Co-Existence With IEEE 802.11 Networks in the ISM Band Without Channel Estimation

Any new deployment of networks in the industrial, scientific, and medical (ISM) band, even though it is license-free, has to co-exist with IEEE 802.11 networks. IoT devices are typically deployed in the ISM band, creating a spectrum bottleneck for competing networks. This article investigates the issue of co-existence of wireless networks with WiFi networks. In our scenario, we consider WiFi as the “primary” or higher priority network co-existing with multiple “secondary” networks that may be used for low priority devices, with both networks operating in the ISM band. Towards this end, we first develop an analytical model for a metric called the “received symbol distance” at the primary receiver to obtain a power control parameter for secondary users. This power control parameter is used to scale the power of the secondary user according to the wireless channel between the primary transmitter and primary receiver. The proposed approach is computationally simple and does not require any estimation of channel coefficients. Simulation results show that the proposed technique can be used to effectively increase the spectrum utilization and the probability of a successful transmission by the secondary user, while not having any harmful effect on the primary user.