# 网络运作：无需微积分的原理简介

Networks Illustrated: Principles without Calculus

## 34 小时

• 英语
• 540

### 课程概况

What makes WiFi faster at home than at a coffee shop? How does Google order its search results from the trillions of webpages on the Internet? Why does Verizon charge \$15 for every GB of data we use? Is it really true that we are connected in six social steps or less?

These are just a few of the many intriguing questions we can ask about the social and technical networks that form integral parts of our daily lives. This course is about exploring the answers, using a language that anyone can understand. We will focus on fundamental principles like “sharing is hard”, “crowds are wise”, and “network of networks” that have guided the design and sustainability of today’s networks, and summarize the theories behind everything from the social connections we make on platforms like Facebook to the technology upon which these websites run.

Unlike other networking courses, the mathematics included here are no more complicated than adding and multiplying numbers. While mathematical details are necessary to fully specify the algorithms and systems we investigate, they are not required to understand the main ideas. We use illustrations, analogies, and anecdotes about networks as pedagogical tools in lieu of detailed equations.

All the features of this course are available for free. It does not offer a certificate upon completion.

WiFi在热点处为什么较慢？

Netflix如何推荐电影？

### 课程大纲

Introduction
An introduction to what this course is about: the fundamentals behind social and technical networks.
5 个视频 （总计 39 分钟）, 3 个阅读材料

Power Control in Cellular Networks
How is it possible that we can all communicate effectively without disrupting each other's calls, messages, or Internet usage? In this lesson, we
will take a look at some of the methods that have been developed for letting us "share" the air over which our phones communicate.
21 个视频 （总计 125 分钟）, 1 个阅读材料, 1 个测验

Random Access in Wifi Networks
In this lesson, we will investigate WiFi, another type of wireless network. Rather than having stringent power control algorithms as we saw for
cellular, WiFi relies on "random access" methods to manage interference among users in the same location.
15 个视频 （总计 98 分钟）, 1 个阅读材料

In this lesson, we will take a look at PageRank, Google's famous algorithm for ordering the results on its search page. PageRank is a prime
example of how coming up with the right "ranking" of a set of items is a difficult yet important question in networking.
11 个视频 （总计 67 分钟）, 1 个阅读材料, 1 个测验

Product Rating on Amazon
The decision of whether or not to purchase something online is often driven by the ratings that previous customers have left for it. In this
lesson, we will take a look at Amazon's review system, and the see how "crowds are wise" is another important networking principle.
11 个视频 （总计 69 分钟）, 1 个阅读材料

Movie Recommendation on Netflix
One of the perks of having a Netflix subscription is getting recommendations of movies to watch. Behind the scenes, Netflix uses powerful algorithms to determine which will be suggested to each person specifically. In this lesson, we will take a look at the main ideas behind these algorithms.
18 个视频 （总计 111 分钟）, 1 个阅读材料, 1 个测验

Midterm
1 个测验

What does it take for a video to become "viral" on YouTube? In this lesson, we will take a look at some of the key factors and models that have been used to explain this phenomenon. At the core is the notion of information cascade in a network, which is the counterpart to the wisdom of crowds.
12 个视频 （总计 77 分钟）, 1 个阅读材料

Influencing People in Social Networks
In this lesson, we will continue with our theme of influence, now paying more attention to people's social networks. We will discuss different
ways of measuring importance and a popular model for influence spread in social networks like Facebook and Twitter.
13 个视频 （总计 89 分钟）, 1 个阅读材料, 1 个测验

Pricing Data
Data makes up a significant part of our cell phone bills. How do cellular providers set these price points? In this lesson, we will see how so-called
usage-based pricing schemes can send better signals than flat- rate, “buffet” schemes, leading to better sharing of the network.
11 个视频 （总计 76 分钟）, 1 个阅读材料

Routing Traffic through the Internet
It is hard to overstate the impact that the Internet has had on society. In this lesson, we will overview the fundamental concepts behind the way
the Internet is designed. We will also take a look at routing, which is the process of determining how packets of information are transported.
22 个视频 （总计 83 分钟）, 1 个阅读材料, 1 个测验

Controlling Congestion in the Internet
The Internet has many important tasks to manage, like routing packets (discussed in the last module) and controlling congestion. This workload is modularized into different functional layers, each responsible for performing a different set of functions, as we will see in this lesson. We will also look at the principles of congestion control, managed at the transport layer.
18 个视频 （总计 77 分钟）, 1 个阅读材料

It's a Small World
Six degrees of separation is a widely told story in popular science. How can it still be a "small world" with the enormity of the Internet today? It
depends on how the social networks are structured, and on how we search for short paths, as we will see in this lesson.
17 个视频 （总计 99 分钟）, 1 个阅读材料, 1 个测验

Final Exam
The final covers the last six lessons in the course (those after the midterm). Like the midterm, the questions are all multiple choice, and tend to
be easier than the homework questions but harder than the in-video quizzes.

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