Data communications and Networking Chapter 3 Data Transmission Reading Book Chapter 3 Data and Computer Communications, 8th edition By wIlliam Stallings
1 Data Communications and Networking Chapter 3 Data Transmission Reading: Book Chapter 3 Data and Computer Communications, 8th edition By William Stallings
Outline Concepts and Terminology Analog and Digital Data Transmission Transmission Impairments Channel Capacit
2 Outline • Concepts and Terminology • Analog and Digital Data Transmission • Transmission Impairments • Channel Capacity
Part 1: Concepts and Terminology Simplified Communications Model Digital bit balog Analog Digital bit stream signal sian al stream Text Text Tral Source Trans mission Receiver Destination mitter Syste ① Input data Transmitte Received Output data Output information g(t) ignal g(t information m
3 Part 1: Concepts and Terminology Simplified Communications Model
Digital Data Transmission Each single bit can be represented by a signal element Each signal element takes some time to send Bit rate the number of bits that can be sent out per unit of time 110011100 time
4 Digital Data Transmission time 1 1 0 0 1 1 1 0 0 Each single bit can be represented by a signal element. Each signal element takes some time to send. Bit rate: the number of bits that can be sent out per unit of time
What is the objective? Maximize the data rate number of bits that the system can transmit in a unit of time -within an acceptable bit error rate Why there could be bit errors? The signal received by the receiver is different from the signal sent from the sender Usually, if data rate becomes higher, it is more difficult for the receiver to recognize the signal higher data rate results in higher bit error rate In order to achieve high data rate with low bit error rate, we need to study the principle of data communications 5
5 What is the objective? • Maximize the data rate: number of bits that the system can transmit in a unit of time —within an acceptable bit error rate • Why there could be bit errors? —The signal received by the receiver is different from the signal sent from the sender • Usually, if data rate becomes higher, it is more difficult for the receiver to recognize the signal —higher data rate results in higher bit error rate • In order to achieve high data rate with low bit error rate, we need to study the principle of data communications