Simple Closed-Form Approximation to Ricean Sum Distributions

This letter focuses on the approximation of Ricean sum distributions of L independent random variables. Although no closed-form expression is available for these exact distributions, a simple but accurate closed-form approximation is proposed. The expression is based on the Central Limit Theorem (CLT) for which an appropriate correction term is added. The result is a rather tight fit with the exact distribution for a wide range of input values and Ricean K-factors.