A feature of wireless networks, network topology refers to the physical placement and arrangement of the nodes in a network's layout. Considering topologies early is an important step in facilitating an effective wireless network.
In many cases, a network will have to communicate across a considerable physical distance or through various surfaces that interfere with signal. This requires the use of links and repeaters that extend the range to a group of nodes (Point-to-Multipoint). Other times, nodes are close together and can be fully connected to each other node on the network (Point-to-Point). Both of these are varieties of network topology.
When measuring most every portion of the radio frequency spectrum, some amount of energy is likely to be detected. When this energy is intentionally emitted for the sake of communication, it's referred to as a signal. When it is being unintentionally emitted and not used for an intended purpose, it is referred to as noise or sometimes as static. The aggregate of all noise measured within given portion of the radio frequency spectrum is referred to as the Noise Floor as it is a baseline that a signal must exceed initiate or maintain a transmission. Noise, like a signal, is typically measured in decibels (dB).