Study of Multi-Link Channel Access Without Simultaneous Transmit and Receive in IEEE 802.11be Networks

Native support for multi-link operation is a key novelty of the future Wi-Fi 7 technology defined by the IEEE 802.11be standard, which is currently under development. With the 6 GHz band recently granted for Wi-Fi operation, the novel multi-link feature enables simultaneous usage of multiple wide channels. Thus, it multiplies the capacity of Wi-Fi networks well beyond the 30 Gbps target of Wi-Fi 7. However, not all stations can simultaneously transmit and receive (STR) information on several links because of cross-channel interference. That is why it is proposed to synchronize the transmissions on different channels. The presence of legacy stations not supporting the multi-link operation raises many issues related to multi-link channel access performance and fairness. This paper evaluates various channel access approaches considered in the context of the Wi-Fi 7 non-STR operation and discusses how to organize channel access in multi-link Wi-Fi 7 congested networks to be both efficient and fair, even in the presence of legacy stations.