Du, ChenyangGuo, JingWang, XinyiYu, HanxiaoFei, ZesongZhou, XiangyunDurrani, Salman2026-06-112026-06-112327-4662https://hdl.handle.net/1885/733810254Backscatter communication and harvest-then-transmit (HTT) communication are regarded as promising technologies for enabling green Internet of Things (IoT). The current works on the joint use of backscatter communication and HTT are limited in single cell scenarios with the fixed backscatter-then-HTT transmission structure. In this work, we propose a transmission scheme with flexible mode selection for the hybrid backscatter-HTT multicell system to achieve much improved communication performance, and then study the joint design for such a system. Specifically, by utilizing multiantenna technology and enabling the flexible mode selecting between backscatter and HTT, a novel transmission scheme is developed. With the aim to maximize the sum rate of the considered system, we formulate a joint optimization problem for the base station transmission beamforming (TB), the transmission mode (TM), and the transmit power (TP) of the hybrid backscatter-HTT devices. To address the formulated nonconvex problem, we propose a block coordinate descent-based algorithm, namely, J3TO, to jointly optimize TB, TM, and TP, by decoupling the original problem into three subproblems. Therein, the weighted minimum mean-square-error approach, matching theory, and the fractional programming technique are leveraged to deal with the subproblems efficiently. Simulation results show that the proposed algorithm flexibly integrates the merits of backscatter and HTT technologies, achieving superior performance across various scenarios, compared with the benchmark schemes, e.g., backscatter-only space division multiple access (SDMA), HTT-only SDMA, and backscatter-HTT TDMA.Received 9 July 2025; accepted 14 August 2025. Date of publication 25 August 2025; date of current version 24 October 2025. This work was supported in part by the Natural Science Foundation on Frontier Leading Technology Basic Research Project of Jiangsu under Grant BK20212001, and in part by the National Natural Science Foundation of China under Grant 62201052. (Corresponding author: Jing Guo.) Chenyang Du, Jing Guo, Xinyi Wang, and Zesong Fei are with the School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China (e-mail: 3220225141@bit.edu.cn; jingguo@bit.edu.cn; bit_wangxy@163.com; feizesong@bit.edu.cn).16enPublisher Copyright: © 2014 IEEE.Backscatter communicationenergy harvestingharvest-then-transmit (HTT)multiple antennastransmission design202510.1109/JIOT.2025.3602056105014546860