Preparation Strategies: Advanced Communications

ESE/IES 2019 prelims have been recently conducted and Electronics and Telecommunication engineering graduates have been looking for preparation strategies for subjects since then especially for Advanced Communications. Since 2017, UPSC has added some new topics to the syllabus of ESE for E&T. The new syllabus is in lieu of the latest communication technology that has come up and to make aspirants acquainted with types of communication technology and how they have evolved. Advance communications is one of the newly added subjects, which is inculcated only in the syllabus of ESE for Electronics and Telecommunication engineering. Though a number of topics form this subject also find a place in GATE preparation strategy, but the subject as a whole has been an integral part of ESE 2017, 2018 and IES 2019, that is it finds a significant place every year since it has been included.

Advanced communications is completely an advanced topic of Electronics and telecommunication engineering. Having a weightage of almost 12 to 14 marks in the preliminary stage and 2 to 3 questions, accounting for almost 35 to 40 marks in mains stage make this subject an inevitable topic for ESE. Also, it is very important to know and learn the concepts involved in this subject, being an electronic communication engineering graduate. This is also one of the major reasons why this subject has got a significant weightage and most of the questions in PSUs or ESE are asked from this topic. Though one needs to be very selective during ESE preparation and which is why it is always recommended to follow study material specifically designed for ESE but if you still face a problem with some specific concept, following are the recommended books to refer:

  1. Electronics communication system: By Wayne Tomasi. The book explains all the concepts starting from the fundamentals through the advanced communications concepts up to the data link layer.
  2. DATA communication and networking: By B. Forouzan. This book is recommended for security, application, and protocols etc.

These two books are sufficient to cover all the concepts related to Advanced communications. To explain the preparation strategy for Advanced communications methodically, the subject has been divided into the following subparts and detailed description and preparation tips for each topic have been given in the following sections:

Optical communication: This part of advance communication deals with guided transmission and in general accounts for about 4 to 6 marks in the preliminary stage of ESE. Following are the contents of optical communications and the topics that they include:

  1. Introduction: This part deals with Tera-Hertz frequency band since, in Communication systems, only the frequency band till GHz are focused upon. To study various elements and functioning beyond the GHz band, block diagrams and elements’ representations are used.
  2. Review of optics: Here, basic concepts regarding light like the nature of light, optic power, critical angle, Snell’s law, numerical aperture, acceptance angle, etc. are looked upon. Taking the discussion further, questions are put up from the relation between numerical aperture and acceptance angle, relative refractive index, etc.

Generally, derivations and numerical are asked from these parts. Objective questions in prelims are mainly put up from the review of optics.

  1. Type of fibers: This subpart deals with how fibers are classified. The basic classification i.e. SMSI (single mode step index), MMSI (multiple mode step index), graded index, etc. are discussed.

Questions from this topic are generally short and objective in nature for prelims or one descriptive answer type in mains

  1. Attenuation/loss: This part of Advanced Communications deals with the practical application of optical communication through the various attenuations or losses incurred. The effects, factors, causes, dispersion characteristics are studied and how to reduce them.
  2. Light sources: The various types of light sources i.e. led or laser, how they are generated, principles involved viz. spontaneous emission, stimulated emission, etc. features and characteristics of different sources are covered in this part.
  3. Light/photodetector: The detector used at the receiving part of the communication link, its types, principles involved and factors affecting characteristics are to be covered here.
  4. Link design: This is the most important subtopic of Advanced Communications. It deals with how components are selected for an optimum link design to incur minimum possible losses. All other concepts find the application Power budget/link budget calculation is the major issue that telecommunication engineering graduates face which is dealt with, in this part.

Optical communication can be studied and summarized very easily with help of charts and tables. This is an easy and highly formula-based topic where every numerical can be solved in no time using simple formulae. This can be a soft target for ESE preparation. Since optical communication is a type of wired communication, next topic deals with the wireless mode of the latest communication technology, which is Satellite communication.

Satellite communications: This topic accounts for about 4 to 6 marks in preliminary and is important to study to understand wireless types of communication technology. The topic covers the following important parts:

  1. Wave propagation: The various types of waves based on their media of propagation, like the ground wave, sky wave, and space wave are to be covered here.
  2. Ground wave: The factors affecting ground waves and the permitted frequency range for its propagation, are the areas of interest in this topic.
  3. Skywave: Limitations of skywave in which one major limitation is MUF (maximum utilization frequency) are seen here. Factors affecting the propagation i.e. day frequency, night frequency are also important concepts to learn. Other than these, various parameters of skywave propagation: Critical frequency, virtual height, MUF under flat earth and under curvature, skip distance and other major drawbacks are important for ESE preparation.
  4. Space wave: Here, skip distance problem of sky waves can be overcome but these are only suitable for short distances.

Questions from this topic are either numerical based on the calculation of MUF, skip distance etc. or long descriptive type in mains.

  1. Introduction: Th introduction to this topic deals with Kepler’s law and orbital law derivation.

Both of these topics are very important for Ese preparation as questions are very frequently asked from these topics, especially in the mains stage.

  1. Type of satellite: Geosynchronous and geostationary satellites, differences between them, geosynchronous earth orbit, propagation time, loss calculations and uplink and downlink frequency of different types of satellites are areas of focus here.
  2. Link design: Most of the conventional questions in ESE mains are related to this topic. To attempt this question successfully though, it is necessary to have a wholesome knowledge of all the other parts of this topic. It deals with the uplink design, the transponder design, and the downlink design.

Cellular/mobile communication: After complete understanding of wired and wireless communication, Advance communications deals with cellular/mobile communication. This part is particularly interesting to study for all the telecommunication engineering graduates since you can learn about the latest communication technology and how the different types of communication technology came into being.

Following are the various parts to cover in cellular/mobile communication:

  1. Introduction
  2. Importance or advantages of cellular communication
  3. Type of cells: Cells are basically how areas are divided for optimum communication between them. Based on the size of a cell, it may be micro, macro or mini.
  4. Techniques of cell splitting or sectorisation to increase capacity without increasing number of cells since increasing number of cells would increase cost.
  5. The architecture of GSM: Bandwidth calculation, handoff, and roaming are the concepts to be studied, related to GSM for ESE preparation.
  6. Generation in GSM: As you use and would know about the latest communication technology, 4G; here, you know about the various generations, 2G, 3G, 4G; their drawbacks and how successive generations of communication technology evolved.
  7. Introduction to CDMA: Working of CDMA, basic uplink and downlink frequency range, number of users and why it is not such a famous technology anymore, is what you can learn here.

Data Communication: This part deals with both wired and wireless networks. Having a weightage of 4 to 5 marks, on an average in ESE, it basically gives information about how data is handled while transmission, various protocols that are being followed and other issues related to security while transmission. Given below are the various subtopics that it includes:

  1. Introduction to data: Type of protocols for data transmission, network architecture, types of network topology (star, bus, ring, hybrid) are useful for ESE preparation here.
  2. System interconnections: Two types of layer models are used all over the world for data communication, namely OSI/ISO, having 7 layers and devices and TCP/IP using 5 layers. Functions, responsibilities, uses, and protocols of each layer are to be studied in detail. Comparison between OSI/ISO and TCP/IP is another important concept here. File transfer protocol (FTP), SMTP (simple mail transfer protocol) are the 2 protocols used widely and studies here.

This particular topic is very important for ESE preparation and is a lot similar in approach to the syllabus of ICT in Paper-1. Studying and learning ICT by connecting with the knowledge of this topic would make it easier to remember both and save on time to prepare for ESE. A number of questions on layers, models, and protocols were found in ESE 2019 and would again find a place in subsequent exams of ESE also.

  1. Security: To safeguard data from one point to another, the safety of data is important. Encryption at sending end and decryption at the receiving end is done for this purpose. Cryptography, various algorithms and other means used for security are to be learned. Security may also be of two types: security towards the message or towards the total entity. Having a brief about both is important for ESE preparation. Other than this, firewalls and type of firewalls i.e. packet proxy, etc. are another area of interest.
  2. Applications: ATM (asynchronous transmission mode) is one application which is important. There are various others that need to be studied and learned.

All being said and explained, advance communications can be tackled very easily with the help of smart short notes, where you keep all your important formulae from all the topics and summary of all the topics in form of charts and tables. Revising only the short notes of the subject and appearing for online tests alone can help you get through this subject in your ESE exam. In addition, Optical communication is one topic that is very important and having the highest weightage. Practice this topic as nicely as you can by solving as many numerical and by revising its concepts and formulae repeatedly. It is also closely related to the non-technical subject ICT in many topics so it serves a two-fold purpose in your ESE preparation. By preparing one subject, you can secure marks of two with a very little extra effort.

All the best!

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