Lecture 1 - Intro to Data Communications PDF

ECEN100 Communications 4: Data Communications LECTURE 1: INTRODUCTION TO DATA COMMUNICATIONS Definition and Importance of Data Communications Just like humans communicate in a variety of ways – by speaking, texting, and emailing – data similarly transfers from one place to another using differ...

ECEN100 Communications 4: Data Communications LECTURE 1: INTRODUCTION TO DATA COMMUNICATIONS Definition and Importance of Data Communications Just like humans communicate in a variety of ways – by speaking, texting, and emailing – data similarly transfers from one place to another using different mediums. The process of moving electronic and digital data is called data communication. Data communication is the process of transferring data from one place to another or between two locations. Data communication refers to the process of transmitting and receiving data between two or more devices over a communication channel. It involves the conversion of data into signals that can be transmitted and then decoding those signals at the receiving end. Basic Components of Data Communication Systems A communication system is made up of the following components: 1. Message: Piece of information that is to be transmitted from one person to another. It could be a text file, an audio file, a video file, etc. 2. Sender: It is simply a device that sends data messages. 3. Receiver: It is a device that receives messages. 4. Transmission Medium or Communication Channels: Communication channels are the medium that connect two or more workstations. 5. Set of rules (Protocol): When someone sends the data (sender), it should be understandable to the receiver also otherwise it is meaningless. It defines how data is transmitted and communicated. Therefore, there are some of rules (protocols) that is followed by every computer connected to the internet and they are: 1. TCP(Transmission Control Protocol): It is responsible for dividing messages into packets on the source computer and reassembling the received packet at the destination or recipient computer. It also makes sure that the packets have the information about the source of the message data, the destination of the message data, the sequence in which the message data should be re-assembled, and checks if the message has been sent correctly to the specific destination. 2. IP(Internet Protocol): It is responsible for handling the address of the destination computer so that each packet is sent to its proper destination. Prepared by: Engr. Rhodonelle S. Duatin, ECE, ECT, RAOC Department of Computer, Electronics and Electrical Engineering  ECEN100 Communications 4: Data Communications Data Communications Models TCP/IP Model The Transmission Control Protocol/Internet Protocol (TCP/IP) model came before the Open Systems Interconnection (OSI) model, and it has four layers. Example of TCP/IP model at host. Application layer where data originates on the sender’s side and used to create data. A web browser is example to generate data that gets sent through the rest of the layers, assisted by the Domain Name System (DNS), which associates web domain names with their Internet Protocol (IP) addresses. In transport layer, the data gets encoded so it can transported through the internet using either the User Datagram Protocol (UDP) or Transmission Control Protocol (TCP) In the network access layer, the data gets the header and a trailer, and these tell the data where to go. This information is then conveyed to the network interface layer. At the network interface or data link layer, the packet of data gets formatted and prepared to be transported and routed through the network. OSI Model The OSI model is another way of transmitting data over the internet. The biggest difference between the OSI and TCP/IP models is the OSI model has seven layers instead of four. Both provide data communication services, enabling users to send and receive information from their IP address using the services made available by their internet service provider (ISP). Example of OSI model at target. In physical layer, this consists of data connection between a device generating data and the network. In datalink layer, it is the point-to-point connection that transmits the data to the network layer. In the network layer, the data gets its address and routing instructions in preparation journey across the network. In transport layer, the data hops between different points on the network on its way to its destination. In session layer, it has a connection that manages the sessions between applications. In the presentation layer, data gets encrypted Prepared by: Engr. Rhodonelle S. Duatin, ECE, ECT, RAOC Department of Computer, Electronics and Electrical Engineering  ECEN100 Communications 4: Data Communications and decrypted and converted into a form that is accessible by the application layer. In application layer, an application, such as internet browser, gets the data and a user can interact with it. Types of Data Transmission Serial and Parallel Serial Communication. In serial communication, data transmission occurs bit by bit on a single communication line or channel. This process means that data bits are sent one after the other in a sequence or series, with the receiving device collecting and reassembling these bits into a complete message. How serial data is transmitted? The device is sending data, called the transmitter, send a start bit to the device receiving the data, known as receiver. The start bit is like a heads up, signaling, to notify that transmitter about to send some data. Next, the transmitter sends the data by bit in a specific order. When all the data bits have been sent, the transmitter sends a stop bit. Start Bit – 0, 8 Data Bits, Stop Bit - 1 The telegraph was one of the first devices for long-distance serial communication, using a single wire to transmit data. Serial communication protocols and standards began to develop in the 1960s. These protocols, such as RS-232, SPI, I2C, RS485, USB, and MIPI, are widely used in electronic circuits, LCDs, OLEDs, computer systems, embedded systems, and telecommunications. Parallel Communication. Parallel communication is a method of transmitting data in which multiple bits are sent simultaneously over multiple channels or cables. These bits are generally sent in data groups of 8 bits, known as bytes, in a single clock pulse. This means each bit is transmitted over a dedicated cable. This technique is like a multi-lane highway, with each 'bit' having its own lane, allowing for simultaneous data transmission. How parallel data is transmitted? The transmitter signals the receiver about data transmission readiness. The data is divided into multiple bit groups, and the transmitter sends all the bits simultaneously over separate communication lines or cables. The receiver gets all the data streams and arranges them in the correct order to reconstruct the original data. Once all parallel bits are received, and data is reconstructed, the communication is complete. Parallel communication is typically faster than serial communication, as it can transmit more data in the same amount of time. However, it is also more complex and requires more hardware. Prepared by: Engr. Rhodonelle S. Duatin, ECE, ECT, RAOC Department of Computer, Electronics and Electrical Engineering  ECEN100 Communications 4: Data Communications Parallel communication is often used in applications where high data rates are required, such as in printers, scanners, and external hard drives. It is also used in some internal computer buses, such as the PCI bus. Analog and Digital Analog-to-Analog Transmission. For example, radio broadcasting where audio signals are modulated onto a carrier frequency and transmitted over the air. Digital-to-Digital Transmission. For example, data communication over a computer network where binary data is transmitted between devices. Analog-to-Digital Transmission. For example, voice communication over VoIP (Voice over Internet Protocol) where analog voice signals are converted to digital data. The analog signal (e.g., voice) is sampled at regular intervals. The sampled values are Prepared by: Engr. Rhodonelle S. Duatin, ECE, ECT, RAOC Department of Computer, Electronics and Electrical Engineering  ECEN100 Communications 4: Data Communications quantized into discrete levels. The quantized values are encoded into a digital format (e.g., PCM). The digital data is transmitted over the network. The receiving device decodes the digital data and converts it back to an analog signal (if needed). Digital-to-Analog Transmission. For example, modem communication where digital data from a computer is converted to analog signals for transmission over telephone lines. Digital data is modulated onto an analog carrier signal (e.g., FSK, QAM). The modulated analog signal is transmitted over the medium (e.g., telephone lines). The receiving modem demodulates the signal to recover the original digital data. 4-QAM Constellation Diagram 8-QAM Constellation Diagram Prepared by: Engr. Rhodonelle S. Duatin, ECE, ECT, RAOC Department of Computer, Electronics and Electrical Engineering  ECEN100 Communications 4: Data Communications Communication Channels and Media Wired (Guided) Media a. Twisted Pair Cable. It consists of pair of insulated copper wires twisted together b. Fiber Optic Cable. It uses light signals to transmit data through thin strands of glass or plastic. c. Coaxial Cable. It has a central core conductor of a solid copper wire enclosed in an insulating sheet and the middle core conductor is made up of copper mesh and lastly an outer metallic wrap that helps in noise cancellation. Commonly used in cable television, broadband internet, CCTV, and ethernet connection setup. Wireless (Unguided) Media a. Radio. Channel for electromagnetic waves with frequencies ranging from 3 kHz to 300 GHz. Commonly used for Wi-Fi, Bluetooth, AM/FM radio, and mobile phone communications. b. Microwaves. Channel for electromagnetic waves with frequencies ranging from 300 MHz to 300 GHz. Commonly used for long-distance communication, satellite links, and point-to- point communication. c. Infrared. Channel for electromagnetic waves with frequencies just below visible light, ranging from 300 GHz to 400 THz. Commonly used for short-range communication such as remote controls and some wireless peripherals. d. Satellite. It operates over wide range of frequencies. L-Band (1-2GHz) for GPS, mobile satellite services, mobile application S-Band (2-4 GHz) for weather radar, satellite telemetry, atmospheric penetration C-Band (4-8 GHz) for satellite television broadcasts X-Band (8-12 GHz) for military application and radar applications Ku-Band (12-18 GHz) for VSAT (Very Small Aperture Terminal) Systems Ka-Band (26.5-40 GHz) for high-throughput satellite services, broadband internet services Prepared by: Engr. Rhodonelle S. Duatin, ECE, ECT, RAOC Department of Computer, Electronics and Electrical Engineering