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UPSC Preliminary Syllabus 2019

The Civil Services Preliminary exam comprises of two compulsory papers of 200 marks each (General Studies Paper I and General Studies Paper II). The questions will be of multiple choice, objective type. The marks in prelims will not be counted for final ranking, but just for qualification for the main exam.


Bluetooth and IEEE 802.11 (Wi-Fi) are two communication protocol standards which define a physical layer and a MAC layer for wireless communications within a short range (from a few meters up to 100 meters) with low power consumption (from less than 1 mW up to 100 mW). Bluetooth is oriented to connecting close devices, serving as a substitute for cables, while Wi-Fi is oriented towards computer-to-computer connections, as an extension of or substitution for cabled LANs. In this paper we offer an overview of these popular wireless communication standards, comparing their main features and behaviors in terms of various metrics, including capacity, network topology, security, quality of service support, and power consumption.

A Modern Study of Bluetooth Wireless Technology

A Bluetooth ad hoc network can be formed by interconnecting piconets into scatternets. The constraints and properties of Bluetooth scatternets present special challenges in forming an ad hoc network efficiently. This paper, the research contributions in this arena are brought together, to give an overview of the state-of-the-art. Simply stated, Bluetooth is a wireless communication protocol. Since it's a communication protocol, you can use Bluetooth to communicate to other Bluetooth-enabled devices. In this sense, Bluetooth is like any other communication protocol that you use every day, such as HTTP, FTP, SMTP, or IMAP. Bluetooth has a client-server architecture; the one that initiates the connection is the client, and the one who receives the connection is the server. Bluetooth is a great protocol for wireless communication because it's capable of transmitting data at nearly 1MB/s, while consuming 1/100th of the power of Wi-Fi. We discuss criteria for different types of scatternets and establish general models of scatternet topologies. Then we review the state-of-the-art approaches with respect to Bluetooth scatternet formation and contrast them

Overview and Evaluation of Bluetooth Low Energy: An Emerging Low-Power Wireless Technology

Bluetooth Low Energy (BLE) is an emerging low-power wireless technology developed for short-range control and monitoring applications that is expected to be incorporated into billions of devices in the next few years. This paper describes the main features of BLE, explores its potential applications, and investigates the impact of various critical parameters on its performance. BLE represents a trade-off between energy consumption, latency, piconet size, and throughput that mainly depends on parameters such as connInterval and connSlaveLatency. According to theoretical results, the lifetime of a BLE device powered by a coin cell battery ranges between 2.0 days and 14.1 years. The number of simultaneous slaves per master ranges between 2 and 5,917. The minimum latency for a master to obtain a sensor reading is 676 µs, although simulation results show that, under high bit error rate, average latency increases by up to three orders of magnitude. The paper provides experimental results that complement the theoretical and simulation findings, and indicates implementation constraints that may reduce BLE performance.

Bluetooth Technology Key Challenges and Initial Research

This paper introduces a number of problems faced by the Bluetooth technology when attempting to use it for building adhoc networks. The paper provides a brief overview of Bluetooth and describes some of the major issues that need to be addressed, if it is to be successful as a networking technology. Some important objectives that any solution must meet are also introduced and motivated. An initial exploration of some key issues such as topology formation and throughput maximization is also provided.

Analysis and characterization of Peer-to-Peer Filesharing Networks

Since Peer-To-Peer file-sharing networks appearance a few years ago, many Internet users have chosen this technology to search for programs, films, songs, documents, etc. This number of users is growing every day. The main reason has been the content (in occasions illegal) that can be found and downloaded over these networks. This article deals with the analysis and characterization of eight P2P Public networks: Gnutella, FastTrack, Freeenet, BitTorrent, Opennap, Edonkey, Soulseek and MP2P. Finally, the authors will show a relationship between their characteristics and, in six of them, between their number of users, files shared and the amount of data shared in their networks

Analog Communication DSBSC Demodulators

The process of extracting an original message signal from DSBSC wave is known as detection or demodulation of DSBSC. The following demodulators (detectors) are used for demodulating DSBSC wave.

Analog Communication - DSBSC Modulators

In this chapter, let us discuss about the modulators, which generate DSBSC wave. The following two modulators generate DSBSC wave. Balanced modulator Ring modulator

Analog Communication - SSBSC Demodulator

The process of extracting an original message signal from SSBSC wave is known as detection or demodulation of SSBSC. Coherent detector is used for demodulating SSBSC wave.

Analog Communication - SSBSC Modulation

In the previous chapters, we have discussed DSBSC modulation and demodulation. The DSBSC modulated signal has two sidebands. Since, the two sidebands carry the same information, there is no need to transmit both sidebands. We can eliminate one sideband. The process of suppressing one of the sidebands along with the carrier and transmitting a single sideband is called as Single Sideband Suppressed Carrier system or simply SSBSC. It is plotted as shown in the following figure.

UPSC Mains Syallabus 2019 document

This document contains the syllabus for UPSC Mains. It also contains the pattern for the main examination.

Decision Tree Induction

Decision tree induction is the learning of decision trees from class-labelled training examples. A decision-tree is a flow-chart like tree structure, where each internal node denotes a test on an attribute, each branch represents an outcome of the test and each leaf node holds a class label. ID3, C4.5 and CART adopt a greedy(nonbacktracking) approach in which decision trees are constructed in a top-down recursive divide-and-conquer manner.