Can I use my terminal freely on any network?

我可以在任何网络上自由使用我的终端吗？

How is access to the network controlled and, especially,is there a piece of equipment to do that?

如何控制对网络的访问，特别是有一台设备可以做到这一点？

These are the questions we will answer in this video.

以下是我们将在本视频中回答的问题。

We must remember that it’s not just data packets corresponding to the video stream I’m watching that are travelling on the network.

我们必须记住，不只是与我正在观看的正在网络上旅行的视频流相对应的数据包。

There’s also a set of control functions to be put into place.

还有一套控制功能可以实施。

We will, for example, verify that the subscriber is authorized to use the network before giving him access.

例如，我们将验证订户是否有权在授予其访问权限之前使用网络。

If he is not authorized because he did not pay his bill, for instance,the access should be refused.

例如，如果他没有获得授权，因为他没有支付账单，则应拒绝访问。

These control procedures require the use of a database.

这些控制程序需要使用数据库。

In 4G, this is called the HSS,  Home Subscriber Server.

在4G中，这称为HSS，归属订户服务器。

It was called the HLR (Home Location Register) in 2G/3G.

它被称为2G / 3G的HLR（归属位置寄存器）。

In the HSS, we find the profile of all the network subscribers, that is, the list of all the subscribers, their identity, their rights, I mean the services subscribed to,and their location.

在HSS中，我们找到所有网络订户的配置文件，即所有订户的列表，他们的身份，他们的权利，我指的是订阅的服务以及他们的位置。

There are also security data, which enable access control.

还有安全数据，可以实现访问控制。

The location of the subscriber is very imprecise.

订户的位置非常不精确。

We’ll look at these elements in other videos.

我们将在其他视频中查看这些元素。

To check the profile of a subscriber or get an idea of his location, we need signaling.

要检查订户的个人资料或了解他的位置，我们需要信号。

What is signaling?Signaling is the set of messages exchanged to manage network access.

什么是信令？信令是为管理网络访问而交换的一组消息。

Signaling does not contain user data, what I mean is, it’s not the video stream or the content of a web page.

信令不包含用户数据，我的意思是，它不是视频流或网页的内容。

It is control information that is useful for the operator.

它是对操作员有用的控制信息。

Signaling corresponds, for example, to access control, to the tracking of terminals when they move.

例如，信令对应于访问控制，以及当终端移动时对终端的跟踪。

The HSS, this is a very important point, only exchanges signaling.

HSS，这是一个非常重要的一点，只交换信号。

It only takes care of control: no data packet corresponding to the video stream, to continue my example, goes through the HSS.

它只关注控制：没有与视频流对应的数据包，继续我的例子，通过HSS。

Throughout this course, we will present elements specific to control in blue.

在本课程中，我们将以蓝色呈现特定于控制的元素。

So, if I try to access the network of an operator other than mine, when I try to access this

network, the terminal will send a message that will be forwarded up to the HSS and it will verify the access.

因此，如果我尝试访问除我的操作员之外的其他操作员的网络，当我尝试访问它时

在网络中，终端将发送一条消息，该消息将被转发到HSS并且它将验证该访问。

If I’m not on the subscriber list, I will be refused access.

如果我不在订户列表中，我将被拒绝访问。

If we analyze a bit what can happen, we have several tens of millions of subscribers in the network.

如果我们分析一下会发生什么，我们在网络中有数千万用户。

That corresponds more or less to several tens of millions of terminals.

这或多或少地对应于数千万个终端。

If, every time someone moves or does something on his terminal, and we want to control access, we have to send a request to the HSS.

如果每当有人在他的终端上移动或做某事，并且我们想要控制访问时，我们就必须向HSS发送请求。

The HSS, even though they are powerful, risk being saturated, having to manage this set of simultaneous control requests.

HSS即使功能强大，也有可能饱和，必须管理这组同时控制请求。

On top of that a lot of signaling exchanges to manage the sporadic we  need nature of transmissions.

最重要的是，为了管理零星的大量信令交换，我们需要传输的本质。

we’ll see this in the course.

我们会在课程中看到这一点。

Therefore, we introduce the MME,  the Mobility Management Entity.

因此，我们介绍了MME，移动管理实体。

The MME manages a very large region and will be connected via the operator’s network to various eNodeBs.

MME管理一个非常大的区域，并通过运营商的网络连接到各种eNodeB。

The objective of the MME is to control mobility, to control the various terminals.

MME的目标是控制移动性，以控制各种终端。

This means that, when I turn my terminal on, it sends a request to the eNodeB which will send a request to the MME at the moment of what we call ‘attachment’ to the network and then the MME checks to see if it knows the subscriber.

这意味着，当我打开终端时，它向eNodeB发送请求，该请求将在我们称之为“附件”到网络的那一刻向MME发送请求，然后MME检查它是否知道 订户。

Generally, he’s not known if this is the first time the terminal is powered up.

一般来说，他不知道这是否是终端第一次通电。

So, the HSS will transmit to the MME the subscriber profile, that is, all his access rights, the services he’s subscribed to.

因此，HSS将向MME发送订户简档，即他所有的访问权限，即他订阅的服务。

Then, for all future access,each time there’s a verification to make, the MME will be able to verify locally the subscriber profile recopied in the MME.

然后，对于所有将来的访问，每次进行验证时，MME将能够在本地验证在MME中重新复制的订户简档。

It’s the equivalent, in a way, to cache memory for programmers.

在某种程度上，它等同于为程序员缓存内存。

So, the MME is the node that will be, in a way, the local or regional conductor.

因此，MME是在某种程度上将是本地或区域指挥的节点。

There are several MMEs in a national French network.

法国国家网络中有几个MME。

Like HSS, the MME only exchanges signaling.

与HSS一样，MME仅交换信令。

MMEs are relatively  powerful machines that can manage around ten million subscribers.

MME是相对强大的机器，可以管理大约一千万用户。

We list the main functions of the MME.

我们列出了MME的主要功能。

The MME communicates with the various base stations to establish, for example, configuration functions.

MME与各种基站通信以建立例如配置功能。

It also communicates with the HSS to get the profiles and security information of the subscribers

present in the zone it manages.

它还与HSS通信，以获取其管理的区域中存在的订户的配置文件和安全信息。

The MME stores these profiles and security data.

MME存储这些配置文件和安全数据。

It manages the control mechanisms related to network access, security and mobility for terminals present in its zone.

它管理与其区域中存在的终端的网络访问，安全性和移动性相关的控制机制。

It also maintains an awareness of the location of the terminals in its area, but in a relatively imprecise way.

它还保持对终端在其所在地区的位置的认识，但是以相对不精确的方式。

It selects the P-Gateway and the S-Gateway when the terminal attaches to the network and connects to the Internet.

当终端连接到网络并连接到Internet时，它选择P-Gateway和S-Gateway。

The data exchanged between the terminal and the servers of the Internet network will travel through this P-Gateway and this S-Gateway.

在终端和因特网网络的服务器之间交换的数据将通过该P-网关和该S-网关。

The MME ensures the “reachability” of the terminal.

MME确保终端的“可达性”。

Finally, it is involved in what is called handover or handoff, that is, the possibility of keeping a session active when the user moves and changes cells.

最后，它涉及所谓的切换或切换，即，当用户移动和更改单元时保持会话活动的可能性。

We can see that the MME is a very important piece of equipment in the core of the 4G network.

我们可以看到MME是4G网络核心中非常重要的设备。