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The real number M-ary QAM system can reduce PAPR and effectively improve the transmission efficiency as it increases gradually the value of M according to the state of channel. However, only approximate performance analysis was performed due to the complexity of the analysis. In this paper, we introduce an exact performance analysis considering the change of a boundary line due to the difference in frequency of use of the signal points. Also, we propose a new constellation of 2 time dimension  ×   -ary QAM with odd  which has better performance in PAPR. In the performance analysis, we obtain the signal point error rate and the bit error 이와 같이 증가하는 모바일 트래픽을 감당하기 위 해서 5세대 이동통신의 도입은 필수적이라고 볼 수

Recently, communication components prefer Bluetooth or Zigbee for PAN. However, using these makes expensive and complicated products such as audio equipments, mobile phones, PC, etc. for transmitting simple messages with low rate. In this paper, we propose wireless communication method using ultrasonic in the audio frequency limit band with speakers and microphones which are in products. We suggest transmitting and receiving methods in the audio frequency limit band for transmitting data without affecting audio signal, and implement an ultrasonic communication modem. Finally, we verify the performance of the ultrasonic communication modem by experiments in an environment with background noise. 키워드초음파 통신, 가청주파수, ASK, FSK, PAN