主題： IEEE 802.11n standard技術淺釋
The IEEE 802.11n standard is established by two competing proposals coming from WWiSE (World-Wide Spectrum Efficiency), backed by companies including Motorola, Broadcom, and TGn Sync backed by Intel, Philips. This standard is built upon previous 802.11 standards by the addition of MIMO (multiple-input multiple-output) or smart antenna systems. MIMO adopts multiple transmitters and receive antennas to increase WLAN data throughput via spatial multiplexing and increase the range by exploiting the spatial diversity as well as more than current wireless networking protocols. The quality of data transmission is further improved. It uses dual frequenices including 2.4GHz and 5GHz. It is also backward compatible to IEEE 802.11a / b / g together and provides wider bandwidth. The estimated maximum data rate can reach 200Mbps or more.
MIMO is the key role to achieve the IEEE 802.11n goal. The important benefits of MIMO are the antenna diversity and spatial Orthogonal Frequency Divison Multiplexing (OFDM) like the following diagram. The OFDM boosts the data throughput rates (higher 600Mbit/s) using two or more antenna arrays with 20MHz and 40MHz channel widths in 2x2, 3x3, or 4x4 configurations. MIMO technology offers the ability to coherently resolve information from multiple signal paths using spatially separated receive antennas. Then the multipath signals are resolved and recover the intelligent information via multi-receivers.
Although the IEEE 802.11n standard is not confirmed yet, some manufacturers such as Linksys, D-Link, Belkin have already promoted the IEEE 802.11n standard series wireless broadband routers (shown as the following diagram) and notebook adapters into markets.
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