Resource Allocation for Active Channels

在过去的十年中，中继辅助通信一直是密集的研究重点。已经在单向或双向中继网络的上下文中提出了许多依赖策略，包括放大转发、解码转发、估计转发，其目的是实现一对或多对源-目的地之间的通信或实现一对或多对收发器之间的信息交换。事实证明，中继信道属于更大类别的信道，即活动信道，其中可以在信道两端之间的某处调整信道行为以获得最佳性能。这样的信道可调节性在传统信道模型（它们在本文中被称为被动信道）中不存在。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，必须在发射机处采取预编码和/或在接收机处均衡信道。 在活动信道中，除了发射机处的信号预编码和/或接收机处的信道均衡之外，还可以调整信道本身。例如，在中继信道中，端到端信道脉冲响应可以通过明智地设计中继操作并在信道特性上以及在信号预编码操作和接收器侧信道均衡上优化某个性能度量来仔细地确定。申请人通过发表在著名期刊上的几篇出版物，即IEEE Transactions on Signal Processing（两篇论文）和IEEE Signal Processing Letters（一篇论文），开创了活跃渠道的研究。在这些公布的结果中，和速率最大化的问题已经研究了i）具有相等的子信道噪声功率的单向有源并行信道，ii）具有不相等的子信道噪声功率的单向有源并行信道，和iii）具有相等的噪声功率的双向有源并行信道。在所有这些研究成果中，有一个共同的假设：在不同的子信道上的接收信噪比（SNR）是线性相关的信道增益平方。基于该假设，然后在单向方案中在源的发射功率上（或者在双向方案中在不同子信道上两个收发器的发射器功率上）使和速率最大化。在该提案中，申请人详细说明了允许对活动信道进行最优资源分配的研究计划。这是通过引入更一般的（非线性）模型来描述子信道SNR和子信道增益来实现的。这样的任务要求该计划专注于研究不同的绩效指标。该研究计划将研究并行信道，旨在提高数据速率，超越当前的网络数据速率。

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.