3GPP Sidelink and its proposed extensions

In an earlier post I discussed briefly about the sidelink: V2V communications are based on D2D communications defined as part of ProSe services in Release 12 and Release 13 of the specification. As part of ProSe services, a new D2D interface (designated as PC5, also known as sidelink at the physical layer) was introduced and now as part of the V2V WI it has been enhanced for vehicular use cases, specifically addressing high speed (up to 250Kph) and high density (thousands of nodes).

Before going further, lets just quickly recap the different V2x abbreviations:

• V2X = Vehicle-to-Everything
• V2V = Vehicle-to-Vehicle
• V2I = Vehicle-to-Infrastructure 
• V2P = Vehicle-to-Pedestrian 
• V2H = Vehicle-to-Home
• eV2X = enhanced Vehicle-to-Everything

I came across this interesting presentation from ITRI that provides lot more details on sidelink and its proposed extension to other topics including eV2X and FeD2D (Further enhanced Device-to-Device).

There are quite a few references in the document that provides more details on sidelink and its operation and extension to other devices like wearables.

There are also details on synchronization and eV2X services.

There is also a very nice D2D overview presentation by Orange that I am embedding below (download from slideshare)

2G / 3G Switch Off: A Tale of Two Worlds

Source: Wikipedia

2G/3G switch off is always a topic of discussion in most conferences. While many companies are putting their eggs in 4G & 5G baskets, 2G & 3G is not going away anytime soon.

Based on my observations and many discussions that I have had over the past few months, I see a pattern emerging.

In most developed nations, 2G will be switched off (or some operators may leave a very thin layer) followed by re-farming of 3G. Operators will switch off 3G at earliest possible opportunity as most users would have moved to 4G. Users that would not have moved to 4G would be forced to move operators or upgrade their devices. This scenario is still probably 6 - 10 years out.

As we all know that 5G will need capacity (and coverage) layer in sub-6GHz, the 3G frequencies will either be re-farmed to 4G or 5G as 2G is already being re-farmed to 4G. Some operators may choose to re-balance the usage with some lower frequencies exchanged to be used for 5G (subject to enough bandwidth being available).


On the other hand, in the developing and less-developed nations, 3G will generally be switched off before 2G. The main reason being that there are still a lot of feature phone users that rely on 2G technologies. Most, if not all, 3G phones support 2G so the existing 3G users will be forced onto 2G. Those who can afford, will upgrade to newer smartphones while those who cant will have to grudgingly use 2G or change operators (not all operators in a country will do this at the same time).

Many operators in the developing countries believe that GSM will be around until 2030. While it may be difficult to predict that far in advance, I am inclined to believe this.

For anyone interested, here is a document listing 2G/3G switch off dates that have been publicly announced by the operators.

2G/3G Switch off Dates from 3G4G

Let me know what you think.

Further reading:

• 2G Network Decommissioning, Ready? - Russell Lundberg, Bangkok Beach Telecom

Smartphone Wi-Fi Analytics for Travel Route Optimisations

Transport for London (TFL), the local government body responsible for transport in London, which also runs the London Underground (known as Tubes) has been using smartphone Wi-Fi data to work out how people travel on the stations.

They did the trial and collected data in 2016 and have also openly talked about it (see this talk for example), they have now published their findings which is available here. One of the interesting findings for example is that 18 different routes taken by customers between King's Cross St Pancras and Waterloo - and many people don't use the shortest route changing Tube lines

Its interesting to think that because many people do not have their Wi-Fi switched on while outside and many others who put their phone in plane more while in the underground (no mobile coverage, in case you are wondering), this data is probably not as detailed as it could have been.

Nevertheless, there is a talk of bringing Mobile connectivity into the underground network. Once its there, the combination of data could be far more valuable.

5G Dual Connectivity, Webinar and Architecture Overview

One of the things that will come as a result of NSA (Non-StandAlone) architecture will be the option for Dual Connectivity (DC). In fact, DC was first introduced in LTE as part of 3GPP Release 12 (see 3G4G Small Cells blog entry here). WWRF (Wireless World Research Forum) has a good whitepaper on this topic here and NTT Docomo also has an excellent article on this here.

A simple way to understand the difference between Carrier Aggregation (CA) and Dual Connectivity (DC) is that in CA different carriers are served by the same backhaul (same eNB), while in DC they are served by different backhauls (different eNB or eNB & gNB).


We have produced a short video showing different 5G architectures, looking mainly at StandAlone (SA) and Non-StandAlone (NSA) architectures, both LTE-Assisted and NR-Assisted. The video is embedded below:

Finally, 3GPP has done a short webinar with the 3GPP RAN Chairman Balazs Bertenyi explaining the outcomes from RAN#77. Its available on BrightTalk here. If you are interested in the slides, they are available here.

Related posts:

• 5G Core Network, System Architecture & Registration Procedure
• 5G: Architecture, QoS, gNB, Specifications - April 2017 Update
• 5G Security Updates - July 2017
• Enhanced 5G Security via IMSI Encryption
• 5G – Beyond the Hype
• Network Sharing is becoming more relevant with 5G

Slides from IEEE 5G Webinar: 5G mmWave Revolution & New Radio

Some of you may find this useful.

A quick starter on 4G voice (for beginners)

I recently did a 4G voice presentation for beginners after realizing that even though so many years have passed after VoLTE was launched, people are still unsure how it works or how its different from CS Fallback.

There are many other posts that discuss these topics in detail on this blog (follow the label) or on 3G4G website. Anyway, here is the video:

The slides are available on 3G4G Slideshare account here. More similar training videos are available here.

NB-IoT based smart bicycle lock

Huawei (see here and here) has partnered with China Telecom and Bike sharing company called Ofo.

ofo developed an IoT smart lock based on NB-IoT technology that lowers power consumption, enables wide coverage, and slashes system resource delays at low cost. NB-IoT lets ofo ensure it has bikes located at key locations when commuter demand is highest. Meanwhile, bikes can be unlocked in less than a second. Both improvements have greatly boosted user satisfaction.

ofo and its partners added key technologies to ofo’s own platform. These included the commercial network provided by China Telecom, and Huawei’s intelligent chip-based NB-IoT solution. When launching its NB-IoT solution earlier this year, ofo founder and CEO Dai Wei said that the cooperation between ofo, Huawei, and China Telecom is a “mutually beneficial joint force of three global leading enterprises.”

At the core is Huawei’s IoT solution, which includes smart chips, networking, and an IoT platform. The solution provides strong coverage in poor-signal areas and a network capacity that’s more than one hundred times stronger than standard terminals. The payment process has dropped from 25 seconds to less than 5, while battery life has been lengthened from 1 or 2 months to more than 2 years, saving costs and reducing the need for frequent maintenance.

ofo’s cooperation with Huawei on NB-IoT smart locks bodes well for improving the industry as whole. Huawei’s technology optimizes lifecycle management for locks, while the sensors on the locks collect information such as equipment status, user data, and operating data. They connect the front- and back-end industrial chains to achieve intelligent business management, enable the bikes to be located in hot spots, facilitate rapid maintenance, and boost marketing and value-added services.

This video gives an idea of how this works:



As per Mobile World Live:

Ofo co-founder Xue Ding said during a presentation the high power efficiency and huge capacity of NB-IoT make the technology ideal to deliver its smart locks, which are really the brains of its operations.

The company offers what is termed station free pushbike hire, meaning bikes can be collected and deposited from any legal parking spot. Users can locate bikes using their smartphone, and unlock it by scanning a barcode.

However, the process can be interrupted by mobile network congestion or if signals are weak – for example in remote areas: “Using NB-IoT, users will not be stuck because of inadequate capacity,” Xue said.
...
Xiang Huangmei, a VP at China Telecom’s Beijing branch, said the low power consumption of the NB-IoT chip in the lock means the battery will last eight years to ten years, so it will never need to be replaced during the standard lifecycle of an Ofo bike.

The NB-IoT network, deployed on the 800MHz band, offers good indoor and outdoor coverage, the VP said citing car parks as an example. One base station can support 100,000 devices over an area of 2.5 square-km.

Finally, to know which operator is supporting which IoT technology, see the IoT tracker here.

Smartphone Batteries Round-up: Technology, Charging & Recycling

Back in 2013, I spoke about Smart Batteries. Still waiting for someone to deliver on that. In the meantime I noticed that you can use an Android phone to charge another phone, via cable though. See the pic below:

You are probably all aware of the Samsung Galaxy Note 7 catching fires. In case you are interested in knowing the reasons, Guardian has a good summary here. You can also see the pic below that summarises the issue.

Lithium-ion batteries have always been criticized for its abilities to catch fire (see here and here) but researchers have been working on ways to reduce the risk of fire. There are some promising developments.

The electrochemical masterminds at Stanford University have created a lithium-ion battery with built-in flame suppression. When the battery reaches a critical temperature (160 degrees Celsius in this case), an integrated flame retardant is released, extinguishing any flames within 0.4 seconds. Importantly, the addition of an integrated flame retardant doesn't reduce the performance of the battery.

Researchers at the University of Maryland and the US Army Research Laboratory have developed a safe lithium-ion battery that uses a water-salt solution as its electrolyte. Lithium-ion batteries used in smartphones and other devices are typically non-aqueous, as they can reach higher energy levels. Aqueous lithium-ion batteries are safer as the water-based electrolytes are inflammable compared to the highly flammable organic solvents used in their non-aqueous counterparts. The scientists have created a special gel, which keeps water from reacting with graphite or lithium metal and setting off a dangerous chain reaction.

Bloomberg has a good report as to why we’re going to need more Lithium.

Starting about two years ago, fears of a lithium shortage almost tripled prices for the metal, to more than $20,000 a ton, in just 10 months. The cause was a spike in the market for electric vehicles, which were suddenly competing with laptops and smartphones for lithium ion batteries. Demand for the metal won’t slacken anytime soon—on the contrary, electric car production is expected to increase more than thirtyfold by 2030, according to Bloomberg New Energy Finance.

Even if the price of lithium soars 300 percent, battery pack costs would rise only by about 2 percent.

University of Washington researchers recently demonstrated the world's first battery-free cellphone, created with funding from the U.S. National Science Foundation (NSF) and a Google Faculty Research Award for mobile research.

The battery-free technology harvests energy from the signal received from the cellular base station (for reception) and the voice of the user (for transmission) using a technique called backscattering. Backscattering for battery-free operation is best known for its use in radio frequency identification (RFID) tags, typically utilized for applications such as locating products in a warehouse and keeping track of high-value equipment. An RFID base station (called a reader) "pings" the tag with an RF pulse, which allows the tag to harvest microwatts of energy from it—enough to return a backscattered RF signal modulated with the identity of the item.



Unfortunately, harvesting generates very little energy; so little, that you really need a new standard. For instance, Wi-Fi signals transmit continuously, but harvesting that energy constantly will only enable transmissions of about 10 feet today. Range will be the big challenge for making this technology successful.

So we wont be seeing them anytime soon unfortunately.

Recycling of materials is always a concern, especially now that the use of Lithium-ion is increasing. Financial Times (FT) recently did a good summary of all the companies trying to recycle Lithium, Cobalt, etc.

Mr Kochhar estimates over 11m tonnes of spent lithium-ion batteries will be discarded by 2030. The company is looking to process 5,000 tonnes a year to start with and eventually 250,000 tonnes — a similar amount to a processing plant for mined lithium, he said.

The battery industry currently uses 42 percent of global cobalt production, a critical metal for Lithium-ion cells. The remaining 58 percent is used in diverse industrial and military applications (super alloys, catalysts, magnets, pigments…) that rely exclusively on the material.

According to Wikipedia, The purpose of the Cobalt (Co) within the LIBs is to act as a sort of bridge for the lithium ions to travel on between the cathode (positive end of the battery) and the anode (the negative end). During the charging of the battery, the cobalt is oxidized from Coᶾ⁺ to Co⁴⁺. This means that the transition metal, cobalt, has lost an electron. During the discharge of the battery the cobalt is reduced from Co⁴⁺ to Coᶾ⁺. Reduction is the opposite of oxidation. It is the gaining of an electron and decreases the overall oxidation state of the compound. Oxidation and reduction reactions are usually coupled together in a series of reactions known as red-ox (reduction-oxidation) reactions. This chemistry was utilized by Sony in 1990 to produce lithium ion cells.

From Treehugger: An excellent investigative piece by the Washington Post called “The cobalt pipeline: From dangerous tunnels in Congo to consumers’ mobile tech” explores the source of this valuable mineral that everyone relies on, yet knows little about.

“Lithium-ion batteries were supposed to be different from the dirty, toxic technologies of the past. Lighter and packing more energy than conventional lead-acid batteries, these cobalt-rich batteries are seen as ‘green.’ They are essential to plans for one day moving beyond smog-belching gasoline engines. Already these batteries have defined the world’s tech devices.

“Smartphones would not fit in pockets without them. Laptops would not fit on laps. Electric vehicles would be impractical. In many ways, the current Silicon Valley gold rush — from mobile devices to driverless cars — is built on the power of lithium-ion batteries.”

What The Post found is an industry that’s heavily reliant on ‘artisanal miners’ or creuseurs, as they’re called in French. These men do not work for industrial mining firms, but rather dig independently, anywhere they may find minerals, under roads and railways, in backyards, sometimes under their own homes. It is dangerous work that often results in injury, collapsed tunnels, and fires. The miners earn between $2 and $3 per day by selling their haul at a local minerals market.

There is a big potential for reducing waste and improving lives, hopefully we will see some developments on this front soon.

Debugging Problem: Same Phones With Different Signal Levels?

I have discussed this problem in past, based on questions asked on various fora (example). Here is a video I made some weeks back. Will be interested to know what other reasons people can come up with 😊.

5G Core Network, System Architecture & Registration Procedure

The 5G System architecture (based on 3GPP TS 23.501: System Architecture for the 5G System; Stage 2) consists of the following network functions (NF). The functional description of these network functions is specified in clause 6.
- Authentication Server Function (AUSF)
- Core Access and Mobility Management Function (AMF)
- Data network (DN), e.g. operator services, Internet access or 3rd party services
- Structured Data Storage network function (SDSF)
- Unstructured Data Storage network function (UDSF)
- Network Exposure Function (NEF)
- NF Repository Function (NRF)
- Network Slice Selection Function (NSSF)
- Policy Control function (PCF)
- Session Management Function (SMF)
- Unified Data Management (UDM)
- Unified Data Repository (UDR)
- User plane Function (UPF)
- Application Function (AF)
- User Equipment (UE)
- (Radio) Access Network ((R)AN)

As you can see, this is slightly more complex than the 2G/3G/4G Core Network Architecture.

Alan Carlton, Vice President, InterDigital and Head of InterDigital International Labs Organization spanning Europe and Asia provided a concise summary of the changes in 5G core network in ComputerWorld:

Session management is all about the establishment, maintenance and tear down of data connections. In 2G and 3G this manifested as the standalone General Packet Radio Service (GPRS). 4G introduced a fully integrated data only system optimized for mobile broadband inside which basic telephony is supported as just one profile.

Mobility management as the name suggests deals with everything that needs doing to support the movement of users in a mobile network. This encompasses such functions as system registration, location tracking and handover. The principles of these functions have changed relatively little through the generations beyond optimizations to reduce the heavy signaling load they impose on the system.

The 4G core network’s main function today is to deliver an efficient data pipe. The existence of the service management function as a dedicated entity has been largely surrendered to the “applications” new world order. Session management and mobility management are now the two main functions that provide the raison d’etre for the core network.

Session management in 4G is all about enabling data connectivity and opening up a tunnel to the world of applications in the internet as quickly as possible. This is enabled by two core network functions, the Serving Gateway (SGW) and Packet Data Gateway (PGW). Mobility management ensures that these data sessions can be maintained as the user moves about the network. Mobility management functions are centralized within a network node referred to as Mobility Management Entity (MME). Services, including voice, are provided as an “app” running on top of this 4G data pipe. The keyword in this mix, however, is “function”. It is useful to highlight that the distinctive nature of the session and mobility management functions enables modularization of these software functions in a manner that they can be easily deployed on any Commercial-Off-The-Shelf (COTS) hardware.

The biggest change in 5G is perhaps that services will actually be making a bit of a return...the plan is now to deliver the whole Network as a Service. The approach to this being taken in 3GPP is to re-architect the whole core based on a service-oriented architecture approach. This entails breaking everything down into even more detailed functions and sub-functions. The MME is gone but not forgotten. Its former functionality has been redistributed into precise families of mobility and session management network functions. As such, registration, reachability, mobility management and connection management are all now new services offered by a new general network function dubbed Access and Mobility Management Function (AMF). Session establishment and session management, also formerly part of the MME, will now be new services offered by a new network function called the Session Management Function (SMF). Furthermore, packet routing and forwarding functions, currently performed by the SGW and PGW in 4G, will now be realized as services rendered through a new network function called the User Plane Function (UPF).

The whole point of this new architectural approach is to enable a flexible Network as a Service solution. By standardizing a modularized set of services, this enables deployment on the fly in centralized, distributed or mixed configurations to enable target network configurations for different users. This very act of dynamically chaining together different services is what lies at the very heart of creating the magical network slices that will be so important in 5G to satisfy the diverse user demands expected. The bottom line in all this is that the emphasis is now entirely on software. The physical boxes where these software services are instantiated could be in the cloud or on any targeted COTS hardware in the system. It is this intangibility of physicality that is behind the notion that the core network might disappear in 5G.

3GPP TS 23.502: Procedures for the 5G System; Stage 2, provides examples of signalling for different scenarios. The MSC above shows the example of registration procedure. If you want a quick refresher of LTE registration procedure, see here.

I dont plan to expand on this procedure here. Checkout section "4.2.2 Registration Management procedures" in 23.502 for details. There are still a lot of FFS (For further studies 😉) in the specs that will get updated in the coming months.


Further Reading:

• 3GPP TR 23.799: Study on Architecture for Next Generation System
• 3GPP TS 23.501: System Architecture for the 5G System; Stage 2
• 3GPP TS 23.502: Procedures for the 5G System; Stage 2