lanian
Newbie level 1
hi,
Today, I measure the 2-stream Tx EVM of WLAN(802.11n) by using the Litepoint for 802.11n. The data is HT40 format.
When I have checked option for channel estimation by long training sequence, the evm fluctuation is high and not good(-25~-29, rarely down to -22! It increase the Re-transmission of the packet)
but i checked option for channel estimation by full packet and recalculate the EVM. The value of evm is very good!! (-30~-33). Is it normal?
So, I guess that channel estimation error cause the evm degradation.
I have question at this point.
What makes the channel estimation error by using LTS? (Phase noise error by PLL?/ or not good baseband signal? or other?)
So, if i want reduce the channel estimation error, what can i do? anything i want to do for enhancing the EVM performance, board-level, RF-chip level, Digital-level, Software. (for information, I have checked the CCDF,Chanel flatness,coupling, I/Q mismatch, LO leakage, and so on. They are all ok. and SISO measurement is done, the fluctuation of SISO EVM is smaller than that of the MIMO measurement)
please help me.
Thank you.
Today, I measure the 2-stream Tx EVM of WLAN(802.11n) by using the Litepoint for 802.11n. The data is HT40 format.
When I have checked option for channel estimation by long training sequence, the evm fluctuation is high and not good(-25~-29, rarely down to -22! It increase the Re-transmission of the packet)
but i checked option for channel estimation by full packet and recalculate the EVM. The value of evm is very good!! (-30~-33). Is it normal?
So, I guess that channel estimation error cause the evm degradation.
I have question at this point.
What makes the channel estimation error by using LTS? (Phase noise error by PLL?/ or not good baseband signal? or other?)
So, if i want reduce the channel estimation error, what can i do? anything i want to do for enhancing the EVM performance, board-level, RF-chip level, Digital-level, Software. (for information, I have checked the CCDF,Chanel flatness,coupling, I/Q mismatch, LO leakage, and so on. They are all ok. and SISO measurement is done, the fluctuation of SISO EVM is smaller than that of the MIMO measurement)
please help me.
Thank you.