Part 3 Data Rate amp Performance Evaluation Prepared By Assist Prof Dr Mahmood Z A Ali 20212022 3 DATA RATE LIMITS A very important consideration in data communications is how fast we can send data in bits per second over a channel Data rate depends on three factors ID: 1031095
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1. Information Technology (IT)(Part 3) Data Rate & Performance Evaluation Prepared ByAssist. Prof. Dr. Mahmood Z. A. Ali2021-2022
2. 3. DATA RATE LIMITSA very important consideration in data communications is how fast we can send data, in bits per second, over a channel. Data rate depends on three factors: 1. The bandwidth available 2. The level of the signals 3. The quality of the channel (the level of noise)Two theoretical formulas were developed to calculate the data rate, one by Nyquist for a noiseless channel, another by Shannon for noisy channel.
3. 3.33.1 Noiseless Channel: Nyquist Bit RateNyquist gives the upper bound for the bit rate of a transmission system by calculating the bit rate directly from the number of bits in a symbol (or signal levels) and the bandwidth of the system. Nyquist theorem states that for a noiseless channel:C = 2 B log22n = 2 B log2 L Where:C= capacity in bpsB = bandwidth in Hz
4. Example 1:Consider a noiseless channel with a bandwidth of 3000 Hz transmitting a signal with two signal levels. The maximum bit rate can be calculated asExample 2:Consider the same noiseless channel transmitting a signal with four signal levels (for each level, we send 2 bits). The maximum bit rate can be calculated as