Broadband Communities

AUG-SEP 2013

BROADBAND COMMUNITIES is the leading source of information on digital and broadband technologies for buildings and communities. Our editorial aims to accelerate the deployment of Fiber-To-The-Home and Fiber-To-The-Premises.

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metrics The Challenges of Wireless Network Design, Part Two Until recently, inexpensive, of-the-shelf equipment was sufcient for MDU wireless coverage. Today, that's no longer the case. As in so many other areas, you get what you pay for! By Mike Nichols / Korcett Holdings T he growing use of smartphones, tablets and other wireless devices makes ubiquitous wireless coverage a necessity. Te January-February 2012 Metrics column, a case study of a Wi-Fi network installation in a student housing community, illustrated some of the pitfalls of designing and installing wireless networks in multiple-dwelling-unit (MDU) housing. It also demonstrated the need for uniform design standards and for clear communications between developers and network designers. Tis column presents high-level information about Wi-Fi that both developers and network designers should understand if they are to meet residents' demands for high-bandwidth, reliable wireless communications. For a more in-depth discussion of wireless technology and design, please contact the author. WhAT'S SO GREAT ABOUT 802.11N? Te principal diference between Class G and Class N wireless products is the addition of multiple-input, multiple-output (MIMO) technology – an important tool for dealing with interference. A primary beneft of MIMO technology is that it can use multiple radiofrequency (RF) chains via multiple antennas. MIMO uses spatial multiplexing, spatial diversity and RF chains to dynamically reconfgure connections with wireless devices in real time. 12 | BROADBAND COMMUNITIES | www.broadbandcommunities.com • Spatial multiplexing is a means of aggregating data links. Imagine running several Cat 5 cables through a house, using diferent routes to tie together a source and destination. Splitting the data transmission evenly over each link would result in a signifcant improvement in throughput, compared with sending all the data over a single link. In addition, if one cable is cut, redundant paths are still available. In summary, spatial multiplexing provides increased speed and redundancy. • Spatial diversity is a means of ensuring that transmitted data reaches its destination. In the example above, suppose data transmitted on one Cat 5 cable is mirrored on one of the other cable runs. Te goal in this case is reliability rather than more bandwidth. If one cable is partially cut, there are still clear paths to traverse. In summary, path diversity results in better quality of service. • RF chains are physical wires that connect wireless chips to one or more antennas inside a wireless device. MIMO achieves antennaspecifc diversity by linking a chip to multiple antennas simultaneously, using multiple RF chains and comparing the connections. Tis drastically increases the number of possible connection combinations and allows the wireless chip to select the best connection between any two points in real time. | August/september 2013

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