The increased demand for communication capacity combined with inefficient utilization of the spectrum that is currently available has led to a shortage of spectrum. An improvement in the inefficient utilization of the current spectrum is possible through the use of opportunistic access to licensed bands, which does not interfere with the primary users. The existence of primary users makes it difficult to access channels, which makes cognitive environments a complex setting in which to perform tasks like routing and spectrum access. The task of creating and maintaining wireless multihop pathways between cognitive nodes is the primary focus of the routing problem in cognitive networks. This task involves determining both the frequency that will be utilised and the hop count at each node along the path. Within the scope of this work, we present a cross-layer optimization technique with the goal of achieving the aforementioned goal. We suggested using an adaptive cross-layer optimised subcarrier distribution technique for WSN so that it could give optimal performance while also consuming a low amount of energy. In order to achieve this goal, a technique known as the Modified Optimal Link State Routing (MOLSR) Protocol was put into place. A fair scheduling algorithm and proportional algorithms are described here to assign the subcarriers to the sensors in accordance with the conditions of their respective channels. In order to draw conclusions about the performance of the proposed MOLSR algorithm, the results of the simulation are analysed, and the findings are compared to those of a typical multicarrier (MC) system in terms of both bit error rate and throughput. To begin, the congestion-aware routing algorithm is put into action in order to modify the data rate of each individual node in accordance with the current queue state and the Received Signal Strength Indicator (RSSI). We are also able to draw the conclusion that the proposed protocol is an extremely energy-efficient system for carrying out optimal stable multipath routing with relatively minimal congestion in the network while the data is being transmitted.