Fading Basics: Narrow Band, Wide Band, and Spatial Channels

White Paper

Radio technologies have undergone increasingly rapid evolutionary changes in the recent past. The first cellular phones used narrow-band FM modulation, which was soon replaced by digital modulation in second & third generation devices. Today, multiple-antenna systems are being employed to increase data rates. These provide improved quality while decreasing operational costs.

As technology progresses to take advantages of more complex channel characteristics, the channel modeling required to emulate the radio environment for testing becomes both more critical and more complex. For instance, when bandwidths are increased (to support higher data rates) receivers become more susceptible to Inter- Symbol Interference (ISI). To ensure that measurements in the lab accurately correlate to the quality of the user’s experience, channel models must account for all aspects of the radio environment.

For narrowband channels (such as early FM radios operating at 25-30kHz bandwidth), a receiver cannot resolve the different paths. In this case, the receiver sees a single composite signal which is the vector sum of all the multi-path components.

This white paper guides a reader through the basic concepts of fading and into some critical RF-related topics such as:

Fading Models
Flat Fading
Why is a Signal Frequency- Selective?
Multi-path Delays and Delay Spread
Multiple antennas

Download the White Paper

First Name*

Last Name*

Company*

Job Title*

Email Address*

Phone Number

Country*

State or Province

We'd like to understand your needs and how we can help.

address1

By submitting this form, you are also granting VIAVI Solutions permission to send you emails about related topics in accordance with our Privacy Policy. You can opt-out at any time by clicking the unsubscribe link in our emails.