NeTS: Medium: Cortex: Rateless Wireless Networking Using Spinal Codes

由于功能强大的移动设备的出现以及数量庞大且数量不断增长的网络密集型移动应用程序，全球对无线网络接入的需求正在以惊人的速度增长。为了满足这种需求并为应用程序提供高吞吐量和低延迟，无线网络协议需要解决一个基本问题：它们需要对抗噪声、来自其他节点和外源的干扰以及信道衰落。这些因素导致无线信道条件随时间变化，使其难以实现高性能。该方案提出了一个理想的解决方案，即在无速率代码的基础上设计一个网络架构。在无速率无线网络中，发送方对数据进行编码，无需任何显式估计或自适应，而隐式地适应噪声、干扰或衰落带来的变幻莫测。接收方在数据到达时处理数据（符号或位），解码，直到消息被成功接收。任何无速率网络的构建模块都是一个强大的编码方案，没有它，这样的愿景只是纯粹的概念。该方案为无线信道引入了一种新颖的无速率码，即脊码，它在消息位上使用伪随机哈希函数来产生伪随机位，这些伪随机位可以直接映射到密集的群集进行传输，也可以与传统的物理层一起使用。实际上，使用散列函数可以在不损失性能的情况下实现低复杂度的代码设计。该提案开发了Cortex，一个建立在脊髓编码之上的无速率无线网络。建议的工作将导致以下领域的贡献：使用脊髓编码的协议和编码和解码算法，研究使用这些算法可实现的速率的理论结果，以及脊髓编码和更高层协议的实现和实验评估。一个好的无速率系统有潜力在具有挑战性的条件下实现高性能，同时也降低了无线架构的复杂性。在此提案期间，pi计划与一些有能力影响标准并使用提议的想法构建商业系统的公司密切互动。教育计划包括在本科课程中引入无速率思想，特别是麻省理工学院的“EECS-II入门”课程（\url{http://mit.edu/6.02}），该课程通过从数据包到比特再到信号的分层，介绍了CS/EE的兴奋之处。研究生水平的教育目标是通过使用Airblue的实践项目来教授无速率无线架构和编码技术的思想，这将补充理论思想，协议设计和架构思维的教学。网络课程和硬件设计课程（MIT课程6.829、6.263、6.266和6.375）都会受到影响。课程材料将通过麻省理工学院开放课程（OCW）广泛提供。

Worldwide demand for wireless network access is increasing at a tremendous rate, thanks to the emergence of powerful mobile devices and a large, growing number of network-intensive mobile applications. To cope with this demand and provide high throughput and low latency to applications, wireless network protocols need to solve a fundamental problem: they need combat noise, interference from other nodes as well as exogenous sources, and channel fading. These factors cause wireless channel conditions to vary with time, making itchallenging to achieve high performance. This proposal posits that an ideal solution to this problem is to design a network architecture over a rateless code. In a rateless wireless network, the sender encodes data without any explicit estimation or adaptation, implicitly adapting to the vagaries introduced by noise, interference, or fading. The receiver processes data (symbols or bits) as it arrives, decoding it, until the message is received successfully.The building block for any rateless network is a strong coding scheme, without which such a vision remains purely conceptual. This proposal introduces a novel rateless code for wireless channels, the spinal code, which uses a pseudorandom hash function over the message bits to produce pseudorandom bits that in turn can be mapped directly to a dense constellation for transmission or can be used along with the traditional physical layer. Effectively, the use of a hash function allows for low-complexity code design without loss of performance. The proposal develops Cortex, a rateless wireless network built atop spinal codes. The proposed work will lead to contributions in the following areas: protocols using spinal codes and algorithms for encoding and decoding them, theoretical results investigating the rates achievable using these algorithms, and an implementation and experimental evaluation of spinal codes and higher-layer protocols.A good rateless system has the potential to achieve high performance under challenging conditions while also reducing the complexity of wireless architectures. Over the duration of this proposal, the PIs plan to interact closely with a few companies that have the ability to influence standards and build commercial systems using the proposed ideas. The education plan includes the introduction of rateless ideas into the undergraduate curriculum, particularly MIT's "Introduction to EECS-II" course (\url{http://mit.edu/6.02}), which introduces the excitement of CS/EE by cutting across the layers, going from packets to bits to signals. The graduate-level education goals are to teach the ideas of rateless wireless architectures and coding techniques by way of hands-on projects using Airblue, which will complement the teaching of the theoretical ideas, protocol design, and architectural thinking. The impact will be felt in courses on networking as well as hardware design (MIT courses 6.829, 6.263, 6.266, and 6.375). The course material will be made widely available through MIT OpenCourseWare (OCW).