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Ç¥ÁعøÈ£ TTAK.KO-10.1307-Part3 ±¸Ç¥ÁعøÈ£
Á¦°³Á¤ÀÏ 2021-12-08 ÃÑÆäÀÌÁö 7
ÇѱÛÇ¥ÁØ¸í ±¤ÇÐ Ä«¸Þ¶ó Åë½Å ¹°¸®°èÃþ ÇÁ·ÎÅäÄÝ µ¥ÀÌÅÍ À¯´Ö(PPDU) ÇÁ·¹ÀÓ Çü½Ä Á¦3ºÎ: ·Ñ¸µ ¼ÅÅÍ ±¤ÇÐ Ä«¸Þ¶ó Åë½ÅÀ» À§ÇÑ ÇÏÀ̺긮µå ´ÙÁßÀÔÃâ·Â Á÷±³ ÁÖÆļö ºÐÇÒ ´ÙÁßÈ­ ÁÖÆļö ÆíÀÌ(MIMO OFDM-FSK) º¯Á¶ ¹æ½Ä
¿µ¹®Ç¥Áظí Physical Protocol Data Unit(PPDU) Frame Format for Optical Camera CommunicationPart 3. Hybrid MIMO OFDM-FSK Modulation Scheme for Rolling Shutter Optical Camera Communication
Çѱ۳»¿ë¿ä¾à OFDM (Orthogonal Frequency-Division Multiplexing)Àº ¿©·¯ ¹Ý¼ÛÆÄ ÁÖÆļö¿¡¼­ µðÁöÅÐ µ¥ÀÌÅ͸¦ ÀÎÄÚµùÇÏ´Â º¯Á¶ ¹æ½ÄÀÌ´Ù. °í¼Ó Åë½Å¿¡¼­ Áß¿äÇÑ ±â¼ú·Î ISI(Intersymbol Interference)·Î ÀÎÇÑ ¿Ö°îÀ» Á¦°ÅÇϱâ À§ÇØ ´ë¿ªÆøÀ» Á÷±³ ºÎ¹Ý¼ÛÆÄ·Î ºÐÇÒÇÑ´Ù. Ǫ¸®¿¡ º¯È¯ ¹æ¹ýÀ» »ç¿ëÇϸé OFDM ½Ã½ºÅÛÀÇ ºÎ¹Ý¼ÛÆÄ°¡ ½ÅÈ£ ¼º´É¿¡ ¿µÇâÀ» ÁÖÁö ¾Ê°í ¼­·Î ÁßøµÉ ¼ö ÀÖ´Ù. ±× ¿Ü¿¡µµ ¿Ö°îÀ» ¹æÁöÇϱâ À§ÇØ OFDM ½Éº¼ ¸ÞÀÌÅ·¿¡ Cyclic-Prefix°¡ Ãß°¡µÈ´Ù.
FSK (Frequency-Shift Keying)´Â ¹Ý¼ÛÆÄ ½ÅÈ£ÀÇ ÀÌ»ê ÁÖÆļö º¯È­¸¦ ÅëÇØ µðÁöÅÐ Á¤º¸¸¦ Àü¼ÛÇÏ´Â ÁÖÆļö º¯Á¶ ¹æ½ÄÀÌ´Ù. ÀÌ ±â¼úÀº ¿ø°Ý ÃøÁ¤, ³¯¾¾ dz¼± ¶óµð¿À Á¸µ¥, ¹ß½ÅÀÚ ID, Â÷°í ¹® °³Æó ÀåÄ¡ ¹× ÀúÁÖÆÄ ¶óµð¿À Àü¼Û°ú °°Àº Åë½Å ½Ã½ºÅÛ¿¡ »ç¿ëµÈ´Ù. CM-FSK´Â Camera M-ary Frequency Shift KeyingÀÇ ¾àÀÚÀ̸ç IEEE 802.15.7-2018¿¡¼­ Ç¥ÁØÈ­µÈ ÀÛµ¿ ¸ðµåÀ̱⵵ ÇÏ´Ù.
±âÁ¸ÀÇ OFDM ¶Ç´Â CM-FSK¿Í ´Þ¸® µÎ °³ÀÇ ÆÄÇü OFDM ¹× FSK¸¦ °áÇÕÇÏ¿© ÀÌ ÇÏÀ̺긮µå ÆÄÇüÀ» ´ÜÀÏ LED·Î Àü¼ÛÇÑ´Ù. µ¥ÀÌÅÍ Àü¼Û·üÀ» ³ôÀ̱â À§ÇØ ÇÏÀ̺긮µå ½Ã½ºÅÛ¿¡ ´ÙÁß ÀÔ·Â ´ÙÁß Ãâ·ÂÀ» Àû¿ëÇÑ´Ù. ¿¹¸¦ µé¾î 3°³ÀÇ LED MIMO¸¦ Àû¿ëÇϸé ÇÏÀ̺긮µå ½Ã½ºÅÛÀÇ µ¥ÀÌÅÍ Àü¼Û·üÀº 3¹è±îÁö Áõ°¡ÇÒ ¼ö ÀÖ´Ù. OCC¸¦ À§ÇÑ MIMO ÇÏÀ̺긮µå OFDM-FSK ü°è¿¡ ´ëÇÑ ÀÚ¼¼ÇÑ ³»¿ëÀ» Á¦¾ÈÇÑ´Ù. ±× ¿Ü¿¡µµ ÇÏÀ̺긮µå OFDM-FSKÀÇ ±¸Á¶¸¦ Á¦¾ÈÇß´Ù.
¿µ¹®³»¿ë¿ä¾à The Orthogonal Frequency-division multiplexing (OFDM) is a modulation method of encoding digital data on multiple carrier frequencies. It is importance technique in high-speed communication, the bandwidth is divided into the orthogonal sub-carrier to eliminate the distortion caused by Intersymbol Interference(ISI). By using Fourier Transform method, the sub-carrier in OFDM system can be overlap on each other without effecting to signal performance. Besides that, the Cyclic-Prefix is added to OFDM symbol making to combat the distortion.
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission. CM-FSK stands for Camera M-ary Frequency Shift Keying, is also an operating mode being standardized in IEEE 802.15.7-2018.
Unlike the conventional OFDM or CM-FSK, we combine two waveforms OFDM and FSK and transmit this hybrid waveform with single LED. To increase the data rate, we applied the Multiple Input Multiple Output for hybrid system. Example, if we apply 3 LEDs MIMO, the data rate of hybrid system can increase to three times. The more detail of the MIMO hybrid OFDM-FSK scheme for OCC, we mention in the sections below. Besides that, we proposed the structure of the hybrid OFDM-FSK.
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°ü·ÃÆÄÀÏ TTAK.KO-10.1307-Part3.pdf TTAK.KO-10.1307-Part3.pdf            

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