5G and the Tactile Internet

Today mobile wireless networks are truly like oxygen and form an indispensable part of our lives. Not only have they been essential for personal and business communications but also have played an important role in socio-economic development of both developed as well as developing countries. Many operators/carriers around the world today are deploying 4G LTE to offer faster access and lower latency for myriad of applications. Mobile network traffic has more than doubled over last decade or so and wireless networks have experienced explosive growth.

The 5G mobile technology is envisioned to address the demands and business needs of 2020 and beyond and it is expected to further empower and jolt the socio-economic development in countless ways unimagined today. 

The Tactile internet will be the next evolution of the Internet of Things (IoT), machine to machine and human to machine communications. The International Telecommunication Union (ITU) defines the Tactile internet as an internet network that combines ultra low latency with extremely high availability, reliability and security. It believes the Tactile internet represents a "revolutionary level of development for society, economics and culture"

The 5G vision is to provide services and enable applications that fall in 3 broad categories described below:

Enhanced Mobile Broadband (eMBB)

eMBB envisions fully connected society. Broadband internet services will be available for all from dense urban areas to rural population and at higher speeds. Some of the use cases that fall in this category are:

• Pervasive Video
• Augmented Reality/Virtual Reality Applications: imagine kids to be able to learn solar system by visually seeing different planets and their characteristics.
• Smart Office : processing large amounts of data in the cloud and instant communication by video 
• High Speed Trains: with concept of Hyperloops now being closer to reality, providing broadband access to users at speeds greater than 500km/h will be possible.

Ultra-Reliability Low Latency Communications (URLLC):

This family of use cases envisions support for Lifeline communications in the event of natural disasters and health and assisted living applications. Going forward, many industries such as automotive, Manufacturing and agriculture will reply on low latency applications to improve quality and productivity. Some of the use cases that fall in this category are:

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•        Factory Automation 
•            Remote Surgery 
•            Connected Drones 
•            Collaborative Robots: A control network for robots 
•            Self-Driving Cars and Automated Traffic Control 
•            TeleHealth

All of the use cases mentioned above require ultra low latency (<1ms and="" availability="" high="" network="" o:p="" reliability.="">

Massive Machine Type Communications (mMTC):

Massive Internet of things means growing number of connected devices (e.g. sensors, cameras, actuators) with varying demands and characteristics. The family of large number of connected and communicating is termed as Machine Type Communications. Last 3-4 years have seen explosive growth in number of smart devices such as wearables and the trend is expected to continue to grow at a rapid rate. This family will include low cost/long-range/low power devices as well as broadband devices. Some of the use cases that fall in this category are :

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•        Smart wearable 
•        Sensor Networks
•            Smart City Applications: smart grid, city wide video surveillance. 
•          Connected Home: imagine a connected refrigerator knows that it is low on Milk, automatically places the order for a carton of milk on amazon and the milk gets delivered at the doorstep.

With 5G all of the above use cases are made possible by availability of huge bandwidth in Super High Frequency (3-30 GHz) and Extreme High Frequency Bands (30 - 100 GHz) along with technological advancement in antenna techniques such as massive MIMO, beam forming and beam steering. Most of the 5G deployments will required bandwidth in the range of 300 - 800 MHz providing the big fat pipe required for enormous data consumption. 

While RF spectrum and physical layer changes provide for data usage, architectural changes such as Edge computing, Network Slicing provide for key differentiating factors required for ultra low latency and machine type communications. 

5G will truly usher in the Fourth Industrial revolution. Expert analysis has predicted the macroeconomic impact of 5G to be $12 trillion by 2035 and the White House has declared 5G to be a national priority !!! 

Wireless Network Balancing - Impact of Artificial Intelligence & Machine Learning

Mobile networks today are highly complex in nature. With evolution of networks from 3G to 4G and explosive subscriber growth, the amount of data flowing through the networks have increased manifold. Along the way, networks have become denser with introduction of new solutions such as femtocells and picocells (personal base stations) that boost mobile network coverage and provide additional capacity. This is where the concept of Self Organizing Networks or as it generally referred to as SON was developed. Old ways of managing the network in terms of service availability or network capacity planning are not scalable. The mobile first world needs an innovative approach to the way modern day mobile networks are managed and the way network coverage and capacity is planned. Similarly, operators need to find ways to reduce CAPEX and OPEX without sacrificing on network quality and maintenance needs.

SON is a concept (set of highly complex algorithms) where automated processes are used to monitor the network and measure its performance and network analytics is used to gauge the feedback for making critical decisions that help manage the complex network and reduce the costs.  There are 3 main areas over which mobile networks use SON algorithms for self-optimizing and balancing:

Self Configuration

Self-configuration allows wireless base stations or access points to be plug and play. They need as little manual intervention as possible.

Self-Optimization

Radio resource is often the bottleneck when it comes to mobile networks. With SON, the radio resources are managed efficiently and intelligently thereby providing optimization of coverage, capacity and interference.

With SON, networks can perform mobility load balancing where by cells which are heavily loaded can transfer load to other cells which are lightly loaded thereby achieving the optimal balance. This load balancing technique can be used even with different radio technologies e.g. between 4G and 3G networks and also during handovers (Handover take place for e.g. when the call is active and you are driving from one place to another without dropping the call.)

Self-Healing

Any complex system experiences intermittent failure or faults/errors. This can lead to service interruption or poor service quality. Self-Healing involves automatic correction of network parameters and removal of failures to mask the effect of the fault or failure. This self-healing capability provides the necessary stability and reliability for mobile networks.

With advent of Machine learning and Artificial intelligence, SON can be done at much larger scale and with more accuracy. Imagine a scenario where a region is facing poor signal coverage or low throughput numbers. While such a issue would have needed much intervention from engineering, going forward smart algorithms can isolate the root cause of such issue and lets say if the cause is some configuration mismatch or routing issue, they can fix the issue without manual intervention. 

AI & ML will be more important as today's wireless networks evolve to 5G. 5G will result in network densification and there will be tons of wireless nodes deployed (Macro cells, femtocells etc) and service automation will be key in scaling of next generation networks and their day to day operation. 

What is 4G ??

4G stands for 4^th Generation wireless standard. International Telecommunications Union (ITU) is a body responsible for standardization. When a wireless standard is defined e.g. 2G, 3G or 4G, ITU puts forth a particular set of requirements. By definition, 4G network requires a mobile device to be able to exchange data at 100Mbits/sec (downlink) and 50Mbps (uplink) using a 20MHz wide channel. 4G networks offer speeds 10 to 12 times faster than previous 3G networks.

Everything you do with your mobile i.e. calling your friend, posting on facebook, taking a photo and uploading it on google cloud, you streaming Netflix on your mobile phone is governed by set of rules, known as protocols. 3GPP (3^rd Generation Partnership Project) is a body that defines the rules or protocols so that one element in the network talks to other element. Why is this important? Because otherwise, you cannot take your phone and use it in some other country on your vacation. 

What we hear today is the term LTE which is often interchangeably used for 4G or in conjunction as 4G LTE.  LTE stands for Long Term Evolution and is not a standard but a path used to achieve 4G speeds and connection rates. Today Verizon covers the entire nation with its best in class 4G LTE network. The figure below shows the building blocks of a basic 4G LTE Network (From Access to Core)

As you can see from the figure above, for a regular user, he/she just makes a call or browses the internet on the mobile phone, sends a whatsapp msg but in practice that single action traverses and touches upon many different elements of a carrier’s network.

Access Network: The UE and the eNB together form an access network. Core Network: Also termed as Evolved Packet Core (EPC) comprises of all the other network elements.

The main building blocks of 4G LTE network are as follows:

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        User Equipment (UE): it is your mobile or any device (tablet, PC, smartphone) that connects to 4G LTE network

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        eNodeB (eNB): In simple terms, these are the radio towers. Your mobile is connected to the network via these towers.

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     MME: Stands for Mobile Management Entity. It is the brain of the core network. It is responsible for mobility management, paging and authentication of the mobile device.

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     Serving Gateway (SGW): It is the interface in between eNB and Core Network. Put is simply, it acts as a router for the mobile device.

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     Packet Gateway (PGW): It serves as a gateway to the external network (e.g. Internet). The external network is termed as Packet Data Network (PDN). A PGW connects to multiple PDNs.

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    Policy and Charging Rules Function (PCRF): It ensures only the authorized users get the desired level of service.

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     Home Subscriber Server (HSS): It is the main database in EPC. Stores all subscriber information.

Wireless Networks - Evolution to 5G !!!

A famous quote read, “Technology must be like Oxygen: Ubiquitous, necessary and invisible.” Which exactly describe today’s wireless networks.

Wireless networks are the oxygen necessary for today’s vast global communication infrastructure. They are the platform over which the entire Digital ecosystem is built. Wireless devices today are capable of doing pretty much everything from making a phone call to using the internet and running applications. Wireless networks today are the backbone of user as well as business communications.

Wireless networks use Radio Frequency technology commonly referred to as RF. The RF signal is an electromagnetic wave that today’s smartphones and computers can detect and connect too. 

There are 2 main components of wireless networks:

-          Access Network

-          Core Network

Access Network: An access network is the invisible user network that connects subscribers or users wirelessly to a particular service provider and, through the carrier/operator network, to other networks such as the Internet. Users connect to the access network via Access point. The access point can be your WiFi Access point or nearest Verizon telecommunications tower (base station).

Core Network: A core network, is the central part of a telecommunications network that provides various services to customers who are connected by the access network. Services such as ability to make a phone call, browse internet, using social media apps such as FB, Twitter etc.

The figure shows the evolution of Wireless Networks from 1980’s to present day i.e. from 1G (1^st Generation) to 4G/5G Era. It all started with basic voice service deployed on analog phones in 1980’s with maximum rate of 2Kbps. Analog communication meant taking human voice and translating it to electronic pulses. Over the years the communication industry has witnessed one of most historic & iconic transformations from analog to digital that enabled services like Video Conferencing and Gaming possible. Digital transformation involved breaking down signal into binary format of 1’s and 0’s.  At every stage the telecommunications infrastructure evolved with providers like Verizon at the forefront of research and development to further the cause of technology. Innovations in wireless space have facilitated creation of popular devices such as iPhone and Samsung Galaxy S7 and services such as Video calling and social media platforms to flourish. 

Wireless evolution has changed the way how business is carried out and has enabled development of several use cases which were unthinkable even a decade ago.

Different Approaches for Voice over LTE ?

There may be different approaches by different mobile operators (read Verizon and ATT) for voice over LTE solution. Primarily this has to do with their LTE deployment strategy. AT&T will go with a phased approach wherein they will deploy LTE in certain markets and cover the rest with HSPA+. This seems to be their strategy which makes sense since HSPA+ also can match ractical UL/DL speeds that LTE provide.

Tmo just announced their HSPA+ rollout in few cities which AT&T should like. So AT&T might adopt a Circuit switched over HSPA approach for 2-3 years before they decide to overlay LTE with nationwide footprint.

Verizon on the other hand is overlaying its current CDMA network with an LTE. So seem likely to adopt IMS core for their LTE implementing VCC.

I read an interesting article about a possible third approach for LTE voice .. and that Dual Radio with single SIM . Verizon surely seems to be using this with Thunderbolt, which is bound to save them some CAPEX (in near term) for not implementing IMS core. But going forward they will certainly upgrade to IMS core to incorporate burgeoning APP world.

For Sprint only time will tell how will they rollout LTE. But they certainly can take a leaf out of this Malaysian operator :)

Voice Over LTE

LTE being a packet based technology; there have been ongoing discussions about Voice implementation over LTE. This is going to be crucial as operators would want just one network to be maintained to reduce their CAPEX and OPEX. There have been quite a few solutions being pondered upon in the 3GPP community.

One way is the CS fallback mechanism to address this. By CS fallback they mean that for voice LTE will handover the call to 2G/3G networks. This is done by MME registering the device with the 2G/3G networks and acting as SGSN communicating with MSC for voice signaling. This will ensure that the voice quality is maintained as of today, but this would also mean that if an existing packet data call is in progress, then it might get suspended or handed over to 2G/3G networks. I am not sure is this will be good idea since earlier generation networks will not have the bandwidth and the capacity to support LTE multi-media applications.

I read a paper about CSoHS (Circuit Switched over HSPA+) . This explains about how HSPA+ radio bearers will be used to carry voice traffic but core used will be CS core.
This can be done via software upgrade on UE as well as RNC. This would add de-jitter and time warping mechanism to ensure smooth voice quality. I hope this can be further extended to LTE, which is approach pursued by VoLGA which stands for Voice over LTE via Generic Access (Thanks to Steve for clarifying this!!). The difference between 2 approaches is avoiding the fallback to legacy networks and also using high capacity radio bearers. Also user not be required to suspend/handoff his data call.

Though these above approaches sound good for now, they would still require different networks to be maintained. Going further, IMS will have an important role to play as it can support end-to-end voice over IP services with call signaling and switching functionality required for voice. It also supports Voice Call Continuity (VCC) that can enable gradual deployment of VoIP.

RevB Knocking on Carrier's Doors

Lately there has been a lot of buzz about LTE. Last week at Mobile World Congress 2009 in Barcelona, major wireless carriers like Verizon, Vodafone, AT&T, T-mobile announced plans to go with LTE as their next generation 4G technology. Verizon went even a step further to detail their vendors, commercial trials and deployment plan. So LTE looks all set to hit the trials by late 2009/early 2010.

Having said that I feel LTE is alteast 3 years away from commercial readiness. And here's why. If we take a deeper look into Verizon earnings call their CAPEX spending for 2008 was almost the same as their previous year. LTE deployment would require billions of dollars in CAPEX. Considering the current market economy, it is hard to imagine Verizon going with an aggressive rollout. So as per Verizon CTO Dick Lynch, we should see LTE rollout in 2011. But I believe it will be more of phased approach with all markets covered by 2013. We should see other carriers also follow the same approach.

LTE boasts of download speeds of about 34Mbps (I would assume it will be 10-15Mbps theoretically). LTE will be a platform for all data centric applications requiring higher speeds in the order of 8-10 Mbps. VoIP should also take off. But the phased approach in LTE deployment would require current 3G networks to support higher speeds. EVDO RevA can only support upto 3Mbps, though theoretically its must less than that (700Kbps-1Mbps).

Here is where EVDO RevB steps in for the 3GPP2 camp. For carriers like Verizon, it should only be a software upgrade not requiring much additional spending. 3 carrier RevB can support downlink speeds of upto 9Mbps and uplink speeds of upto 5Mbps. Qualcomm also announced availability of MSM8960 chipset supporting both LTE and EVDO RevB at MWC 2009. So if carriers decide to roll out RevB along with phased out LTE approach, they should see availability of dual mode handsets supporting LTE/RevB handovers with seemless mobility. This would enable applications designed for LTE getting traction soon resulting in rich user experience. Nobody wants their video conferencing session being closed just because they moved from LTE to EVDO network.

Now RevB makes even more sense to Sprint. The beleaguered carrier just lost 1.4M subs in Q4. WiMax even though being a good technology with time to market advantage, its facing the same destiny as EVDV. So even if WiMax is prevalent, I see it more of a backhaul solution than 802.16e. Moreover its now Clearwire's headache. So now Sprint is left with its EVDO RevA network. Their rival Verizon is moving to LTE. So they need a network that can compete with Verizon in terms of speed, supporing data hogging applications. And year on year there has been consistent increase in data usage. Cisco even predicts data usage going up with video services accounting for 64% of mobile traffic by 2013. Surely if the carriers are to support around 5GB demand for data per month they ought to have network that can meet the demand. With EVDO RevA I do not see that happening. Also the incremental cost of deploying RevB will be much less.

I think both Verizon and Sprint should go for RevB in order to get maximum out of their current 3G networks before we see 4G taking over. 3GPP camp will also do the same with Tmobile, AT&T upgrading their networks to HSPA + coupled with phased LTE rollout.