Blog-1: 4th Generation Mobile Telephony

As someone who has been only 8 months into telecom, writing a blog with the purpose of educating others is a little audacious. I intend to learn first. What follows is a mix of research and field experience that I have gained as a part of my job.

An investment of over 70,000 crores. Optical fibers running up to 125,000 km and more than 35,000 Own built towers. Such is the sheer scale of the upcoming 4G project by a certain private player in India. For a company which has traditionally built plants and factories in few select locations, this is a different ballgame. However, the firm has had experience in Telecom industry. About 14 years ago, they started their first telecom venture. This time around they are making it bigger and better. It is a massive project.

This topic of 4G in India is so huge that I can start anywhere I like and write endlessly. But I’ll try to remain focused in my approach. This piece will deal with the history of Telecom in India followed by the different generations of telephony. Once we get a fair idea of 4G we will touch upon network basics and the kind of infrastructure that is required to maintain such a complex network. We will finish off with the business basics in this industry.

Itihaas

Telecom in India is a lot older than we might think. The first land line (electric telegraph) was introduced on experimental basis in 1851 for the use of East India Company. It took another 30 years for the telephonic services to be opened for public. Post-independence, all foreign telecom companies were nationalized as was the case with other industries. Govt. had monopolized telecom until the 80s. This is when for the first time, entry of private players was allowed (only in equipment manufacturing). In 1985, Government set up the Department of Telecom. Over the next ten years, Indian economy liberalized, TRAI (Telecom Regulatory Authority of India) was set up and NTP (New Telecom Policy) was announced. The NTP opened the floodgates for all private players. Private operators could now make national and international calls making it one of the most important milestones in the making of Indian Telecom industry.

In the 2000s, many private operators – Reliance Communications, Vodafone, Airtel, Idea, Loop Mobile and others successfully entered the Indian market. At present the total number of telephone subscribers is nearly 970 million (Dec 2014) and growing at the rate of 70 million per year. Indian telecom market is heavily biased towards voice services. Data usage is pretty low as compared to US and Europe. The introduction of 3G promised a great deal of data services which unfortunately didn’t materialize. Perhaps with the 4G revolution, we will achieve the vision of Digital India.

4G, also known as the 4th generation mobile technology is the latest in mobile telephony. Europe and USA first adopted 4G back in 2009. Airtel was the first operator to introduce 4G in India in 2012. Since we are talking about 4G I think I will provide a brief overview of the earlier generations too. Let us start with the very first generation and see how it has improved over the years.

There are two types of telephony – fixed and mobile. Fixed as you might have guessed is the landline which we know of. Mobile on the other hand signifies wire-less communication. All the generations starting from 0G to 4G refer to mobile communications. 0G (Zero generation – was perhaps named in hindsight) is really old. You don’t even see them in the classic black and white movies. Its ecosystem would contain a telephone which was partially mobile and mobile stations. The telephone would consist of a handset attached to a transceiver (transmitter and receiver). This transceiver would communicate with mobile stations relaying signals back and forth. The voice is sent and received in analog form. In the simplest terms analog is a way of representing information. Another way of doing the same is digital. Let us keep it at that and if you wish to understand more please refer this. 0G was also one way communication (also known as half-duplex) that is only one party can talk at a time. Once the signals are transmitted from handset to transceiver to mobile station, they are further relayed to other mobile stations for establishing connection (I have squeezed this part too much. I’ll touch upon this a little later when we discuss the aspects of a mobile network and how a call is made).

1G, the very first generation mobile phone sent analog signals to mobile towers (frequency modulated- to boost their energy for their journey to towers). Again to un-complicate what I just wrote, our voice signals are very weak. They need energy to be transferred to mobile towers. So we mix our weak voice signals with high energy signals and send them together. Once the voice signal plus high energy signal reaches the mobile tower, they are digitized for further transmission (Remember digital? A form of representing information. So when I say they are digitized, I mean they changed the way they were representing information from analog to digital).

The revolution came with the introduction of 2G, the most popular mobile generation. It is a completely digital way of communication (even the voice which we generate is digitized and transmitted). It is also full duplex meaning people can communicate two way and do not have to wait for each other to finish their sentences. It was originally designed for voice communication. The data rates were also limited to 64Kbps (an 8 bit sampling rate of 8 KHz voice – ring any bells engineers). Then came 2.5G and 2.75G which were minor modifications enabling higher data speeds. 3G the next generation was designed for higher data usage. We all hear different theoretical maximum speeds for 3G- 3.1Mbps, 14.4 Mbps and others.

If you research more on this more you will find that in 3G, speeds depend on the type of standard (UMTS, HSPA, HSDPA etc.) and the same applies to 2G (GPRS and EDGE) too. In simple terms, ITU (International Telecommunication Union) decides on a set of parameters for defining a generation. The parameters can include minimum data transmission speed, peak speed, switching type and other technical stuff. If a technology/ standard meets the criteria it can be termed as that generation technology. So in essence what we call as 1G, 2G, 3G or 4G, are nothing but theoretical concepts. Let me take a simple example. If 3G definition dictates that the speed should be more than 100Kbps, then any telecommunication standard fitting that definition can be considered a 3rd generation technology.

I have searched a lot but I couldn’t find out the minimum defined speed rates for a standard to be called 4G. It is my hunch that the minimum speed of 4G should be higher than the maximum speed of 3G. Most commonly used 3G standards such as HSPA/ HSDPA have theoretical limit of 21.1 Mbps. So anything above that should be considered 4th generation. 4G speeds should also have peak throughput of 100Mbps (moving user) jumping up to 1Gbps in case of stationary mobiles. Also the entire network is IP based. I am tempted to write down the actual download speed I witnessed in one of the cities, but I’ll wait.

I am afraid what I am about to write will become too technical but this is something which is essential to describe. 4G as I mentioned is completely IP based i.e. it depends on packet switching. All the previous generations were either a pure circuit switched system or a hybrid of circuit and packet switched system. Picture this. You want to send a letter to your friend. You can do it in two ways –

  • Write the address of your friend in the letter and pass it on to the next guy you see. The next guy may not know the exact location of the friend but may pass it on to someone who knows, or someone who is closer to the friend. Same will be repeated till it reaches nearby the friend after which someone who knows the address will deliver it to your friend
  • Do not write an address. But predefine to whom you will pass on the letter in advance. For example you will give it to A. A knows B, B knows C and C knows your friends. So the letter will travel from you to A to B to C and then to your friend

The difference between the above two methods is that in the first one, if you send multiple letters it may so happen that the letter exchanges different hands. But in the second case it’ll always go through the same chain. In the first case people are not reserved/ tied up for the letter transmission but in the second case we have reserved specific people to do the job.

The first way is analogous to packet switching. The second one to circuit switching. So when I say 4G is completely packet switching based, they just send information with the address on it hoping it’ll reach the destination. But in case of 2G and 3G, the link between caller and receiver is defined before a call is made and reserved for that call.

I hope this has given an insight into the history of Indian Telecom industry and a tour of the different mobile technologies. Though I have touched a little bit on the network side, I will write about it in great detail in the next piece

https://www.dnb.co.in/IndianTelecomIndustry/OverviewTI.asp

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