Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme

This work leverages an Intelligent Reflecting Surface (IRS) to improve throughput performance of a wireless powered communication network (WPCN). A novel hybrid multiple access strategy is conceived, where the IRS set the time-division multiple access (TDMA) to allocate its phase shifts, each of whi...

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Main Authors: Yizheng Ma, Ruoyi Wu, Yi Zhang, Yupeng Shang, Linzhen Zhu
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/10870200/
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author Yizheng Ma
Ruoyi Wu
Yi Zhang
Yupeng Shang
Linzhen Zhu
author_facet Yizheng Ma
Ruoyi Wu
Yi Zhang
Yupeng Shang
Linzhen Zhu
author_sort Yizheng Ma
collection DOAJ
description This work leverages an Intelligent Reflecting Surface (IRS) to improve throughput performance of a wireless powered communication network (WPCN). A novel hybrid multiple access strategy is conceived, where the IRS set the time-division multiple access (TDMA) to allocate its phase shifts, each of which performs the non-orthogonal multiple access for multiple Internet of Things (IoT) devices. These devices firstly collect energy in a non-linear manner disseminated by a power station (PS) at downlink wireless energy transfer (WET) stage. The gathered energy is then utilized by these devices to convey data information to an access point (AP) by employing the TDMA protocol with flexible time slots at the uplink wireless information transfer (WIT) stage. During each time slot, the NOMA protocol is utilized for all IoT devices’ data transmission, thus creating a hybrid TDMA-NOMA framework. To assess the overall performance of the system model under investigation, we aim to maximize the network throughput, subject to the constraints of the downlink WET and uplink WIT time scheduling, the power allocation for each time slots, and unit-modulus IRS phase shifts of downlink WET and uplink WIT, thereby highlighting energy harvesting and information transmission capabilities. The formulated problem is inherently not jointly convex due to the coupled nature of the variables, making it difficult to resolve directly. To deal with this challenge, a power allocation factor is first introduced for each IoT device, and then an alternating optimization (AO) algorithm is proposed to jointly design the power allocation, IRS phase shifts, and time scheduling in an alternated fashion. To be specified, the optimal power allocation factor can be obtained using interior-point methods for given time scheduling and IRS phase shifts. Also, the time slots of downlink WET and uplink WIT stages are theoretically derived in closed-form expressions using the Lagrange dual method and the Karush-Kuhn–Tucker (KKT) conditions. Additionally, the semi-closed-form expressions of IRS phase shifts during WET and WIT stages are iteratively achieved through Riemannian Manifold Optimization (RMO) and quadratic transformation (QT)-based Alternating Direction Method of Multipliers (ADMM) algorithms. Finally, the numerical results are demonstrated to highlight the effectiveness of the proposed algorithm, the optimal IRS phase shift design, and the optimal WET time scheduling design in comparison to the benchmarks.
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id doaj-art-2eb07a6598e2401fa6bde55b3b3cff98
institution Kabale University
issn 2169-3536
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publishDate 2025-01-01
publisher IEEE
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spelling doaj-art-2eb07a6598e2401fa6bde55b3b3cff982025-02-11T00:00:55ZengIEEEIEEE Access2169-35362025-01-0113233842339810.1109/ACCESS.2025.353798810870200Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA SchemeYizheng Ma0https://orcid.org/0009-0009-4024-7706Ruoyi Wu1Yi Zhang2Yupeng Shang3Linzhen Zhu4https://orcid.org/0009-0004-5036-3907Department of Electrical and Electronic Engineering (EEE), University of Nottingham Ningbo China, Ningbo, ChinaCollege of Electrical and Electronic Engineering, Wenzhou University, Wenzhou, ChinaDepartment of Electrical and Electronic Engineering (EEE), University of Nottingham Ningbo China, Ningbo, ChinaSchool of Electrical and Information Engineering, Tianjin University, Tianjin, ChinaDepartment of Robotics, University of Michigan, Ann Arbor, MI, USAThis work leverages an Intelligent Reflecting Surface (IRS) to improve throughput performance of a wireless powered communication network (WPCN). A novel hybrid multiple access strategy is conceived, where the IRS set the time-division multiple access (TDMA) to allocate its phase shifts, each of which performs the non-orthogonal multiple access for multiple Internet of Things (IoT) devices. These devices firstly collect energy in a non-linear manner disseminated by a power station (PS) at downlink wireless energy transfer (WET) stage. The gathered energy is then utilized by these devices to convey data information to an access point (AP) by employing the TDMA protocol with flexible time slots at the uplink wireless information transfer (WIT) stage. During each time slot, the NOMA protocol is utilized for all IoT devices’ data transmission, thus creating a hybrid TDMA-NOMA framework. To assess the overall performance of the system model under investigation, we aim to maximize the network throughput, subject to the constraints of the downlink WET and uplink WIT time scheduling, the power allocation for each time slots, and unit-modulus IRS phase shifts of downlink WET and uplink WIT, thereby highlighting energy harvesting and information transmission capabilities. The formulated problem is inherently not jointly convex due to the coupled nature of the variables, making it difficult to resolve directly. To deal with this challenge, a power allocation factor is first introduced for each IoT device, and then an alternating optimization (AO) algorithm is proposed to jointly design the power allocation, IRS phase shifts, and time scheduling in an alternated fashion. To be specified, the optimal power allocation factor can be obtained using interior-point methods for given time scheduling and IRS phase shifts. Also, the time slots of downlink WET and uplink WIT stages are theoretically derived in closed-form expressions using the Lagrange dual method and the Karush-Kuhn–Tucker (KKT) conditions. Additionally, the semi-closed-form expressions of IRS phase shifts during WET and WIT stages are iteratively achieved through Riemannian Manifold Optimization (RMO) and quadratic transformation (QT)-based Alternating Direction Method of Multipliers (ADMM) algorithms. Finally, the numerical results are demonstrated to highlight the effectiveness of the proposed algorithm, the optimal IRS phase shift design, and the optimal WET time scheduling design in comparison to the benchmarks.https://ieeexplore.ieee.org/document/10870200/IRS-assisted WPCNhybrid TDMA-NOMALagrange dual methodKKTRiemannian optimizationquadratic transformation (QT)
spellingShingle Yizheng Ma
Ruoyi Wu
Yi Zhang
Yupeng Shang
Linzhen Zhu
Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme
IEEE Access
IRS-assisted WPCN
hybrid TDMA-NOMA
Lagrange dual method
KKT
Riemannian optimization
quadratic transformation (QT)
title Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme
title_full Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme
title_fullStr Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme
title_full_unstemmed Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme
title_short Throughout Maximization for IRS-Assisted WPCN With Hybrid TDMA-NOMA Scheme
title_sort throughout maximization for irs assisted wpcn with hybrid tdma noma scheme
topic IRS-assisted WPCN
hybrid TDMA-NOMA
Lagrange dual method
KKT
Riemannian optimization
quadratic transformation (QT)
url https://ieeexplore.ieee.org/document/10870200/
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AT yizhang throughoutmaximizationforirsassistedwpcnwithhybridtdmanomascheme
AT yupengshang throughoutmaximizationforirsassistedwpcnwithhybridtdmanomascheme
AT linzhenzhu throughoutmaximizationforirsassistedwpcnwithhybridtdmanomascheme