المجلة الدولية للعلوم والتقنية

This research investigates the effects of Channel Quality Indicator (CQI) feedback delays on the Joint User Scheduling Scheme (JUS) and the Separated Random User Scheduling Scheme (SRUS) within an LTE-Advanced (LTE-A) system utilizing carrier aggregation. The study will compare scenarios involving delayed channel information against those with perfect channel knowledge across various deployment contexts. The analysis considers CQI delays ranging from 3 to 6 milliseconds, with the upper limit set at 6 milliseconds, as delays exceeding this threshold are deemed impractical for LTE-A systems. This range effectively reflects the delays associated with LTE-A feedback protocols and the realistic processing times of evolved Node B (eNB). The focus is on a downlink Orthogonal Frequency Division Multiplexing (OFDM)-based carrier aggregation system, which comprises multiple eNode-Bs and numerous User Equipments (UEs) distributed randomly within the cell. Each component carrier (CC) is made up of R Resource Blocks (RBs), with each RB containing K subcarriers in the frequency domain and one frame in the time domain. The traffic model employed in this study is a continuous data stream (Full Buffer), which serves, as a useful baseline despite being an idealized scenario, as scheduling and user throughput remain unaffected by the volume of data in the transmission buffer................. Keywords: .......CQI delay, Scheduling, LTE-A