Ibrahim M.Zahara M.M.Noaman S.Ragab A.S.Department of communicationsTELECOM EGYPTMSA UNIVESITYEgypt; Department of Communications EngineeringAL AZHAR UNIVESITYEgypt2020-01-092020-01-09201319928645https://cutt.ly/Qr1fqP7ScopusProviding WiMax broadband services via high altitude platforms (HAPs) is still an open research issue. One of the major problems affecting the system performance on the link level is Doppler Effect caused by the mobility of the served users. This paper investigates the Doppler effects on the bit error rate of mobile users in the downlink of the WiMax802.16m standard. The system key parameters that affect the error bit rate performance are also studied. These parameters include the channel propagation model. The Bit Error Probability (BEP) is the performance metric used to evaluate the downlink performance. Numerical results provided through simulations show that providing WiMax through high altitude platforms enhances the BER performance over that expected from conventional terrestrial systems. � 2005-2013 JATIT& LLS. All rights reserved.EnglishOctober University for Modern Sciences and ArtsUniversity for Modern Sciences and ArtsMSA Universityجامعة أكتوبر للعلوم الحديثة والآدابOctober University for Modern Sciences and ArtsUniversity for Modern Sciences and ArtsMSA Universityجامعة أكتوبر للعلوم الحديثة والآدابDoppler effectHAPsIEEE802.16mMobilityWimaxArticle