What's new

WiGIG - 802.11ad in a nutshell

  • SNBForums Code of Conduct

    SNBForums is a community for everyone, no matter what their level of experience.

    Please be tolerant and patient of others, especially newcomers. We are all here to share and learn!

    The rules are simple: Be patient, be nice, be helpful or be gone!

sfx2000

Part of the Furniture
Really short summary of the papers I'm linking below;
  • On the PHY, a single carrier data stream with 16-QAM modulation at the high end is used for raw data speeds of around 4 GBit/s.
    • There is a Low Power Single Carrier PHY - the main difference here is lower modulation schemes
  • Optionally - For higher speeds up to 7 Gbit/s, Orthogonal Frequency Division Multiple Access (OFDM) with 355 sub-carriers and 64-QAM modulation at the high end are used.
  • Four PHY's can be in use concurrently - the Control PHY is required - the Single Carrier PHY is common for many, the OFDM PHY is higher bandwidth, but at a cost of complexity and power, and there is the Low Power PHY which is single carrier, but lower requirements
    • Data Link speeds, similar to other 802.11 implementation will be quite a bit slower
    • PHY bandwidth is 2 GHz - for all PHY specs - SC/OFDM/LP-SC and of course the mandatory Control PHY
    • The Control PHY is a much clearer delineation between control (management) and data planes - this is a clear difference with 802.11 a/b/g/n/ac
    • Beamforming is part of the specification, as 60GHz by nature is directional, hence the name: ‘Directional Multi-Gigabit’ DMB PHY.
    • The PHY itself is much simpler compared to 11ac - mostly because there is no legacy to be concerned with - it's greenfield technology
    • Should note that currently with 60GHz and 802.11ad - everything is Single User, Single Input/Output - so in 802.11 speak - it is SU-SISO
  • Signals can’t penetrate walls, in fact, even a piece of paper may significantly impair or block WiGIG - one should consider it more like a light bulb in the room - anywhere the light touches directly, that's pretty much the coverage of 11ad
  • Primary Use Case - In-room coverage over a distance of 10 meters or less
  • On the MAC layer, and here's where at some point we might see some of the innovation in 11ad find it's way back into the WiFi arena
    • Scheduling and Coordination - transmissions are separated into beacon intervals and each interval has zones which are exclusively used for sending beacons in different directions (due to the directional nature of signals at 60 GHz), for beamforming preparation and for sending data packets.
    • Fast Transfer Function - some might have missed this snippet - it's part of the standard to continue data transmission in the 2.4 / 5 GHz band when the 60 GHz link suddenly fails. Likewise, it can also be used to transfer an ongoing data stream back to 60 GHz when the signal is redetected.

Interesting reading below:

http://eprints.networks.imdea.org/1...f_a_wlan_ieee_802.11ad_model_in_ns_3_2016.pdf

https://cdn.rohde-schwarz.com/pws/d...ation_notes/1ma220/1MA220_2e_WLAN_11ad_WP.pdf

Alt Link for the Rohde and Schwarz paper - https://www.rohde-schwarz.com/de/ap...-beu-60-ghz-application-note_56280-50625.html

http://cp.literature.agilent.com/litweb/pdf/5990-9697EN.pdf

Enjoy!
 
Last edited:
There is one thing that I find strange with many 802.11ad routers, if 60GHz is attenuated so easily, why do they place the antennas behind the plastic casing of the router, why not expose the PIFA antenna directly in order to avoid attenuating the signal as much as possible, especially with routers like the AD7200 only transmitting at 16.7dBm on the 60GHz band?
 
Last edited:
802.11 PHY types...

S46_802.11ad_T1.png


802.11ad Frame Types

802-11-ad-frame-types.jpg




Channel MAP across different regulatory domains

802.11ad_wifi_band_per_regions.png
 
Last edited:
There is one thing that I find strange with many 802.11ad routers, if 60GHz is attenuated so easily, why do they place the antennas behind the plastic casing of the router, why not expose the PIFA antenna directly in order to avoid attenuating the signal as much as possible, especially with routers like the AD7200 only transmitting at 16.7dBm on the 60GHz band?

Certain materials are not a good match, so they end up being transparent to the RF.

It's not a PIFA - it's an array - most are 12*2 or 16*2... here's an example.

11ad_example.jpg
 
And a bit more stuff...

Notice that attenuation at 60GHz is pretty low for plastic...

Frequency-and-attenuation-of-various-materials.png
 
And while it's early - most of the 802.11ad chips are standalone, at some point, they will be more tightly integrated - mostly to reduce cost, but also to improve the user experience - remember above that I mentioned Fast Transfer (to/from 11n/11ac and 11ad) - common MAC is one way to implement...

whos-ready-for-80211ac-and-ad-16-728.jpg
 

Latest threads

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!
Top