When we encode a signal (a stream of bits) in the physical layer, we convert the bits into different voltage levels. We have a choice of the signal level range, and how many different levels to use,...

Extracted text: When we encode a signal (a stream of bits) in the physical layer, we convert the bits into different voltage levels. We have a choice of the signal level range, and how many different levels to use, but all communicating nodes must agree on the encoding scheme so that they may properly decode the signal later. For example, we might encode values as either 0 volts (OV) or 5 volts (5V), therefore using two signal levels. We might encode 0V, 10V, 20V, 30V, 40V, 50V and have six signal levels. There is no "correct" choice of encoding scheme for all situations. a) How would the distance of a link affect this decision? (The physical distance between two communicating machines which are using the same encoding scheme) b) In what way might cost be an issue when deciding the scheme?