| 单词 | 802.11g |
| 释义 | 802.11g Also known as Wi-Fi ( Wi reless Fi delity).The IEEE standard (June 2003) for an 802.11 wireless local area network (WLAN) operating in the 2.4-GHz band at a signaling speed of up to 54 Mbps. Backward-compatible with 802.11b, 802.11g divides the available radio frequency (RF) spectrum into 14 channels, each of which has a width of 25 MHz. In the United States, the FCC allows the use of 11 channels, only three of which can be used in a confined area at any given time without overlap. Four channels are available in France, 13 in the rest of Europe, and only 1 in Japan. Like 802.11a, 802.11g uses orthogonal frequency division multiplexing (OFDM) at data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps, with the attainable speed being highly sensitive to distance and line of sight (LOS). At 5.5 Mbps and 11 Mbps, the modulation technique reverts to complementary code keying (CCK), which also is used in 802.11b. At 2 Mbps, it reverts to direct sequence spread spectrum (DSSS) and quadrature phase-shift keying (QPSK), and at 1 Mbps to DSSS and binary phase-shift keying (BPSK), again defaulting to the 802.11a specification. Tri-mode components allow 802.11a/b/g-equipped terminals and access points (APs) to interoperate, although supporting multiple simultaneous protocols affects performance negatively. See also 802.11, 802.11a, 802.11b, AP, BPSK, CCK, channel, DSSS, FCC, IEEE, LOS, modulation, OFDM, QPSK, RF, spectrum, and WLAN. |
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