"Know almost Knowledge" - 5G
https://zhuanlan.zhihu.com/p/55998832
thank
~ This article is a summary of invited several answers, hoping to make it clear 5G I understand.
1 Introduction
Since the birth of human society, how to efficiently and quickly transmit information is always the pursuit of human unshaken. From text to printing, from the tower to the radio signal from the mobile phone to the Internet, the pace of development of modern science and technology have been dependent on the speed of information dissemination, new information dissemination tend to bring about changes in society turned upside down. 5G is the progress of the latest wave of mobile communication stage.
5G is a fifth-generation mobile communication systems (5th generation mobile / wireless / cellular system) for short, is a new generation of mobile communication systems following the 4G (LTE / WiMax).
2. Pre-knowledge
International communication standards
Communication is a two-way behavior, the two sides agreed in advance transmission transceiver need to complete the successful completion of data exchange. Probably because of different country, a different communication system, so when countries of common mobile devices is difficult in the chaotic early mobile communication base station and handset manufacturers, the high cost of international roaming. In order to facilitate international communication, companies need a unified national standard, which is an international communications standard birth.
Organization for Standardization
In the early standard design, in order to define a standard issue to be solved, affiliated with the United Nations ITU (ITU) to be collected more demand from all regions of the working groups and forums, publishing design goals of this communication, and collect technical advice , responsible for the final assessment. The ITU is not involved in the development of specific criteria, which specific technical work is mainly done by the addition of a number of industry standards organizations such as 3GPP and IEEE.
4G era, 3GPP LTE standards dominate (we currently use 4G technology), IEEE dominate the WiMax standards (once in Japan, Taiwan and commercial). At present, 5G standardization work done by the 3GPP. Standards need to see progress 5G of 3GPP schedule, the current 5G is divided into two stages: Release 15 and Release 16, is known as New Radio (NR).
Release 15 is the current 5G first version.
Pictures from ng-voice
A new generation of communications technology is the need to improve data transmission speed, then how to do it?
How to improve data transmission speed
Any lifting of the communication data transfer rate are not open around the Shannon channel capacity formula:
It is readily appreciated slightly, in the same way we 5G will improve the data transfer rate: improve bandwidth and improve signal to noise ratio.
3. Target
In designing the scenes and goals 5G, ITU directly uses two scenarios to promote Chinese IMT-2020 group (mMTC and URLLC), and summarized eMBB, so these scenarios are:
- Enhanced Mobile Broadband (eMBB, Enhanced Mobile Broadband),
- Large-scale machine communication (mMTC, Massive Machine Type Communications)
- Ultra low latency and reliable communications (URLLC, Ultra-Reliable and Low Latency Communications).
FIG from ITU-R may be different from their description,
Come self ITU-R
Phone, video, daily work belongs eMBB, smart city, the machine is huge things belong mMTC, car networking requires low latency and high reliability belong URLLC.
Come self ITU-R
Comparative 4G, the peak rate up from 1Gbit / s to 20Gbit / s, the user can experience the bandwidth from 10Mbit / s upgrade to 100Mbit / s, spectrum efficiency upgrade 3 times, can support 500km / h mobile communication, network delay from 10ms raised to 1ms, the number of connections per square kilometer device from a raised to
a communication device 100-fold improved energy efficiency, improve data throughput per second per square meter 100 times.
Spectrum
Enhance the previously mentioned review the spectral transmission rate mode. In order to achieve the target speed 5G raised, at least requires two spectrum: main spectrum and millimeter-wave spectrum. In fact, Huawei released the spectrum proposal, the proposed plan in three sessions spectrum to 5G, the three-band spectrum are:
- 2 ~ 6GHz (C-band), for use as the main spectrum, both coverage and data transmission, also referred to sub6G spectrum.
- 6GHz or more (such as 24 ~ 29GHz, 37 ~ 43.5GHz), for processing a particular scene, as ultra-fast data transmission.
- 2GHz or less (such as 700MHz), for wide area coverage and indoor scenes coverage.
来自5G SpectrumPublic Policy Position from Huawei
4. Comparison with the 4G
Probably will be appreciated that as fast transfer rate, low transmission delay.
Specifically it is,
A millimeter wave (bandwidth upgrade)
More advanced beamforming (to enhance the signal to noise ratio)
VLSI antenna, full-duplex radio (signal to noise ratio and enhance bandwidth, airspace).
Millimeter Wave
300MHz-3GHz spectrum generation radio communication 1-4 employed in good penetration, a large coverage area, etc., but there is an important drawback: the bandwidth is too narrow! ! Too many wireless devices in this band! ! Spectrum has been divided over fast.
Spectrum nor a negative, so for large-capacity high-speed data transmission, only available spectrum to find above 3GHz.
We look up, and that is a millimeter-wave band (3GHz-300GHz). The presence of two specific portions of the millimeter wave spectrum, the oxygen absorption band (57-64 GHz) and a water vapor absorption bands (164GHz-200GHz), two communication bands can not be used, so that a millimeter wave band 252GHz total bandwidth available ( here we should re-emphasize 1-4 on behalf of all commercial communications in crowded spectrum below 3GHz).
5G is of course actually use that many bands in the millimeter wave spectrum allocation in the national, sub-millimeter-wave band width to 5G of about 3-6GHz, it was enough to improve the data transfer rate of about 10 times.
However, it is emphasized that, 5G standards require three-band, millimeter wave band is mainly responsible for high-speed data transmission, millimeter-wave current standard has not been determined. Although there has been use of millimeter wave radar, aerospace and military communications, but there are many, many civilian communications challenges. . This is also very, very hot wireless communications research, in this answer is not in-depth look.
More advanced beamforming
4G base station antenna is a directional antenna and the omnidirectional antenna mix (thanks comment alert area), because of the narrow millimeter waves. 5G coverage, path loss, severe weather complex, it is necessary to focus the energy emitted by the beam to complete the design, so as to enhance receiving signal energy, to enhance the signal to noise ratio (recall here channel capacity formula), and coverage.
After beamforming directional beam can help improve the coverage of base station. Moreover, the base station will be more energy efficient.
In fact, since the 5G relates Massive MIMO beamforming and tracking user narrow beam of millimeter waves, inter-cell scheduling and beam switching LOS and NLOS base station issues, will be more difficult, this is a great same wireless communication research direction. Many people consider now academia by dividing the sectors within the base station coverage to help multiple antenna beam switching.
Sectorized Antenna
Ultra-large-scale antenna (Massive MIMO)
Wireless communication systems is necessary to give a multi-antenna weights for each antenna, in order to improve spatial diversity / or a multiplexing gain. While the real case, the algorithm is non-linear and computational complexity, the more complicated the more antennas.
But surprisingly, the number of antennas very, very much of the time, a simple linear pre-coding can be a good approach for optimal results. So Massive MIMO made since attracted a lot of attention.
Massive MIMO test bed
Massive MIMO 5G, there may be a large number of applications, not only large macro base stations, small millimeter wave transmitter may also be equipped with Massive MIMO system, since the narrow beam of millimeter wave antenna, the short antenna length, more suitable Massive MIMO applications.
Back to the topic, the benefits of Massive MIMO is the maximum use of airspace resources, can provide multiple users simultaneously beams serving cells through beamforming, and at the same time the user can improve signal to noise ratio, improve data transfer rate. But Massive MIMO pre-coding, channel estimation has been a problem.
Full duplex radio (not currently in Release 15)
All existing wireless transmitter devices are half-duplex, half-duplex means that simultaneously transmit signals unacceptable signal --- otherwise interfere with themselves. (After all, not human, what he says district could not tell yet ....
The radio signal is simultaneously transmit and receive full-duplex, so that data transmission rate can X2, of course, the cost of self-interference in the figure (red arc) problem, even when the user too much, the interference between users will be in the X2.5G The core network design is based on C-RAN-based, which means that self-interference mitigation by scheduling the center, while the use of directional antennas, beam forming, absorbent shield (absorptive shielding) and cross-polarization (cross-polarization) to complete isolation between the transceiver.
Such full-duplex radio is applied. 5G.
Progress is above the physical layer. 5G, together use, that is, how to achieve "the transmission speed fast".
Low propagation delay
We are speaking here of the delay is the round-trip latency, probably can be understood as the total time data access and core network required round-trip. Since radio propagation velocity is relatively fixed, it can not be compressed, so there are two ways of reducing: losses reduce the signaling network and the compression process.
Reduce the signaling way is to minimize the loss of unnecessary signaling, such as
- Full-duplex technology to reduce channel estimation by time,
- Because the millimeter-wave Doppler spread very little, so it can reduce CP prefix of the OFDM signal, compression OFDM frame length,
- By design the millimeter wave base grid, reducing interference and delay
Compression network processing, image understanding is flat corporate hierarchy, decentralization of decision-making power. Such "escalate" fewer times, will significantly reduce the unnecessary network overhead. It also mentioned other main answer.
Standard compression mode the core network, it is "without unnecessary processing unit", in other words a control structure and data transport structure separation. Of course, now there are many other solutions.
A better idea is now compressed academic network structure very hot "fog computing" fog calculation, the number of repetitive calculations is decentralized, the calculation processing unit to do wireless access points (base station, etc.), so that it can be used as a different type of "calculation register" greatly reduce network latency.
Another is very orthodox, of course, very hot research direction "wireless caching" wireless cache, the cache contents of this idea is to reduce the transmission delay.
fog computing
These are delaying the progression of the section 5G, mainly MAC layer technology, probably talking about how effective scheduling of resources, how to reduce latency.
The relationship between the WiFi
Of course, as the user is concerned, my own experience is the most intuitive WiFi is much cheaper than xG, if we ignore the cost of wired broadband router and can even be considered a WiFi Internet connection is free of charge. However, in most cases, prices can only reflect part of the technical factors. If a small home network, extended to the whole country and the world is xG. But between this and a wide range of small-scale, there is a great difference.
For simplicity, this difference between the two, we need to start talking about demand.
Demand difference
Competitive
就WiFi和xG来说，技术上，他们的区别有点类似区域自治和中央集权，这种思路导致了大部分WiFi节点都是私人(或者公司，或者城市)建设，而xG基站是运营商在全国建设。
换句话说，就是在无线信号传输过程中，因为各个私人路由器之间没有交流且共享相同频谱，所以WiFi的数据传输是竞争性的，而xG的数据传输是非竞争的，有中心化资源调度的。
这大概就像公路和铁路，开车出门上路，我们不知道下一个路口会不会突然出现一长串闪着红色尾灯的各种汽车堵在前面；而铁路就不会有这种困扰，前方多远有车，最高可以跑多快都有中心调度系统告诉司机。
私密性
同时，一般意义上，WiFi连接的是私人有线宽带，而xG的基站连接的是运营商的骨干网，因此，WiFi普遍会有私密性要求，不能未经许可随意接入。
(不能白看，也不能白... （:
移动性
因为WiFi连接的是私人有线宽带，私人宽带接入点固定，同时宽带是有线的，它不会到处乱跑。这意味着WiFi对移动性需求很低，覆盖范围小，一般只用考虑步行速度对信号传输的影响，不考虑小区切换，而xG的基站存在很高的移动性和小区切换需求(基站覆盖范围称为小区)，需要考虑比如汽车，火车等高速物体。
除非汽车本身有个WiFi，不然应该是没有人在汽车上一直连着WiFi的吧？目前WiFi有WDS模式，但是还是不如运营商的小区切换成熟。
这样的竞争/非竞争，私密性和移动性要求会带来一系列从功能，技术到覆盖，接入，频谱，速度等等的不同。
技术区别
1.频谱/接入
频谱或许是竞争性最直接的导火索。
WiFi使用的频谱(2.4GHz/5GHz) 是非授权频谱，就是说这段频谱并未分配/拍卖给个人或公司，任何人/企业都可以用自己的WiFi设备随意接入。xG使用的频谱是授权频谱，除了获得该频谱的运营商，其他人都无权使用此频谱。
So, now we open the phone a WiFi, you will see a very long list of wireless immediately, most of them are 2.4GHz routers. This means that this band is very congested, there may be a lot of noise-like interference.
This means that, if the same other technologies, this band phones, WiFi signal to noise ratio will be relatively low, which can lead to reduced coverage WiFi signal, the transmission rate is slow. Therefore, the current WiFi protocols in the expansion 5GHz, 60GHz and so lower interference band.
There are long lists of what hot, and WiFi frequency band is limited, it will certainly have a channel resource contention. So, WiFi core of the air interface protocol is CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance). This is done before its transmission to make detection channel, if the channel is busy, wait a random time before sending. But detection is not real-time, so there are still two possible routes together to detect idle spectrum while transmitting data, this time the problem arises collision, will take the form of retransmissions again.
CSMA / CA
XG and, since the access channel assigned by the base station, and will be considered in the allocation algorithm disturbances, so comparison, the same technical coverage of base stations will be larger. Meanwhile, xG before signal transmission, the base station has been assigned a unique "line", it is not necessary to transmit the detection of the forward channel, the collision of the retransmission requirement is low.
In addition a significant difference concerning access, because operators need access to the full site, so there is no password xG is, they use identification SIM card costs by charging gateway. Private WiFi and usually requires a password.
2. The covering, WiFi network and a mobile communication network
Speaking above the WiFi coverage usually low, compared to the base station because under high transmit power, low frequency interference, so that more wide coverage.
Because the speed of the network may be affected by too many factors, so this section does not discuss the issue of speed WiFi and xG, in fact, than anyone else who fast on both are possible.
But companies such as buildings, if you want to expand the WiFi coverage, in order to facilitate service employees. In this case, a single wireless router is certainly not a single company building the wireless router coverage will exceed the radio power set by the state, so the need for multiple joint networking router, such as a wireless router is responsible for one room, while the other routers using the same name, and cooperate with each other, thus forming a wireless network throughout the building.
We all know that the decision of the single-node system is the most efficient system. That is, if the wireless network, if there are multiple nodes cooperation, the most efficient way is to have a full network controller, to help each router scheduling and allocation / space / spectrum resources.
In a WiFi network (WLAN), the home router is the collection of one AP (Access Point, access point) and separate AC (Access Controller, the controller). AC with control of the whole network, and allocates resources.
As shown below:
WLAN design of FIG response from the summer - known almost https://www.zhihu.com/question/59991119/answer/228596693
So if we expand that?
To rise across the country, the data processing speed of a single AC apparently is not enough, then each requires a similar AC region, and also between the respective AC need to work together, exchanges. This creates a wireless core network (Core Network).
And each AP on the formation of a radio access network (Radio Access Network).
Operator's mobile communication network, mainly by the core network and access network of two parts.
The following diagram, this wireless router network (WLAN) is not just like a?
5G network structure
From single-route, multi-route network to the company level, the national level to the base station coverage, which is probably the difference and connection between the WiFi and xG.
6. 2019 may progress
5G involves many roles, from here or standard, operators, equipment providers and terminal operators point of view, respectively, for example.
Standard
in order to consider the compatibility with 4G, 5G are two types of networking evolution: Non-standalone (NSA, non-independent network) Standalone (SA, independent network). NSA's implementation is to assist small-scale building through 5G 4G existing network, and gradually evolved into a complete 5G network. SA independent meant direct construction 5G network.
NSA which will facilitate the use of existing 4G network, can save money, and can 5G to market faster; however 5G features and targets achieved are limited.
SA will avoid the integration process with the 4G network interoperability issues, but the high initial cost, deployment time is long.
But obviously, 5G early operators interested in NSA is the largest model; 5G network short time we will be able to experience the NSA is realized in the form.
Figure from testandverification
Therefore, Release 15 is also divided into three versions, each defined with different content, namely NSA version, SA version and late drop version.
So 3GPP schedule is kind of how it?
schedule
December 2017, 3GPP completed Rel15 NSA version; June 14, 2018, 3GPP version released Rel15 SA, and by the end of 2018, in order to ensure the stability and compatibility of 5G first deployment, 3GPP Rel 15 late decision to postpone drop version.
Therefore, the 2019 standard part of the work is nearing completion of Rel 15 late drop and Rel 16 RAN1. Here's a quick explanation of their contents.
Comparison of the original schedule:
2019, the completion of the upcoming version 15 late drop in Rel is involved in some of the details scenes completion NSA mode: NR NR to a two-way connection of (NR-NR dual connectivity). We can see, on a drawing NSA, 5G NR mainly done through the data link and control the LTE network, the core network and not have access to 5G.
And NR-NR dual connectivity diagram illustrating the meaning of the following:
late drop according to network wherein four kinds of scenes
The main work Rel 16 RAN is a radio access network (RAN). Conceptually, it is used to provide a communication connection between the device and the operator core network, a base station is arranged widely representative radio access network. Work Rel 16 to be discussed mainly related to (from Nokia):
Non-orthogonal frequency-division multiplexing , the non-ground radio access (such as satellite, etc.), wireless network enhanced vehicle, unlicensed spectrum like. Specific can facie FIG.
Which need to mention 5G in three scenes: eMBB (enhanced MobileBroadband) enhanced mobile broadband, mMTC (massive Machine Type Communications) large scale of things, URLLC (Ultra-Reliable and Low Latency Communications) high reliability and low latency.
- eMBB scene standardization work has been completed.
- mMTC scene may not progress this year: 3GPP has proposed to ITU, 4G LTE stage in its development of the NB-IoT and eMTC meet ITU needs to 5G of things, a lot of evaluation studies. GSMA last May 16 issued a new report "NB-IoT and LTE-M under the 5G environment" (NB-IoT and LTE-M in context at The 5G), highlighted NB-IoT and LTE-M and other authorized mobile Internet of things (IoT) network will play an integral role in the future 5G, especially in the "large-scale Internet of things" development.
- URLLC will focus on topics Rel 16. Possible and there will be a fierce competition.
That was 19 years 5G standardization work may progress.
Operators
China's 5G test should be the world's largest regional 5G test, divided into two stages: 5G 5G technology research and product development test test.
Pictures from the IMT-2000 to promote the group
Most operators and equipment manufacturers are ongoing system verification and application demonstration, the main goal is a unified environment, start a single system, a single terminal, network and operational testing, and began to 5G classic application tests. So we can see that some time ago the news a lot of typical application scenarios.
The figure above Step3, images from IMT-2000 to promote the group
2018年年初就运营商们已经在怀柔已经建设了超过100个基站，包括3.5GHz，4.9GHz，26GHz，39GHz和2.1GHz频段，是全球最完整的5G室内外一体化网络。
目前正处于5G典型应用演示与验证阶段，中国移动与当地政府合作，验证5G分级自动驾驶体系在公交方面的应用，目前在成都BRT的项目，通过跟成都公交公司集团的合作，解决目前公交车的节能、安全、准点的问题。
2018年12月5日，全国首条5G环线在成都正式开通，全国首辆5G公交开通试运行，在全国率先实现5G外场试商用。在时速40公里的公交车上，5G网络实时峰值速率达到了2375mbps，这意味着短短几秒即可完成一部蓝光电影的下载。
中国移动的智能移动医疗车可提供多种应用。例如，远程操控类，以远程超声检测为例，通过5G+机械臂的结合，基于触觉交互反馈系统，真正实现远在千里之外的医生对病人进行相关的检测。
目前中国联通的5G组网计划是，2019年完成组网验证，网络规划和试商用：
不过总的来说，我国4G建设刚刚完成不久，现在启动5G，运营商会面临巨大的成本压力。而且现在更新5G网络，在短暂的5G高费用之后，流量会加速贬值，运营商可能会进一步被互联网企业挤压生存空间，沦落为管道商。
所以，目前国内电信运营商的动力没有4G时候那么充分。
预计2019年，5G将会开始进入城市规模组网测试阶段。中国移动，联通，电信都将会建设城市级别的预商用/实验性网络。
设备商
上一段中有提到目前运营商和设备商都正在进行系统验证，不仅仅是运营商要实验设备，设备商也需要开发新型基站来满足5G需求。在Step1的关键技术验证和Step2的技术方案验证中，各个设备商的表现参差不齐（2016年的数据）。
以上数据至今已过2年，有点过时了，不过也能管中窥豹看出一点设备商的端倪。
2018年中的IMT2000会议上，华为表示自己已经能够提供端到端的商用产品及解决方案：
华为已经在全球部署50+预商用网络：
大唐已经发布了一些5G商用产品，包含基站，BBU等：
三星即将在2019年发布核心网，基站等产品。
不过总的来说，5G系统的设计更加复杂，壁垒进一步提升，而天线、基站设计越来越难，因此设备商的地位其实是大大提升了的。很多小型厂商会面临技术壁垒挑战，设备商的技术垄断可能会在2019年越来越明显-----可能有些厂商压根就做不出来，或者做出来了也太贵。
总的来说运营商和设备商的供求关系可能会发生改变，招标权利可能会转移到设备商。
综上所述，2019年将会是设备商发力抢占市场的一年，会根据Rel 16的发布同时调整自己的产品线，华为可能目前是领先者。
终端商
在5G初期，终端商还不是主角，因此2019年各大终端商可能只是会发布新一代的5G手机。在这里只谈谈有能力做出5G SoC的几家公司吧。
高通，华为，三星，英特尔，联发科。
先给出进展：
2016年10月，高通率先发布骁龙X50外挂式5G基带芯片,采用28nm制造工艺，支持毫米波和sub-6G频段, 并于MWC2017，同年10月, MWC2018上分别公布改进方案，支持2G/3G/4G/5G多模式, 并公布手机样机和包括天线，射频模组在内的5G解决方案。今年10月又缩小了尺寸...但是，据公开资料，制造工艺依然没有升级, 采用28nm 工艺。
2017年，英特尔发布了首款XMM8060外挂式5G基带，并在今年11月公布了升级版XMM8160，支持2G/3G/4G/5G多模式，同时支持毫米波和sub-6G频段，不过预计于19年中期发货。
2018年2月，华为发布了巴龙5G01，这是号称第一款完全符合3GPP标准的5G商用基带，不过因为尺寸过大，并不能给手机使用，同时这也不是多模基带，必须配合4G基带一起使用。在华为的规划中，还未发布的巴龙5000是给5G手机使用的基带芯片，不过目前并没有什么消息透露出来。
2018年8月15日，三星推出了Exynos Modem 5100， 据报道这是业内第一款完全兼容3GPP Release 15规范，支持2G/3G/4G/5G多模式，同时支持毫米波和sub-6G频段的芯片，支持8载波聚合，预计今年年底出货，这款基带处理器采用10nm工艺制程。
2018年10月，高通还改进了X50的尺寸，它变得更小了。
2018年，联发科推出其首款 5G基带芯片M70，该基带芯片预计要到 2019年年初或年中商用。
预计，2019年华为，三星，高通，联发科都将发布相应的终端设备，供给各种手机厂商，大家会在今年年中看到一波新的5G手机。
至于5G模块能不能用，要看今年运营商网络铺的有多快了。
完。
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