Samsung's 3GPP-Compliant PS-LTE Network

After having been discussed for years by others, Samsung finally announced back in April that they are powering the world’s first 3GPP-compliant nationwide public safety LTE (PS-LTE) network in Korea, in collaboration with leading mobile operators.

A press release from them said:

This PS-LTE network, operating in the 700MHz spectrum, offers fast and reliable connectivity to first responders in over 330 public safety organizations and agencies, including police, firefighters, emergency medical services and the military.

The deployment includes Samsung’s Mission-Critical Push-to-Talk (MCPTT) with multimedia broadcast capabilities, known as evolved Multimedia Broadcast Multicast Service (eMBMS). This enables simultaneous transmission to up to 2,500 user devices per cell, which is more than twice the volume of devices supported by previous generation technologies.

In this buildout, the PS-LTE network was also interconnected with the existing LTE-Maritime (LTE-M) and LTE-Railway (LTE-R) networks that were already operating in the 700MHz spectrum.

With nationwide coverage, the network serves as a unified platform that helps ensure interoperability among various public safety institutions. This delivers real-time accessibility and enhanced communications capabilities among public safety agencies and personnel in emergency situations.

Years after talking about eMBMS, it's still alive and kicking.

Meet the world's first 3GPP-Compliant Nationwide Public Safety(PS) Network with MCPTT Service & eMBMS in Korea powered by @SamsungNetworks

PS-LTE network @ 700MHz band for 300+ PS orgs.https://t.co/Io6q86ZGfl pic.twitter.com/impMwTnKGW

— Neil Shah (@neiltwitz) April 26, 2021

They also released an Infographic and a Whitepaper.

In a recent Networks Techtalk, Timothy Paul discussed Samsung’s latest end-to-end MCPTX solutions that provide powerful data and video communications capabilities designed for first responders and public safety officials. The video of that is embedded below:

Related Posts:

• Connectivity Technology Blog: Kima - Faroese Telecom's Mission Critical Communications Solution
• Connectivity Technology Blog: Virve 2.0 is becoming a broad-band service
• The 3G4G Blog: Virve 2.0 - Finland's 4G/5G Public Safety Network
• Connectivity Technology Blog: Verizon and Nokia Put Small Cell in the Air at #OCR2019
• Connectivity Technology Blog: Air-to-Ground (A2G) Network for Emergency Communications
• The 3G4G Blog: 5G Private and Non-Public Network (NPN)
• The 3G4G Blog: Update from 3GPP on LTE & 5G Mission Critical Communications
• The 3G4G Blog: Update on UK's Emergency Services Network (ESN) from #BAPCO2019
• The 3G4G Blog: A practical use of MOCN in ESN
• Telecoms Infrastructure Blog: Meshing for BYOC (Bring Your Own Coverage) 

Carrier Aggregation (CA) and Dual Carrier (DC) enhancements in Release-13

Recently I posted a summary whitepaper of 3GPP Release-13 by 5G Americas. This article from NTT Docomo technical journal complements that nicely and provides in depth analysis of selected features.

The article (embedded below) focuses on Carrier Aggregation (CA),Dual Carrier (DC) enhancements, LAA and LWA. In this post, I am going to restrict the discussion to CA and DC.

The following is from the magazine article:

Carrier Aggregation (CA):

Up to Release 12 CA, a maximum of 5 LTE carriers called “Component Carriers” (CCs) could be configured for a User Equipment (UE). This enables a maximum 100 MHz bandwidth for data communications, which achieves a theoretical peak data rates of approximately 4 Gbps, assuming eight Multiple Input Multiple Output (MIMO) layers and 256 Quadrature Amplitude Modulation (QAM) for downlink, and 1.5 Gbps assuming four MIMO layers and 64QAM for uplink.

In Release 13, the maximum number number of CCs that can be configured for a UE simultaneously was increased to 32 to archive higher data transmission rates with wider bandwidths. This enables a maximum 640-MHz bandwidth for data transmission, achieving peak data rates of approximately 25 Gbps for downlink with 8 MIMO layers and 256QAM, and 9.6 Gbps for uplink with 4 MIMO layers and 64QAM.
...
Release 13 introduced the new function to enable PUCCH configuration for a Secondary Cell (SCell) in addition to the PCell in uplink CA. When CA is performed with this function, CCs are grouped together either with the PCell or SCell with PUCCH (PUCCH-SCell). UE sends UCI for CCs within each group by using the PCell or PUCCHSCell. With this new function, uplink radio resource shortages can be resolved by offloading UCI from macro cell to the small cells while keeping the macro cell as the PCell.

Dual Carrier (DC):

Release 12 designed DC to achieve user throughput comparable with that of CA by aggregating multiple CCs across two eNBs. In release 13, DC was further enhanced with higher uplink throughput and more flexible deployment.

In DC, separate eNBs allocate uplink resources independently for a UE. Hence, Release 13 addresses how to allocate adequate uplink resources on multiple CCs for UE. Typically, eNB calculates the required uplink resources based on the uplink buffer amount reported from UE. In DC, since both eNBs calculate the amount of uplink resources based on the report and allocate them to the UE independently, excess uplink resource allocation over actual amount of remaining data will occur. In particular, with small data packets, if resources are allocated by both eNBs, the UE may send all data to only one of them, and send padding (meaningless bit strings) to the other eNB, which wastes radio resources.

To prevent the excess uplink resource allocation for the small data packets described above, new uplink transmission control methods were introduced. In Release 13 DC, UE buffer status reporting and uplink data transmission are controlled based on the amount of uplink data buffered in the UE.

If the amount of the buffered data is smaller than the threshold configured by the eNB, the UE performs buffer status reporting and uplink data transmission only to one of the eNBs, just like DC in Release 12. In contrast, if the amount of the buffered data is larger than the threshold, the UE transmits to both eNBs. This buffer size-based mechanism solves the uplink resource over-allocation problem since only one eNB is aware of the buffered data and allocates resources when the amount of the buffered data is small.


The paper is embedded as follows:

Related posts:

• Inside 3GPP Release-13 - Whitepaper by 5G Americas
• Dedicated Core Networks (DCN) for different traffic types
• New whitepaper on Narrowband Internet of Things
• LTE-Advanced Pro (a.k.a. 4.5G)

Interference cancellation in high density small cells deployment

I looked at some 3GPP Release-12 small cells enhancements in an earlier blog post here. David Chambers, ThinkSmallCell has also published a post on 3GPP small cells enhancements in Release-12 and Release-13 which is available here.

In a recent NTT Docomo technical journal, there is an article that focuses on Interference suppression and cancellation techniques that have been introduced as part of 3GPP Release-12. These techniques can be used in conjunction with high density small cells Hetnet deployment. The article is embedded below.

Wi-Fi: Future Roadmap and LTE

At the WBA Wi-Fi Global Congress, Intel provided a good summary of the way things are progressing in the WiFi world, including the standards updates that are going on. Luckily I found a video by the same author in from an IEEE conference which is also embedded below.

Wi-Fi is becoming important and a useful rule of thumb is that the spectrum in 5GHz is roughly around 10 times that of 2.4GHz and the spectrum is 60GHz is roughly around 10 times that of 5GHz. (not all spectrum is available everywhere so just use this as a rough guide).


As I mentioned in a presentation I gave this week, there are three different approaches being proposed at the radio level; LTE-U, LAA and LWA. I wrote a post on LWA not long back on the 3G4G blog here.



Dave Wright from Ruckus Wireless has kindly shared a recent presentation on different proposals for LTE operation in unlicensed spectrum. The timeline above shows how quickly things are moving. Here is a the presentation

It would be important from Wi-Fi vendors point of view that LTE-WiFI Link Aggregation is standardised as part of Release-13 as there would be an option which would be agreeable to everyone.

LTE-LAA updates - Jan 2015

There has been quite a few updates on LTE LAA in the past month. First, there is this good video from Ericsson explaining what it is:

The 3GPP chairman recently presented a status update about developments on unlicensed spectrum at an IEEE 802 meeting last month. His presentation is embedded below:

3GPP & unlicensed spectrum from Zahid Ghadialy

IEEE 802 group have their own presentation on the co-existence lessons learned. This is embedded below:

Ericsson has also got a recent presentation on this topic. As can be seen, they expect a solution to be available in 2016-17. Presentation embedded below (download link here)

Finally, if you watched the video by Ericsson, they mention that one of the key milestones of 5G is to be able to combine licensed and unlicensed technology. One of the technologies being proposed in 5G is called Multi-Stream Aggregation (MSA). MSA allows multiple access technologies over licensed and unlicensed bands effectively. The picture above shows how it would work in theory. It may be more difficult in practise though. 

Non-ideal backhaul for Small Cells

Recently I came across this Linkedin discussion on What is "non-ideal backhaul" so I thought it may be worth adding it to the blog. The simplest of explanation can be seen from the picture above that is extracted from 3GPP TR 36.932.

An ideal backhaul is defined as latency less than 2.5 microseconds and a throughput of upto 10Gbps. All other types of backhaul is non-ideal.

Another way of putting this is: If you look at the Release 12 study and technical report on Small Cell Enhancements, it is regarded as a backhaul that cannot carry a RRH to eNodeB link, which in turn has been interpreted as not meeting CPRI round trip and bandwidth requirements (via Kit Kilgour)

If you know anything additional, please feel free to add it in comments.

Tight, Tighter and Very Tight Integration between LTE and WiFi Networks

For those who are unfamiliar about the trusted and non-trusted access, I strongly recommend reading our whitepaper on Cellular and WiFi Integration here.

The standard and the most popular Integration approach between LTE and Wi-Fi is via the Trusted architecture as shown above.

There is a proposal for RAN level Integration which would result in Even Tighter Integration of WiFi

Now some researchers are proposing a Very Tight coupling between LTE and Wi-Fi which would mean that regardless of the access, the UE can be sent data from the same data stream over WiFi and LTE. Though this is radical, these approaches are already being thought about for '5G'. Whether it will happen in a future release of 4G or 4.5G remains to be seen. Here is the complete paper embedded below:

Very Tight Coupling between LTE and Wi-Fi for Advanced Offloading Procedures from Zahid Ghadialy

3GPP Definitions of Small Cells

While the Small Cell Forum defines the different types of Small cells clearly and these Small Cells can be said to contain the complete/partial functionality of the eNodeB, 3GPP definitions of Small Cells can be a bit fuzzy sometimes.

Generally, in the 3GPP documentation, there is a reference to Femtocells and Picocells. Femtocells are Small Cells that are defined as Closed Access (see my old post here) by 3GPP. The open access small cells are referred to as Picocells. Sometimes remote radio heads (RRH's) are also referred to as Small cells, open access type.

Relays, even though not referred to as Small Cells by 3GPP, is also referred to as Small Cells by some people.

Do you know of anything else?

Open, Closed and Hybrid Access Small Cells

A question that often keeps cropping up regularly is regarding the open access and closed access small cells. Before we look at the explanation of these cells, lets see the different types of cells (from 3GPP TS 36.304) in brief:

Acceptable cell: An "acceptable cell" is a cell on which the UE may camp to obtain limited service (originate emergency calls and receive ETWS and CMAS notifications).

Suitable cell: A "suitable cell" is a cell on which the UE may camp on to obtain normal service. It is mandatory for the UE to have a USIM card belonging to the operator to which this cell belongs.

Barred cell: A cell is "barred" if it is so indicated in the system information. Its not available for use by anyone.

Reserved cell: A cell is reserved if it is so indicated in system information. It is reserved for operator use only.

Restricted Cell: A cell on which camping is allowed, but access attempts are disallowed for UEs whose access classes are indicated as barred.

Camping on the cell: With the cell selection, the UE searches for a suitable cell of the selected PLMN and chooses that cell to provide available services, further the UE shall tune to its control channel. This choosing is known as "camping on the cell".

To keep the discussion simple, I have ignored that some UE's may belong to MVNO and the PLMN Id of the operator would be stored as Equivalent PLMN Id.

Now lets look at a simple explanation of the different types of small cells.

Open Access: All (suitable) cells are open access by default. This means that they can be accessed by any device belonging to the operator whom the cell belongs to. Some people also refer to these cells as Open Subscriber Group (OSG) cells.

Closed Access: A (suitable) cell is closed when only certain devices can camp on them. These devices form a part of whitelist stored in a database to allow camping on the cell. Devices that are not part of the whitelist are not allowed to camp on this cell, even though they belong to the same operator and this cell is a suitable cell. The devices are said to belong to ‘Closed Subscriber Group’ (CSG). The cell is said to be a CSG cell as its transmitting CSG Indication set to 'true' and the CSG Identity.

Residential Femtocells are generally Closed Access but there are exceptions. Softbank, Japan for example gives open access Femtocells that can also provide coverage to users nearby. Another example is the operator Free in France that also offers similar open access Femtocells.

Hybrid Access: A (suitable) cell can also be hybrid access, thereby allowing all devices that either belong to a CSG or non-CSG to camp onto it. A hybrid cell may offer prioritised and/or additional services to the users that belongs to the CSG it is a part of.

I am not aware of any Hybrid Access Small Cells deployment to date. Please feel free to correct me.

Small Cells Research Bible

Here is a detailed research on Small Cells from Mehdi Bennis and Walid Saad presented in IEEE Dyspan 2014, this month. Feel free to add any comments for questions you may have.

Recent Advances in Wireless Small Cell Networks from Zahid Ghadialy

3G / 4G Small Cells Mobility Scenarios - 3GPP Technical Report

3GPP has an excellent Technical Report (TR) 37.803 that covers different mobility scenarios and enhancements for 3G HNB and 4G HeNB. Its an interesting read if you are involved in this activity. Embedded below for reference.

Mobility enhancements for Home Node B (HNB) and Home enhanced Node B (HeNB) from Zahid Ghadialy

Dual-connectivity, Bearer split and other Release-12 small cell enhancements

3GPP TR 36.842 has some interesting details on the small cells enhancements for Release-12. There is too much details for me to go through at the moment but there is some discussions. One of them is on the Dual connectivity and another is Bearer split. The concept of Master eNB (MeNB) and Secondary eNB (SeNB) seems to have been introduced. Here are some interesting definitions:

Bearer Split: in dual connectivity, refers to the ability to split a bearer over multiple eNBs.

Dual Connectivity:Operation where a given UE consumes radio resources provided by at least two different network points (Master and Secondary eNBs) connected with non-ideal backhaul while in RRC_CONNECTED.

Master Cell Group: the group of the serving cells associated with the MeNB.

Master eNB: in dual connectivity, the eNB which terminates at least S1-MME and therefore act as mobility anchor towards the CN.

Secondary Cell Group: the group of the serving cells associated with the SeNB.

Secondary eNB: in dual connectivity, an eNB providing additional radio resources for the UE, which is not the Master eNB.

Xn: interface between MeNB and SeNB. Since the current E-UTRAN architecture was selected as baseline in this study, Xn in this TR means X2.

There is also the concept of RRC diversity which can help mobility. as per 36.842

RRC diversity is a potential solution for improving mobility robustness. With RRC diversity, the handover related RRC signalling could additionally be transmitted from or to a potential target cell as illustrated in Figure 7.1.3-1.  RLF could in this case be prevented as long as the UE is able to maintain a connection to at least one of the cells.  This will eventually lead to a more successful handover performance (i.e. avoiding UE RRC re-establishment procedure). The RRC diversity scheme could also be applied for handovers from the macro to pico cells, between macro or between pico cells.

Finally, the security aspects for this Bearer split and dual connectivity is also being discussed. See the latest Rel-12 security update here.

Carrier Wi-Fi: Automatic handovers in the next generation Wi-Fi

Ericsson published a paper in their journal last month about how the next generation of Wi-Fi and its integration in the 3GPP core would help moving between Wi-Fi networks and the Cellular network seamlessly.

People who read the 3G4G blog regularly would know that this is done using the Access Network Discovery and Selection Function (ANDSF). For details see here.

Another post from the 3G4G blog explains the key challenges in moving between the Cellular and Wi-Fi technology. If not done properly, the QoE can be really off putting for the end user.

The Ericsson paper highlights the following as the top-three priorities for the next generation carrier Wi-Fi:

• Traffic steering 3GPP/Wi-Fi – to maintain optimal selection of an access network so quality of experience can be ensured and data throughput maintained;
• Authentication – to provide radio-access network security for both SIM- and non-SIM-based devices; and
• DPI, support for unified billing and support for seamless handover – achieved by integrating with the core infrastructure already deployed for 3GPP access.

3GPP has been working extensively in the new releases to come up with new features that would solve some of the issues and limitations that is affecting widespread deployment of carrier Wi-Fi and seamless roaming between the different technologies. Sometime back I provided the list of the features that are being released as part of different 3GPP releases, available here.

The Ericsson paper is available on Slideshare, embedded below:

Small Cells and Wi-Fi in 3GPP Releases

Here is a quick chart of features of Small Cells and Wi-Fi introduced by 3GPP in different releases. Please feel free to suggest anything that has been missed out.

Small Cells in LTE - 3GPP Rel-8 to Rel-12

A simple picture showing the Small Cells support in different 3GPP releases. For more details refer to the 3G4G blog here.