Table 1 Comparison between joint uplink and downlink communication networks.
From: Learning uplinks and downlinks transmissions in RF-charging IoT networks
References | Working principle | SWIPT | Downlink | Uplink | Non-linear energy model | Energy evolution | Learning | Decision variables |
|---|---|---|---|---|---|---|---|---|
HAP first charges users followed by data transmission to each user. | TS | TDD | TDD | ✗ | ✗ | ✗ | Time allocation Transmission power | |
Users harvest energy whenever HAP transmits data to users. | PS | NOMA TDMA | NOMA-TS TDMA | ✗ | ✗ | ✗ | Time allocation Transmission power Beamformer | |
HAP transmit energy and data in multiuser MIMO system. | PS | TDD | TDD | ✗ | ✗ | ✗ | Beamformer Time allocation Power split ratio | |
HAP transmits energy and data to users using NOMA. | PS TS | NOMA | NOMA | ✗ | ✗ | ✗ | Time allocation Power splitting ratio | |
An OFDMA system with uplinks and downlinks sub-carriers. | PS | FDD/TDD | FDD/TDD | ✗ | ✗ | ✗ | Subcarrier allocation Transmission Power Power splitting ratio | |
Different sub-carriers for energy delivery and data transmissions. | N/A | OFDM | NOMA | ✗ | ✗ | ✗ | Sub-carrier allocation Transmission Power Power splitting ratio | |
Different sub-carriers for energy harvesting and data transmissions. | N/A | TDD | TDD | ✗ | ✗ | ✗ | Transmit Power | |
High and low frequency bands for energy and data transmissions. | N/A | TDD | TDD | ✔ | ✗ | ✗ | Transmit power Charging duration | |
This work | HAP transmits data and energy to users using NOMA, and receives data from devices over the same channel. | PS | NOMA | Aloha-SIC | ✔ | ✔ | ✔ | Transmit power, Power split ratio, Transmit probability, Slot selection, Frame size |
