The proliferation of mobile devices and the heterogeneous environment of wireless communications have increased the need for additional spectrum for data transmission. It is not possible to altogether allocate a new band to all networks. which is why fully efficient use of the already available spectrum is the demand of the day. Cognitive radio (CR) technology is a promising solution ... http://ashleyshomestores.shop/product-category/power-reclining-sofa-with-adjustable-headrest/