D2D user and cellular user communication scheme based on NOMA

LTE network adopts non orthogonal multiple access to enhance network capacity and D2D to improve spectral efficiency. Allowing D2D users to share the spectrum resources of cellular users using non orthogonal multiple access technology can alleviate the current shortage of spectrum resources, but it will also introduce interference between D2D users and cellular users. This paper proposes a research scheme for the sharing between D2D users and cellular users based on non orthogonal multiple access (NOMA) technology. SIC technology is used to eliminate the interference between cellular users and D2D users. This scheme not only optimizes the system throughput by adjusting the transmission power of users, but also improves the performance of edge users. The simulation results show that the communication scheme between D2D users and cellular users based on NOMA is superior to the traditional cellular resource allocation scheme and interference control scheme in performance

Throughput of distributed queueing-based LoRa for long-distance communication

Abstract LoRa, due to its advantage of long-range communication capability, is promising for Internet of Things (IoT) and space-air-ground communications. However, the conventional MAC protocol used with LoRa is classified as an Aloha-based algorithm, which leads to drastic decrease in throughput when a huge amount of end-devices try to access the network. To achieve stable and high throughput of LoRa, we propose a design to combine the distributed queueing (DQ) and in-band-full-duplex (IBFD) technologies. The usage of DQ mechanism is benefit for fast collision resolution, while the IBFD-enabled gateway helps to reduce the heavy control overhead of DQ. The designs of access procedure and frame structure are discussed in detail. The outage probability and average throughput are evaluated under imperfect self-interference cancelation. Also, a mathematical programming method is developed to optimize the spreading factor and code rate. Numerical results show that our proposal gains an extra enhancement of 1.83-fold in throughput