Wirelessly Powered Cell-Free IoT: Analysis and Optimization

Abstract

In this paper, we propose a wirelessly powered Internet of Things (IoT) system based on the cell-free massive MIMO technology. In such a system, during the downlink phase, the sensors harvest radio-frequency (RF) energy emitted by the distributed access points (APs). During the uplink phase, sensors transmit data to the APs using the harvested energy. Collocated massive MIMO and small-cell IoT can be treated as special cases of cell-free IoT. We derive the tight closed-form lower bound on the amount of harvested energy, and the closedform expression of SINR as the metrics of power transfer and data transmission, respectively. To improve the energy efficiency, we jointly optimize the uplink and downlink power control coefficients to minimize the total transmit energy consumption while meeting the target SINRs. Extended simulation results show that cell-free IoT outperforms collocated massive MIMO and small-cell IoT both in terms of the per user throughput for uplink, and the amount of energy harvested for downlink. Moreover, significant gains can be achieved by the proposed joint power control in terms of both per user throughput and energy consumption.Index Terms-Cell-free massive MIMO, Internet-of-things, power control, wireless power transfer.

Design and Analysis of Full-Duplex Massive Antenna Array Systems Based on Wireless Power Transfer

“…We consider a wireless powered massive network as shown in Fig. 2, where cell radius is considered to be R o = 250 m. The HAP is located at the center of cell, K ul = 5 UEs are randomly located within a reference distance (RD) of R i = 25 m from the HAP, which is the case for smallcell scenarios [21], [24], and K dl = 3 CUs are randomly distributed across the whole of the cell. we assume that p p = p a and the energy conversion efficiency is set to be η = 0.7.…”

“…A well recognized 5G use case is the coexistence of machine type devices and cellular users and how to power up such devices for efficient data transfer is an important issue. To this end, the considered system model has been actively considered in the present literature such as [21]- [24].…”

Cell-Free IoT Networks With SWIPT: Performance Analysis and Power Control

“…Those contributions indicated that the mMIMO architecture is able to broaden the application prospect of SWIPT and accelerate the deployment of SWIPT in practice. Although the largescale antenna architecture helps enhance the energy capturing and information reception efficiencies for a vast majority of sensors, the system performance of cell-edge sensors is still hindered by heavy pathloss [17]- [20].…”

“…Besides, all the APs are connected to a central server (CS) through the robust fronthaul networks to exchange useful information and signaling. Indeed, compared with a traditional cellular mMIMO, the cell-boundaries vanish in the CF case and the ubiquitous distribution of APs contribute to alleviating substantial performance degradations of cell-edge sensors by shortening the communication distances between the terminals and served APs [17], [18].…”

CURE: Enabling RF Energy Harvesting Using Cell-Free Massive MIMO UAVs Assisted by RIS

“…However, they assume perfect channel state information (CSI) without considering the uplink communications. Another group of works minimize the total transmitted energy for wirelessly-powered cell-free IoT by considering a linear energy harvesting model with only Rayleigh fading (e.g., [13]). Instead, adopting a Rician fading channel model with random phase shifts to each of the antennas of the APs would have been more general like the real environment.…”