Hongbo Zhu

• Professor
• Professor (Full) at Nanjing University of Posts and Telecommunications

This paper investigates the uplink achievable rates of massive multiple-input multiple-output (MIMO) antenna systems in Ricean fading channels, using maximal-ratio combining (MRC) and zero-forcing (ZF) receivers, assuming perfect and imperfect channel state information (CSI). In contrast to previous relevant works, the fast fading MIMO channel matr...

In this paper, we study the multiple-input multiple-output wiretap channel for simultaneous wireless information and power transfer, in which there is a base station (BS), an information-decoding (ID) user, and an energy-harvesting (EH) user. The messages intended to the ID user is required to be kept confidential to the EH user. Our objective is t...

Light serves as an efficient information carrier for communication across air, land, and underwater environments due to its diverse propagation behaviors. Here, we establish a complete-mapping mobile all-light communication network that merges wired modes with wireless moving and fixed nodes, utilizing light sources of different wavelengths. To add...

We investigate the spectral and energy efficiencies of the uplink in an integrated satellite-terrestrial cell-free massive multiple-input multiple-output (IST-CF-mMIMO) system assisted by rate-splitting multiple access (RSMA). In the IST-CF-mMIMO system, the terrestrial users employ RSMA to transmit a message as a superposition of two parts with di...

As one of the most critical tasks currently, it is essential to excavate the status update performance. In this paper, we combine access control and pilot design to minimize average age of information (AoI) in cell-free (CF) massive multiple-input multiple-output (MIMO) system with grant-free (GF) random access, where the positions of both the acce...

With the continuous advancement of the Unmanned Aerial Vehicle (UAV) communication industry, the efficient allocation of scarce spectrum resources to UAVs has become a pressing issue. Given the unique nature of UAVs and the broadcast nature of wireless channels, there are significant instances of unregulated flight operations and malicious attacks,...

Cell-free multiple-input multiple-output (MIMO) system is a promising solution for wireless communications. However, the potential in improving system performance is restricted due to the capacity-limited fronthaul links. To tackle this problem, we utilize the compress-and forward approach, which leverages various compression and encoding technique...

Cell-free multiple-input multiple-output (MIMO) generally uses a star topology for superior communication but faces high costs due to long cables. An economical alternative, the stripe topology, is suitable for specific deployments but cannot meet user demands in densely populated areas due to limited fronthaul capacity. To address these limitation...

Distributed dual-function radar system is an emerging trend in next-generation wireless systems, offering the possibility of improved parameter estimation for target localization as well as improved communication performance. With sufficient resource allocation, the achievable minimum estimated mean square error (MSE) and maximum total communicatio...

Semantic communication is envisioned as a potential communication paradigm enabled by artificial intelligence and is promising to break the Shannon limit for future 6G networks. This paradigm benefits unmanned aerial vehicles (UAVs) to conserve communication resources and minimize latency by only transmitting task-relevant semantic information. How...

Studies on novel sub-6GHz indoor surface wave communication channel models are presented. With the aid of a surface wave launcher that based on planar magnetic dipole antennas, a wireless coupled, indoor surface wave channel measurement apparatus is constructed to validate the channel characteristics, i.e., path loss, channel impulse response, and...

Rate splitting multiple access (RSMA) provides a flexible transmission framework that can be applied in mobile edge computing (MEC) systems. However, the research work on RSMA-assisted MEC systems is still at the infancy and many design issues remain unsolved, such as the MEC server and channel allocation problem in general multi-server and multi-c...

In the context of Internet-of-Things, this paper considers a cell-free (CF) massive multiple-input multiple-output (MIMO) system for ultra-reliability and low latency communication (URLLC) assisted by multiple reconfigurable intelligent surfaces (RIS). We derive the closed-form expression of the downlink achievable rate under multiple correlated RI...

This paper establishes a novel transmission framework that amalgamates downlink training with rate-splitting multiple access, thereby being expected to enhance the spectral efficiency (SE) of a cell-free massive multiple-input multiple-output enabled Internet-of-Things (IoT) system. Considering a correlated Ricean fading environment coupled with im...

Unmanned aerial vehicles (UAVs) have demonstrated success in delivering goods, but their delivery distances are limited due to their finite battery capacity. While roadside charging stations can replenish the battery, they cause delays and prevent timely delivery. In this paper, we present a novel UAV charging scheduling and speed control framework...

Reconfigurable Intelligent Surface (RIS) presents a promising solution for achieving a balance between communication quality and power consumption. However, traditional reflecting RIS designs are limited to covering signals within a 180-degree range. Fortunately, the development of Simultaneous Transmitting and Reflecting RIS (STAR-RIS) technology...

III-nitride multi-quantum well (MQW) diodes can modulate the light emitted by another diode with the same MQW structure by varying the bias voltage owing to the spectral overlap between the electroluminescence spectrum and spectral responsivity curve of the MQW diodes. Here, we investigate bias-controlled modulation by monolithically integrating an...

Wireless optical communication plays a vital role in mobile communication networks, and both drones and vehicles are essential mobile communication nodes. Here, image identification technology, gimbal, and full-duplex optical communication systems are integrated to manage the challenging issues of light alignment and target tracking for mobile full...

Channel mismatch, resulting from channel non-reciprocity (NRC) and channel aging, can make the estimated channel outdated when used for precoding and detection. In this paper, we investigate the impact of channel mismatch for cell-free massive multiple-input multiple-output systems in the context of Internet-of-Things (IoT) networks. Assuming that...

The key idea of this paper is to leverage channel angle information to propose a low-complexity mode switching design in simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided multi-antenna non-orthogonal multiple access (NOMA) systems, which is suitable to both downlink and uplink transmissions by applying t...

Reconfigurable intelligent surface (RIS) is envisioned as a potential technology to improve spectrum efficiency with low energy consumption. Moreover, the spectrum reuse technologies are also extensively applied in various networks, such as vehicle-to-vehicle (V2V) in transportation system, machine-to-machine (M2M) in industrial Internet of Things...

The reconfigurable intelligent surface (RIS) is considered a promising technique to improve the performance of user equipments in service dead zones in cell-free massive multipleinput multiple-output (CFmMIMO) systems. In this paper, we investigate the impact of channel aging on the uplink CFm- MIMO system aided by RISs with spatially correlated el...

In recent years, the Integrated Satellite Aerial Terrestrial (I‐SAT) network has garnered significant attention as an innovative and integrated communication system. However, it still encounters interference in the face of the complex external environment. In this context, reconfigurable intelligent surface (RIS) provides a key way of solving this...

In this correspondence, we investigate a hardware-impaired uplink cell-free massive multiple-input multiple-output (MIMO) system with intelligent reconfigurable surfaces (IRSs) under correlated Ricean fading channels. Based on the imperfect channel knowledge, we derive tight closed-form expressions for the lower-bound achievable rate and study the...

Cooperation can help unmanned aerial vehicles (UAVs) improve their plans to visit charging stations and avoid congestion, but can be hindered by privacy concerns. We propose a new, privacy preserving, joint routing, and charging scheduling framework which allows multiple cellular-connected UAVs to jointly optimize their routes and charging schedule...

In this paper, we consider the cell-free massive multiple-input multiple-output (MIMO) system for supporting ultra-reliable and low-latency communication (URLLC) transmission, where a large number of access points (APs) serve a small number of users in the short packet regime. Assuming channel aging and channel spatial correlation, we derive the cl...

Clustered Vehicular Federated Learning (CVFL) can be used to improve traffic safety, increase traffic efficiency, and reduce vehicle carbon emissions. Therefore, it is extremely promising in intelligent transportation systems. However, in practice, it is difficult to accurately cluster vehicular clients with mobility according to data distribution....

This paper considers the cell-free massive multiple-input multiple-output (MIMO) system for ultra reliable and low-latency communication (URLLC) under non-reciprocal channels and pilot contamination. To investigate the impact of the channel non-reciprocity, we model it as a random variable using the more realistic truncated Gaussian distribution. I...

Fault prediction is an important application in the Industrial Internet of Things (IIoT) to ensure the safety of industrial systems and factories. Currently, deep learning-based fault prediction models are more popular, and multi-factory co-operation is required to improve the accuracy and generality of fault prediction models. Federated learning c...

Most existing works on dual-function radar-communication (DFRC) systems mainly focus on active sensing, but ignore passive sensing. To leverage multi-static sensing capability, we explore integrated active and passive sensing (IAPS) in DFRC systems to remedy sensing performance. The multi-antenna base station (BS) is responsible for communication a...

In this paper, a new method for rotational angle and speed measurements is proposed by integrating a GaN optoelectronic chip with a stepped disc. The optoelectronic chip that integrates a light-emitting diode (LED) and a photodiode (PD) is fabricated by wafer-level microfabrication. The disc is designed with a spiral staircase shape, and has increa...

Integrating optoelectronic devices with various functions into a monolithic chip is a popular research frontier. The top-down integration scheme on silicon-based III-nitride wafers has unique advantages. A monolithic III-nitride on-chip system with lighting source, electrical absorption modulator, waveguide and photodetector with the same structure...

Intelligent reflecting surface (IRS) assisted cell-free (CF) massive multiple-input multiple-output (mMIMO) offers substantial potential for enhancing spectral efficiency, energy efficiency, and coverage areas. In this letter, we introduce a novel approach aimed at maximizing the sum-rate in the downlink of IRS-assisted CF mMIMO systems. Our approa...

The integration of wireless light communication into a wireless fidelity (Wi-Fi) module and gateway enables real-time integrated communication networks that satisfy practical application demands. In particular, wireless green light communication tools can operate underwater and in free-space environments. Here, we design, fabricate, and characteriz...

Space–air–sea communication networks are of great interest to meet the demand for close and seamless connections between space, land, and ocean environments. Wireless light communication can expand network coverage from land to the sky and even the ocean while offering enhanced anti-interference capabilities. Here, we propose and establish an all-l...

Quantum well (QW) diodes have the capability to function as a light-emitting diode or a photodiode and inherently feature a partial emission-detection spectral overlap. Therefore, QW diode can sense light emission from another diode sharing the same QW active region. In association with distributed Bragg reflection (DBR) technique, we here present...

In this paper, we study the transmit and receive beamforming vectors in a downlink integrated sensing and communication (ISAC) system, where a base station (BS) performs the downlink communication with user equipments (UEs) and active sensing tasks simultaneously. While reflected signals are utilized for passive sensing at the receive access points...

As a promising paradigm to support wireless connections among massive devices, the Internet of things (IoT) is facing several challenges. Among them, the energy supply to IoT devices, the weak computation ability of IoT devices, and the stringent latency requirement of IoT applications are three major challenges, which can be tackled by radio frequ...

Federated learning (FL) can not only improve training efficiencies for various intelligent recognition tasks (IRTs) in intelligent transportation system (ITS) with lower training latency, but also enhance data privacy during neural network training. Meanwhile, Internet of vehicles (IoV), supporting data transmission in ITS, is characterized by dyna...

To enhance the generalization of neural networks based channel state information (CSI) feedback approaches in massive multiple-input multiple-output (MIMO) systems, we propose a novel CSI feedback approach based on meta-transfer learning to overcome the impact of dynamic channels. Specifically, neural-level scaling and shifting operations are intro...

Thanks to the customization of channel propagation, reconfigurable intelligent surface (RIS)-aided cell-free (CF) massive multiple-input multiple-output (MIMO) is recognized as a competitive candidate technique for the future communication system. However, only the limited performance gain can be afforded by passive RIS due to the double-fading eff...

This Letter reports a collinear optical interconnect architecture for acoustic sensing via a monolithic integrated GaN optoelectronic chip. The chip is designed with a ring-shaped photodiode (PD) surrounding a light-emitting diode (LED) of a spectral range from 420–530 nm. The axisymmetric structure helps the coaxial propagation of light transmissi...

Driven by the development of time-sensitive applications, short packet transmission (SPT) design has become the key point in the ultra-reliable and low-latency communications (URLLC) area. The primary challenge in it is that the delay caused by pilot overhead cannot be neglected. To deal with this issue, this paper presents a frame structure adopti...

This paper investigates the uplink performance of a general cell-free massive multiple-input multiple-output (CF-mMIMO) system, in which all access points (APs) and user equipments (UEs) suffer from hardware impairments (HWIs). Besides, there are several reconfigurable intelligent surfaces (RISs) that aim to improve the coverage quality, spectral e...

This letter investigates the physical layer security of reconfigurable intelligent surface (RIS) aided integrated-sensing-and-communication (ISAC) systems, in which the high-power radar signal is used as the interference to disturb the eavesdropper. We formulate a joint beamforming optimization problem of active beamforming of base station and pass...

Emerging deep-ultraviolet (DUV) light communication with attractive features fulfills the increasing demand for novel wireless communication without electromagnetic interference or solar noise influence. Here, we propose, manufacture, and characterize a solar-blind full-duplex light communication system using 275-nm DUV light-emitting diodes (LEDs)...

Mobile edge computing (MEC) is a promising paradigm to handle the mismatch between computation-intensive applications and resource-limited devices. Nevertheless, as most internet of things (IoT) terminals are battery-limited, the computation gain of MEC may be compromised due to insufficient battery energy for task offloading. Wireless power transf...

Unmanned aerial vehicles (UAVs) have been extensively applied to goods delivery and in-situ sensing. It becomes increasingly probable that multiple UAVs are delivering goods and carrying out sensing tasks at the same time. The destinations of the UAVs are usually required to jointly design their trajectories and sensing selections, leading to priva...

To handle the ever-increasing IoT devices with computation-intensive and delay-critical applications, it is imperative to leverage the collaborative potential of edge and cloud computing. In this paper, we investigate the dynamic offloading of packets with finite block length (FBL) in an edge-cloud collaboration system consisting of multi-mobile Io...

We study the physical layer security for short packet communications in wireless powered internet of things networks. The problem of optimizing the packet error rate and the packet length for maximizing the total secrecy throughput is investigated. Since the problem is challenging to solve due to its non-convexity, we develop a low-complexity algor...

Machine learning-based random access schemes have gained significant attention in recent years. However, optimizing the access delay of such schemes remains a challenge. In this letter, we focus on analyzing and optimizing the mean access delay of the deep neural network-based double-contention random access (DCRA) scheme, proposed in our earlier w...

Grant-free random access (GFRA) becomes attractive in Internet-of-Things (IoT) due to its low signaling overhead and short access latency. In this paper, we invetigate GFRA in a multicel massive multiple-input-multiple-output (MIMO) system. As the IoT device usually has sporadic traffic, we set a packet buffer for each device to describe its tempor...

The unmanned aerial vehicle (UAV) enabled mobile edge computing (MEC) is a promising paradigm for providing extensive coverage and additional computation services to the Internet of Things (IoT) devices with smart applications, which are normally computation-intensive and delay-critical, especially in some remote areas or emerging scenarios without...

Proactive eavesdropping is an effective approach to improve the performance of wireless information surveillance, where suspicious users are legitimately eavesdropped by authorized monitors. For the situation when no monitor is available, we propose to authorize unsuspicious users to surveil suspicious users provided that the quality-of-service (Qo...

The Industrial Internet of things (IIoT) is one of the typical application scenarios in the beyond fifth generation (B5G) wireless communication systems. Due to numerous metal obstacles and machines, the industrial channel, especially at the millimeter-wave (mmWave) bands, exhibits complex characteristics that haven’t been considered in existing li...

Wireless federated learning (FL) is a distributed learning framework, in which mobile devices (MDs) collaboratively train a model while protecting data privacy. Considering selfishness of MDs, they are unwilling to sacrifice their resources to assist model training without any reward, which may limit performance of FL. In this paper, we propose an...

In this paper, a two-layer large scale fading precoding (LSFP) method is proposed in a downlink cell-free massive multiple-input multiple-output (mMIMO) system. In the first LSFP layer, the access points are responsible for designing distributed precoding and power control coefficients for each user equipment (UE). While for the second LSFP layer,...

Electric vehicles (EVs) provide sustainable and eco-friendly transportation. However, long-range driving is challenging due to limited battery capacity. While charging stations can replenish the battery, they are not as widely deployed as gas stations, causing the battery depletion of EVs. This paper presents a novel optimal charging strategy for E...

Reconfigurable intelligent surface (RIS) is a promising solution to programmable wireless channels. However, most existing RIS phase optimization algorithms, relying on iterative processes, suffer from high latency and poor scalability. To address this issue, we propose a low-complexity scheme based on deep unfolding. Specifically, we consider a do...

Unmanned Aerial Vehicle (UAV) swarms have found widespread applications in executing high-complexity and remote-risk missions. However, the limited onboard resources and energy of UAV swarms may hinder their support for computation-intensive yet delay-sensitive applications, especially when faced with exponentially growing big data. This paper focu...

With rapid adoption in vertical industries and further assistance of edge computing, Internet-of-Things (IoT) applications are experiencing phenomenal growth. However, the concurrence of heterogeneous IoT devices, limited system resources, and varying network conditions poses an ultimate challenge to resource scheduling for meeting the increasingly...

This paper investigates the achievable rate and spectral efficiency (SE) of an uplink cell-free massive multiple-input multiple-output Internet-of-Things (mMIMO-IoT) network over Ricean fading channels, where both access points and user equipments (UEs) are equipped with multiple antennas. We derive tight closed-form expressions for the lower-bound...

Cell-free massive multiple-input-multiple-out (CF-mMIMO) systems provide limited coverage because of expensive wired fronthaul between access points (APs) and central processing unit (CPU). To address this challenge, we propose a novel framework where an unmanned aerial vehicle (UAV), acting as an aerial AP, works coherently with the ground APs to...

Wireless technologies can be used to track and observe freely moving animals. InGaN/GaN light-emitting diodes (LEDs) allow for underwater optical wireless communication due to the small water attenuation in the blue-green spectrum region. GaN-based quantum well diodes can also harvest and detect light. Here, we report a monolithic GaN optoelectroni...

This paper studies a simultaneously transmitting and reflecting reconfigurable intelligent surface aided non-orthogonal multiple access system with two paired users. To ensure the quality of service requirement of the reflected user, we propose a joint power and discrete amplitude allocation scheme, which can reduce channel estimation workload and...

In this paper, the performance of cell-free massive multiple-input multiple-output (CF-mMIMO) systems under the transceiver non-ideal radio-frequency responses (NI-RF-RPs) that rely on the superimposed pilot (SP) and regular pilot (RP) transmission protocols is investigated. Specifically, the transceiver NI-RF-RPs encapsulate the non-ideal amplitud...

Semantic communication in the 6G era has been deemed a promising communication paradigm to break through the bottleneck of traditional communications. However, its applications for the multi-user scenario, especially the broadcasting case, remain under-explored. To effectively exploit the benefits enabled by semantic communication, in this paper, w...

It is an irreversible trend to build a green and sustainable vehicular network facing with the dramatic increase in urban traffic. Reducing energy consumption has been an important aspect for green transportation. Reconfigurable intelligent surface (RIS) is considered as a promising technology to enhance the communication quality with higher energy...

Optical fiber curvature sensors have been considered as a promising option for human motion detection due to its good toughness, bending flexibility and anti-electromagnetic interference. However, for wearable devices, the miniature configuration is preferred, and a high integration of the light emitter, receiver and guided fiber is essential to co...

This paper investigates an intelligent reflective surface (IRS) aided secure wireless communication system, in which a multi-antenna base station (BS) transmits confidential messages to multiple users via symbol-level precoding (SLP). We consider the two cases where the eavesdropper (Eve) has no channel state information (CSI) and global CSI, respe...