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Protocol layers and sub-topics OSI model by layer 7. Application[show] 6. Presentation[show] 5. Session[show] 4. Transport[show] 3. Network[show] 2. Data link[show] 1. Physical[show] v t e Courses and textbooks in the field of data transmission typically deal with the following OSI model protocol layers and topics: Layer 1, the physical layer: o Channel coding including • Digital modulation schemes • Line coding schemes • Forward error correction (FEC) codes o Bit synchronization o Multiplexing o Equalization o Channel models Layer 2, the data link layer: o Channel access schemes, media access control (MAC) o Packet mode communication and Frame synchronization o Error detection and automatic repeat request (ARQ) o Flow control Layer 6, the presentation layer: o Source coding (digitization and data compression), and information theory. o Cryptography (may occur at any layer)
Applications and history Data (mainly but not exclusively informational) has been sent via non-electronic (e.g. optical, acoustic, mechanical) means since the advent of communication. Analog signal data has been sent electronically since the advent of the telephone. However, the first data electromagnetic transmission applications in modern time were telegraphy (1809) and teletypewriters (1906), which are both digital signals. The fundamental theoretical work in data transmission and information theory by Harry Nyquist, Ralph Hartley, Claude Shannon and others during the early 20th century, was done with these applications in mind. Data transmission is utilized in computers in computer buses and for communication with peripheral equipment via parallel ports and serial ports such as RS-232 (1969), Firewire (1995) and USB (1996). The principles of data transmission are also utilized in storage media for Error detection and correction since 1951. Data transmission is utilized in computer networking equipment such as modems (1940), local area networks (LAN) adapters (1964), repeaters, hubs, microwave links, wireless network access points (1997), etc. In telephone networks, digital communication is utilized for transferring many phone calls over the same copper cable or fiber cable by means of Pulse code modulation (PCM), i.e. sampling and digitization, in combination with Time division multiplexing (TDM) (1962). Telephone exchanges have become digital and software controlled, facilitating many value added services. For example the first AXE telephone exchange was presented in 1976. Since the late 1980s, digital communication to the end user has been possible using Integrated Services Digital Network (ISDN) services. Since the end of the 1990s, broadband access techniques such as ADSL, Cable modems, fiber-to-the-building (FTTB) and fiber-to-thehome (FTTH) have become widespread to small offices and homes. The current tendency is to replace traditional telecommunication services by packet mode communication such as IP telephony and IPTV. Transmitting analog signals digitally allows for greater signal processing capability. The ability to process a communications signal means that errors caused by random processes can be detected and corrected. Digital signals can also be sampled instead of continuously monitored. The multiplexing of multiple digital signals is much simpler to the multiplexing of analog signals. Because of all these advantages, and because recent advances in wideband communication channels and solid-state electronics have allowed scientists to fully realize these advantages, digital communications has grown quickly. Digital communications is quickly edging out analog communication because of the vast demand to transmit computer data and the ability of digital communications to do so. The digital revolution has also resulted in many digital telecommunication applications where the principles of data transmission are applied. Examples are second-generation (1991) and later cellular telephony, video conferencing, digital TV (1998), digital radio (1999), telemetry, etc.
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DC COURSE FILE
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GEETHANJALI COLLEGE OF ENGINEERING
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Convolution Codes: Encoding, decodi
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III. To inculcate positive attitude
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7. Importance of the course and how
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DC 12: Compute the power and bandwi
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10. Course mapping with PEO’s and
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13.Micro plan : Sl. no Unit No. Tot
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14.Detailed Notes UNIT 1 : Elements
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A communication system may transmit
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the wavelength is extremely long, m
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asic elements of digital communicat
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4. Channel introduced many types of
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5. Bandwidth is another scarce reso
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Pulse Code Modulation ‣ PCM gener
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77777333333333333333333333333333333
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• The most common technique for s
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Pulse Code Modulation (PCM) : • P
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Figure 3.11 Illustration of the qua
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Quantization (nonuniform quantizer)
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Time-Division Multiplexing(TDM):
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Let m n where T The error signal is
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3. Simplify receiver design Because
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Figure 3.27 Block diagram illustrat
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Adaptive Differential Pulse-Code Mo
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ASK, OOK, MASK: • The amplitude (
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Frequency Shift Keying: • One fre
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s t Acos 2f ct 3 Acos 2f
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QAM and QPR: • QAM is a combinati
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Generation and Detection of Coheren
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Figure 6.29 Signal-space diagram fo
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UNIT 3 Base Band Transmission And O
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• The tails of hI(t) decay as 1/|
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• precoding d b d k k k2 symbol 1
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h( t) N 1 n w n sin c t T b
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• Equalization : to compensate fo
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e n y n 2E en 2E en 2Eenxnk
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- Flexibility - Same H/W may be tim
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Interpretation of Eye Diagram:
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The set of source symbols is called
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We will usually neglect to mention
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Note that if Condition1 is satisfie
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where dmin is the minimum Hamming d
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Linear Block Codes - example 1: •
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• S null can be represented by it
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G 1 0 I | P 0 0 0 1 0 0 0 0
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• Compared with the systematic co
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Convolutional Codes ◊ The encoder
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Convolution Codes ‣ Encoding, ‣
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x m m ''' j j 2 j Here each messa
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Representing convolutional codes: C
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- encoder state diagram for (n,k,L)
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• For this reason the non-survive
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sequence is 1 1 0 0 0 0 0 (why?). N
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Error Correction: • If there is n
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correct:1+1+2+2+2=8;8 ( 0.11) 0.88
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Motivation: Performance of Turbo Co
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Performance as a Function of Number
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General Model of Spread Spectrum Sy
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Slow and Fast FHSS: • Frequency s
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- 10 bit spreading code spreads sig
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Direct Sequence Spread Spectrum Usi
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15.Additional Topics: Voice coders
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'Toll Quality' voice coders, such a
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The well-known Shannon-Hartley law
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its for a known permutation of the
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16. Question papers: B. Tech III Ye
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e received code word 110110. Commen
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17. Question Bank 1. (a) State and
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21. A Discrete Memory less Source (
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19. Unit wise Bits CHOOSE THE CORRE
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(d) 5 Answers 1.C 2.D 3.B 4.A 5.C 6
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Page 171 and 172: code No: 56026 Set No. 2 JAWAHARLAL
Page 173 and 174: B) (Power required)/( Minimum Band
Page 175 and 176: A) 5 B) 4 C) 2 D) 3 3. Which of the
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Page 179 and 180: A) maximum when the source is conti
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Page 183 and 184: Code No: 07A5EC09 Set No. 2 JAWAHAR
Page 185 and 186: Cont…..2 Code No: 07A5EC09 :2: Se
Page 187 and 188: 8) For the data word 1110 in a (7,
Page 191 and 192: a) 0 bits b) 1 bit c) 2 bits d) inf
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Page 199 and 200: Amplitude of 1v.This speech signal
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Page 211 and 212: 25. STUDENTS LIST B.TECH III YEAR I
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Page 215 and 216: Group 8: 36 13R11A04K1 POLISETTY VE
Page 217 and 218: Unit 2 Pulse-Amplitude Modulation :
Page 219 and 220: Unit 3 Differential Pulse-Code Modu
Page 221 and 222: MISSING TOPICS UNIT 1 Hartley's law
Page 223 and 224: encoding the desired information an
Page 225 and 226: • f c denotes center frequency
Page 227 and 228: An interleaver installed between th
Page 229 and 230: Subject Contents 1.7. 1. Synopsis p
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