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open-sdr / openwifi

open-source IEEE 802.11 WiFi baseband FPGA (chip) design: driver, software
GNU Affero General Public License v3.0
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openwifi use FDD mode #369

Closed wangdan25 closed 7 months ago

wangdan25 commented 7 months ago

openwifi currently uses FDD mode to realize simultaneous receiving and transmitting, but when AP is working, I find that their receiving and transmitting frequency Settings are the same. Isn't FDD requiring different receiving and transmitting frequencies? Won't interference be caused if the frequencies are the same?

JiaoXianjun commented 7 months ago

https://www.sciencedirect.com/science/article/abs/pii/S0140366423002244?via%3Dihub https://arxiv.org/abs/2204.07354

wangdan25 commented 7 months ago

Thank you for your answer. I have read this paper.But at present, openwifi uses the normal FDD mode, and the frequency of receiving and sending is the same, and it seems to work normally, here I do not understand how it is to achieve frequency division duplex

wangdan25 commented 7 months ago

Thank you for your answer. I have read this paper.But at present, openwifi uses the normal FDD mode, and the frequency of receiving and sending is the same, and it seems to work normally, here I do not understand how it is to achieve frequency division duplex

JiaoXianjun commented 7 months ago

wifi never use fdd.

wangdan25 commented 7 months ago

Maybe I misunderstood, because I saw that the device tree parameter "adi,frequency-division-duplex-mode-enable" in the zedboard used by openwifi was enabled

JiaoXianjun commented 7 months ago

yes. you are right. but that does not matter. we set tx rx frequency to the same in the fdd mode.

wangdan25 commented 7 months ago

I seem to understand some, combined with your paper, although the AD9361 register configuration uses FDD mode, but in the TX state will actually turn off the RX LO, so strictly speaking, it is not received and sent at the same time.