Types of Fading in wireless communication

- Dec 17, 2018-

Introduction
As we know wireless communication system consists of transmitter and receiver. The path from transmitter to the receiver is not smooth and the transmitted signal may go through various kinds of attenuations including path loss, multipath attenuation etc. The signal attenuation through the path depends on various factors. They are time, radio frequency and path or position of transmitter/receiver. The channel between transmitter and receivercan be time varying or fixed depending upon whether the transmitter/receiver are fixed or moving with respect to each other.

What is fading?

The time variation of received signal power due to changes in transmission medium or paths is known as fading. Fading depends on various factors as mentioned above. In fixed scenario, fading depends on atmospheric conditions such as rainfall, lightening etc. In mobile scenario, fading depends on obstacles over the path which are varying with respect to time. These obstacles create complex transmission effects to the transmitted signal.

Considering various channel related impairments and position of transmitter/receiver following are the types of fading in wireless communication system. 
➤Large Scale Fading: It includes path loss and shadowing effects.
➤Small Scale Fading: It is divided into two main categories viz. multipath delay spread and doppler spread. The multipath delay spread is further divided into flat fading and frequency selective fading. Doppler spread is divided into fast fading and slow fading. 
➤Fading models: Above fading types are implemented in various models or distributions which include Rayleigh, Rician, Nakagami, Weibull etc. 

As we know, fading signals occur due to reflections from ground and surrounding buildings as as well as scattered signals from trees, people and towers present in the large area. There are two types of fading viz. large scale fading and small scale fading.

So, in M2M applications, we usually suggest customers to use 4G-to-Ethernet communication ways. Our R58 series Industrial 4G LTE Router is integrated with 5 Ethernet ports, can satisfy most projects requirements. What is more, the R58 Industrial 4G M2M Router also supports 4G and ADSL backup. The router detects a network problem and fails over to a stand-by 4G network, ensuring the customers' SLAs are upheld.

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