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Tag: 802.11ac

Got a D-Link DIR-850L to replace DIR-845L

August 6, 2013 / / 0 Comments

Got DIR-850L at London Drugs. It is only $10 more than the one I got, DIR-845L at Costco. I did not see the benefits of SmartBeamTM Technology. So I spend $109 to get a new router with 802.11AC support. 802.11AC is a new standard. See new technologies data from Wiki.

  • Extended channel binding
    • Mandatory 80 MHz channel bandwidth for STAs (vs. 40 MHz maximum in 802.11n), 160 MHz available optionally
  • More MIMOspatial streams
    • Support for up to eight spatial streams (vs. four in 802.11n)
  • Multi-user MIMO(MU-MIMO)
    • Multiple STAs, each with one or more antennas, transmit or receive independent data streams simultaneously
      • “Space Division Multiple Access” (SDMA): streams not separated by frequency, but instead resolved spatially, analogous to 11n-style MIMO
    • Downlink MU-MIMO (one transmitting device, multiple receiving devices) included as an optional mode
  • Modulation
    • 256-QAM, rate 3/4 and 5/6, added as optional modes (vs. 64-QAM, rate 5/6 maximum in 802.11n)
    • Controversy has been raised that this modulation rate is not suitable for any architecture other than extremely small cells and would be completely useless to 3GPP
  • Other elements/features
    • Beamforming with standardized sounding and feedback for compatibility between vendors (non-standard in 802.11n made it hard for beamforming to work effectively between different vendor products)
    • MAC modifications (mostly to support above changes)
    • Coexistence mechanisms for 20/40/80/160 MHz channels, 11ac and 11a/n devices

dir850l-box

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How to choose the right router

April 25, 2013 / / 0 Comments

To choose the router or upgrade your home network, first you should know what standard you need.
There are three main standards on market now.
Standard Max Speed
802.11g 54Mbps
802.11n 600Mbps
802.11ac 1.3Gbps
802.11g was introduced many years ago, I wrote a post eight years ago related the wireless network.
802.11ac is still a draft standard. It means most products from different company are not same. They may not work together compatibly. The good news is that IEEE will issue the final approved version of 802.11ac the end of this year 2013. Here is the timeline.
The Max Speed described above is in theory. When the router working inside the house, walls, furniture, these kind of obstacles reduce the speed by 50%.
There are also frequence, bandwidth, channel issue for your router.
for 802.11g, 2.4GHz, there are 13 channel. 20MHz each channel
for 802.11n, 2.4GHz or 5GHz, 20MHz each channel, bonding channels.
for 802.11ac, 5GHz,
Bonding channels is double the bandwidth, or 40Mhz. It means faster.

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