[Discuss-gnuradio] Questions

[Amr Youssef]

Hi all , i have some questions  :

In OFDM Modulator Block , in Mapper Sub-block , in path of : ./lib/digital_ofdm_mapper_bcv.cc

 1- I saw the following comment inside the code :  " Eventually, we will get rid of the occupied_carriers concept. " , the question how you get rid of the occupied carriers concept in the code and why ? . as i see the code depends strongly on this concept .

2- Why the concept of occupied carriers is used  and why filling only part of FFT size not all of it  ?

3-Inside the code ,  string carriers = "FE7F" .  I have two questions here , the first is ,  when converting to bits : 1111111001111111 , why there is two zeros at DC instead of one zero only ?
The second question is , you started with "FE7F" .  Why  didn't  you start with "E7"  and then pad F's from both sides  (looping) as  you did later !?

4- Also , for the following segment of the code : diff = (d_occupied_carriers - 4*carriers.length())  .  Why you are multiplying by four instead of eight when converting from Character Domain to Bit Domain ? or you deal with them as HEX only ?


4- How many OFDM Symbols exist in one packet ?

5- What is the maximum packet size ?

6- What is the difference between coming message and the packet . Are they the same thing ?  or Does one message contain more than one packet ?

Thanks in-advance
Amr ,