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Hello,
We wanted to change the modulation scheme to BPSK (we are based off OFDM Ref Design v4) for the base and full rate, and by reading documentation, code and other posts, below is the list of things we needed to change. Could you please confirm this is all we need to modify?
1. Call warpmac_setBaseRate (BPSK). This would change the modmasks for the base rate to use BPSK.
2. Call warpmac_setFullRate (BPSK)
3. Modify the value of the global variable 'numBaseRate' to a value of 4
We changed all these values, but cannot get a packet to be received. Is this all we need to change? And would this ensure that the whole packet would be modulated BPSK?
Also, some more general questions. It was mentioned in the documentation that we need to know the full rate modulation scheme beforehand, and that it cannot determine it on a per packet basis yet (to arrive in future revisions). However, from looking at the code, we set the modmasks for the fullrate to all 0xF's, which from the code suggests dynamic modulation. The function setFullRate does not alter the modmasks, it just changes the full rate modulation parameter that we insert into the packet header. Therefore, how does the receiver know what the modulation scheme is if that information is encoded in each packet? From what I can tell, the modulation scheme is not stored anywhere except the in the modmasks.
Any help is greatly appreciated,
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Those are the right parameters to change. A few things to help narrow down the problem:
-Do you receive only bad packets after these changes, or no packets at all?
-If you send short packets (like 20 bytes instead of a full 1500), are any received successfully?
-Try changing just the full-rate to BPSK, leaving the base-rate at QPSK. I know this doesn't make much sense in practice, but if it works, it will help identify where the problem is.
baldeeshk wrote:
Therefore, how does the receiver know what the modulation scheme is if that information is encoded in each packet? From what I can tell, the modulation scheme is not stored anywhere except the in the modmasks.
You're right- the model and code already support dynamic modulation for the full-rate symbols in each packet. There is 1 byte in the header that specifies the modulation scheme to use for that packet's full-rate symbols. Both the Tx and Rx cores use this byte to configure themselves per-packet. The index of this byte in the header is configurable using the mimo_ofdmRx_setByteNums() function.
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Thanks! We were getting an unrelated clocking problem that was causing the missed packet.
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