多中继OFDM系统选择性子载波中继和功率分配算法

Selective subcarrier relaying and power allocation algorithm for multi-relay-assisted OFDM systems

对于多中继OFDM放大转发协作通信系统,在各个中继节点功率独立受限的条件下,中继节点转发子载波的数目较多时,每个子载波所能分配到的功率较少,而将此中继节点转发的部分子载波转由空闲的中继节点转发,可以获得更大的功率增益。为此,本文提出了一种改进算法。在中继节点距离源节点较近时,充分利用空闲中继节点的功率,提高系统容量,在中继节点距离源节点较远时,削减中继节点数目,降低系统复杂度。仿真结果表明,本文算法在中继节点距离源节点较近时获得了更大的系统容量,在中继节点距离源节点较远时,保持系统容量基本不变,降低系统复杂度,易于实现。

For multi-relay-assisted Orthogonal Frequency Division Multiplexing （OFDM） cooperative systems with Amplify-and-Forward （AF） mode, when relay nodes are close to the source node, higher system gain can be achieved, otherwise, the system will get lower gain. Under the condition that each relay node has individual power constraint, the more subcarriers relay nodes forward, the less power of each sub-carrier is allocated. Greater power gain can be acquired when some of the sub- carriers are forwarded by idle relay nodes instead of the previous busy node. Therefore, we propose an improved algorithm. In this algorithm, when relay nodes are close to the source node, we make full use of the power of the free relay nodes to increase system capacity. When relay nodes are far from the source node, the relay node number is reduced to decrease system complexity. Simulation results show that the improved algorithm can obtain higher system capacity when the relay nodes are close tothe source node, and it also can approximately maintain system capacity unchanged with lower system complexity when relay nodes are far from the source node.