IEEE 802.11n-2009 is an amendment to the wireless networking standard aimed at improving network throughput by increasing data rates from 54 Mbps to 600 Mbps using MIMO technology and 40 MHz channels. The document outlines the advancements made over previous standards, including MAC layer enhancements and various modulation techniques, while also discussing compatibility and deployment challenges. It highlights the potential applications of 802.11n in enhancing wireless access for devices like laptops and smartphones.

1. IEEE 802.11n NITHINKUMAR C.N B.P.C. College , Piravom

2. IntroductionIEEE initiated the IEEE 802.11 project in 1990.In 1997, IEEE first approved the interoperability standard for WLANs.In 1999 , IEEE ratified two amendments to the IEEE 802.11 standard-IEEE 802.11a and 802.11b.In 2003 , IEEE released the IEEE 802.11g amendment.In 2006 , the first IEEE 802.11n draft was introduced.

3. What is IEEE 802.11n? IEEE 802.11n-2009 is an amendment to IEEE 802.11-2007 wireless networking standard to improve network throughput over the two previous standards with a significant increase in the maximum raw data rate from 54 Mbps to 600 Mbps with the use of four spatial streams at a channel width of 40 MHz .

4. IEEE 802.11n builds on previous 802.11 standards by adding multiple-input multiple-output(MIMO) and 40 MHz channels to the PHY (physical layer) , and frame aggregation to the MAC layer.New components in IEEE 802.11nPHY Enhancements, applicable to both 2.4GHz and 5GHzThe new PHY supports OFDM modulation with additional coding methods, preambles, multiple streams and beam-formingMultiple Input Multiple Output (MIMO) Radio Technology With Spatial MultiplexingHigh throughput PHY – 40 MHz channels – Two adjacent 20 MHz channels are combined to create a single 40 MHz channel.MAC EnhancementsTwo MAC aggregation methods are supported to efficiently pack smaller packets into a single MPDUBlock Acknowledgement – A performance optimization in which an IEEE 802.11 ACK frame need not follow every unicast frame and combined acknowledgements may be sent at a later point in time.

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18. Compare to traditional Single Input Single Output Radio (with optional receive diversity)channelBitsDSPDSPRadioRadioBitsTXRXWhat is MIMO?Multiple Input Multiple Output (MIMO)Transmit and Receive with multiple radios simultaneously in same spectrum

19. Spatial Division MultiplexingMultiple independent data streams are sent between the transmit and receive antennas to deliver more bits in the specified bandwidthRadioRadioDSPDSPRadioMore BitsRadioMore BitsRadioRadioTXRXCross-paths between antennas are automatically decoded by the receiver, assuming sufficient “richness” in the propagation environmentIEEE 802.11b-1999IEEE 802.11b-1999 or 802.11b, is an amendment to the IEEE 802.11 specification that extended throughput up to 11 Mbps using the same 2.4 GHz band. It uses CSMA/CA media access method.Eventhough 802.11b is a direct extension of the DSSS modulation technique defined in the original standard, it uses Complementary code keying(CCK) as its modulation technique.

20. IEEE 802.11a-1999IEEE 802.11a-1999 or 802.11a is an amendment to the IEEE 802.11 specification that added a higher data rate of up to 54 Mbps using the 5 GHz band. It uses a 52-subcarrier orthogonal frequency-division multiplexing (OFDM) with a maximum raw data rate of 54 Mbps , which yields realistic net achievable throughput in the mid-20 Mbps.

21. IEEE 802.11g-2003IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11specification that extended throughput to up to 54 Mbps using the same 2.4 GHz band as 802.11b. 802.11g hardware is fully backwards compatible with 802.11b hardware.The modulation scheme used in 802.11g is orthogonal frequency-division multiplexing.

22. IEEE 802.11k-2008IEEE 802.11k-2008 is an amendment to IEEE 802.11-2007 standard for radio resource management. It defines and exposes radio and network information to facilitate the management and maintenance of a mobile Wireless LAN.It provides information to discover the best available access point.

23. IEEE 802.11r-2008IEEE 802.11r-2008 or fast BSS transition (FT) is an amendment to the IEEE 802.11 standard to permit continuous connectivity aboard wireless devices in motion, with fast and secure handoffs from one base station to another managed in a seamless manner.IEEE 802.11r specifies fast Basic Service Set(BSS) transitions between access points by redefining the security key negotiation protocol.