Xiangqian Xiu - IEEE Xplore Author Profile

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Hierarchical Federated Learning (HFL) has been introduced to enhance the communication efficiency and scalability of traditional Federated Learning (FL). In addition, the integration of Non-Orthogonal Multiple Access (NOMA) into the HFL framework serves to bolster system capacity and spectral efficiency. However, the formidable challenge of energy efficiency persists, particularly in energy-constr...Show More
Federated Learning (FL) has gained prominence as a decentralized approach for training a shared machine learning model across multiple participants without compromising their private raw data. Nevertheless, integrating such a framework into wireless network presents unique challenges, including limited radio resources and heterogeneous participant resource configurations. To tackle these issues, t...Show More
This paper investigates federated learning in a wireless communication system, where random device selection is employed with non-independent and identically distributed (non-IID) data distribution. In order to mitigate the weight divergence issue, age-weighted federated stochastic gradient descent (FedSGD) is designed, where a weighting factor is introduced to scale local gradients according to t...Show More
Sparse code multiple access (SCMA) is one of the competitive non-orthogonal multiple access techniques for the next generation multiple access systems. One of the main challenges is high computational complexity and the SCMA-aided codewords, that is, each terminal device maintains its local data and codewords, which provides no incentive for model updating to accommodate rapidly changing vehicle c...Show More
In this paper, a federated learning (FL) based system is investigated with non-independent and identically distributed (non-IID) dataset, where multiple devices participate in the global model aggregation through a limited number of sub-channels. By analyzing weight divergence and convergence rate, a new metric is proposed based on age-of-information (AoI), which incorporates latency and can provi...Show More
This paper investigates a reconfigurable intelligent surface (RIS)-assisted unmanned aerial vehicle (UAV)-enabled wireless powered communication network (WPCN). In the system, a UAV acts as a hybrid access point (HAP) to charge users in the downlink (DL) and receive messages in the uplink (UL). In particular, the RIS is exploited to significantly enhance the efficiency of both the DL and UL transm...Show More
Reconfigurable intelligent surfaces (RISs) have attracted extensive attention in millimeter wave (mmWave) systems because of the capability of configuring the wireless propagation environment. However, due to the existence of a RIS between the transmitter and receiver, a large number of channel coefficients need to be estimated, resulting in more pilot overhead. In this paper, we propose a joint s...Show More
Communication networks are becoming increasingly content-centric, and reusable content like viral information and video on demand are often requested by multiple users. Caching at the user equipment enables device-to-device (D2D) communications to be used to deliver requested contents which will help reduce data traffic at base stations and also enhance the achievable data rates. In this paper, we...Show More
Cell-free massive MIMO is a promising technology to meet the requirements of future wireless networks. It uses multiple access points (APs) spread over a large coverage area to serve multiple User Equipment (UEs) simultaneously. In order to make it practical and ensure good performance, it is important to carefully determine which APs should serve particular users. In this work, we propose a metho...Show More
Hierarchical Federated Learning (HFL) has been proposed to achieve larger-scale model training and more efficient communications compared to conventional Federated Learning (FL). However, both inappropriate edge association strategy and aggregation frequency may consume massive energy in users with poor channel conditions or degrade the HFL convergence performance due to Non Independent and Identi...Show More
Federated Learning (FL) is widely regarded as a leading distributed machine learning paradigm, owing to its outstanding performance in preserving privacy and conserving communication resources. To use it efficiently in wireless communication networks, novel transmission schemes that jointly consider the model propagation and training features are required. In this paper, a novel joint user schedul...Show More
Reconfigurable intelligent surface (RIS) is a promising technique that smartly reshapes wireless propagation environment in the future wireless networks. In this paper, we apply RIS to an unmanned aerial vehicle (UAV)-assisted non-orthogonal multiple access (NOMA) network, in which the transmit signals from multiple UAVs to ground users are strengthened through RIS. Our objective is to minimize th...Show More
Combining simultaneous wireless information and power transfer (SWIPT) and an intelligent reflecting surface (IRS) is a feasible scheme to enhance energy efficiency (EE) performance. In this paper, we investigate a multiuser IRS-aided multiple-input single-output (MISO) system with SWIPT. For the purpose of maximizing the EE of the system, we jointly optimize the base station (BS) transmit beamfor...Show More
This article considers a reconfigurable intelligent surface (RIS) enhanced multi-antenna secure transmission system in the presence of both active eavesdroppers (AEves) and passive eavesdroppers (PEves). We propose a zero-forcing (ZF) beamforming strategy that can steer transmit beam to the null space of AEves' channel, while simultaneously enhancing the SNRs for a legitimate user equipment (UE) a...Show More
Reconfigurable Intelligent Surfaces (RIS) provides an emerging affordable solution by leveraging massive low-cost reconfigurable reflective array elements. In this letter, by utilizing low-cost passive reflecting elements, a joint hybrid beamforming with discrete phase shifts design is studied in RIS-assisted multiuser simultaneous wireless information and power transfer (SWIPT) systems. However, ...Show More
Power consumption and hardware cost are two of the main challenges for realizing beyond fifth generation (B5G) and sixth generation (6G) wireless communications. Recently, the emerging reconfigurable intelligent surface (RIS) has been recognized as a promising tool for enhancing the propagation environment and improving the spectral efficiency of wireless communications by controlling low-cost pas...Show More
In the wireless powered communication network (WPCN), the wireless energy acquisition is weak due to the fading characteristic of the wireless link, which is hard to supply energy to wireless sensor. Reconfifigurable intelligent surface (RIS) is a promising performance enhancing technology for WPCN, which can improve the energy and spectral effificiency, expand the network coverage, and thus impro...Show More
Combining simultaneous wireless information and power transfer (SWIPT) and intelligent reflecting surface (IRS) is a feasible scheme to enhance the energy efficiency (EE) performance. In this paper, we investigate a multiuser IRS-aided multiple-input single-output (MISO) system with SWIPT. For the purpose of maximizing the EE of the system, we jointly optimize the base station (BS) transmit beamfo...Show More
The application of non-orthogonal multiple access (NOMA) to multi-layer multicast video streaming is envisioned to address the explosively growing demand for capacity which is dominated mostly by multimedia content. In this paper, a joint power allocation and subgrouping scheme is developed to enhance the performance of NOMA-based multi-layer multicast systems. An optimization problem is formulate...Show More
Plane spiral orbital angular momentum (PSOAM) mode-groups (MGs) and multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) serve as two emerging techniques for achieving high spectral efficiency (SE) in the next-generation networks. In this paper, a PSOAM MGs based multi-user MIMO-NOMA system is studied, where the base station transmits data to users by utilizing the generated P...Show More
The combination of unmanned aerial vehicles (UAVs) and millimeter wave (mmWave) multiple-input multiple-out (MIMO) system is regarded as a key enabling technology for beyond 5G networks, as it provides high data rate aerial links. However, establishing UAV-enabled mmWave MIMO communication is quite challenging due to the high hardware cost in terms of radio frequency (RF) chains. As a cost-effecti...Show More
The emerging intelligent reflecting surface (IRS) can significantly improve the system capacity, and it has been regarded as a promising technology for the beyond fifth-generation (B5G) communications. For IRS-assisted multiple input multiple output (MIMO) systems, accurate channel estimation is a critical challenge. This severely restricts practical applications, particularly for resource-limited...Show More
Coded multicasting is considered to be an effective approach to simultaneously serve multiple users in the same frequency/time/code resource, which is made possible by exploiting the information available in users’ caches. Recently, non-orthogonal multiple access (NOMA) has emerged as an alternative transmission technique for cache-aided network. In cache-aided NOMA system, cache-enabled interfere...Show More
The intelligent reflecting surface (IRS)-assisted millimeter wave (mmWave) communication system has emerged as a promising technology for coverage extension and capacity enhancement. Prior works on IRS have mostly assumed perfect channel state information (CSI), which facilitates in deriving the upper-bound performance but is difficult to realize in practice due to passive elements of IRS without ...Show More
Non-orthogonal multiple access (NOMA) is effective in enhancing the spectral efficiency and sum rate of a system as compared to an orthogonal scheme. In addition to this, as mobile users consume more rich content, the role of device-to-device communications (D2D) and wireless caching will become more prominent in further optimizing the usage of resources. In this paper, we propose a system in whic...Show More