M6L2: Generations of Mobile phone technology

How many of you have played with this?

Most of us. If you ask your parents, how was the experience, they would say that in most of the cases, it would show, “This line is busy”.

Have you ever wondered how this worked?

They use a method known as circuit switching.

In case of circuit switching network, a dedicated link of fixed bandwidth must be established before the call is made between users. This stays alive till the call is active.

As you can see the bandwidth is dedicated between User A and User C. In those times, this task of switching nodes was managed by PSTN (Public switch telephone networks) and centralized phone network facilities.

So, when you make a phone call, you ask the PSTN to establish a dedicated circuit for you. It does this by finding unused channels by allocating nodes all along the way through the network and dedicates them to your call. When you start exchanging data (talking) all your data follows the same path or circuit through the network. If you pause in your conversation the circuit, you're using is idle, wasting bandwidth. But you never lose data because you have a guaranteed, reserved circuit. Now if the bandwidth is not available, other users had to wait till your call is terminated. This switching technique uses Multiplexing, which can be either TDM (Time Division Multiplexing) or FDM (Frequency Division Multiplexing). Multiplexing divides a large pipe (in our case bandwith) into independently usable portions

Then came packet switching, that promises more efficient usage of bandwidth since the users can share the same bandwidth at the same time. Data is packed in packets and no reserved channel is created ahead of time. Each packet belonging to a single message may take a different route through the network. the data is “packed” in a certain order and will be “unpacked” in the reverse order by the receiver, by using the code that are specific to each user. Thus, packet switching places the intelligence in the end nodes, rather than the phone company facilities, with a simple underlying network that only directs packets from one side to the other. This could be done through a multiplexing method known as Code division that spreads the code along the circuit.

TDMA: uses a common signal path (bandwidth) but allots specific time interval for each user. These time intervals are called as frames. This is akin to queue system where the data gets to flow, only after its path is clear. Here the uplink and the downlink happens through the same frequency bands, but at different time slots FDMA: Here the common signal path (bandwidth) is shared by dividing it into smaller virtual bandwidths. Individual bandwidth is allocated to each user data. This is akin to multiple data flowing parallel to each other. Each data flows on its own dedicated highway. Here the uplink & downlink also happens through separate Frequency Bands CDMA: This technique allocates code to each set of data that are specific to each user. This is akin to token that is unique to each user. (Unique means one and only one).

Thus, packet switching, requires a less complicated infrastructure. It is easier and more affordable than circuit switching. Since all the bandwidth can be used at once, packet switching is more efficient.

 Then came wireless telephony. The first generation was called 1G. It used analog signals to transfer the data.

First let us understand analog and digital. Since, later after GPRS came, almost every wireless communication shifted to digital.

What is the meaning of the word analogy?

The dictionary meaning says that analogy is a comparison between one thing and another. In most of the cases, we use one or more set of examples or a case studies, that the audience understands easily. Later-on, the same is used to compare with another event or process, that shows significant amount of resemblance with the former one. Using such techniques in the classroom helps to explain or clarify the concept easily.

Not only, we use this in our day to day communication but also in our day to day life. For example, in our wall clock, we understand the current time, by comparing the position of the hour hand with the number written below. Or when we use a clinical thermometer, we compare the height of the mercury with the scale to the right of it. In the same way, when we drive the car, we understand the speed by comparing the position of the pointer with the number written below. In all the cases, we compare it with numbers or scale, that makes it easier for us to understand. Similar is the case of analog signals.

In this case, we compare the amplitude with the numbers of Y axis and the time interval on X axis. Since we compare, it is called analog.

An analogue signal is continuous in time and is used to measure changes in some physical phenomena such as light, sound, pressure, or temperature. These values along Y axis may vary continuously with the passage of time.

Since 1G (First generation used analogue signal), it used circuit switching. As mentioned earlier, analogue signals are continuous and therefore they cannot be broken. But wait, we are talking about wireless communication and haven’t included data yet.

1G was used for communication and not for surfing on internet. Later, after 1990s, when there was explosion of internet, newer generations of wireless communication started arriving and they started providing internet as a service in addition to communication. It was called 2G and GSM (Global system for mobile communication). GSM used multiplexing which was either TDMA (Time division multiple access) or FDMA (Frequency division multiple access) or both.

2G introduced data services starting with SMS text messages. However, it was still dependent of circuit switching to carry data between the users.

When packet switching technique started attaining maturity, it was realized that the same could also provide faster and better internet speeds on wireless handsets. In order to integrate packet switching that could carry user data to and from the internet to the wireless handset, GPRS (General packet radio service) was invented. It was used to connect with the internet. One of the biggest limitations of it was that it could provide very less speeds. The data rates could reach at the most 114Kbps and could be used to send SMS and MMS (Multimedia through messaging). GPRS used Wireless Application Protocol (WAP), which was specially designed communication protocol for mobile browsers.

This got evolved to EGPRS or EDGE. EGPRS stands for Enhanced General Packet Radio Service and denotes GPRS networks operating with the aid of the newer EDGE (Enhanced Data for Global Evolution) standard. EDGE operates by transferring data packets under a greater number of pathways simultaneously for faster data speeds. EDGE speeds can reach 236 kbps, though again real-world speeds are usually lower.

Then came 3G and it could provide peak data rates of at least 2Mbps, as it used Wideband CDMA (WCDMA). It could use both circuit/packets switching.

The basic difference between the CDMA and WCDMA is bandwidth. While CDMA uses 1.25 MHz frequency bandwidth, WCDMA uses 5 MHz bandwidth to transfer the data. As a result, a greater number of packets could be transferred at a time.

As per 1994 National Telecom Policy (NTP), there were different licenses for different services like cellular v/s basic, wire v/s wireless, cable TV v/s satellite etc.). With the arrival of 3G in other countries, the union government made an addendum to NTP in the year 1999. It tried to provide single unified license wherein the service provider could provide basic & cellular services using any technology in various geographical areas. However, for each area (circle), they had to take separate license, that was provided on first come first served basis without any auction or tendering process. CAG reported the losses due to this method which eventually, came to be known as 2G Scam. In the year 2012, the government made some further changes to the NTP. Now it includes bidding for the required spectrum by the telecom company. The company can use any frequency to provide any technology The 2012 NTP removed all the different categories of license mentioned in 1999 policy and implemented one nation / one license policy.

3G then tried to integrate HSPA (high speed packet access) and HSPA plus technology to provide faster internet speeds. In this case, two specific protocols are used in tandem, high speed downlink packet access (HSDPA) and high-speed uplink packet access (HSUPA). HSPA could offer speeds up to 14.4 Mbps.

An improved version of high-speed packet access technology, known as Evolved HSPA or HSPA+ offers 42 Mbps of throughput per cell. By using dual cell deployment and multiple input, multiple output architecture, HSPA+ networks can achieve maximum throughput of 168 Mbps overall.

The International Telecommunication Union recognized HSPA+ as a fourth generation (4G) technology in December 2010. HSPA+, however, offers significantly slower speeds than the predominant 4G LTE.

You might have seen that some companies offer better network coverage than others. Have you ever wondered why? Waves with longer wavelengths have longer range, meaning they can travel more than the ones with wavelengths lesser than them. Lower frequencies imply larger wavelengths. Microwave band starts from 0.3 GHz and ends at 300 GHz. Lower frequency spectrum (0.85 – 0.90 Ghz) provides better coverage & building penetration compared to higher frequencies (1.8 – 2.1 GHz). Hence, companies that offer communication networks prefer to use lower frequencies, to provide better network coverage to their customers.

LTE, or Long-Term Evolution, is considered a “true” 4G network. LTE is an IP (Internet protocol) based system resulting in a marked reduction in latency (the time taken by data to go and return). Because of this, LTE is not compatible with 2G and 3G networks and thus, functions on an entirely different wireless spectrum.

Pre-4G or 4G LTE can provides peak data rates up to 100Mbps. It uses either Wi-Max or Long-Term Evolution (LTE), while actual 4G can provide 1 Gbps speeds.

VoWiFi: Voice over WiFi, just like your WhatsApp or messenger call, it's just another name for VoIP, when you are using WiFi. ViLTE: Video over LTE, just like Skype but without a need to login, you can directly video call through phone dialer. VoLTE: Voice over LTE, it is voice transmission using data packets by a method called packet switching.

5G will help to achieve Internet of things (IOT) in real sense. IOT is a proposed development of the Internet in which everyday objects have network connectivity, allowing them to send and receive data. (As of now, the telecom providers in India don't have the necessary spectrum to deploy 5G).

Technology → Features                 ↓	1G	2G	3G	4G	5G
Start/ deployment	1970-1980	1990-2004	2004-2010	Now	Probably 2020
Data bandwidth	2 Kbps	64 Kbps	2 Mbps	1 Gbps	Higher than 1 Gbps
Technology	Analog cellular Tech.	Digital Cellular Tech.	CDMA 2000 EDGE	Wi-Max, Wi-Fi, LTE	WWWW
Multiplexing	FDMA	TDMA, CDMA	CDMA	CDMA	BDMA/ mMIMO (massive MIMO)
Switching	Circuit	Circuit, Packet	Packet	All packet	All Packet
Core network	PSTN	PSTN	Packet N/W	Internet	Internet

Technologies for 5G MIMO: Multiple Input Multiple Output technology uses multiple antennas at the transmitter and receiver end to enable a variety of paths for each antenna to carry the data. This is a MIMO router mMIMO means massive MIMO. In case of massive, there are 32 or more logical antenna ports in the base station BDMA: In BDMA technology, the base station allocates separate antenna beam to each mobile phone or mobile station. This could be done after evaluating position of the mobile stations as well as their moving speeds, then deciding widths and directions of beams for mobile stations with respect to the base station. All the mobile stations communicate with base station when these are in its line-of-sight (LoS) and all the beams are distinct for each individual station. So simultaneous data transmission is possible to different mobile stations at different angles.

5G will use spectrum in the existing LTE frequency range (0.6 GHz to 6 GHz) and millimeter wave bands (24–86 GHz). Millimeter band or extremely high frequency (EHF) refers to the spectrum between 30 Ghz and 300 Ghz, since they have short wavelengths that range from 10 millimeters to 1 millimeter. So far, only radar systems and satellites use millimeter waves. Beyond, 300 Ghz is the terahertz band which is harmful for human body. The high frequency of millimeter waves makes them a very efficient way of sending large amounts of data such as computer data, or many simultaneous television or voice channels. However, very high-power millimeter waves have the capability to heat up the surface of the skin, upon exposure. Hence, there are cases of police and military using the same for crowd control, in certain nations. In case of India, TRAI is planning to 3.6 GHz for the deployment of 5G networks. Millimetre-length electromagnetic waves were first investigated in the 1890s by Indian scientist Jagadish Chandra Bose.

Millimeter waves are not capable of penetrating structures and other obstacles. Even leaves or rain can absorb these signals. This is also why 5G networks will have to adopt the small base station method to enhance traditional cell tower infrastructure. Because millimeter waves have high frequencies and short wavelengths, the antennas used to receive them can be smaller, allowing for the construction of small base stations. We can predict that, in the future, 5G mobile communication will no longer depend on the construction of large-scale base stations, but rather many small base stations. This will allow 5G to cover peripheral areas not reached by large base stations. Hence when 5G will start arriving, more number of base stations and transmitting antennas will be deployed. Long term exposure to millimeter wave frequency radiation may affect other living organisms and plants. However, further research is required to confirm this claim.

Every time your device tries to access the internet, it is assigned an IP address. IP address act as an identifier for a specific machine on a network. The IP address is also called IP number and internet address. IP address specifies the technical format of the addressing and packets scheme. Most networks combine IP with a TCP (Transmission Control Protocol). It also allows developing a virtual connection between a destination and a source. When the internet was first invented in the 1970s, the Internet Protocol Version 4 (IPv4) was established and allowed space for a total of 4.2 billion addresses. With the proliferation of modems, laptops, video games consoles, smartphones, tablet and internet-enabled devices like smart TVs, smart fridges, smart thermostats and AI voice assistants, we have so many more devices that need internet connectivity than ever predicted that IPv4 addresses have almost all run out. To keep the internet running, standards bodies developed a new standard called IPv6, which will enable many more hosts to be connected and a lot more data traffic to be transmitted, and internet service providers (ISP) across the world have been migrating users over since mid-2016. IPv6 also called IPng (Internet Protocol next generation). Features of IPv4 ·         Connectionless Protocol ·         Allow creating a simple virtual communication layer over diversified devices ·         It requires less memory, and ease of remembering addresses ·         Already supported protocol by millions of devices ·         Offers video libraries and conferences Features of IPv6 ·         Hierarchical addressing and routing infrastructure ·         Stateful and Stateless configuration ·         Support for quality of service (QoS) ·         An ideal protocol for neighboring node interaction Basis for differences IPv4 IPv6 Size of IP address IPv4 is a 32-Bit IP Address. IPv6 is 128 Bit IP Address. Addressing method IPv4 is a numeric address, and its binary bits are separated by a dot (.) IPv6 is an alphanumeric address whose binary bits are separated by a colon (:). It also contains hexadecimal. Example 12.244.233.165 2001:0db8:0000:0000:0000:ff00:0042:7879 Network Configuration Networks need to be configured either manually or with DHCP. IPv4 had several overlays to handle Internet growth, which require more maintenance efforts. IPv6 support autoconfiguration capabilities. Mobility & Interoperability Relatively constrained network topologies to which move restrict mobility and interoperability capabilities. IPv6 provides interoperability and mobility capabilities which are embedded in network devices. Security Security is dependent on applications - IPv4 was not designed with security in mind. IPSec(Internet Protocol Security) is built into the IPv6 protocol, usable with a proper key infrastructure. Packet size Packet size 576 bytes required; fragmentation optional 1208 bytes required without fragmentation Combability with mobile devices IPv4 address uses the dot-decimal notation. That's why it is not suitable for mobile networks. IPv6 address is represented in hexadecimal, colon- separated notation. IPv6 is better suited to mobile networks.