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Enabling CSMA for LoRaWAN TR013-1.0.0 ©2023 LoRa Alliance ® Page 16 of 18 The authors reserve the right to change specifications without notice. APPENDIX 1: CAD CONFIGURATION 396 397 Appropriate configuration of the CAD module is key to enabling accurate detection of potential 398 collisions and improved energy efficiency during LoRaWAN CSMA. A single CAD operation is 399 comprised of two parts. First, the radio switches to receive mode, gathering samples for a 400 duration of a set number of symbols. Second, the radio briefly processes the received samples 401 to check the presence of LoRa symbols and informs the MCU whether a symbol is found. 402 Recent versions of LoRa radios allow the configuration of parameters such as the number of 403 symbols per CAD and various thresholds that influence detection. However, CAD modules 404 belonging to previous radio generations come preconfigured and further configuration is not 405 allowed. Therefore, CAD modules of those generations can be used with the default 406 configuration. 407 408 The rationale of configuring the CAD module is to achieve the highest energy efficiency per 409 CAD while maintaining sufficient detection accuracy. For radios that allow CAD configuration, 410 several parameters can be optimized. However, listing optimized configurations for each radio 411 is not plausible due to the large number of LoRa radios. As such, an example of optimal 412 configuration for the SX1262 is summarized in Table 2. As CAD parameters for other radios 413 that allow configuration is similar, the reader is requested to refer to their respective 414 datasheets to find radio-specific values that offer optimal detection, e.g., cadSymbolMin, 415 cadDetPeak, and cadSymbolNum. 416 417 A noteworthy parameter for consideration is cadSymbolNum, which configures the duration 418 that the radio tunes to receive mode to sample the channel. A cadSymbolNum=2 implies 419 that each CAD requests the radio module to sample the channel for two symbol durations, 420 which varies based on the set SF. Accurate detection of the presence of an on-going 421 transmission requires maintaining false positives to a minimum across a wide range of RSSI. 422 In the case of the SX1262, the application note [AN1200.48] highlights CAD configuration 423 parameters, which are highlighted in Table 2. The registers, cadDetMin, cadDetPeak, 424 and cadSymbolNum allow configuring the sensitivity of a single CAD operation. 425 426 SF CAD Settings cadDetMin cadDetPeak cadSymbolNum SF7 10 22 2 symbols SF8 10 22 2 symbols SF9 10 24 2 symbols SF10 10 25 2 symbols SF11 10 26 2 symbols SF12 10 30 2 symbols Table 2: Optimal CAD settings for the SX1262 for two symbols 427 For radios that allow configurable CADs, consecutive CADs may be combined to form a 428 single CAD to realize a slight energy gain. For example, a DIFS phase consists of two CADs 429 that together consume four symbols. These two consecutive CAD operations can be merged 430 into a single CAD operation of four symbols. Optimized parameters for a four symbol CAD 431 are different to those described in Table 2 and can be found in [AN1200.48]. 432