A Two-Step Approach to Power Allocation for OFDM Signals Over Two-Way Amplify-and-Forward Relay
A Two-Step Approach to Power Allocation for OFDM Signals Over Two-Way Amplify-and-Forward Relay
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DOI：
10.1109/tsp.2010.2040415
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发表时间：
2010-04
影响因子：
5.4
通讯作者：
Yong-Up Jang;Eui-Rim Jeong;Y. H. Lee
中科院分区：
文献类型：
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作者：
Yong-Up Jang;Eui-Rim Jeong;Y. H. Lee
在双向中继信道（TWRC）中，终端T1和T2通过放大转发（AF）中继T3交换正交频分复用（OFDM）信号，并提出了一种有效的OFDM功率分配技术.通过用限制所有终端的功率之和的总功率约束替换限制每个终端的功率的常规和速率最大化问题的个体功率约束，来制定和速率最大化问题。总功率约束下的最大化问题产生了一个更有效的功率分配策略比传统的问题与个人的功率约束。结果表明，对于一个单音系统（N=1），可以得到总功率约束下的最大化问题的封闭形式的解决方案。在此基础上，提出了一种两步次优方法，首先将功率最优分配给每个音调，然后在每个音调上将分配的功率分配给三个终端。所提出的方法被示出为分配总功率的50%的中继T3的信道无关。结果表明，所提出的方法是相当简单的实现比传统的双重分解方法（DDM），但前者的性能几乎是相同的，后者。
A two-way relay channel (TWRC) in which two terminals T 1 and T 2 exchange orthogonal frequency division multiplexing (OFDM) signals with the help of an amplify-and-forward (AF) relay T 3 is considered here, and an efficient technique for allocating powers to N parallel tones of OFDM is developed. A sum rate maximization problem is formulated by replacing the individual power constraints of the conventional sum rate maximization problem, which limit the power of each terminal, with the total power constraint limiting the sum of powers of all terminals. The maximization problem with the total power constraint yields a more efficient power allocation policy than the conventional problem with individual power constraints. It is shown that the closed-form solution of the maximization problem under the total power constraint can be obtained for a single-tone system (N=1). Based on this result, a two-step suboptimal approach is proposed in which the power is optimally assigned to each tone first, and then at each tone the assigned power is distributed to the three terminals. The proposed method is shown to assign 50% of the total power to relay T 3 irrespective of the channels. It is demonstrated that the proposed method is considerably simpler to implement than the conventional dual-decomposition method (DDM), yet the performance of the former is almost identical to that of the latter.