Spectral Efficiency
Sašo Tomažič · Encyclopedia of Wireless and Mobile Communications · 2007
Spectral efficiency is a measure of the performance of channel coding methods. It refers to the ability of a given channel encoding method to utilize bandwidth efficiently. It is defined as the average number of bits per unit of time (bit rate) that can be transmitted per unit of bandwidth (bits per second per Hertz). The term channel encoding refers to the procedure of mapping a bit stream to an analog signal, which can be transferred through a physical channel and later, after reception, decoded to yield the original bit stream, as shown in Fig. 1. The received signal may be distorted in various ways and corrupted by noise and other interference on the channel. This can cause the bit stream at the output of the channel decoder to be different from the bit stream at the input of the channel encoder. The ratio of erroneously received bits to all transmitted bits is called the BER and is used as a measure of performance. A small BER is