Throughput Optimization for Massive MIMO Systems Powered by Wireless Energy Transfer

Abstract

Abstract-This paper studies a wireless-energy-transfer (WET) enabled massive multiple-input-multiple-output (MIMO) system (MM) consisting of a hybrid data-andenergy access point (H-AP) and multiple single-antenna users. In the WET-MM system, the H-AP is equipped with a large number M of antennas and functions like a conventional AP in receiving data from users, but additionally supplies wireless power to the users. We consider frame-based transmissions. Each frame is divided into three phases: the uplink channel estimation (CE) phase, the downlink WET phase, as well as the uplink wireless information transmission (WIT) phase. Firstly, users use a fraction of the previously harvested energy to send pilots, while the H-AP estimates the uplink channels and obtains the downlink channels by exploiting channel reciprocity. Next, the H-AP utilizes the channel estimates just obtained to transfer wireless energy to all users in the downlink via energy beamforming. Finally, the users use a portion of the harvested energy to send data to the H-AP simultaneously in the uplink (reserving some harvested energy for sending pilots in the next frame). To optimize the throughput and ensure rate fairness, we consider the problem of maximizing the minimum rate among all users. In the large-M regime, we obtain the asymptotically optimal solutions and some interesting insights for the optimal design of WET-MM system.

Energy harvesting empowered cognitive metro-cellular networks

“…Thus definition of cognition must be extended and harvesting aware algorithms must be devised for the deployment of the self-sustainable networks. Energy harvesting and microwave power transfer have been extensively explored in context of cellular networks in [2], [3], [4], [5], [6], [7], [8] However, most of these studies assume the stochastic energy arrival models. In practice, energy harvested from the natural sources such as sun has a deterministic behavior.…”

Online Power and Time Allocation in MIMO Uplink Transmissions Powered by RF Wireless Energy Transfer

“…Uplink (UL) wireless information transmission (WIT) powered by WET was studied in [14][15][16][17][18]. In [14], the massive MIMO system powered by WET adopts slotted transmissions, where each slot is divided into three phases for channel estimation, DL power transmission, and UL data transmission, respectively.…”

“…In [14], the massive MIMO system powered by WET adopts slotted transmissions, where each slot is divided into three phases for channel estimation, DL power transmission, and UL data transmission, respectively. The hybrid access point (H-AP) operating in full duplex (FD) mode was studied in [16], where H-AP transmits energy in the DL and receives information in the UL simultaneously.…”

“…Besides, none of these works has considered the battery capacity, thus ignoring the possibility of energy overflow or the opportunities for the user equipment (UE) to optimize the use of harvested energy across UL WIT slots. In [14][15][16], the UE allocates all the harvested energy for the UL WIT in the current slot, and maximizes single slot performance (such as data rates). This approach has been shown a lower data rate than uniformly distributing energy between energy arrivals [6][7][8].…”

“…• We emphasize finite capacity batteries for the UL MIMO data transmission powered by RF WET, which represent more practical scenarios and offer more flexibility of distributing the harvested energy between energy arrivals compared with existing works [14][15][16]. This system prevents the limitation of the environment and weather as renewable EH systems and prevents the artificially high performance arisen from ignoring the energy overflow as WET enabled system with infinite capacity batteries.…”