Long Bao Le

• PhD
• Full Professor at National Institute of Scientific Research

Many practical Internet of Things (IoT) applications require deploying End Nodes (ENs) in hard-to-access places where replacing batteries is difficult or impossible. As a result, the ENs demand high energy efficiency. Long Range Wide Area Network (LoRaWAN) is an IoT protocol that aims to achieve low energy consumption. However, the energy consumpti...

LoRaWAN is a widespread protocol by which Internet of things end nodes (ENs) can exchange information over long distances via their gateways. To deploy the ENs, it is mandatory to perform a link budget analysis, which allows for determining adequate radio parameters like path loss (PL). Thus, designers use PL models developed based on theoretical a...

In this work, we study the joint optimization of multiple unmanned aerial vehicles (UAVs)’ trajectories, power allocation, user-UAV association, and user pairing for UAV-assisted wireless networks employing the nonorthogonal multiple access (NOMA) for uplink communications. The design aims to minimize the total energy consumption of ground users wh...

Mobile edge caching, which exploits the content popularity information, can lead to significant reduction in network congestion and operation cost. However, designing an efficient cache update mechanism is challenging because imperfect prediction of time-varying content popularity and several cost factors such as cache update and backhaul costs mus...

Most existing designs for UAV-based wireless networks consider individual service periods; therefore, they may not efficiently utilize the UAV energy and radio resources to serve users with complex data transmission requirements over consecutive service periods. To address this limitation, we propose a novel persistent design framework where UAV tr...

We design an unmanned aerial vehicle (UAV) based wireless network with wireless access and backhaul links leveraging an intelligent reflecting surface (IRS). This design aims to maximize the sum rate achieved by ground users (GUs) through optimizing the UAV placement, IRS phase shifts, and sub-channel assignments considering the wireless backhaul c...

In this paper, we study the trajectory control, sub-channel assignment, and user association design for unmanned aerial vehicles (UAVs)-based wireless networks. We propose a method to optimize the max-min average rate subject to data demand constraints of ground users (GUs) where spectrum reuse and co-channel interference management are considered....

We are delighted to introduce the readers to this special Section of the IEEE TRANSACTIONS ON COGNITIVE COMMUNICATIONS AND NETWORKING (TCCN), which aims at soliciting the original research and practical contributions on novel architectures, applications, and technologies of the convergence of Collaborative Distributed Machine Learning (CD-ML) and e...

In this paper, we study the resource allocation and trajectory optimization for multi-UAV based wireless networks. Our design maximizes the number of admitted users while satisfying their data transmission demands, which formulates a mixed-integer nonlinear problem. To tackle its difficulty, we first introduce soft admission variables and propose a...

Intelligent signal processing for wireless communications is a vital task in modern wireless systems, but it faces new challenges because of network heterogeneity, diverse service requirements, a massive number of connections, and various radio characteristics. Owing to recent advancements in big data and computing technologies, artificial intellig...

Mobile edge computing (MEC) has been envisioned as a promising paradigm to handle the massive volume of data generated from ubiquitous mobile devices for enabling intelligent services with the help of artificial intelligence (AI). Traditionally, AI techniques often require centralized data collection and training in a single entity, e.g., an MEC se...

Mobile edge computing (MEC) has been envisioned as a promising paradigm to handle the massive volume of data generated from ubiquitous mobile devices for enabling intelligent services with the help of artificial intelligence (AI). Traditionally, AI techniques often require centralized data collection and training in a single entity, e.g., an MEC se...

With the help of inter-vehicle communication (IVC), autonomous vehicles (AVs) can drive cooperatively, thus significantly improve road safety, traffic efficiency, and environmental sustainability. While substantial research has been conducted to investigate the efficiency of AVs in transportation systems, few attempts have been carried out to explo...

The next generation of networks will need to support massive requests for services that have very stringent performance requirements, and their delivery involves significant computing and storage resources. Prominent examples are the mobile augmented and virtual reality services, processing of large-scale IoT data, and mobile data analytics. In ord...

Intelligent signal processing for wireless communications is a vital task in modern wireless systems, but it faces new challenges because of network heterogeneity, diverse service requirements, a massive number of connections, and various radio characteristics. Owing to recent advancements in big data and computing technologies, artificial intellig...

Driven by the emergence of new compute-intensive applications and the vision of the Internet of Things (IoT), it is foreseen that the emerging 5G network will face an unprecedented increase in traffic volume and computation demands. However, end users mostly have limited storage capacities and finite processing capabilities, thus how to run compute...

Network slicing provides great opportunities for network service providers (SPs) to scale up and achieve higher revenue by enabling fast and efficient creation of new services and customizable networks for enterprises and user equipment (UEs). This can only be achieved at the expense of more complicated radio resource management and service/trading...

In this paper, we propose the joint interference cancellation, fast fading channel estimation, and data symbol detection for a general interference setting where the interfering source and the interfered receiver are unsynchronized and occupy overlapping channels of different bandwidths. The interference must be canceled before the channel estimati...

Network function Virtualization (NFV) and Mobile Edge Computing (MEC) are promising 5G technologies to support resource-demanding mobile applications. In NFV, one must process the service function chain (SFC) in which a set of network functions must be executed in a specific order. Moreover, the MEC technology enables computation offloading of serv...

This letter studies the admission control and network slicing design for 5G New Radio (5G-NR) systems in which the total bandwidth is sliced to support the enhanced mobile broadband (eMBB) and ultra reliable and low latency communication (URLLC) services. We allow traffic from the eMBB bandwidth part to be overflowed to the URLLC bandwidth part in...

The fifth-generation wireless network (5G) is expected to support vehicle to infrastructure (V2I) communication which requires an accurate understanding of its highly mobile and dynamic propagation environment for efficient physical layer design. Towards this end, this paper proposes a joint design of adaptive channel prediction, beamforming, and s...

With the help of inter-vehicle communication (IVC), autonomous vehicles (AVs) can drive cooperatively, thus significantly improve road safety, traffic efficiency and the environmental sustainability. While substantial research has been conducted to investigate the efficiency of AVs in traffic systems, few attempt has been carried out to explore the...

In this paper, we propose the joint channel estimation, interference cancellation, and data symbol detection for unsynchronized communications of different bandwidths over overlapping channels. To this end, we have to estimate the Effective Interference Coefficients (EICs) and the desired channel coefficients. We construct a two-phase framework whe...

We study the mobility-aware computation offloading design for mobile edge computing (MEC) based vehicular wireless networks which considers random mobility of the vehicle and its potential handover during the offloading process. The computation offloading decision is made by comparing the average total costs due to the local and remote computation...

This letter studies the scheduling problem which determines how time-frequency resources of different numerologies can be allocated to support heterogeneous services in 5G wireless systems. Particularly, this problem aims at scheduling as many users as possible while meeting their required service delay and transmission data. To solve the underlyin...

Under the connected vehicle environment, autonomous vehicles (AVs) could bring numerous advantages including: improving the traffic flow, enhancing safety and alleviating air pollution. However, optimally operating AVs at signalized multi-lane intersections is a challenging problem due to the complex interaction of vehicles between lanes. It is thu...

Data compression (DC) has the potential to significantly improve the computation offloading performance in hierarchical fog-cloud systems. However, it remains unknown how to optimally determine the compression ratio jointly with the computation offloading decisions and the resource allocation. This optimization problem is studied in this paper wher...

This paper proposes a novel joint channel estimation and beamforming approach for multicell wideband massive multiple input multiple output (MIMO) systems. With the proposed channel estimation and beamforming approach, we determine the number of cells $N_{c}$ that can utilize the same time and frequency resource while mitigating the effect of pil...

5G wireless systems will extend mobile communication services beyond mobile telephony, mobile broadband, and massive machine-type communication into new application domains, namely the so-called vertical domains including the smart factory, smart vehicles, smart grid, smart city, etc. Supporting these vertical domains comes with demanding requireme...

In this paper, we jointly optimize computation offloading and resource allocation to minimize the weighted sum of energy consumption of all mobile users in a backhaul limited cooperative MEC system with multiple fog servers. Considering the partial offloading strategy and TDMA transmission at each base station, the underlying optimization problem w...

Driven by the emergence of new compute-intensive applications and the vision of IoT, the 5G network will face an unprecedented increase in traffic volume and computation demands. However, end users mostly have limited storage capacities and finite processing capabilities, thus how to run compute-intensive applications on resource-constrained users...

Fog computing is transforming the network edge into an intelligent platform by bringing storage, computing, control, and networking functions closer to end users, things, and sensors. How to allocate multiple resource types (e.g., CPU, memory, bandwidth) of capacity-limited heterogeneous fog nodes to competing services with diverse requirements and...

More network operators have recently provided CDN (Content Delivery Network) services where traffic engineering techniques such as the BS association are jointly employed with content delivery. This deployment attempts to reduce the network operating cost and enhance the QoS (Quality of Service) of end users. Toward this end, we study the base stat...

Data compression has the potential to significantly improve the computation offloading performance in hierarchical fog-cloud systems. However, it remains unknown how to optimally determine the compression ratio jointly with the computation offloading decisions and the resource allocation. This joint optimization problem is studied in the current pa...

Considered as a key technology in 5G networks, mobile edge computing (MEC) can support intensive computation for energy-constrained and computation-limited mobile users (MUs) through offloading various computation and service functions to the edge of mobile networks. In addition to MEC, wireless heterogeneous networks (HetNets) will play an importa...

Intelligent offloading of computation-intensive tasks to a mobile cloud server provides an effective mean to expand the usability of wireless devices and prolong their battery life, especially for low-cost internet-of-things (IoT) devices. However, realization of this technology in multiple-input multiple-output (MIMO) systems requires sophisticate...

In wireless network virtualization, guaranteeing service contracts with different mobile virtual network operators (MVNOs) and optimizing energy efficiency are crucial for the success of the virtualization scheme deployed by an infrastructure provider (InP). In this paper, a novel design framework is proposed for resource allocation in an OFDMA vir...

Fog computing is transforming the network edge into an intelligent platform by bringing storage, computing, control, and networking functions closer to end-users, things, and sensors. How to allocate multiple resource types (e.g., CPU, memory, bandwidth) of capacity-limited heterogeneous fog nodes to competing services with diverse requirements and...

This paper studies the caching problem for heterogeneous small-cell networks with bandwidth allocation and caching-aware base station (BS) association. The caching control and bandwidth allocation problem aims at minimizing the request miss ratio. To solve this problem, we propose a Line-Search-based-Iterative (LSBI) algorithm which determines the...

The emerging edge computing paradigm promises to deliver superior user experience and enable a wide range of Internet of Things (IoT) applications. In this paper, we propose a new market-based framework for efficiently allocating resources of heterogeneous capacity-limited edge nodes (EN) to multiple competing services at the network edge. By prope...

The emerging edge computing paradigm promises to deliver superior user experience and enable a wide range of Internet of Things (IoT) applications. In this work, we propose a new market-based framework for efficiently allocating resources of heterogeneous capacity-limited edge nodes (EN) to multiple competing services at the network edge. By proper...

This paper presents a mathematical model for the energy bidding problem of a virtual power plant (VPP) that participates in the regular electricity market and the intraday demand response exchange (DRX) market. Different system uncertainties due to the intermittent renewable energy sources, retail customers' demand and electricity prices are consid...

Many current deregulated markets allow multiple wind power producers (WPPs) to jointly offer energy in the short term electricity market via an external agent such as a wind power aggregator. This paper proposes a budget balanced, fair, and stable framework to share the profit due to the joint wind energy offering, which is modeled as a core select...

Most existing content caching designs require accurate estimation of content popularity, which can be challenging in the dynamic mobile network environment. Moreover, emerging hierarchical network architecture enables us to enhance the content caching performance by opportunistically exploiting both cloud-centric and edge-centric caching. In this p...

Efficient content caching plays a crucial role in quality of service (QoS) enhancement and congestion mitigation of the backhaul and core networks for the fifth-generation (5G) wireless network, which must support a large amount of multimedia and video content. Wireless network virtualization (WNV) provides a novel paradigm shift in 5G system desig...

This paper proposes a novel approach for designing channel estimation, beamforming and scheduling jointly for wideband massive multiple input multiple output (MIMO) systems. With the proposed approach, we first quantify the maximum number of user equipments (UEs) that can send pilots which may or may not be orthogonal. Specifically, when the channe...

This paper proposes a novel approach for designing channel estimation, beamforming and scheduling jointly for wideband massive multiple input multiple output (MIMO) systems. With the proposed approach, we first quantify the maximum number of user equipments (UEs) that can send pilots which may or may not be orthogonal. Specifically, when the channe...

The next generation wireless networks (i.e. 5G and beyond), which would be extremely dynamic and complex due to the ultra-dense deployment of heterogeneous networks (HetNets), poses many critical challenges for network planning, operation, management and troubleshooting. At the same time, generation and consumption of wireless data are becoming inc...

In this paper, we study the joint computation offloading and resource allocation problem in the two-tier wireless heterogeneous network (HetNet). Our design aims to optimize the computation offloading to the cloud jointly with the subchannel allocation to minimize the maximum (min-max) weighted energy consumption subject to practical constraints on...

Full-Duplex (FD) wireless technology enables a radio to transmit and receive on the same frequency band at the same time, and it is considered to be one of the candidate technologies for the fifth generation (5G) and beyond wireless communication systems due to its advantages including potential doubling of the capacity and increased spectrum utili...

In this paper, we study the joint prioritized link scheduling and resource allocation for OFDMA-based wireless networks which serve two classes of wireless links, namely nonprioritized (low-priority) and prioritized (high-priority) links. Our design aims to maximize the number of scheduled nonprioritized links and their sum rate while guaranteeing...

Hybrid analog/digital precoding architectures are a low-complexity alternative for fully-digital precoding in millimeter-wave (mmWave) MIMO wireless systems. This is motivated by the reduction in the number of radio frequency and mixed signal hardware components. Hybrid precoding involves a combination of analog and digital processing that enable b...

We consider the resource allocation for the virtualized OFDMA uplink Cloud Radio Access Network (CRAN) where multiple wireless operators (OPs) share the CRAN infrastructure and resources owned by an infrastructure provider (InP). The resource allocation is designed through studying tightly coupled problems at two different levels. The upper-level p...

This paper proposes a novel joint channel estimation and beamforming approach for multicell wideband massive multiple input multiple output (MIMO) systems. With the proposed channel estimation and beamforming approach, we determine the number of cells $N_c$ that can utilize the same time and frequency resource while mitigating the effect of pilot c...

One of the important use-cases of 5G network is the vehicle to infrastructure (V2I) communication which requires accurate understanding about its dynamic propagation environment. As 5G base stations (BSs) tend to have multiple antennas, they will likely employ beamforming to steer their radiation pattern to the desired vehicle equipment (VE). Furth...

Do you need to design efficient wireless communications systems? This unique text provides detailed coverage of radio resource allocation problems in wireless networks and the techniques that can be used to solve them. Covering basic principles and mathematical algorithms, and with a particular focus on power control and channel allocation, you wil...

One of the important use-cases of 5G network is the vehicle to infrastructure (V2I) communication which requires accurate understanding about its dynamic propagation environment. As 5G base stations (BSs) tend to have multiple antennas, they will likely employ beamforming to steer their radiation pattern to the desired vehicle equipment (VE). Furth...

We propose a wireless virtualization framework based on the Stackelberg game model for resource allocation in downlink orthogonal frequency division multiple access (OFDMA) wireless networks. Specifically, the wireless virtualization model enables an infrastructure provider (InP) to effectively lease radio resources to multiple mobile virtual netwo...

In this paper, a novel framework is proposed to jointly optimize user association and resource allocation in the uplink cognitive femtocell network (CFN). In the considered CFN, femtocell base stations (FBSs) are deployed to serve a set of femtocell user equipments (FUEs) by reusing subchannels used in a macrocell base station (MBS). The problem of...

This paper studies the data scheduling and admission control problem for a backscatter sensor network (BSN). In the network, instead of initiating their own transmissions, the sensors can send their data to the gateway just by switching their antenna impedance and reflecting the received RF signals. As such, we can reduce remarkably the complexity,...

This paper presents a cooperative game theoretic approach to tackle the cost allocation problem for a virtual power plant (VPP) which consists of multiple demand-side resource aggregators (DRAs) participating in the short-term two settlement electricity market. Given the considered game is balanced, we propose to employ the cooperative game theory’...

We consider the joint WiFi offloading, admission control, and network management for the integrated WiFi and OFDMA-based cellular network. Specifically, we propose a quality-of-service (QoS) and mobility-aware admission control scheme that efficiently offloads macrocell traffic to WiFi and integrates a novel bandwidth borrow-return strategy while...

Millimeter wave (mmWave) communication systems have attracted significant interest regarding meeting the capacity requirements of the future 5G network. The mmWave systems have frequency ranges in between 30 and 300 GHz where a total of around 250 GHz bandwidths are available. Although the available bandwidth of mmWave frequencies is promising, the...

This paper examines a CoMP system where multiple base-stations (BS) employ coordinated beamforming to serve multiple mobile-stations (MS). Under the dynamic point selection mode, each MS can be assigned to only one BS at any time. This work then presents a solution framework to optimize the BS associations and coordinated beamformers for all MSs. W...