Two enhanced schemes for coordinated spatial reuse in IEEE 802.11be: Adaptive and distributed approaches

Abstract

Coordinated spatial reuse (CSR) is a novel mechanism that has attracted significant discussion in the upcoming Wi-Fi standard. Once a sharing access point (AP) acquires a transmission opportunity (TXOP), it informs a neighboring AP, designated as a shared AP, of the maximum tolerable interference level. The shared AP then calculates its maximum transmit power accordingly, thereby reducing interference and ensuring successful parallel transmissions. However, the CSR has three drawbacks. Firstly, it lacks explicit criteria for selecting multiple shared APs, disregarding the cumulative interference that arises from multiple shared APs. Secondly, excessive signaling occurs due to the periodic update and exchange of received signal strength indicator (RSSI) information among all the APs. Thirdly, the area throughput may suffer due to the low signal to interference plus noise ratio (SINR) experienced by shared APs, as only the shared AP constrains transmit power while the sharing AP transmits at its maximum.

To address these drawbacks, we propose two enhanced schemes for CSR. The first is adaptive CSR (ACSR), which can easily assess whether a neighboring AP should participate in CSR and adaptively determine the desired number of shared APs. The final transmit powers determined for shared APs in ACSR ensure that both the sharing AP and the shared APs meet the SINR requirements, thereby enhancing the performance of CSR. Furthermore, we propose a distributed CSR (DCSR) scheme, which formulates area throughput as a convex optimization problem. In DCSR, each AP independently and concurrently solves its own local optimization problems, drastically reducing the signaling overhead for RSSI update and exchange while obtaining optimal transmit powers for all involved APs. The DCSR scheme can adaptively determine the optimal number of shared APs. The proposed DCSR effectively overcomes all the drawbacks of the original CSR.

Analysis results show that the ACSR and DCSR outperform the CSR, achieving 1.45 and 2.57 times higher area throughput, respectively, and increasing the number of successful parallel transmissions (NSPT) by 1.45 and 2.8 times, respectively.