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TECH TRENDS By Ray Coulombe Raising the Bar(s) in Wireless New options in Wi-Fi and beyond R ecently, I was reading about Apple's new MacBook Air and its ultra-fast wireless capability, 802.11ac. After a little research, I thought it and related wireless technologies would be a good topic to cover in my first SD&I; column. One of the consistent trends we have seen in networking is the continuous increase in network speeds. In wired networks, more devices are appearing with 10 Gbps capability, while 40 Gbps and 100 Gbps equipment is on the horizon. Wireless, too, has seen a migration in its transmission capabilities. In cellular data, most current devices are either 3G or 4G, with 5G imminent (the "G" refers to the current generation of wireless technology employed). Different vendors have various implementation solutions. It's interesting to note that Samsung, in May, 2013, announced a key technical breakthrough in the use of millimeter-wave technology at 28 GHZ supporting their 5G approach, promising speeds in excess of 1 Gbps. IEEE defines a family of wireless standards in the 802.11 family. We should all be familiar with 802.11 a, b, and g (most home routers support these) and possibly 802.11n, which upped the maximum bandwidth ante over 802.11g from 54 Mbps to 600 Mbps. It did so by providing for the use of multiple antennas using MIMO (multiple input, multiple output) technology. 802.11n operates at either 2.4 GHz or 5 GHz and provides approximate ranges of 230 ft. (indoors) and 820 ft. (outdoors). The first generation of 802.11n devices that came to market a few years ago sup20 ported a maximum data rate of 300 Mbps by running two spatial streams. Each stream could carry 75 Mbps of data per 20 MHz of spectrum, over a double-wide 40-MHz channel. Newer devices, supporting three spatial streams, offer 450 Mbps capability, and the maximum 600 Mbps can only be achieved with four spatial streams. Something Spatial So, what is a spatial stream? Spatial multiplexing (SM) splits up the data into pieces and sends each piece along parallel "spatial" channels (streams), providing greater speed and use of available spectrum. Space-division multiple access (SDMA) is a MIMO technique which concentrates power in the direction of the receiving unit for which the signal is directed and reducing it in the directions where other units are present. The technique of "beamforming" uses intelligent control of phase and amplitude to create positive or negative interference of the radio waves, allowing reception or cancellation of a signal at a particular user. It is able to identify the rough location of the device it is talking to, relies on information about the wireless channel that is fed back to the transmitter by the receiver, and adjusts the appropriate antenna(s) accordingly. WiFi to Handle BYOD Issues Fifth-generation Wi-Fi, 802.11ac, can be thought of as an enhanced 802.11n, but operates only at 5 GHz. It increases the number of parallel spatial streams to eight, with the effect of significantly improved wireless network speeds. It is expected to help accommodate the need in an enterprise for increased bandwidth to deal with increasing numbers of smart devices (BYOD) and the growing use of video streaming. 802.11ac devices are expected to be dual- www.SecurityInfoWatch.com | SD&I; | September 2013