Multi-link operation (MLO) is a key feature of Wi-Fi 7, which is currently under development. MLO improves throughput and latency by allowing two devices to establish multiple links between them. The maximal gains are achieved when the links do not interfere, and the devices can use them independently. Otherwise, inter-channel interference prevents successful frame reception. In this case, the Wi-Fi 7 standard forbids simultaneous transmission and reception on such links. This demo shows the effect of cross-link interference in Wi-Fi and discuss that even with notable cross-link interference, simultaneous transmission and reception are still possible in some cases.

Non-orthogonal multiple access (NOMA) is a well-accepted technology for future Wi-Fi systems to improve spectral efficiency. NOMA allows an access point (AP) to simultaneously serve multiple devices by splitting the transmit power between them. Using the superposition coding the AP combines signals of different frames with predefined power weights. However, as it is already known, the phase noise caused by hardware imperfections limits the performance of NOMA transmissions. The paper proposes a practical, easy-to-implement, and backward-compatible method to rotate the constellation of the low power signal in order to make it more robust to the phase noise. A mathematical model is developed to find such a rotation angle that minimizes the bit error rate (BER) of the low power frame. A new NOMA Wi-Fi prototype testbed is developed with the new feature of constellation rotation ability, which is used to validate the performance of our proposed method. Many experimental results show the proposed constellation rotation approach significantly decreases the BER in high signal-to-noise scenarios.

Non-Orthogonal Multiple Access (NOMA) is currently considering as a promising technology for increasing the network efficiency in heterogeneous scenarios with different types of traffic and interference conditions. In spite of numerous theoretical works, there are few experimental studies of NOMA, most of which consider cellular networks. In this short paper, we present our pioneering NOMA testbed for Wi-Fi networks. Because the Wi-Fi technology is much simpler and cheaper than the cellular ones, we expect that the testbed can be used by the research community to validate various solutions designed for NOMA in real equipment.