The ionospheric layers critical parameters are very vital for application of terrestrial communication; however due to lack of observation, especially, in Africa sector, they are not well characterized. Fortunately ionosonde station in Djibouti has measured ionospheric layers parameters for about a decade, but the data from this station has not been used for detail investigations of the characteristics of the ionosphere, thus thesis presents the statistical study of ionospheric critical parameters by using long- time data in East Africa longitudinal sector. The ionosonde measurement is used to validate the known ionospheric model, i.e., the IR-2016.The performance of IRI-2016 in reproducing foF1 and foF2 is validated over Djibouti (Geographic latitude 11.50N and longitude 42.80E), East Africa by considering ionosonde measurements deployed at Djibouti. The modeled and observed ionosonde data of foF2 and foF1 was analyzed for the year from 1971to 1981 in terms of monthly, seasonal and mean annual variations. therfore our result indicates that the maximum foF2 was observed during equinoctial months whereas the minimum was recorded during solstice months. Besides, the model could capture trends, dynamics and peak values of the measured foF2 and foF1. The model overestimated the observed foF2 and foF1 values in most cases. The miss modeling analysis indicated that the annual or monthly deviation of modeled foF2 from observed values can reach up to 5MHz.