The Ionospheric Plasma and Electrodynamics Instrument (IPEI) onboard ROCSAT -1 is designed to measure the ion composition, density, temperature and drift velocity at the 600 km altitude along the ROCSAT-1 orbit within the latitude band of ¡_35o. The unique features of the 100% duty cycle together with the 1 kHz sampling rate capability of the IPEI payload will enable us to make a significant contribution to the study the dynamic behavior of low-latitude ionospheric phenomena such as the bottom- side sinusoids, the equatorial spread F and the latitude effect of space weather phenomena during the active phase of Solar Cycle 23.