WLAN - 802.11ad                                                          Home : www.sharetechnote.com

 

 

 

 

802.11ad is a specially designed to work in extremely high frequency and with extremly wide bandwidth offering the high throughput relatively simple structure. What I mean by 'relatively simple structure' mean 'without using high degree of MIMO and high order modulation technique'. It doesn't really mean that 802.11ad is easy to implement. In terms implementation, we need to overcome various technical issues that should work at mmWave (60 Ghz) range. Overall characteristics (features) of 802.11ad can be summarized as in the following diagram.

 

 

 

In terms of throughput, you may see 802.11ad does not provide much higher throughput than 802.ac. Actually theoretical max throughput of 802.11ac (8 stream, 256 QAM) is higher than 802.11ad. However, in regular / common operation, higher throughput would be more easily achieved with 802.11ad.

 

At least as of now (Jun 2017), 802.11ad does not support MIMO and does not support very high order modulation scheme (e.g, 64 QAM or higher). Then you may ask.. how can we achieve such a high throughput without using higher order modulation or high degree MIMO ?  The answer is simple.. just use super-wide bandwidth :).  A single channel 802.11ad bandwidth is up to 1.88 Ghz (almost 2 Ghz). This can be a big challenge in baseband implementation. (Of course, RF side challenge is to develop / implement 60 Ghz components.

 

 

PHY Frame

 

< Control PHY Frame >

 

 

 

< Single Carrier PHY Frame >

 

 

 

< Low Power Single Carrier PHY Frame >

 

 

 

< OFDM PHY Frame >

 

 

 

 

Additional MAC Frame Types

 

In 802.11ad, Following new Frame Types are added to the existing type.  

 

Type

Type Description

Sub Type

Sub Type Description

01

Control

0000-0001

Reserved (This is changed from existing field)

01

Control

0110

Control Frame Extension

11

Extension

0000

DMG(Directional Multi Gigabit) Beacon

11

Extension

0001-1111

Reserved

 

When Frame Extension type is configured, the structure of Frame Control field is defined as follows

 

 

The Control Frame Extension bit field is defined as follows (802.11ad - Table 8-1aŚControl Frame Extension).

 

Type

Sub Type

Control Frame Extension

Description

01

0110

0000

Reserved

01

0110

0001

Reserved

01

0110

0010

Poll

01

0110

0011

SPR

01

0110

0100

Grant

01

0110

0101

DMG CTS

01

0110

0110

DMG DTS

01

0110

0111

Grant ACK

 

 

References :

 

[1] Wikipeida : Wireless Gigabit Alliance

[2] Understanding IEEE 802.11ad Physical Layer and Measurement Challenges

[3] WLAN 802.11ad Tutorial

[4] WLAN 802.11ad physical layer

 

 

 

 

 

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