In this blog, we analyze the current state of commercial 5G network construction of KT and SK Telecom, and the difference of 5G value pursued.

 

First Release: 2019.03.29  

Last Updated: 2019.10.11

 

 

1. End-to-End 5G Network Architecture

 

The 5G network can be functionally divided into 5G Core network and 5G RAN, and can be divided into Central Cloud and Edge Cloud which are geographically deployed in the mobile operator's network.

 

KT	SK Telecom
KT 5G Network Architecture: 5G Core, 5G RAN and 5G Edge Cloud (Last updated: 2019.06.12) pdf file download	SK Telecom 5G Network Architecture: 5G Core, 5G RAN and 5G Edge Cloud (MEC) (Last updated: 2019.10.11) pdf file download

 

 

2. Location of Edge Clouds (Edge Cloud has GW-U/UPF, CU and MEC)

 

KT (8 sites)	SK Telecom (2 sites)
8 Cities: Guro, Hyehwa, Daejeon, Daegu, Gwangju, Busan, Jeju and Wonju	2 Cities: Sungsoo, Dusan
출처	출처

 

The 5G Edge is one of the biggest features of the 5G network that was not in the 4G era. The services that 5G pursues can be summarized as "providing ultra-low latency, large capacity like wired optical cable" to the terminal. The 5G edge is a network infrastructure that realizes this, brings new revenue generation to telecom operators, and provides users with a new experience different from existing 4G.

 

KT said on March 6 that it has built an edge cloud in eight central offices nationwide (Guro, Hyehwa, Daejeon, Daegu, Gwangju, Busan, Jeju and Wonju). In the edge cloud, 5G Core UP (GW-U / UPF) and 5G RAN CU are located, and there are also Mobile Edge Computing (MEC) servers that perform data processing for 5G devices in the vicinity of the devices. The Central Cloud is located in Guro, etc., and the 5G Core CP (GW-C / UDR, UDM, PCF, SMF, AMF, etc.) is located.

 

SK Telecom also announced that it has built Edge Cloud / MEC on March 14th. However, it did not disclose how many were built. However, from the above picture (Source: KT, Mar. 23, 2019), SK Telecom's edge cloud is Sungsoo in Seoul and Dusan in Daejeon.

 

In the 5G era, the edge cloud that is built in the operator network to provide ultra-low latency and high-capacity services efficiently (terminating the GTP mobile session at a close distance from the user and providing IP services such as AR / VR, V2X and Smart X / Y /Z ) and KT is now the most advanced in Korea.

 

 

3. Value of 5G (Which is Better?: 5G alone or 5G+LTE)

 

KT	SK Telecom
5G alone KT emphasizes: Latency (10ms)	5G+LTE Aggregation SK Telecom insists: Speed (2.7Gbps)
출처	출처

 

At a value of 5G, KT emphasizes ultra low latency (ms) and SK Telecom emphasizes speed (bps).

 

KT's '5G alone' (not aggregated with LTE) is slower than the '5G + LTE aggregation' in bps. However, KT emphasizes that 5G alone greatly reduces the response time of applications. This is because 5G has low latency in the air section between the UE and the base station (ultra-low delay characteristics of 5G = 1ms frame size 1ms and LTE frame size 10ms) and KT has built an edge cloud in 8 cities.

 

KT, on the other hand, argues that latency of 5G + LTE aggregation is downgraded to latency of LTE because data is transmitted through two paths.

 

5G alone would be advantageous for applications such as web surfing and VR, and 5G + LTE aggregation would be advantageous for applications such as downloading large files.

 

 

4. 5G Core

 

The core network architecture of 4G and 5G (NSA: None-Standalone, SA: Standalone) is shown below. Currently, both companies have commercialized the 5G NSA, and 5G SA is expected to be commercialized next year. The 5G NSA core network can be 2 or 3 in the figure below. In case of KT, it corresponds to 3. SK Telecom and LG U+ correspond to 2.

 

 

KT	SK Telecom
5G NSA Commercialization (2018.12) 5G SA will be commercialized in 2020	5G NSA Commercialization (2018.12) 5G SA will be commercialized in 2020
Samsung, Cisco	Samsung, etc.
Commercialized version in 2019 is shown on the left (GW-C, GW-U)   2018.11.14: KT, CUPS 기술의 5G 초저지연 코어 장비 구축완료	Source   Source: SK Telecom, 2019.03

 

5G NSA option of three mobile operators in Korea is 5G NSA Option 3 (eNB is Mobility Anchor) that uses EPC core and provides dual connectivity between eNB and gNB. Option 3 is divided into 3 / 3a / 3x, and all Korean operators adopted Option 3x.

 

 

 

5. 5G RAN (Cell Site)

 

KT	SK Telecom
3.5GHZ, 100MHz, 32TRX	3.5GHz, 100MHz, 32TRX
Samsung, Ericsson, Nokia	Samsung, Ericsson, Nokia
Samsung	Samsung     4G: Seperated Antenna/RU 5G: Inegrated Antenna /RU
출처	출처
• In Pyeongchang Olympic 5G network, DU has RLC, MAC, PHY and RU has only RF. However, in the 5G commercial network, PHY layer is separated into H-PHY and L-PHY, and L-PHY is deployed in RU. • 3.5GHz (100MHz): Same as SK Telecom • 28GHz (800MHz): expected to be the same as SK Telecom	• 3.5 GHz (100 MHz): CU and DU are located in the central office. RU is located at the cell site, and the interface between DU and RU is eCPRI   • 28 GHz (800 MHz): CU is located in the Central office. DU and RU are located at the cell site as one body, the interface between CU and DU is F1
	Source: SK Telecom, 2018.09
	Source: SK Telecom, 2019.03

 

 

Both companies have commercialized 3.5GHz 5G base stations in December 2018 and 28GHz base stations are not yet commercialized.

 

The 5G RAN (gNB) consists of CU (RRC, PDCP), DU (RLC, MAC, PHY-High) and RU (PHY-Low, RF). KT and SKT placed CU and DU in its own central office, not cell site. The RU is located at the cell site, DU and RU are connected through the fronthaul network, and the interface is eCPRI.

 

 

 

6. 5G Fronthaul

 

KT's his fronthaul network was built by Passive WDM equipment with a point-to-point topology and is called '5G MUX' in KT terminology.

SK Telecom's fronthaul network is a ring topology, and COT in Korea is an active WDM device and Cell site's RN is a passive WDM device. This is called '5G-PON' in SK Telecom terminology.

 

KT	SK Telecom
5G MUX (Passive WDM, P2P, eCPRI 25Gbps)   Source: KT	5G-PON (Semi-Active, Ring, eCPRI 10Gbps)   Source: SK Telecom
Solid, etc.	HFR, Solid, Coweaver

 

 

 

7. 5G B2B Service (Vertical Market, On-Site Private 5G)

 

Up to 4G, services and mobile networks have been designed for mobile phones used by indinidual users (B2C).

The technical characteristics of 5G, which distinguishes it from 4G technology, are ultra high capacity, ultra-low delay, and massive connectivity.

The opportunity for 5G is to penetrate existing manufacturers that have existed for a long time using these 5G's features.

In this direction, Korea is drawing a new business model. The chart below shows how the Korean operators are making these efforts.

 

KT	Source: KT Seminar, 2019.09.26
SK Telecom	Source: SK Telecom Press Conference, 2019.08

 

KT	SK Telecom
5G Smart Factory (2019.03.07)     5G Smart Factory (2019.03.06)     5G AR Glass (2019.02.25)	5G Smart Office (2019.02.18)     5G Smart Factory (2018.12.11)