Resource Allocation for Active Channels

在过去的十年中，中继辅助通信一直是研究的焦点。在单向或双向中继网络的背景下，已经提出了许多依赖策略，包括放大和转发、解码和转发、估计和转发，目的是使一个或多个源-目的地对之间的通信或使一个或多个收发器对之间的信息交换成为可能。事实证明，中继通道属于更大的一类通道，即活动通道，其中通道行为可以在通道的两端之间进行调整，以获得最佳性能。这种信道的可调性在传统的信道模型中是不存在的（在这里它们被称为被动信道）。实际上，在传统的无线信道模型中，端到端信道通常是给定的，并且对信道行为没有控制。为了补偿信道，必须在发送端进行预编码和/或在接收端进行信道均衡。***在有源信道中，除了在发射机进行信号预编码和/或在接收机进行信道均衡外，还可以调整信道本身。例如，在中继信道中，可以通过明智地设计中继操作并优化信道特性、信号预编码操作和接收机侧信道均衡的某些性能指标来仔细确定端到端信道脉冲响应。申请人在IEEE《信号处理学报》（2篇）和《IEEE信号处理快报》（1篇）等知名期刊上发表多篇论文，在积极渠道上率先开展研究。在这些已发表的结果中，研究了具有等子信道噪声功率的单向有源并行信道，具有不等子信道噪声功率的单向有源并行信道，以及具有等噪声功率的双向有源并行信道的和速率最大化问题。在所有这些研究成果中，有一个共同的假设：不同子信道上接收到的信噪比（SNRs）与信道增益的平方线性相关。基于这一假设，在单向方案中，和速率大于源的发射功率（或者在双向方案中，大于两个收发器在不同子信道上的发射功率）。在本提案中，申请人详细介绍了一项研究计划，该计划允许对活跃渠道进行最佳资源分配。这是通过引入更一般的（非线性）模型来描述子信道信噪比和子信道增益来实现的。这样的任务需要这个程序集中研究不同的性能指标。该研究计划将研究并行信道，目的是在当前网络数据速率基础上提高数据速率。**

In the past decade, relay-assisted communications have been the center focus of intensive research studies. Numerous relying strategies, including amplify-and-forward, decode-and-forward, estimate-and-forward, have been proposed in the context of one-way or two-way relay-networks with the aim to enable communications between one or more pairs of source-destination or to enable information exchange between one or more pairs of transceivers. It turns out that the relay channel belongs to a larger class of channels, namely active channels, where the channel behavior can be adjusted, for optimal performance, somewhere between the two ends of the channel. Such channel adjustability does not exist in traditional channel models (which they are herein referred to as passive channels). Indeed in traditional models of wireless channels, the end-to-end channel is often given and there is no control on the channel behavior. To compensate the channel, one has to either resort to precoding at the transmitter and/or equalize the channel at the receiver. ***In active channels, the channel itself can be adjusted in addition to signal precoding at the transmitter and/or channel equalization at the receiver. For example, in a relay channel, the end-to-end channel impulse response can be carefully determined through judiciously designing the relaying operation and optimizing a certain performance metric over the channel characteristics and over the signal precoding operation and receiver side channel equalization. The applicant has pioneered the research in active channels through several publications which appeared in prestigious periodicals, namely IEEE Transactions on Signal Processing (two papers) and IEEE Signal Processing Letters (one paper). In these published results, the problem of sum-rate maximization has been studied for i) one-way active parallel channels with equal sub-channel noise powers, ii) one-way active parallel channels with unequal subchannel noise powers, and iii) two-way active parallel channels with equal noise powers. In all these research outcomes, there is one common assumption: the received signal-to-noise ratios (SNRs) over different sub-channels are linearly related to the channel gains squared. Based on this assumption, then the sum-rate is maximized over the transmit powers of the source in one-way schemes (or the transmitter powers of the two transceivers over different sub-channels in two-way schemes). In this proposal, the applicant details a research program that allows optimal resource allocation for active channels. This is achieved by introducing more general (nonlinear) models to describe the sub-channel SNRs and sub-channel gains. Such a task requires this program to focus on studying different performance measures. This research program will study parallel channels with the aim to increase the data rate beyond current network data rates. **