On the Sum of Squared \eta-\mu Random Variates With Application to the   Performance of Wireless Communication Systems
  The probability density function (PDF) and cumulative distribution function of the sum of L independent but not necessarily identically distributed squared \eta-\mu variates, applicable to the output statistics of maximal ratio combining (MRC) receiver operating over \eta-\mu fading channels that includes the Hoyt and the Nakagami-m models as special cases, is presented in closed-form in terms of the Fox's H-bar function. Further analysis, particularly on the bit error rate via PDF-based approach, is also represented in closed form in terms of the extended Fox's H-bar function (H-hat). The proposed new analytical results complement previous results and are illustrated by extensive numerical and Monte Carlo simulation results. 
Imran Shafique Ansari, (Student Member, IEEE), Ferkan Yilmaz, (Member,   IEEE), and Mohamed-Slim Alouini, (Fellow, IEEE)
cs.IT math.IT math.PR math.ST stat.TH