中文摘要：

为了增加传统OFDMA蜂窝系统的上行链路覆盖,采用了两跳中继方式.在两跳中继蜂窝系统模型的基础上,将概率理论应用于基于译码转发中继的OFDMA系统中.通过数值计算,获得两跳中继OFDMA蜂窝系统的上行链路覆盖闭合表达式,并提出了有效覆盖半径的概念.假设用户在小区范围内服从均匀分布,从两跳中继系统的上行链路出发,分别对单小区和多小区情况下的覆盖性能进行理论分析,得到了系统覆盖优化模型,然后采用迭代算法对中继站部署的最优位置进行求解.最后实验结果表明,在多小区情况下,两跳中继蜂窝系统所获得的有效覆盖半径要明显小于单小区情况.此外,通过选取合适的参数,整个系统可以获得最大的有效覆盖半径.

英文摘要：

To increase the uplink coverage of traditional OFDMA（ orthogonal frequency division multiple access） cellular systems,a two-hop relay was adopted. Based on the system model of the two-hop relay cellular systems,the probability theory was applied to DF（ decode-and-forward） relay-enhanced OFDMA systems. The closed form expressions of the model on the system coverage were obtained by mathematical calculating and a definition of the effective coverage radius was proposed. Assuming that users were obeyed with a uniform distribution in the cell,the coverage performance of single cell and multi-cells for the uplink transmission were analyzed,respectively.Then,the optimization model of the system coverage was derived,and an iterative algorithm was used to determine the optimal position of the relay station. The experimental results showthat when considering the multi-cell scenario,the effective coverage radius of the two-hop relay cellular systems was significantly smaller than that of the single cell. Moreover,by selecting the appropriate parameters,the entire system can obtain the maximum effective coverage radius.