico. Los resultados hasta ahora obtenidos avalan por un lado, la periodicidad de diferentes momentos históricos y por otro, la continuidad en determinados estilos cerámicos que se observa para tiempos prehispánicos. Por último, se discute el alto grado de reutilización espacial y material, como así también el rol de nuestra disciplina en torno a un patrimonio vivo y dinámico amenazado por la creciente urbanización.

IEEE 802.11ax Spatial Reuse Improvement: An Interference-Based Channel-Access Algorithm

Wi-Fi is the dominant way of connecting indoor mobile devices to the Internet. The main reason behind the huge adoption of this technology is the simplicity of the IEEE 802.11 protocols, which offer low-cost ownership and maintenance combined with the ability to provide high data rates to end users. The increasing demand in traffic volumes leads to the continuous deployment of access points (APs), resulting in densification of the IEEE 802.11 networks. This densification, instead of enhancing the efficiency of wireless local area networks (WLANs), degrades their overall performance due to cochannel interference between overlapped basic services sets (OBSSs). One of the main goals of the IEEE 802.11ax amendment now under development is to address the WLAN densification problem by improving spatial reuse (SR).

Analytical Investigation of Two Benchmark Resource Allocation Algorithms for LTE-V2V

Short-range wireless technologies will enable vehicles to communicate and coordinate their actions, thus improving people's safety and traffic efficiency. Whereas IEEE 802.11p (and related standards) had been the only practical solution for years, in 2016 a new option was introduced with Release of 14 long-term evolution (LTE), which includes new features to enable direct vehicle-to-vehicle (V2V) communications. LTE-V2V promises a more efficient use of the channel compared to IEEE 802.11p, thanks to an improved PHY layer and the use of orthogonal resources at the MAC layer. In LTE-V2V, a key role is played by the resource allocation algorithm and increasing efforts are being made to design new solutions to optimize the spatial reuse. In this context, an important aspect still little studied, is therefore that of identifying references that allow, first, to have a perception of the space in which the resource allocation algorithms move and, second, to verify the performance of new proposals. In this paper, we focus on a highway scenario and identify two algorithms to be used as a minimum and maximum reference in terms of the packet reception probability (PRP). The PRP is derived as a function of various parameters that describe the scenario and settings, from the application to the physical layer. Results, obtained both in a simplified Poisson point process scenario and with realistic traffic traces, show that the PRP varies considerably with different algorithms and that there is room for the improvement of current solutions.

Joint User-AP Association and Resource Allocation in Multi-AP 60-GHz WLAN

The advancement of integrated millimeter-wave products opens the possibility of leveraging communications in 60-GHz band to meet the unprecedented traffic demand in WLAN. Despite the vast bandwidth available, millimeter-wave signals suffer from high attenuation and weak diffraction ability. Therefore, wireless communication at 60 GHz is characterized by the inherent directivity and susceptibility to blockage. Multiple Access Point (AP) architecture is proposed for 60-GHz WLAN to enhance spatial reuse and survive blockage. In the presence of multiple APs in the network, this paper addresses the important problem of user-AP association and resource allocation. We study three schemes of different complexity and investigate how to maximize user throughput with joint consideration of AP assignment and transmission scheduling. To solve the formulated problem, we propose a branch-and-cut-based solution procedure. We perform a detailed comparative analysis of the three schemes and advocate to use one-shot AP assignment-based scheduling scheme due to its simplicity and good performance. To deal with real-time traffic and human blockage, we propose an online algorithm to implement the one-shot AP assignment-based scheme to avoid frequent service disruption. Our results show that the proposed online algorithm is competitive when compared with the optimal offline algorithm.

On Performance Evaluation of Dynamic Sensitivity Control Techniques in Next-Generation WLANs

Dynamically adapting carrier sensing range, also known as dynamic sensitivity control (DSC), could be an attractive proposition for improving the spatial reuse in dense wireless local area networks. This paper shows the promise and pitfalls of a DSC technique proposed in the IEEE 802.11ax standard and highlights a solution to mitigate these issues. An analytical framework is also presented for the performance evaluation of DSC techniques.

Concurrent Transmission Scheduling for Perceptual Data Sharing in mmWave Vehicular Networks

Sharing perceptual data with other vehicles enhances the traffic safety of autonomous vehicles because it helps vehicles locate other vehicles and pedestrians in their blind spots. Such safety applications require high throughput and short delay, which cannot be achieved by conventional microwave vehicular communication systems. Therefore, millimeter-wave (mmWave) communications are considered to be a key technology for sharing perceptual data because of their wide bandwidth. One of the challenges of data sharing in mmWave communications is broadcasting because narrow-beam directional antennas are used to obtain high gain. Because many vehicles should share their perceptual data to others within a short time frame in order to enlarge the areas that can be perceived based on shared perceptual data, an efficient scheduling for concurrent transmission that improves spatial reuse is required for perceptual data sharing. This paper proposes a data sharing algorithm that employs a graph-based concurrent transmission scheduling. The proposed algorithm realizes concurrent transmission to improve spatial reuse by designing a rule that is utilized to determine if the two pairs of transmitters and receivers interfere with each other by considering the radio propagation characteristics of narrow-beam antennas. A prioritization method that considers the geographical information in perceptual data is also designed to enlarge perceivable areas in situations where data sharing time is limited and not all data can be shared. Simulation results demonstrate that the proposed algorithm doubles the area of the cooperatively perceivable region compared with a conventional algorithm that does not consider mmWave communications because the proposed algorithm achieves high-throughput transmission by improving spatial reuse. The prioritization also enlarges the perceivable region by a maximum of 20%.

Throughput Maximization using Spatial Reusability in Multi Hop Wireless Network

Throughput Maximization using Spatial Reusability in Multi Hop Wireless Network

Adaptive Resource Allocation for WiMAX Mesh Network

Worldwide Interoperability for Microwave Access is a technology used to enable fast and cost-effective network deployment as well as facilitating multimedia based services and applications available to the users. However, Interference constitutes a major constraint in the widespread use of shared resources for interaction among devices. In this paper, a greedy resource allocation mechanism, which consists of Learning Automata based Greedy Channel Assignment and Learning Automata based Greedy Centralized Scheduling algorithms, is presented to cope with interference as well as to improve spatial reuse in the resource allocation mechanism. Finally, the simulation results demonstrate that our proposed algorithms outperform existing approaches.

Target Wake Time: Scheduled Access in IEEE 802.11ax WLANs

The increasing interest in ubiquitous networking, and the tremendous popularity gained by IEEE 802.11 WLANs in recent years, is leading to very dense deployments where high levels of channel contention may prevent meeting the increasing user demands. To mitigate the negative effects of channel contention, the TWT mechanism included in the IEEE 802.11ax amendment can have a significant role, as it provides an extremely simple but effective mechanism to schedule transmissions in time. Moreover, in addition to reducing the contention between stations, the use of TWT may also contribute to taking full advantage of other novel mechanisms in the IEEE 802.11 universe, such as multiuser transmissions, multi-AP cooperation, spatial reuse and coexistence in high-density WLAN scenarios. Overall, we believe TWT may be a first step toward a practical collision-free and deterministic access in future WLANs.

Collaborative Spatial Reuse in wireless networks via selfish Multi-Armed Bandits

Next-generation wireless deployments are characterized by being dense and uncoordinated, which often leads to inefficient use of resources and poor performance. To solve this, we envision the utilization of completely decentralized mechanisms to enable Spatial Reuse (SR). In particular, we focus on dynamic channel selection and Transmission Power Control (TPC). We rely on Reinforcement Learning (RL), and more specifically on Multi-Armed Bandits (MABs), to allow networks to learn their best configuration. In this work, we study the exploration-exploitation trade-off by means of the ε-greedy, EXP3, UCB and Thompson sampling action-selection, and compare their performance. In addition, we study the implications of selecting actions simultaneously in an adversarial setting (i.e., concurrently), and compare it with a sequential approach. Our results show that optimal proportional fairness can be achieved, even when no information about neighboring networks is available to the learners and Wireless Networks (WNs) operate selfishly. However, there is high temporal variability in the throughput experienced by the individual networks, especially for ε-greedy and EXP3. These strategies, contrary to UCB and Thompson sampling, base their operation on the absolute experienced reward, rather than on its distribution. We identify the cause of this variability to be the adversarial setting of our setup in which the set of most played actions provide intermittent good/poor performance depending on the neighboring decisions. We also show that learning sequentially, even if using a selfish strategy, contributes to minimize this variability. The sequential approach is therefore shown to effectively deal with the challenges posed by the adversarial settings that are typically found in decentralized WNs.

Interference Hypergraph-Based Resource Allocation (IHG-RA) for NOMA-Integrated V2X Networks

Vehicular communication network is a core application scenario in the fifth generation (5G) mobile communication system which requires ultrahigh data rate and ultralow latency. Most recently, nonorthogonal multiple access (NOMA) has been regarded as a promising technique for future 5G systems due to its capability in significantly improving the spectral efficiency and reducing the data transmission latency. In this paper, we propose to introduce NOMA in device-to-device-enhanced vehicle-to-everything (V2X) networks, where resource sharing based on spatial reuse for different V2X communications are permitted through centralized resource management. Considering the complicated interference scenario caused by NOMA and spatial reuse-based resource sharing in the investigated NOMA-integrated V2X (NOMA-V2X) networks, we construct an interference hypergraph (IHG) to model the interference relationships among different communication groups. In addition, based on the constructed IHG, we further propose an IHG-based resource allocation (IHG-RA) scheme with cluster coloring algorithm, which can lead to both effective and efficient resource block assignment with low computational complexity. Simulation results verify the efficiency of our proposed IHG-RA scheme for NOMA-V2X communications in improving the network sum rate.

High-efficiency WLANs for dense deployment scenarios

In this article, we review the latest technical attributes such as orthogonal frequency division multiple access (OFDMA), multi-user MIMO (MU-MIMO) and enhanced clear channel assessment (CCA) for better spatial reuse used in the 802.11ax amendment to the 802.11 standard that leads to PHY and MAC enhancements for high-density scenarios of access points (APs). IEEE 802.11ax, also referred to as high-efficiency wireless local area network (WLAN) (HEW), provides mechanisms to thoroughly utilize the unlicensed spectrum bands (2.4 and 5 GHz) and strengthen the user experience. The functional requirements of HEW are stressed on interactive video transmission latency and access efficiency to meet quality of service (QoS) requirements. Finally, we investigate three configurations—MU-MIMO, OFDMA and combination of both or mixed mode—for 4-user AP transmission schemes in 802.11ax. The performance of the MU schemes varies with packet size and operating SNR. OFDMA is more efficient than MU-MIMO at low SNRs for all packet sizes, which means 5th percentile stations (STAs) can get desired throughput.

PCS Threshold Selection for Spatial Reuse in High Density CSMA/CA MIMO Wireless Networks

Multiple-input multiple-out (MIMO) equipment improves the spectral efficiency of wireless local area network (WLAN) systems. However, in a large-scale or dense MIMO WLANs, overlapping radio cells or basic service sets (BSSs) are inherent. This prevents multiple concurrent transmissions and degrades spatial reuse. The inability to separate multiple simultaneous transmissions in space is detrimental to overall system performance. The carrier sense multiple access collision avoidance (CSMA/CA) protocol uses the physical carrier sensing (PCS) threshold to determine channel state at the physical layer (PHY) and decide on the number of concurrent transmissions allowed per time slot. Since the PCS threshold determines the spatial reuse under the CSMA/CA protocol, which consequently determines the interference level and the network aggregate throughput, we address PCS threshold selection for dense uplink (UL) MIMO WLAN systems. A closed-form expression is derived for selecting the PCS threshold based on the fundamental parameters of the network where nodes are randomly placed according to a Poisson point process (PPP). We obtain the PCS threshold value that maximizes the spatial density of throughput (SDT) and study the effectiveness of the proposed framework under moderate to high node density. In addition, we analyze the effect of WLAN density on interference from concurrent transmitters. The key observation is that PCS threshold selection should take into account key network characteristics including node density, target SINR or threshold, path-loss exponent and antenna configuration.

Interference Hypergraph-Based 3D Matching Resource Allocation Protocol for NOMA-V2X Networks

Vehicle-to-everything (V2X) communications are regarded as the key technology in future vehicular networks due to its ability in providing efficient and reliable massive connections, improving traffic efficiency and safety, and supporting in-vehicle entertainment and working. Recently, non-orthogonal multiple access (NOMA), as a promising solution in the fifth-generation (5G) mobile communication systems, has drawn much attention because it can significantly improve the network throughput and lower the accessing and transmission latency to meet the quality-of-service (QoS) requirements of many 5G-enabled applications. Noticing these, in this paper, we consider a device-to-device (D2D)-enhanced V2X network, in which NOMA is introduced to increase the capacity. In our studied NOMA-V2X system, except for the NOMA-based intra-group resource reuse, the D2D-enabled resource sharing based on spatial reuse among all the V2X communication groups is also permitted through centralized resource management, leading to a significantly improved network performance but a more complicated and challenging interference scenario. In order to efficiently manage the interference and allocate the resource in the NOMA-V2X network, we create a weighted 3-partite interference hypergraph (IHG) to imitate the complex interference environment in our studied scenario. Then, with the help of this hypergraph, we make another step to put forward an IHG-based 3-dimensional matching (IHG-3DM) resource allocation protocol with a greedy 3DM algorithm and an iterative 3DM algorithm. As a consequence, the network throughput is significantly improved with the help of our proposed IHG-3DM resource allocation protocol for the investigated NOMA-integrated V2X communications, which is verified by the simulation results.