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What is 5 G ?

 

"I don't know -:)." was the answer to this question when I first wrote this page in mid 2013 and the answer hasn't changed until the mid 2016. From late 2016 many things started happening in 3GPP and now (Mar 2017) we got several TRs (38.801, 38.802, 38.803, 38.804) that describes the details of technical requirement to be specified in formal NR(5G) specification, meaning that now we know what 5G (NR) will look like in pretty much detail.

If you want to get the formal 3GPP definition right away, just jump to Formal (3GPP) Definition but I will keep all of the other definitions as well in case when you are interested in tracking down what kind of vision multiple major players had and how those visions has been consolidated into the formal definition (requirement).

 

Nothing about 5G is defined officially in any standard organization as of now. However there are several organization that describes key technical component or key performance indicator (KPI) that may envision on what 5G will be like. I would put the list of features from several different organization.

 

 

 

Initial Definition

 

When the first talk about 5G started and some of prototyping test result came out, the focus was mainly around throughput. (This kind of focus hasn't been changed much until mid 2013)

 

At least, one thing for sure will be that the data rate will be at least several G bps. (The final goal of 4G data rate is 1 Ghz and we still have a long way to go to achieve this 1Gb rate).

 

By now (as of Nov 2015), you may see a couple of dozen whitepapers about the 5G. If you read through all of these whitepapers, you would notice that the key concepts they claim in the documents are almost same. Personally, I would recommend you to read through the documents from METIS. I think METIS documents are by far the most extensive and most in-depth. The only problem is that those documents are too thick :)

 

Followings are some of my personsl keywords about the 5G reading through most of these papers.

Keywords

Description

Extremly High Data Rate By far, we don't know yet (as of Nov 2015) what would be the maximum throughput. But I think it will be targeted to be at least around 10 Gbps.
Extremly Low Data Rate Just achieving the extermly low throughput has no technical problem. But critical technological issue is that achieving the extremely low data rate with extremly low cost and extremely low energy (battery) consumption. Refer to MTC criteria for the details.
Extremly Low Latency

We don't know yet (as of Nov 2015) what would be the target latency. But by far, around 1 ms latency are the most commonly mentioned number. (In terms of subframe length, it would be around 100us or 200 us)

Super High Frequency

The words 'High Frequency' or 'Low Frequency' can be misleading because it would be a relative concept, but I say 'Super High Frequency' comparing to current cellular communication frequency (mostly under 3 Ghz). By far (as of Nov 2015), the most frequently commented frequenty blocks are 6 Ghz, 15 Ghz, 20~30Ghz and the highest frequency being tried is a little bit over 70 Ghz.

Super Wide Bandwidth

The words 'Wide Bandwidth' or 'Narrow Bandwidth' can be misleading because it would be a relative concept, but I say 'Super Wide Bandwidth' comparing to current cellular communication bandwidth (100 MHz, ideal max in 4G). The most commonly mentioned bandwidths are 160 Mhz, 400 Mhz, 800 Mhz. Currently the widest bandwidth being mentioned are 2 Ghz bandwidth.

Softwares as much as possible Many components in core network would be software based and with this it would become very flexible and accomdate news features in short time frame

 

 

Formal (3GPP) Definition

 

Recently (as of Jun 2016) there has been a couple of RAN meeting with major focus on 5G and several official technical terms has been defined.

 

The first thing to be defined would be 'what is the name that refers to the whole 5G technology ?'. As we call 4G as LTE, there must be similar name for 5G. What is it ? At least for now, the official name for 5G is NR that stands for New Radio. (I already see many people saying NR is not a proper name because 5G does not refers only to Radio Technology.. but anyway for now, NR is the official term.

 

Then what is official definition of NR. Since there is no single line official definition for LTE, there is no single line official definition for NR. But in my personal definition, I would say 'NR is a collection of technology from Physical layer to Core Network that need to achieve the followiing three major feature (requirement) as illustrated below. The term shown in this diagrams are also formal 3GPP terms and you will see these terms in most of the 3GPP documents on NR. So it would be good for you to get familiar with these terminologies.

 

 

 

 

Build up Intuition on 5G

 

Before you read, just enjoy these video clips and let your brain build up its own intuition(Insight).

 

 

Definition by METIS

 

More organized and formal definition can be made from METIS which were proposed in Aug, 2013. Even though METIS does not put forth explicit 'definition', it proposes several KPI (Key Performance Indicator). I think we can say "A communication system satisfying the METIS KPI can be categorized as 5G".

Following is the list of KIPs and test cases performing the measurement of KPIs proposed by METIS. (Refer to D1.1 and D2.1 METIS document for details)

 

 

Technical Requirement proposed by METIS to meet 5G goal are :

  • 10-100 times higher typical user data rate, where in a dense urban environment the typical user data rate will range from 1Gbit/s to 10Gbit/s;
  • 1,000 times more mobile data per area (per user), where the volume per area (per user) will be over 100 Gbps/km2;
  • Support for 10-100 times more connected devices;
  • 10 times longer battery life for low-power massive machine communications where machines such as sensors or pagers will have a battery life of a decade;
  • Support of ultra-fast application response times, where the end-to-end latency will be less than 5ms with high reliability;
  • Ability to fulfil these requirements under a similar cost and energy dissipation per area as in today’s cellular systems.

 

 

Definition by 5GNOW

 

5GNOW does not decribe much about high level definition or use model of 5G. I guess any 5G high level definition fall into the scope of METIS definition/use model. 5GNOW discuss more on lower level impelmentation of 5G. Key implementation Item discussed/proposed by 5GNOW is as follows.

 

 

After I've read most of 5GNOW Deliverable document, the key words that pop-up consitantly in my mind are

  • Asynchronous
  • Bursty low data rate transmission
  • Enhanced PRACH

Think on your own why these would be issues and then refer to 5GNOW Deliverable Documents.

 

 

Definition by SKT

 

Following came from the white paper issued by SKT (SK Telecom, South Korea)

 

 

Following table also comes from SKT WhitePaper . To be honest, I am not sure how much of these items will be eventually adopted by the industry standard, but I think this can be a good list of starting points if you want to do some more detailed research on specific technologies for future communication. I recommend you to read the original WhitePaper a couple of times and search the related document (e.g, Related Paper and Thesis for each items)

 

1. Realistic UX and 5G Contents Process
  Object/space Recognition Fast Recognition of surrounding objects and spaces by a camera or sensors
  Real Time Rendering and Display Display(Rendering) of an object in realtime recognized by glass or HMD
  Real Time Hologram Processing Reconstructing a real image of an object with 360 degree field of view in 3D space
2. Efficient Processing & Transmission of Tactile Multimedia
  MMT(MPEG Media Transport) a special MPEG technology to minimize latency in media transmission in All-IP network
  High Efficiency Multimedia Coding Multimedia Coding Technique for efficient creation/transmission of realistic 3D multimeidia contents (e.g, MVC : Multi-view Video Encoding)
  Cloud-based Computing, Caching and Orchastration Dynamic Allocation and Orchestration of cloud resource and caching to process realistic high volume multimedia
3. Cloud-based All-IP Network and Service Platform
  NFV-based Virtualied Core Network Operation Techniques to build the cloud by virtualizing a standard hardware and operate a range of networ/service functions on the software-based network.
  Virtualized RAN Techniques to centralize and virtualize DU(Digital Unit) of a base station into a standard HW based cloud and process RAN signals in real time.
  SDN and integrated Orchestraion Effective control and lifecycle management of the software-based network services from a centralized & unified network service orchestrator
4. Analytics-based Network Intelligence & Optimization
  Big Data Analysis Techniques to process, analyze and infer large volume of multi-dimensional/unstructured data
  Network Intelligence & Analysis Techniques to optimize operation and performance of networks from information on performance, log, traffic
  Analytics-based SON Techniques to automatically detect abnormality, to optimize and take necessary measures
5. Fast, Flexible Transport Network
  POTN (Packet Optical Transport Network) All-IP/All-Optical transport technology that converges multiple layers to increase simplicity and efficiency of network
  Transport SDN Integrated Networking technology to efficiently use and automatically control network resources in multi-layer, multi-vendor, multi-domain networking environment
6. Beyond-Cellular Network Architecture
  Direct D2D Communication Techniques to directly share information and data between devices
  Contents Centric Networking (CCN) A network architecture that stores content in a transport equipment on the network path and provides it by a mapped name of content
7. Enhanced Operation for Multi-cell/HetNet
  Elastic Cell Techniques to dynamically select and communicate with a cell best for the user's current channel environment in real time
  Aggregation of Heterogeneous Networks Techniques to improve data rate by combining cellular networ with different networks such as WiFi or with unlicensed LTE band
8. Ultra-Dense Small Cell
  Dynamic interference control and coordination Techniques to improve signal Quality at cell edges by enabling nearby cells to cooperate in real time
  HetNet SON Techniques to automatically optimize wireless network operation in diverse cell environment to improve QoS
9. Wideband High Frequency RF & 3D BeamForming
  3D BeamForming Techniques that provies RF environment for high-speed transmission by controlling electromagnetic waves or forming multiple beams in the vertical and horizontal directions
  Beam Switching/Tracking Techniques that provides an optimal link by selecting an optimal beam out of many or changing the direction of the antenna beam according to the location of the user.
10. Enhancement of Multiple Antenna Technology including Massive MIMO
  UE-Specific Beamforming Techniques that suppresses mutual interference between multiple terminals by utilizing independent and sharp beams
  CSI/CQI Feedback Techniques that enhances accuracy of CSI and CQI while minimizing uplink signaling overhead
11. Advanced IoT & New Waveform/Duplex
  Cellular-based MTC (Machine Type Comm) High Capacity multiple access & machine data processing technology to support IoT service on mobile communication network
  New Waveform (NOMA, FBMC) Transmit and receive technology that increases efficiency of accommodating multiple users and data through reciever interference cancellation and filter-based interference supporession
  Hybrid duplex & Full Duplex Communication Flexible allocation scheme for DL/UL resources and simultaneous transmit and receive technology based on self - interference cancellation

 

 

Definition by 4G America

 

The contents in this section is based on the WhitePaper : 4G Americas' Recommendations on 5G Requirements and Solutions.

 

 

 

Definition By NTT DoCoMo

 

The contents in this section is based on the WhitePaper : 5G Radio Access: Requirements, Concept and Technologies - DOCOMO 5G White Paper

 

< Trends in Technology and Motivation for 5G >

 

This trend is mainly represented as M2M, MTC, IoT these days. Actually each component technology is already available and has been adopted by various area, but they hasn't been integrated across wide area. We need a flexible cellular network that can integrate all of these diverse component and 5G will be playing a crucial role for this.

These are emerging technolgies meaning relatively new technology, but development/implementation for each components has been adopted for a while. But this hasn't been a target for cellular communication since the required data rate is too high. To connect these applications to cellular network, we need a new celluar technology that support extermely high data rate. This extremly high data rate will be one of the key feature of 5G.

 

 

< Key Requirement >