Wireless and Cellular Telecommunications, Third Edition
Just in time for the rebounding wireless industry, this updated classic text offers an in-depth engineering guide for both voice and data services, Wi-Fi, 3G, WiMAX, and more.
TABLE OF CONTENTS Wireless and Cellular Telecommunications, Third Edition
Chapter 10: Types of Non-Cochannel Interference
10.1 SUBJECTIVE TEST VERSUS OBJECTIVE TEST
Voice quality often cannot be measured by objective testing using parameters such as the carrier-to-noise ratio C/N, the carrier-to-interference ratio CI I, the baseband signal-to-noise SIN, and the signal to noise and distortion ratio (SINAD). In a mobile radio environment, multipath fading plus variable vehicular speed are the major factors causing deterioration of voice quality.
Only the following methods can help to correct this imbalance.
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Let the received carrier level be high to increase the signal level.
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Let the receiver sensitivity be high to lower the noise level.
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Maintain a low distortion level in the receiver to increase SINAD.
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Use a diversity receiver to reduce the fading.
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Use a good system design in a mobile radio environment and a good adjacent-channel rejection to reduce the interference.
However, when a transceiver is deployed in a mobile radio environment, a subjective test is still the only way to test this receiver, using different types of analog modulation, such as single-sideband, double-sideband, amplitude, and frequency modulation (SSB, DSB, AM, FM), also different types of digital modulation, such as ASK, FSK, MSK, QPSK, QAM, etc.
10.1.1 The Subjective Test
A subjective test can be set up according to the criterion that 75 percent of the customers perceive the voice quality at a given C/N as being "good" or "excellent," the top two levels among the five circuit-merit (CM) grades. [1] The simulator of this test must be adjusted for different mobile speeds. The...
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