Clear Channel Assessment vs. RTS/CTS/ACK

Cong Nguyen

Other Parts Discussed in Thread: CC1101, SIMPLICITI

Hi, I'm a bit confused regarding CC430's Clear Channel Assessment and how it fits into the FAMA-NCS protocol, which I'm adapting for a project.

FAMA-NCS uses carrier sense to acquire the single-channel network before transmitting, in which it sends a RTS to the intended receiver, waits for a CTS and start sending data with that CTS. Any surrounding nodes listening on the network, once heard the CTS will back off. Now reading up on the CCA feature, it seems CCA does all of these internally already. Is it fair to assume that using CCA I no longer need to do any RTS/CTS with the intended receiver to acquire the channel before transmitting?

over 8 years ago

0 PM over 8 years ago

TI__Mastermind 27145 points

Hi,

CCA on CC430 is related to the RF Carrier. If you are referring to RTS/CTS, which are used in UART signals then those two are different.

CCA is used to indicate if the current RF channel is free or busy. This decision is based on Carrier Sense level on the receiver. The receiver checks the RSSI level on that channel before it transmits, if the RSSI is below the preset thresold level then it starts tranmitting.

Please refer to the section 17.5 of the CC1101 data sheet for further details. The followinf is the link to the data sheet.

http://www.ti.com/lit/ds/symlink/cc1101.pdf

Thanks,

0 Cong Nguyen over 8 years ago in reply to PM

Intellectual 290 points

Hi, regarding the RTS/CTS, it's from the FAMA-NCS protocol (ccrg.soe.ucsc.edu/.../chane.monet97.pdf). Collision avoidance is a must as the project I have needs to facilitates connections for 100+ nodes. Using CCA would replace a lot of the manual checking required in the protocol including usage of the RTS and CTS.

Just a side question, regarding SimpliciTI, can it be used in a multicasting ad-hoc configuration? Thank you for your time.

0 Leo Hendrawan over 8 years ago in reply to Cong Nguyen

TI__Guru 56650 points

Hi,
SimpliciTI supports broadcast messages, but not multicast:

processors.wiki.ti.com/.../SimpliciTI_FAQ

Sub-1 GHz

Sub-1 GHz forum

Clear Channel Assessment vs. RTS/CTS/ACK