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Stay Connected with the Next Generation of Wireless

Although 802.11a/b/g networks continue to be popular today, the next generation of wireless applications, such as real-time voice and video streams for remote monitoring, will require more bandwidth and reliability. To meet the growing needs of these bandwidth-hungry applications, the latest IEEE 802.11n standard (published in 2009) offers blazing data rates of up to 300 Mbps. 802.11b only supports a mere 11 Mbps while 802.11a and 802.11g top out at 54 Mbps each. If you're looking to deploy a reliable and secure wireless network for high-bandwidth applications, IEEE 802.11n is for you.

Meet 802.11n
IEEE did more than just boost the bit rates supported by 802.11a/b/g when they developed 802.11n. By dramatically changing the basic frame format 802.11 devices use to communicate with each other, 802.11n offers WLANs increased channel size, higher modulation rates, and reduced overhead. 802.11n can operate in either the 2.4 or 5 GHz bands and is backwards-compatible with existing 802.11a/b/g deployments to future-proof your wireless investments.

 802.11 Spec

MIMO Technology
The key technique behind enhanced data rates in 802.11n networks, called Multiple Input Multiple Output (MIMO), refers to a link where the transmitting end and the receiving end are both equipped with multiple antennas. Radio signals reflect off objects, creating multiple paths. In conventional transmission this causes interference and fading, but MIMO leverages the multipath phenomenon. On the transmission side, MIMO uses spatial multiplexing to send multiple parallel data streams simultaneously over the same channel, thereby increasing the data rate and transmission power. On the receiving end, MIMO allows multiple signals to be combined into a single signal, eliminating the effects of multipath fading. MIMO actually takes advantage of radio reflection to improve wireless range and reliability.

Channel Bonding
The amount of data that can be delivered relies on the channel width used in data transmission. By bonding two or more channels together, more bandwidth is available for data transfer. 802.11n uses channel bonding to combine two adjacent 20 MHz channels into a single 40 MHz channel in both the 2.4 and 5 GHz bands to provide increased channel width and the ability to transmit more data.

Frame Aggregation
Every frame transmitted by an 802.11 device has fixed overhead that limits the effective throughput. To reduce this overhead, 802.11n introduces frame aggregation, which is the process of packing multiple frames in a single transmission. With this mechanism, instead of several sets of overhead for different frames, only one set of overhead is used, which greatly reduces the average delay and increases the throughput performance of the 802.11 WLAN.

What's in it for You?
Thanks to improvements such as MIMO, 802.11n achieves greater SNR (signal-to-noise ratio) on the radio link, as well as more efficient MAC protocol and radio transmissions. These improvements translate into benefits in three areas: reliability, predictable coverage, and throughput.

  • Reliability: Higher SNR means that more interference is needed to corrupt a transmission, which translates directly into more reliable communication and higher data rates.

  • Low interference: Thanks to MIMO technology, areas that previously suffered from destructive multipath interference now make use of that same multipath effect to provide robust communication.

  • High throughput: Since 802.11n is backwards-compatible, even legacy 802.11 devices will be able to take advantage of higher throughput rates when deployed on an 802.11n network.

A Case in Point
For train video surveillance, if each carriage has six cameras installed, and each camera runs in full D1 mode with a 2 Mbps data rate, then two carriers will use a total data rate of 24 Mbps. This poses obvious challenges for 802.11a/b/g networks that only support up to 20 Mbps of throughput. Moxa offers 802.11n products with up to 120 Mbps throughput that can deliver demanding video streaming applications on trains. Additionally, MIMO technology and frame aggregation can transmit superior quality video streams. MIMO enables higher bandwidth, reduced interference, and enhanced connectivity, while frame aggregation ensures that content is combined to support streaming video.


Contact us at Tel No. +603-8024 0306 or E-mail Address enex@excelnex.com for more details and assistance.


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