This presentation briefly describes the Wi-Fi 6 Technology or the latest wi-fi: IEEE802.11ax which I have used at IIT Madras to present and explain my course work(reading assignment). here I have covered all the problems, solutions, and benefits of wi-fi 6, how Wi-Fi evolved, standards, security, advantages, and innovations.
2. Overview of Wi-Fi
• Wi-Fi, orWireless Fidelity, based on the IEEE 802.11 standards for WLAN.
• Allows us to connect to the Internet from anywhere without wires.
• Internet connectivity occurs through a wireless router.
• Send and receive data indoors and out; anywhere within the range of a
base station by Radio waves.
3. Evolution of IEEE 802.11 standards:
Over the past 20 years, IEEE 802.11 commonly referred to asWi-Fi has evolved from 2 Mbps to over
gigabit speeds., a 1,000-fold increase in throughput.
4. 802.11ax AT A GLANCE
• Contains a new PHY protocol with higher modulation and coding schemes.
• Adoption of an OFDMA approach.
• Unlike its predecessor, the 802.11ac, 802.11ax is a dual-band technology working in the 2.4
GHz and 5 GHz frequencies.
• In 802.11ax,OFDMA is frame-based : an MU frame contains data to/from different users
and various tones are assigned to the users for the entire frame duration.
• periodic channel reservations (namely, the QuietTime periods) can be used to protect
direct link communications.
• Introducing OFDMA inWi-Fi affects the other MAC and PHY functionality.
• Support up to 8x8 MU-MIMO.
• 1024 QAM-a high SNR and 25% high data rate compared to 256 QAM .
• also supports the transmission of multiple streams to a single client or multiple clients
simultaneously.
5. Problems:
• Number and variety of devices is increasing.
• Another challenge comes from the diminishing asymmetry in traffic patterns.
• power consumption for battery-operated devices.
• To improve the Quality of Service (QoS) for multiple users.
• suffer from frequency selective interference, which significantly impairs the practically
achievable rates.
• prone to the Doppler effect mainly caused by reflections from fast moving objects such as cars
and trains.
• Quadrupling the symbol duration means 4 times more calculations at the receiver side, bring
problems for low-costWi-Fi devices.
• in dense networks, load balancing is also an important problem.
6. Why we need it?
• problems associated with dense, high-traffic environments such as airports, stadiums,
trains and offices.
• increases the n0 of streams to 12 across the 2.4 and 5 GHz bands, whereasWi-Fi 5 has a
limit of 8.
• provides higher connection speed and cost effective.
• more paths to communicate with yourWi-Fi router.
• designed for the Smart Home.
• ideal for 4K/8K UHD streaming.
• Multi-user techniques, such as MU-MIMO and OFDMA, have been improved to increase the
network efficiency and network capacity. While the previous standards supported MU-MIMO
for downlink connections, Wi-Fi 6 supports 8x8 connections for both uplink and downlink.
7. OFDMA
• Brings an improvement over prior versions ofWi-Fi that use orthogonal frequency division
multiplexing (OFDM). It subdivides theWi-Fi channel into smaller frequency.
• OFDMA channel consists of a total 256 subcarriers which can be grouped into smaller
subchannels known as resource units( RUs).
• OFDMA is much more efficient than EDCA.
• Enables an access point(AP) to synchronise communication (uplink and downlink ) with
multiple individual clients.
• for backward compatibility ,WI-FI 6 radios still support OFDM.
8. Proposed solution:
• comes with 12 antenna chains for dual band (8x8 in 5GHz / 4x4 in 2.4GHz), helping
it deliver best-in-class throughput ,Wider Coverage.
• 802.11ax contains a new PHY protocol with higher modulation and coding schemes
• amendment also introduces new modulation techniques 1024 QAM in addition to
legacy BPSK, 16-QAM, 64-QAM, and 256-QAM.
• To improve the resistance to high mobility, the amendment proposes to
periodically insert in the PHY packet payload mi ambles, i.e., copies of the HE-LTF
field.
9. • to improve the performance in case of dense networks such as airports,
stadiums, trains and offices : BSS Color, QuietTime Period, Channel
Bonding and Preamble Puncturing,Virtualization, Load Balancing.
• for low-costWi-Fi devices : provides the possibility to extend the tail of a
frame with an extension.
• 802.11ax also allows performing a UL MU transmission just after a DL MU
transmission and extends this idea by allowing an STA to doze during UL
transmissions or theTXOP of another STA in the same BSS.
• proposes an additional way for acknowledging UL MU transmissions by
sending new Multi STA BlockACK (BA) frames.
• proposes OMAX ,a novel OFDMA-based MAC protocol .
10. OVERLAPPING BSS MANAGEMENTAND SPATIAL REUSE
• to improve the performance in case of dense networks.
• BSS coloring: inherited from 802.11ac and 802.11ah, allows to distinguish inter- and intra BSS
frames.
• QTP : allows a STA to request the AP for a QTP which is a series of periodic time intervals of
equal duration used for ad hoc or direct links operation.
• Virtualization:One of the widespread features in modern APs is the support for multiple “virtual”
APs (VAPs).This means that a single physical device can create multiple independent BSSs.
• Opportunistic power save (OPS) : mechanism allows anAP to split a beacon interval into several
subintervals
• Microsleep operation, which enables a STA to switch off its radio just for the duration of an alien
frame; i.e., they can switch off their radio interface during some transmissions, when they
cannot be involved in the frame exchange process.
• modulations generate a palette of data rates with a maximum of 9.6 Gbps.
• supports bidirectional MU-MIMO for both uplink and downlink capabilities.
11. Performance Analysis:
• With OFDMA, adjacent subcarriers (tones) are grouped together into a resource
unit (RU) and a sender can choose the best RU for each particular receiver, which
actually results in higher Signal-to-Interference-plus-Noise Ratio (SINR),
Modulation and Coding Scheme (MCS) and throughput.
• OFDMA provides a 6 times higher throughput than legacy DCF(Distributed Coordination
Function).
12. Power management and security
• Legacy Power Management : two state – Awake and doze.
• In the awake state, an STA can transmit and receive frames, while in the doze state, its radio is
switched off. An active STA is always awake.
• Microsleep:802.11ax extends this idea by allowing an STA to doze during UL transmissions or the
TXOP of another STA in the same BSS.
• TWT (Target wakeup time): In order to minimize the contention between STAs and to reduce power
consumption,TGax adapted theTWT mechanism.
• WPA3: also known as Wi-Fi Protected Access 3, is the third iteration of a security certification program
developed by theWi-Fi Alliance.WPA3 is the latest, updated implementation of WPA2.
• WPA3 protects against offline password guesses by allowing a user only one guess, making
the user have to interact with the Wi-Fi device directly, meaning they would have to be
physically present every time they want to guess the password
13. Benefits:
• introduces the Multiple BSSID support, which allows the sending of identical information
for all the BSSs simultaneously.
• Better Security
• Better Mobility
• High speed even when congested.
• Increased battery life.
• TWT :In order to minimize the contention between STAs and to reduce power
consumption.
Drawback : the synchronization ofTWT SPs between STAs is beyond the scope of the
standard.
• Opportunistic Power Save :(OPS) mechanism allows an AP to split a beacon interval into
several subintervals
