Advantages of M-ary signalling – summary

  • A higher information transfer rate is possible for a given symbol rate and corresponding channel bandwidth,

or

  • A lower symbol rate can be obtained, leading to a reduced bandwidth requirement for a given information transfer rate. (Both result in an increase of bandwidth efficiency – bits/second/Hz)

 

  Disadvantages of M-ary signalling – summary

  • M-ary baseband signalling results in reduced noise/interference immunity when compared with binary signalling (see Section 3.5), as it becomes more and more difficult to distinguish between symbol states.

  • It involves more complex symbol recovery processing in the receiver.

  • It imposes a greater requirement for linearity and/or reduced distortion in the TX/RX hardware and in the channel (except for orthogonal M-FSK).