NeTS: Small: Transmit Only: Green Communication for Dense Wireless Systems

该提案旨在实现“绿色”物联网（IoT）和使用仅传输设备的绿色通信的愿景。据预测，到2020年，将有500亿台嵌入式设备部署在我们的周围环境中，其中大部分将通过无线通信向云报告数据。因此，必须设计功率消耗最小化并且带宽利用最优化的绿色通信技术。然而，现有的通信协议并未针对功耗和带宽利用率进行优化，因为它们旨在促进通信方之间可靠的双向信息交换-它们的要求与物联网应用完全不同。 新兴物联网应用的需求，如单向通信流、密集部署、小数据包大小，都是显著简化网络设计的机会。本计画的目的是简化嵌入式装置的通讯协定设计，将接收功能从嵌入式装置中移除，使嵌入式装置只将无线资源用于发送应用资料，以达到最低的功率消耗与最大的频宽利用率，并研究一套能在使用仅传输装置的无线网路中达到高吞吐量的演算法。对于只传输网络来说，最大的挑战是处理数据包冲突，因为发送器无法知道其他发送器是否同时发送。仅发送可以被认为是单输入多输出多址（SIMO-MAC）信道，但在SIMO-MAC中，仅发送与信息理论界以前的工作之间存在根本差异-在几乎所有以前的研究中，虽然发送器之间不进行通信，但它们确实依赖于来自接收器的反馈来做出与编码和/或调度相关的传输决策。另一方面，仅传输假设一旦网络被部署并且在操作中，每个发送器就没有来自其他发送器或接收器的任何反馈。在这种情况下，为了减少数据包冲突，并进一步确保数据包冲突不会导致数据包丢失，本项目提出了一套策略，以主动控制网络拓扑结构以及网络部署前的传输调度。首先，一个最佳的接收器放置策略和基于网络动态的发射器放置策略，提出了利用事实，更强的信号可以在接收器处解码，以最大限度地减少在冲突期间的数据包丢失。其次，提出了一种传输调度算法，以重叠可以一起解码（由不同的接收机），以尽量减少冲突的传输。所提出的调度算法还考虑了发射机的移动性，以尽量减少其对网络吞吐量的负面影响。

This proposal is targeted at realizing the vision of a "green'' Internet of Things (IoT) and green communication using transmit-only devices. It is predicted that by 2020, there will be 50 billion embedded devices deployed in our ambient environment, most of which will be reporting data to the cloud through wireless communication. Thus, it is imperative to design green communication technologies in which power consumption is minimized and bandwidth utilization is optimized. Existing communication protocols, however, are not optimized for power consumption and bandwidth utilization because they were designed to facilitate reliable two-way exchange of information between communicating parties -- their requirements are completely different from those of IoT applications. The needs of emerging IoT applications, such as unidirectional communication flow, dense deployment, small packet sizes, are all opportunities for significantly simplifying network design. This project aims to simplify the protocol design by removing receiving functions from the embedded devices, such that they only spend radio resources on sending application data, thus minimizing power consumption and maximizing bandwidth utilization.This project will study a set of algorithms that can achieve high throughput for wireless networks using transmit-only devices. The biggest challenge for a transmit-only network is the handling of packet collisions as the transmitters do not have any means of knowing whether others are transmitting at the same time. Transmit-only can be thought of as a single-input-multiple-output multiple access (SIMO-MAC) channel, but there is a fundamental difference between transmit-only and previous work in SIMO-MAC from the information theory community - in almost all of the previous studies, while transmitters do not communicate among themselves, they do rely on feedback from receivers to make transmission decisions related to encoding and/or scheduling. Transmit only, on the other hand, assumes once the network is deployed and in operation, each transmitter does not have any feedback from other transmitters or receivers. In this case, to reduce packet collisions, and to further ensure packet collisions do not lead to packet loss, this project proposes a set of strategies to pro-actively control the network topology as well as transmission schedules before network deployment. First, an optimal receiver placement strategy and a network dynamics based transmitter placement strategy are proposed to minimize the packet loss during a collision by exploiting the fact the stronger signal can be decoded at the receiver. Second, a transmission scheduling algorithm is proposed to overlap transmissions that can be decoded together (by different receivers) to minimize the collisions. The proposed scheduling algorithm also takes into consideration transmitter mobility to minimize their negative impact on the network throughput.