Chapter 7
Noise
Noise performance and noise calculations are the most important aspects in radio planning. The quality of any radio link is not defined by the absolute signal level, but by the signal-to-noise ratio. The lower the noise is relative to the signal level, the better the radio performance. Radio quality and mobile data rates are dependent on a certain signal-to-noise ratio. The better the SNR, the better the quality, the higher the data rate on the radio link will be.
Many RF planners consider the issue regarding noise in DAS systems, on the UL of their link budget to be ‘black magic’. However, if you do not overcomplicate the subject of noise, the concept is really pretty straight forward and easy to understand. Understanding noise and noise calculations is crucial for the radio planner in designing any RF system. Radio planners need to understand that passive loss in a DAS system will also increase the total system noise figure. Noise power generated by amplifiers and the base station also has a big impact on the performance of the radio link.
Over the following pages, I will present the basics of noise, by presenting examples of amplifier configurations and analyzing the performance step by step. All the examples on the next pages have been calculated on a standard scientific pocket calculator (the one on the cover on this book). You do not need advanced computer programs to be in control of the noise calculations when designing passive or active DAS solutions. ...
