中文摘要：

针对协作通信中的中继选择问题，提出不同功率分配方式下的自适应中继选择方案，仅在必要时引入额外中继。在源节点和中继节点等功率分配时，利用定义的可行双中继区域缩小候选中继搜索范围。在最优功率分配时，利用几何规划方法对潜在中继进行遍历搜索。仿真结果表明，与传统固定选择方案相比，该方案可有效降低系统功耗。

英文摘要：

For the relay selection in cooperative communications, adaptive relay selection strategies are proposed for different power allocation schemes, where an additional relay can be employed when it is necessary. For Equal Power Allocation（EPA） among the source and relays, the search range of candidate relays can be effectively decreased by using the defined feasible two-relay region. For Optimal Power Allocation（OPA）, the potential relays can be searched exhaustively by geometric programming. Numerical simulation results show that the proposed adaptive relay selection strategy with power optimization can significantly reduce the power consumption of the system compared with the traditional fixed selection strategy.