LoRa Modulation Basics | CSS Modulation

LoRa Modulation Basics | CSS Modulation | Advantages, Properties

This page describes LoRa modulation basics. It mentions LoRa modulation advantages or properties. The Lora modulation is also known as CSS modulation (Chirp Spread Spectrum modulaion).

The LoRa Wireless tutorial covers following sub topics:
Main page LoRa tutorial LoRa Frequency Bands LoRa 868 and 900 channels list LoRa protocol stack LoRa MAC layer LoRaWAN classes LoRa features LoRa Transceiver module LoRaWAN wireless transceiver vendors

In this LoRa modulation technique, spreading of spectrum is obtained by generation of a chirp signal which varies continuously in frequency. Due to this timing offset and frequency offset are equivalent between the LoRa transmitter and receiver parts. This will make receiver design very simple due to avoidance of complex algorithms. Moreover frequency bandwidth of chirp is equivalent to spectral bandwidth of the LoRa modulated signal.

It is robust modulation technique compare to other spread spectrum techniques such as DSSS. It addresses all the issues encountered in the DSSS and at the same time provides low cost and low power based solution. It is also known as CSS modulation due to Chirp Spread Spectrum technique employed.

Following equation/formula mentions relation between bit rate, chip rate and symbol rate of LoRa modulation.
Rb = SF * ( 1/[2^SF/BW] ) bits/sec
Where,
SF = Spreading factor
BW = Bandwidth of modulation

LoRa modulation incorporates error correction feature in the physical layer and hence will improve the error correction capabilities in the system at the cost of increase in the redundancy. The LoRa bit rate in bps can be defined by the following equation/formula for this system. Refer LoRa bit rate calculator>> which does calculation of LoRa data rate or bit rate as per this equation.

LoRa modulation Advantages | LoRa modulation properties

Following are the properties or advantages of LoRa Modulation:
➨Both bandwidth and frequency are scalable.
➨It delivers constant power envelope and hence power amplifier used for FSK can be reused which saves cost.
➨As it provides processing gain, lesser output power can deliver same RF link budget.
➨It is resistant against any in-band as well as out of band interference types due to its higher BT product. Moreover LoRa signal is immune against multipath fading due to its broad spectrum shape. Hence it can be employed in both urban/ suburban environments.
➨LoRa modulation based signal is doppler resistant as doppler shift introduces very small frequency shift and also negligible time shift in the baseband signal.
➨It delivers about four times more coverage range compare to FSK modulation due to its robust nature against interference and fading.
➨It helps in achieving enhanced capacity due to simultaneous transmission of multiple spread signals on the same RF channel with the help of different spreading factors.
➨It discriminate between time and frequency erros linealy and hence it is considered to be ideal modulation technique for radar as well as real time localization applications.
Also refer Advantages and disadvantages of LoRaWAN>>.

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LoRa Modulation Basics | CSS Modulation | Advantages, Properties

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