Removing the MAC Layer in Massive MIMO Framework

Updated Mar 22, 2018

Reported In

Software

  • LabVIEW Communications MIMO Application Framework
  • LabVIEW Communications System Design Suite

Issue Details

I am using the Massive MIMO Framework and LabVIEW Communications. I tried to control all 1200 subcarriers but it seems that I can only control 1169 (i.e. spectrum is constant). My guess is that the other 30 subcarriers are 'wasted' on packet control.  I don't need the MAC layer for my work so is there a way I can remove it and gain control of the rest of the subcarriers?

Solution

It is possible to remove the MAC layer. However, this includes changing the code on an FPGA level. A breakdown of the packet architecture that includes the MAC layer elements on page 11 of the manual. In the Transport Block Structure table below, the 8 bites that you do not have control of are the Length and CRC PHY. 
The Length and CRC bits are created within the MIMO Bit Processor Packet Content Generator FPGA code as highlighted in the attached picture. Making changes within "MIMO Bit Processor Packet Content Generator.gcdl" and "MIMO FCS Add.gcdl" is the right place to bypass those fields and bring the full 300 bytes of control up to the host.  

 

Additional Information

This could have downstream consequences of modifying or bypassing these block fields prior to the OFDM symbol creation. So we would not recommend deleting these from the diagram but potentially bypassing them with a case structure. 

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