IEEE 802.11ad Standard

There is an enormous amount of unlicensed spectrum worldwide at 60 GHz. IEEE 802.11ad was introduced to address the developing 60 GHz market. To distinguish it from other standards, IEEE 802.11ad includes two specific requirements:

1. Enable fast session transfer between 802.11 PHYs,
2. Maintain the 802.11 user experience — Fast session transfer provides seamless rate fallback and rate rise between VHT in the 60 GHZ and 2.4/5 GHz PHYs for multi-band devices. It also enables combo 60 GHz + 2.5/5 GHz devices to deliver expected WLAN coverage. However, it is not mandatory for devices to have multi-band capability.

VHT in the 60 GHz maintains the 802.11 user experience by maintaining the network architecture of the 802.11 system, e.g., infrastructure basic service set, extended service set, access point and station.

802.11ad reuses and maintains backward compatibility to 802.11 management plane, e.g., association, authentication, security, measurement, capability exchange and the management information base (MIB). It also supports an operation mode that enable a throughput of at least 1 Gbps.

The Physical Layer

802.11ad has three packet structures:

1. Control PHY is designed for low SNR operation prior to beamforming.
2. Single Carrier (SC) PHY enables low power / low complexity transceivers.
3. Low Power SC PHY is a derivative of the SC PHY. It provides additional support for further reduction in implementation processing power with simpler coding and shorter symbol structure.

IEEE 802.11ac Standard

IEEE 802.11 initiated a group to investigate very high throughput (VHT) technologies. The Wi-Fi Alliance provides the following general usage models: wireless display, distributed high definition TV (HDTV) rapid upload/download backhaul, outdoor campus, auditorium and manufacturing floor. Specific usages include video streaming around a house, rapid sync-and-go and wireless I/O.

Streaming around the home will involve TVs and DVRs with wireless capability and 100+ Mbps aggregate of videos from DVR can be displayed wirelessly on TVs in different rooms. Rapid sync-and-go will allow users to quickly sync movies or pictures between mobile devices, such as a phone and a laptop. With a 1 Gbps radio link, transferring a 1 GB video file will take less than a minute.

802.11ac operates in the 5 GHz band. Its scope includes:

1. Single link throughput supporting at least 500 Mbps,
2. Multi-station throughput of at least 1 Gbps,
3. Exclusion of 2.4 GHz band,
4. Backward compatibility and co-existence with legacy 802.11 devices in the 5 GHz band.

How does 802.11ac support VHT?

802.11n supports features such as MIMO, 40 MHz and packet aggregation to significantly increase data rates of 802.11a/b/g. As an evolution of 802.11n, 802.11ac adds 80 MHz, 160 MHz and non-contiguous 160 MHz (80 + 80 MHz) channel bandwidth. 802.11ac enhances throughput with its multi-user capability in the form of downlink multi-user MIMO (DL MU-MIMO).

802.11ac Channelization