I got a web seminar invite from Information Week on a new WiFi Standard - 802.11ac. But I don’t need to wait for a seminar to read up on the new standard.
http://en.wikipedia.org/wiki/IEEE_802.11ac - Wikipedia has a page on this.
For boats and yachts for now I wouldn’t worry about this on the Marina Hotspot (your topside WiFi antenna for Hotspots – if you have one?) side as of yet. We’re still looking for any benefit from 802.11n which was the last WiFi Standard update. The Internet connection behind a WiFi hotspot might be 10 Mb/s Cable (or less) and so getting a faster link to them wouldn’t make any difference if the backhaul is multiples of slower than the wireless link speed.
However on board the vessel – if you have application(s) that have a “Need for Speed” such as video streaming on board the boat – video camera viewing – other multimedia – engineering applications that need faster speed – or you just want to be in the forefront of wireless technology inside the boat … you might want to start looking into 802.11ac capable wireless access points.
Spatial Streams, Multi-Antenna – Multiple Input Multiple Output (multi-user even?), and 256 QAM – Oh My!
Lions and Tigers and Bears, Oh My!
QAM 16 Demonstration – imagine 256 QAM …
(Digital 16-QAM with example constellation points. [Constellation Diagram])
“Like many digital modulation schemes, the constellation diagram is a useful representation. In QAM, the constellation points are usually arranged in a square grid with equal vertical and horizontal spacing, although other configurations are possible (e.g. Cross-QAM). Since in digital telecommunications the data are usually binary, the number of points in the grid is usually a power of 2 (2, 4, 8, …). Since QAM is usually square, some of these are rare—the most common forms are 16-QAM, 64-QAM and 256-QAM. By moving to a higher-order constellation, it is possible to transmit more bits per symbol. However, if the mean energy of the constellation is to remain the same (by way of making a fair comparison), the points must be closer together and are thus more susceptible to noise and other corruption; this results in a higher bit error rate and so higher-order QAM can deliver more data less reliably than lower-order QAM, for constant mean constellation energy. Using higher-order QAM without increasing the bit error rate requires a higher signal-to-noise ratio (SNR) by increasing signal energy, reducing noise, or both.” [http://en.wikipedia.org/wiki/256QAM.]
“IEEE 802.11ac is a wireless computer networking standard of 802.11, currently under development (Draft 4.0[1]), providing high-throughput wireless local area networks on the 5 GHz band.[1] Standard finalization is in late 2012, with final 802.11 Working Group approval in late 2013.[1] According to a study, devices with the 802.11ac specification are expected to be common by 2015 with an estimated one billion spread around the world.[2]
Theoretically, this specification will enable multi-station WLAN throughput of at least 1 gigabit per second and a maximum single link throughput of at least 500 megabits per second (500 Mbit/s). This is accomplished by extending the air interface concepts embraced by 802.11n: wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256 QAM).”
* Alan’s Final Note: So 802.11ac should be coming to a theatre near you – showing up in Laptop and other portable devices and becoming available in wireless access points. Also note this new standard is in the 5 Ghz band as opposed to the more commonly used (up till now?) 2.4 Ghz band. It’s a different antenna if we were talking about a topside antenna … but in portable computing devices and on board access points the antennas will be already built-in. The question of what frequency band came to me again while re-reading the above quote paragraph – as we already have to be careful with 2.4 Ghz channels because they overlap. It’s common in installation use only channels 1, 6, and 11 in the 2.4 Ghz WiFi band because of this overlap in the channels RF bandwidth. It will be interesting to know, going forward, how the 5 Ghz band is used as far as overlap and interference with other services (e.g. radar and military applications … example given TDWR) see:
http://en.wikipedia.org/wiki/List_of_WLAN_channels
If you are interested in the interference / overlap situation in 5 Ghz, as I am, have a look at:
“This will enable faster peer-to-peer Wi-Fi Direct data transfer and higher quality screen-casting/throwing from phones and tablets to large flatscreens via Wi-Fi Display. But again, the higher speeds will come at the expense of using wider swaths of bandwidth in the currently relatively uncluttered 5 GHz band. There goes the neighborhood!”
* As some ham radio guys would say with the U-Verse expanded frequency band use (now in the same frequencies used for H.F. SSB Radio) – “There goes the neighborhood!”
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Alan Spicer Marine Telecom
+1 954-683-3426
communications @ marinetelecom.net
