Hi Abdelwahab,
I see that you're seeking clarification on how the number of subcarriers is determined, specifically why there are 300 subcarriers in the 'NR Perfect Channel Estimate' example.
The number of subcarriers in a given bandwidth is determined by the number of Resource Blocks allocated, which is specified by the input parameter `NSizeGrid`. In the "Perfect channel estimate" example, the number of RBs, denoted as `NRB`, is set to 25. Given that each Resource Block comprises 12 subcarriers, multiplying the two gives us the total number of subcarriers: 25 RBs × 12 subcarriers/RB = 300 subcarriers. For further information, you can refer to the following documentation page: https://www.mathworks.com/help/5g/ref/nrperfectchannelestimate
Guard bands are intentionally designated frequency spaces that remain unoccupied; they serve as protective margins between adjacent frequency channels or bands. Their primary purpose is to prevent signal interference, which helps to maintain the integrity and quality of communications. Because no signal is transmitted over these guard bands, they are not included in the signal estimation process.
For a detailed explanation of NR frequency ranges and the role of guard bands, the following page will be useful:
Hope this helps.
