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- Doplňkové klíčování kódu (v angličtině Complementary Code Keying, z toho zkratka CCK) je modulační schéma, které používají bezdrátové sítě (WLAN) fungující na standardu IEEE 802.11b. V roce 1999 bylo CCK včleněno jako doplněk Bankerova kódu v bezdrátové digitální síti k dosažení rychlosti vyšší než 2Mb/s, avšak na úkor horšího dosahu signálu. (cs)
- Complementary Code Keying (CCK) ist ein Modulationsverfahren, welches bei drahtlosen Netzwerken (WLAN) entsprechend der IEEE 802.11b-Spezifikation eingesetzt wird. CCK ersetzt hier das beim Original-Standard IEEE 802.11 eingesetzte Direct Sequence Spread Spectrum (DSSS). Im Gegensatz zu DSSS werden bei CCK Informationen auch im Spreizcode kodiert, wodurch sich die erreichbare Übertragungsrate deutlich erhöhen lässt (bei 802.11b auf brutto 11 MBit/s). (de)
- Complementary code keying (CCK) is a modulation scheme used with wireless networks (WLANs) that employ the IEEE 802.11b specification. In 1999, CCK was adopted to supplement the Barker code in wireless digital networks to achieve data rate higher than 2 Mbit/s at the expense of shorter distance. This is due to the shorter chipping sequence in CCK (8 bits versus 11 bits in Barker code) that means less spreading to obtain higher data rate but more susceptible to narrowband interference resulting in shorter radio transmission range. Beside shorter chipping sequence, CCK also has more chipping sequences to encode more bits (4 chipping sequences at 5.5 Mbit/s and 8 chipping sequences at 11 Mbit/s) increasing the data rate even further. The Barker code, however, only has a single chipping sequence. The complementary codes first discussed by Golay were pairs of binary complementary codes and he noted that when the elements of a code of length N were either [−1 or 1] it followed immediately from their definition that the sum of their respective autocorrelation sequences was zero at all points except for the zero shift where it is equal to K×N. (K being the number of code words in the set). CCK is a variation and improvement on M-ary Orthogonal Keying and uses 'polyphase complementary codes'. They were developed by Lucent Technologies and Harris Semiconductor and were adopted by the 802.11 working group in 1998. CCK is the form of modulation used when 802.11b operates at either 5.5 or 11 Mbit/s. CCK was selected over competing modulation techniques as it used approximately the same bandwidth and could use the same preamble and header as pre-existing 1 and 2 Mbit/s wireless networks and thus facilitated interoperability. Polyphase complementary codes, first proposed by Sivaswamy, 1978, are codes where each element is a complex number of unit magnitude and arbitrary phase, or more specifically for 802.11b is one of [1, −1, j, −j]. Networks using the 802.11g specification employ CCK when operating at 802.11b speeds. (en)
- Le complementary code keying (CCK) est un procédé de modulation du signal numérique basé sur le codage de bits permettant d'obtenir les séquences de débits 5,5 Mbit/s et 11 Mbit/s dans la bande de fréquences des 2,4 GHz. Ce procédé est utilisé pour les transmissions de données par liaison sans fil (WLAN) et, plus particulièrement, décrit dans le standard IEEE 802.11b appartenant au groupe de normes IEEE 802.11 (Wi-Fi). (fr)
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- Doplňkové klíčování kódu (v angličtině Complementary Code Keying, z toho zkratka CCK) je modulační schéma, které používají bezdrátové sítě (WLAN) fungující na standardu IEEE 802.11b. V roce 1999 bylo CCK včleněno jako doplněk Bankerova kódu v bezdrátové digitální síti k dosažení rychlosti vyšší než 2Mb/s, avšak na úkor horšího dosahu signálu. (cs)
- Complementary Code Keying (CCK) ist ein Modulationsverfahren, welches bei drahtlosen Netzwerken (WLAN) entsprechend der IEEE 802.11b-Spezifikation eingesetzt wird. CCK ersetzt hier das beim Original-Standard IEEE 802.11 eingesetzte Direct Sequence Spread Spectrum (DSSS). Im Gegensatz zu DSSS werden bei CCK Informationen auch im Spreizcode kodiert, wodurch sich die erreichbare Übertragungsrate deutlich erhöhen lässt (bei 802.11b auf brutto 11 MBit/s). (de)
- Le complementary code keying (CCK) est un procédé de modulation du signal numérique basé sur le codage de bits permettant d'obtenir les séquences de débits 5,5 Mbit/s et 11 Mbit/s dans la bande de fréquences des 2,4 GHz. Ce procédé est utilisé pour les transmissions de données par liaison sans fil (WLAN) et, plus particulièrement, décrit dans le standard IEEE 802.11b appartenant au groupe de normes IEEE 802.11 (Wi-Fi). (fr)
- Complementary code keying (CCK) is a modulation scheme used with wireless networks (WLANs) that employ the IEEE 802.11b specification. In 1999, CCK was adopted to supplement the Barker code in wireless digital networks to achieve data rate higher than 2 Mbit/s at the expense of shorter distance. This is due to the shorter chipping sequence in CCK (8 bits versus 11 bits in Barker code) that means less spreading to obtain higher data rate but more susceptible to narrowband interference resulting in shorter radio transmission range. Beside shorter chipping sequence, CCK also has more chipping sequences to encode more bits (4 chipping sequences at 5.5 Mbit/s and 8 chipping sequences at 11 Mbit/s) increasing the data rate even further. The Barker code, however, only has a single chipping sequen (en)
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- Doplňkové klíčování kódu (cs)
- Complementary Code Keying (de)
- Complementary code keying (en)
- Complementary code keying (fr)
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