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CC1310: CC1310 : How to achieve Full duplex communication

Bhausaheb choudhari
Prodigy 220 points
Part Number: CC1310

Hi,

I am using CC1310 raw RF in HS mode for communication.

But as CC1310 is a half duplex and needs to switch between Rx and Tx mode to have bidirectional communication and it needs ~700 us to 900 us time for the mode switching.

Is it possible to use four CC1310 to have full duplex communication - one pair of CC1310 for RX and TX at one side and another pair for CC1310 RX and TX at other side so that a full duplex communication can be achieved?

If yes, what different frequencies we can use for TX and RX so that there wont be any interference?

Or any other method to achieve full duplex communication over RF.

Regards,

Bhausaheb

  • 0
    TI__Mastermind 39860 points
    A few assumptions:
    One RF link between Unit A and Unit B and another RF link between Unit C and Unit D
    Furthermore assume you have two units placed next to each other; Unit A and Unit C next to each other and the same for Unit B and Unit D
    Since this is full duplex we can assume that if Unit A is in Rx Unit C will be in Tx (and vice versa)
    The Rx units should be able to receive signal levels down to the sensitivity limit

    In the above scenario Unit C (Tx) will block Unit A (Rx) and Unit B (Tx) will block Unit D (Rx) unless the links are spaced several tens of MHz apart.
  • 0 in reply to Sverre
    Prodigy 220 points

    Hi Sverre,

    To clearly specify the set up

    One side of RF                                  Other side of RF 

    Unit A (Rx) <------------------------------- Unit C(Tx)

    Unit B (Tx) -------------------------------> Unit D(Rx)

    Unit A and B are part of 1st module and Unit C and D are part of 2nd module and we need achieve full duplex communication between these 2 modules.

    Unit A will always acts as a Rx and Unit C always acts as a Tx, similarly Unit B acts as a Tx and Unit D acts as a Rx.

    in this scenario, Unit A and B are 2 RF chips in one module and Unit C and D are 2 RF chips in other module.

    So, in this scenario is it possible to achieve full duplex communication between 2 modules using these pair of RF chips dedicated for Rx and Tx?

    what frequency we need to set so that A and C doesn't interfere with B and D?

    Regards,

    Bhausaheb

  • 0 in reply to Bhausaheb choudhari
    TI__Mastermind 39860 points
    Your summary is the same as I wrote although yours is easier to read and understand.

    You target HS mode so I assume you mean 4 Mbps. The sensitivity limit is then approx -80 dBm.

    If we assume the Tx output power is +14 dBm and that the receiver should be able to receive signal as low as -80 dBm, the Rx unit needs a blocking performance of approx 90 dB (the power picked up by the RX antenna will not be +14 dBm, and for simplicity let's assume it is +10 dBm). 90 dB blocking performance is only possible if the frequencies are several 10's of MHz apart and you use a narrowband SAW filter. FCC (915 MHz band) and ETSI (868 MHz band) does not allow operation several 10's of MHz apart.

    You write that the switching time is 700 - 900 us. This is not correct. The fastest way to change between RX and TX is by using command chaining. W have done some tests doing this. TX - RX: 270 us. RX - TX: 320 us
  • 0 in reply to Sverre
    Prodigy 220 points
    Thanks Sverre for the answer.

    Considering the limitations described above , what could be the possible ways to achieve full duplex RF communication using TI RF chips?

    Regards,
    Bhausaheb
  • 0 in reply to Bhausaheb choudhari
    TI__Mastermind 39860 points
    Using CDMA might be an option (different spreading for the two links), but is not something we have implemented.

    We (LPRF) does not have any RF chips that can do full duplex by using two different channels only. Sorry, but I cannot speak for other divisions within TI.