Tight approximation for coherent MPSK symbol error probability

Many bounds for symbol error probability of MPSK have been used in the literature because a closed form expression that does not require a numerical integration for MPSK symbol error probability has not yet been derived. The bounds for MPSK symbol error probability used in the past are simple to calculate but inaccurate, or accurate but complex. A very simple and extremely tight new approximation is presented of symbol error probability for coherent MPSK.