IEEE 802.11ad

        

802.11ad is developed by Wireless Gigabit Alliance, which later merged with Wi-Fi Alliance. In the technology set of IEEE Wireless LAN, it is the latest addition. An exceptional throughput of 7Gbps (theoretically) is offered by the 802.11ad wireless standard. Operating frequency band of 802.11ad is 60GHz. Short wavelength of 5mm is used at this frequency which makes the antenna affordable and compact. As compared to previous specs the transfer rates of 802.11ad are much higher (Stroud, 2017). There are four channels defined for the band but all are not available universally. Only channel 2 is accessible in the regions so it’s a default channel.

Channels in 60 GHz band

         ·      Features:

       Key features of 802.11ad are low data rates in the single carrier, robust modulation. It has an energy saving mode for the devices which operates on the battery (for the low power single carrier). At the receiver side, its beamforming feature optimizes the power and the interference can be overcome during the real-time transmission.

        ·         802.11ad Physical Layer:

         The addition of 11ad physical layer was an amendment and is called “Directional Multi-Gigabit PHY (DMG)”. There are three modulation modes available for directional multi-gigabit PHY and these control PHY, single carrier (SC PHY) and OFDM PHY. Packet structure is same in all these three modulation modes but differs in coding, type of modulation used and in defining the fields individually.

DMG PHY General Packet Structure

         Control PHY:

         To monitor and establish the connection between several devices the control PHY mode is used for controlling messages and/or signaling exchange. In all the devices the support is mandatory for this mode. The modulation used is BPSK and preamble (STF) is longer to make transmission more robust. The length of control header packet is 40 bit.

         Single Carrier PHY:

        In Single carrier mode, the transmission range is 385 Mbit/s up to 4.620 Gbit/s. An energy saving encoder is defined as additional low power SC for supporting the power consumption sensitive devices.

         OFDM PHY:

     OFDM PHY is implemented to achieve high data rates. The length of its header is 64 bit. Depending on the data rates different modulations are used.

           ·         Potential Usage Models:

                  There are different potential usage models of 802.11ad.

    1.      USR communication (ultra-short range):
    The usage model 1 is USR communication (ultra-short range). The content can be transferred quickly between the mobile/ portable devices and a fixed device with 100msec fast link setup and the data rate is 10 Gbps.

         2.      8 K UHD wireless transfers at smart home:

      Usage model 2 is 8 K UHD wireless transfers at smart home. For streaming of 8k UHD, the minimum data rate of 28Gbps, 60 frames/s, 24 bits/p is required for the link. It is used in Sony HMZ-T3 and VR goggles by Oculus.

         3.      Mobile devices:

       Model usage 3 is mobile devices. As for transmitting high data rate is required by some mobile devices like tablets or smartphone that operate various functions like internet access, video streaming, and data transfer etc.

         4.      High-speed download service:

      Fourth is high-speed download service in which the range is short with up to 10cm TX/RX separation. Content sync is huge in which connection time is short “touch and go”.

         5.      AR and VR:

       Usage model 5 is augmented reality AR and virtual reality VR. It supports the video quality up to 3D 4k with the usually indoor operating environment (range <10ft).