###### Abstract
Therefore, the statistical analysis can separate the two probability distributions of the noise and noise plus CCI and can estimate the mixing rate between them, where the mixing rate is equivalent to the COR. This study proposes an estimation scheme for the desired signal power, CCI power, and COR based on the chirp modulation scheme of LoRa. In the proposed scheme, the chirp pattern selected by the transmitter is estimated from the tentative chirp demodulation. In accordance with the estimated chirp pattern, the POD and PUD are estimated from the spectrum of the received signal. The desired signal components are specified by the differentials from the POD to PUD, and the desired signal power is then estimated from them. Multiple PUDs are estimated from multiple packets; thus, their dataset is composed of the mixed data between the noise components and noise plus CCI components. Based on the assumption that the dataset is modeled by the random process of the double Gaussian mixture probability density functions, we estimated each Gaussian probability density function and mixed rate using an expectation-maximization algorithm (EM algorithm) [14]. From the estimation result, the CCI power, noise power, and COR were estimated. In the proposed scheme, the estimation error of the chirp pattern degraded the estimation accuracy. A cyclic redundancy check (CRC) was utilized to determine the demodulation accuracy of the packet. If the CRC detects a packet error, the PUD estimated from the packet is deleted; however, the measured PUD does not involve random sampling. In particular, as the CCI increases, packet errors occur more frequently. Therefore, more estimated samples with larger CCI power are deleted; thus, the accuracy of estimating CCI power is degraded. In the proposed scheme, if the CRC detects a packet error and the tentatively estimated CCI power exceeds a certain threshold, the measured PUD is still employed for the estimation. Because the occurrence of the packet error is caused by a large CCI, we assume that the estimation result for a larger CCI power is more likely to be accurate. We employed the tentative estimation results of the mean and deviation of the CCI power estimated from all the packets with no error decided by the CRC to determine the threshold. The specific contributions of this study are as follows:  
1. An estimation scheme of the desired signal power, CCI power, and COR based on the chirp modulation of LoRa is proposed. 2. A packet selection based on the estimated CCI power is proposed to improve the estimation accuracy. 3. A channel selection criterion for maximizing the PDR performance is constructed. We showed the proposed estimation scheme of the desired signal power, CCI power, and COR based on the chirp modulation of LoRa [15; 16; 17]. This paper explains the mechanism of the proposed estimation scheme in detail and adds the extensive simulation performance evaluations for clarifying the advantage of the proposed estimation scheme. However, an access scheme based on the estimated power and COR is not indicated. This study explains the detailed mechanism of the proposed scheme, indicates the access protocol based on the estimated power and COR, and evaluates the PDR of this access scheme to clarify the advantages of the proposed scheme. An overview of this study is as follows: Section 2 presents the conventional studies of our considered estimation scheme. We describe the system model assumed in Section 3. Section 4 explains the proposed estimation in detail. Section 5 presents the channel-selection scheme based on the estimated power and COR. The numerical results obtained by the computer simulation are presented in Section 6. Finally, Section 7 concludes the paper.