Subcarrier Requirement Analysis for Downlink OFDMA Cellular System

摘要

In Orthogonal frequency division multiple access(OFDMA) cellular system,the user at the different location requires different number of subcarriers to satisfy the data rate requirement.We determine average subcarrier requirement for downlink OFDMA cellular system without power control based on the Interference to signal ratio(ISR).A typical downlink OFDMA cellular system model is proposed.Based on this model,we calculate the Cumulative distribution function(CDF) of ISR,and obtain the analytical expression of the average number of subcarriers required in the whole cell.Through numerical calculation and Monte-Carlo simulations,we analyze the impact of the various parameters on the average number of subcarriers required of the downlink OFDMA cellular system in random subcarrier allocation policy.And the results are compared with that in grouping subcarrier allocation and adaptive subcarrier allocation.These study results are useful in the performance evaluation,design,planning of resources and call admission control of OFDMA cellular networks like LTE.