Evolution of networks
Lecture –
Evolution of 802.11 networks
Marek Natkaniec
natkanie@kt.agh.edu.pl, Tel: 40-40
Faculty of Informatics, Electronics and Telecommunications
Department of Telecommunication
Agenda
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Standardization efforts
Main Wi-Fi bottlenecks
IEEE 802.11aa
IEEE 802.11ac
IEEE 802.11ad
IEEE 802.11ae
IEEE 802.11af
IEEE 802.11ah
IEEE 802.11ai
IEEE 802.11aj, ak, aq, ax, ay, az
Envisioning Future of Wi-Fi
Future research directions
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Activity History
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June 1897: Marconi lecture “Signaling through Space without Wires”
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1970: ALOHAnet operational (Abramson, 9600 baud)
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1976: Metcalf & Boggs: “Ethernet: Distributed Packet-Switching for
Local Computer Networks”
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1980: Project 802 formed (1 Mbps initially, revised to 20 Mbps 1982)
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1980: Ethernet Bluebook published (September, Digital. Intel, Xerox)
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1981: FCC issues NOI for unlicensed spectrum
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1983: First version of 802.3 10Base5 spec. completed
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1985: FCC opens ISM Band- spread spectrum allowed
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1985: First version of 802.3 published (10 Mbps)
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1987: Project 802.4L – Wireless Token Bus begins
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1989: ISM frequency bands 900MHz, 2.4GHz and 5GHz allowed
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1990: IEEE 802 drops 802.4L starts 802.11 project
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1990: 802.3 10BASE-T (802.3i) released
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1997: IEEE 802.11 standard approved (2.4GHz – 1 and 2 Mbps)
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1999: Formation of WECA (now Wi-Fi Alliance)
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Market Size and Trends
• Wi-Fi has connected ever-expanding range
of user-centric devices last 10 years
• By 2013, Wi-Fi was installed in more than 4
billion devices [ABI Research, Nov. 2013]
• By 2016, more than 725 million households
around the world will have Wi-Fi connection
Wi-Fi Hotspot Public Access
– 48.000.000+ public hotspots in 132 countries
(2014) and 341.000.000+ (2018)
• Source: iPass Inc.
– 1.2 Billion connects
• Source: In-Stat
– 46% of data traffic from mobile devices was
transmitted over the Wi-Fi networks or
femtocells (2014)
• Source: Cisco
– 95% of US hotels offer Wi-Fi
• Source: American Hotel & Lodging Assn
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Data traffic transmitted through
computer networks (Wi-Fi, mobile,
fixed) – forecast 2014-2019
Internet traffic with
management traffic
Internet traffic without
management traffic
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Devices with integrated Wi-Fi interfaces
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Trends impacting Wi-Fi Evolution
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Summary of Major PHY Projects
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A - 20 MHz BW, 5GHz
B - 20 MHz BW, 2.4 GHz
G - 20 & 40 MHz BW, 2.4 GHz
N - 20 & 40 MHz BW, 2.4 & 5GHz
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AC – 20 to 160 MHz BW, 5GHz
AD – 2 GHz BW, 60 GHz
AF – TV White Space Spectrum
AH – Unlicensed spectrum below 1 GHz
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PHY Project Sequence
100 Gbps
10 year
yardstick
10 Gbps
ad
ac
1 Gbps
802.3
milestones
100 Mbps
n
g
a
10 Mbps
b
802.11
milestones
Original
1 Mbps
100 Kbps
80
85
90
95
00
05
15
10
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Capacity vs. Coverage
• Various rates and coverage due to different
spectrum
– Low frequency spectrum - long range
– High frequency spectrum - high rate
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Augmented Spectrum Heterogeneity
• Region-dependent spectrum availability
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IEEE 802.11 – Key Technical Attributes
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Specifications for
the Physical and
MAC Layers
Backward
compatibility
with legacy 802.11
standard
Maximize spectral
efficiency and
performance
Co-existence with
other device sharing
the 2.4GHz and
5GHz frequency
bands
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IEEE 802.11 standards
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IEEE 802.11-1997: The WLAN standard was originally 1 Mbit/s and 2
Mbit/s, 2.4 GHz RF and infrared (IR) standard (1997), all the others
listed below are Amendments to this standard, and Recommended
Practices 802.11F, 802.11T.
IEEE 802.11a: 54 Mbit/s, 5 GHz standard (1999, shipping products in 2001)
IEEE 802.11b: Enhancements to 802.11 to support 5.5 Mbit/s and 11 Mbit/s
(1999)
IEEE 802.11c: Bridge operation procedures; included in the IEEE 802.1D
standard (2001)
IEEE 802.11d: International (country-to-country) roaming extensions (2001)
IEEE 802.11e: Enhancements: QoS, including packet bursting (2005)
IEEE 802.11F: Inter-Access Point Protocol (2003) Withdrawn February 2006
IEEE 802.11g: 54 Mbit/s, 2.4 GHz standard (backwards compatible with b)
(2003)
IEEE 802.11h: Spectrum Managed 802.11a (5 GHz) for European compatibility
(2004)
IEEE 802.11i: Enhanced security (2004)
IEEE 802.11j: Extensions for Japan (2004)
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IEEE 802.11 standards
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IEEE 802.11-2007: A new release of the standard that includes
amendments a, b, d, e, g, h, i, and j. (July 2007)
IEEE 802.11k: Radio resource measurement enhancements (2008)
IEEE 802.11n: Higher-throughput improvements using MIMO (multiple-input,
multiple-output antennas) (September 2009)
IEEE 802.11p: WAVE—Wireless Access for the Vehicular Environment (such as
ambulances and passenger cars) (July 2010)
IEEE 802.11r: Fast BSS transition (FT) (2008)
IEEE 802.11s: Mesh Networking, Extended Service Set (ESS) (July 2011)
IEEE 802.11T: Wireless Performance Prediction (WPP)—test methods and metrics
IEEE 802.11u: Improvements related to HotSpots and 3rd-party authorization of
clients, e.g., cellular network offload (February 2011)
IEEE 802.11v: Wireless network management (February 2011)
IEEE 802.11w: Protected Management Frames (September 2009)
IEEE 802.11y: 3650–3700 MHz Operation in the U.S. (2008)
IEEE 802.11z: Extensions to Direct Link Setup (DLS) (September 2010)
IEEE 802.11-2012: A new release of the standard that includes
amendments k, n, p, r, s, u, v, w, y, and z (March 2012)
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IEEE 802.11 standards
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In
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IEEE 802.11aa: Robust streaming of Audio Video Transport Streams (June 2012)
IEEE 802.11ac: Very High Throughput <6 GHz; (December 2013)
IEEE 802.11ad: Very High Throughput 60 GHz (December 2012)
IEEE 802.11ae: Prioritization of Management Frames (March 2012)
IEEE 802.11af: TV Whitespace (February 2014)
process
IEEE 802.11mc: Roll-up of 802.11-2012 + aa, ac, ad, ae & af to be published as
802.11-2016 (~ 2016)
IEEE 802.11ah: Sub 1 GHz license exempt operation (e.g., sensor network,
smart metering) (~ March 2016)
IEEE 802.11ai: Fast Initial Link Setup (~ November 2015)
IEEE 802.11aj: China Millimeter Wave (~ June 2016)
IEEE 802.11ak: General Link (~ May 2016)
IEEE 802.11aq: Pre-association Discovery (~ July 2016)
IEEE 802.11ax: High Efficiency WLAN (~ May 2018)
IEEE 802.11ay: Next Generation 60 GHz (~ December 2017)
IEEE 802.11az: Next Generation Positioning (NGP) (~ March 2020)
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IEEE 802.11 Revisions
MAC
11d
Intl roaming
IEEE
Std
802.11
-1997
11e
QoS
11k
RRM
11s
Mesh
11h
DFS & TPC
11u
WIEN
11v
Network
Management
11i
Security
11f
Inter AP
11z
TDLS
11r
Fast Roam
11aa
Video Transport
11ae
QoS Mgt Frames
11w
Management
Frame
Security
802.11
-2016 (TBC)
802.11
-2003
802.11
-2007
802.11
-2012
11a
54 Mbps
5GHz
11j
JP bands
11n
High
Throughput
(>100 Mbps)
11af
TV Whitespace
11ac -VHT
>1 Gbps @ 5GHz
MAC
&
PHY
11b
11 Mbps
2.4GHz
11g
54 Mbps
2.4GHz
11p
WAVE
11y
Contention
Based
Protocol
11ad - VHT
>1 Gbps @ 60GHz
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Main Wi-Fi bottlenecks (1/2)
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Current CCA protocol is over-protective in dense areas
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Retransmissions are inefficient and use a lot airtime
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In dense areas, majority of packets are control and management frames
Legacy device protection reduces network capacity
significantly
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Near by devices transmit static high power levels
Control and management traffic takes a lot of airtime
from user data
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RF is sent to all directions and receiver tries to receive it from all directions
Benefits of antenna directivity and beam steering are not yet in use
No dynamic transmit power control
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Wi-Fi network have a lot of retransmissions consuming airtime
Need a perfect packet delivery, information is not combined between successive
retries
RF spreads evenly everywhere
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Wi-Fi radios hold back and do not transmit
Legacy devices are over protected, benefits of new technologies are reduced
Mobile/cellular networks interfere Wi-Fi
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Co-existence has not been considered, lacking especially RF filtering at Wi-Fi
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Main Wi-Fi bottlenecks (2/2)
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Channel access gets congested with large amount of devices
– Channel access is contention based and efficiency could be better
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Wi-Fi signal processing does not work well with large delay
spread
– Large delay spread causes receivers problems decoding the data
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One size fits all -- Home Wi-Fi = Stadium Wi-Fi = Medical Wi-Fi
– No differentiation in operation or capability to optimize towards needs
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Radio traffic flows not properly prioritized for system level
capacity
– Protocols are inefficient with high load, clients and APs are equal
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Wi-Fi lacks performance management capability
– No visibility to user experience and capability optimize network
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Wi-Fi is half duplex technology – cannot receive when transmits
– This cuts efficiency
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New use cases have not been considered with the 802.11
standard
– Wi-Fi is used in ways which were not considered during standardization
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Use of spectrum, time and spatial dimensions could be enhanced
– Current technologies allow more efficient operation
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
• Main challenges addressed by IEEE 802.11aa
Area
Challenge in current 802.11
networks
Solution
Multicast
Lack of reliable and scalable
mechanism
Groupcast with retries
Streaming
Lack of differentiation between frames
of audio (video) streams
Intra-access category
prioritization
Streaming
Lack of mechanism for graceful
degradation of AV stream quality
Stream Classification Service
Interference
Large number of 802.11 deployments
causes inter-network interference
Overlapping BSS
management
• Interworking with IEEE 802.1Q SRP (Stream Reservation Protocol)
• Compatibility with the relevant mechanisms defined by IEEE
802.1AVB (802.1Qat, 802.1Qav, 802.1AS) for multimedia stream
transport
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
• Mapping of IEEE 802.1D user priorities to IEEE 802.11e
and IEEE 802.11aa ACs and transmit queues
802.1D
802.11e 802.11aa
802.1D
user
access
transmit
designation
priority
category
queue
Description
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Network
Control (NC)
VO
VO
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Voice (VO)
VO
A_VO
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Video (VI)
VI
VI
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Controlled
Load (CL)
VI
A_VI
Non-time-critical but loss sensitive, such as streaming multimedia or
business-critical traffic; usually used for applications that require reservation
mechanisms or admission control decisions.
3
Excellent
Effort (EE)
BE
BE
Also non-time-critical but loss sensitive; for best-effort services delivered to
the most important customers.
0
Best Effort
(BE)
BE
BE
Non-time-critical and loss insensitive. This is the most common traffic type,
predominant in today’s networks.
2
Spare (-)
BK
BK
-
BK
Non-time-critical and loss insensitive, but of lower priority than best effort;
includes bulk transfers and other data transfer that are permitted on the
network but that should not impact the use of the network by other users and
applications.
1
Background
(BK)
BK
Both time- and safety-critical, consisting of traffic needed to maintain and
support the network infrastructure.
Time-critical, characterized by less than 10 ms delay.
Time-critical, characterized by less than 100 ms delay.
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
Groupcast with Retries
• Reduces network traffic by delivering the same data
stream to multiple recipients simultaneously.
• Current standard IEEE 802.11 defines two methods
of transmitting group addressed frames: broadcast
and directed multicast (group addressed frames are
converted to individually addressed frames). The first
solution is unreliable; the second is non-scalable.
• 802.11aa proposes a new mechanism called
Groupcast with Retries (GCR) which makes groupcast
transmissions more reliable.
• The groupcast originator (the station or AP providing
the GCR service) decides which policy to use.
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
Intra-access Category Prioritization
• The intra-access category prioritization mechanism ensures
prioritization between individual AV streams.
• It extends the granularity of EDCA traffic differentiation by
dividing the transmit queues for Voice (VO) and Video (VI)
ACs into two: primary and alternate. Therefore, there are six
transmit queues in total: Primary Voice (VO), Alternate Voice
(A_VO), Primary Video (VI), Alternate Video (A_VI), Best
Effort (BE), and Background (BK).
• The transmit queues are mapped to four independent EDCA
functions.
• The head-of-line frames which belong to the VO and A_VO
(VI and A_VI) queues are selected to be passed to the
appropriate VO (VI) EDCA function using a dedicated
scheduler. This is realized using strict priority or credit-based
scheduling (with two queues) as defined in IEEE 802.1Q 23
IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
In WCBSA, frame selection is based on an internal credit parameter. A frame
belonging to a given queue is selected only if (i) for the primary queue credit is
non-positive and (ii) for the alternate queue credit is either positive or when credit
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is equal to zero and the primary queue is empty.
IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
Stream Classification Service
• SCS allows streams to be arbitrarily (i.e., not based on the
802.1D user priority) mapped to the primary and alternate
queues.
• This is an optional service which may be realized using layer
2 and/or layer 3 classification. Additional information can
also be provided to determine if the described traffic stream
allows frame dropping. A designated Drop Eligibility Indicator
(DEI) bit indicates that in this stream frames may be
dropped. Therefore, by noticing that AV streams can tolerate
a certain degree of packet loss, 802.11aa refrains from
perfect reliability at the MAC layer.
• Such graceful degradation of AV streams is especially helpful
if the capacity of the wireless channel is insufficient.
• The combination of the two intra-AC queues and two settings
of DEI allows four different priority types for both VO and VI.
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
Each SCS stream is identified by an SCSID which is used by a station to request
the creation, modification, or deletion of an SCS stream. It is also used by an AP
to identify the SCS stream in SCS responses. To start an SCS service, a station
sends a request specifying the traffic class and priority for the new stream. The AP
may accept or reject the requirements specified by the station. Once accepted and
classified, the stream is assigned to an AC and tagged with a specific DEI
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IEEE 802.11aa: Robust streaming of
Audio Video Transport Streams
OBSS Management
• OBSSs working on the same channel are becoming more and more
common because of the wide diffusion of 802.11 networks and the limited
availability of channels. Although the carrier sense mechanism in principle
does not require any frequency planning (because it is based on a
temporal division of BSSs operating on the same channel), it has been
shown that severe performance impairments can occur due to the neighbor
capture effect. This occurs when a BSS is between two BSSs which do not
hear each other.
• In the presence of greedy traffic, the BSS in the middle can be prevented
from accessing the channel indefinitely because it senses the medium
permanently busy.
• In order to limit the neighbor capture effect and extend admission control
and scheduling decisions, a new mechanism called OBSS management has
been proposed. The mechanism is based on two main components:
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i) a mechanism for quantifying the load and interference status of each BSS and signaling this
information to the neighbor BSSs;
ii) a mechanism for performing channel selection and cooperative resource sharing on the
basis of such information. Load and interference information are distributed in a QLoad report,
which can be sent by the AP upon request or optionally included in beacon frames.
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IEEE 802.11ac:
Very High Throughput <6GHz
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Throughput up to 6,93 Gbps
Transmission in very wide channels: 80 MHz and 160 MHz (optional)
Increase the number of spatial streams in MIMO system up to 8x8
Introduces modulation 256-QAM
– The maximum available configuration: AP with 8 antennas and 4 stations with 2
antennas, 160 MHz channel width, 256-QAM modulation, 5/6 coding rate – each
station can obtain 1,73 Gbps
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Support for MU-MIMO
– The possibility of parallel transmission from AP to 4 stations (downlink)
– Dedicated to mobile devices, e.g. smartphones
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5 GHz frequency band (only)
– 256-QAM in commercial devices in 2,4 GHz band
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Dynamic reservation of radio resources – the RTS/CTS control frames
transmission in independent 20-MHz channels
Replacing of RIFS (Reduced Inter‐Frame Spacing) time period (defined in
IEEE 802.11n amendment) with more efficient function of frames aggregation
– increasing of total A-MPDU (Aggregated MPDU) size up to 1048575 octets
(the maximum size of A-MPDU in IEEE 802.11n is only 65535 octets)
Backward compatibility with 802.11a and 802.11n amendments
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IEEE 802.11ac:
Very High Throughput <6GHz
• 80 and 160 MHz channels
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IEEE 802.11ac:
Very High Throughput <6GHz
• RTS/CTS with Bandwidth Signalling
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IEEE 802.11ac:
Very High Throughput <6GHz
• RTS/CTS with Bandwidth Signalling
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IEEE 802.11ac:
Very High Throughput <6GHz
• Spatial streams
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IEEE 802.11ac:
Very High Throughput <6GHz
• 256 QAM
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IEEE 802.11ac:
Very High Throughput <6GHz
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IEEE 802.11ac:
Very High Throughput <6GHz
• Multi-User MIMO
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IEEE 802.11ac:
Very High Throughput <6GHz
• Large(r) frame size
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IEEE 802.11ac:
Very High Throughput <6GHz
• Forms of aggregation
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IEEE 802.11ac:
Very High Throughput <6GHz
• Forms of aggregation
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IEEE 802.11ad:
Very High Throughput 60GHz
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Equivalent of IEEE 802.11ac amendment in 60 GHz frequency band
Large limitations compared to lower frequency bands
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Frequency band from 57 GHz up to 66 GHz (channels 1-4) – European
Union, 57,05 GHz up to 64 GHz (channels1-3) - U.S.A. and Canada
The transmission range up to 10m with maximum throughput of 6,75
Gbps
Three independent transmission techniques: spread spectrum (Control
PHY), single carrier SC (Single Carrier PHY) and OFDM (OFDM PHY) –
different concept of frame formation and maximum available
transmission throughput:
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– Much less coverage of reliable transmission (the losses on the distance of 1m
for 60 GHz band are 68 dB - 21,6 dB higher then for 5 GHz frequency band)
– The losses caused by signal propagation through materials and shadowing
effect by the human body (from few up to 30 dB)
– 27,5 Mbps for spread spectrum (π/2-DBPSK modulation),
– for SC it changes from 385 Mbps (π/2-BPSK modulation) up to 4,62 Gbps
(π/2-16-QAM modulation)
– 6,76 Gbps for OFDM technique (64-QAM modulation)
2,5 Gbps (π/2-QPSK) for power-saving mode
It competes with IEEE 802.15.3c, WiGig, and WirelessHD standards
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IEEE 802.11ad:
Very High Throughput 60GHz
• New user experiences
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IEEE 802.11ae: Prioritization of
management frames
• This concise document defines:
– (a) a mechanism for the flexible
prioritization of management
frames
– (b) a signaling protocol for the
exchange of frame prioritization
policies.
• The prioritization mechanism is
called the QoS management frame
(QMF) service. At its core is a QMF
policy which provides a mapping
between the management frame
types/subtypes and the EDCA ACs
. This means that all management
frames are sent in an AC as
defined by the current QMF policy.
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IEEE 802.11ae: Prioritization of
management frames
Type of Frame
(Re)Association
Request/Response
Probe Request (individually
addressed)
Probe Response
Beacon, ATIM, Disassociation,
Authentication,
Deauthentication
Channel switch announcement
Extended channel switch
announcement
QoS frames
Measurement pilot
Tunneled Direct-Link Setup
Discovery Response
Fast BSS Transition
High Throughput frames
Security Association Query
frames
QMF Policy and QMF Change
Policy
Hybrid Wireless Mesh Protocol
Mesh Path Selection
Congestion Control
Self Protected frames
Deenablement of Dynamic
Station Enablement
Frame Description
Handover between APs
Scanning initialization
(unicast)
Scanning result
Network maintenance
Initialization of channel
switching
Initialization of extended
channel switching
QoS signaling (e.g., TSPEC
exchange)
Basic scanning information
Part of direct-link setup
Pre-handover setup to speed
up the handover process
Support for data rates greater
than 100 Mb/s
Procedure for robust
management frame protection
Dedicated frames for the
dissemination of QMF policies
Path selection in mesh BSS
Congestion information
dissemination in mesh BSS
Management of security
associations
Related to the operation in the
3650 to 3700 MHz band in the
United States
QMF Access Category
VO
Dissemination of
QMF Policies
Infrastructure BSS
Yes
(in responses)
Mesh BSS
No
VO
No
No
BE
Yes
No
VO
Yes (beacon)
No
VO
No
No
VO
No
No
VO
No
No
VO
No
No
VO
No
No
VO
No
No
VO
No
No
VO
No
No
BE
Yes
Yes
VO
No
No
VO
No
No
VI
No
No
VO
No
No
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IEEE 802.11af: TV Whitespace bands
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Frequency bands VHF and UHF (from 54 up to 790 MHz)
The usage of cognitive radio technology, with the use of measurements to
discover the available frequency bands.
It is possible to realize WLAN operation in frequency bands reserved for TV
channels and wireless microphones
PHY layer based on IEEE 802.11ac
Channel width from 6 up to 8 MHz (with respect to the country regulation)
Possibility of channel bonding – up to 4 channels
MIMO up to 4 spatial streams with the use of STBC codes (Space–Time Block
Code) or MU-MIMO
Maximum available throughput 26,7 Mbps for 6 and 7 MHz channels and 35,6
Mbps for 8 MHz channel
– assuming 4 streams and 4 bonded channels, the maximum possible throughput is
426,7 Mbps for 6 and 7 MHz channels and 568,9 Mbps for 8 MHz channel
The usage of GPS system to determine the location of base station is
mandatory
U.S.A. allows to use the maximum transmission power equal to 100 mW for 6
MHz channel or 40 mW, if the transmission in the neighboring channel is
discovered
In Europe ETSI recommends to use the dynamic transmit power control
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algorithm
IEEE 802.11ah: Sub 1 GHz license
exempt operation
•
The usage of ISM band in the frequency range below 1 GHz for the
purpose of WLAN formation with extended range of operation – this allows
to support M2M (Machine to Machine) communications
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868-868.6 MHz (Europe), 902-928 MHz (USA), 950 MHz -958 MHz (Japan)
Limitation of energy consumption – cooperation of stations in sensor
network
PHY layer based on 802.11 a/g with the possibility of usage of 26 channels
– each channel guarantees the throughput on the level of 100 kbps
The gathering of stations to decrease the contention level when accessing
the radio channel, especially for hidden nodes scenario
The possibility of relay stations use – the limitation of overheads related to
retransmission procedures by relay stations
– The maximum number of hops should be limited to two
– Bidirectional TXOP period, which allows to realize the transmission in both
directions during the single TXOP period
•
•
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The support of few thousands of stations by the single AP
The introduction of sectors within the single BSS (Basic Service Set) area
to decrease the contention and interferences level
The extension of power-saving mechanism to limit the signaling overhead
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IEEE 802.11ai: Fast Initial Link Setup
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The procedure FILS (Fast Initial Link Setup) for secure link setup
between AP and station in a very short time period (less than
100ms)
Use case: Large number of mobile users are constantly entering and
leaving the coverage area of an existing extended service set
Obtaining the IP address and immediate start of traffic exchange
with the use of AP
The reduction of messages required for secure connection setup
between AP, station and authentication server from 27 to 4
The speed up of initial setup procedure (about 15-times) –
reduction of handover time from about 10s to less than 0,5s
The correction of handover procedure when changing the AP with
different SSID identifier
The limitation of management frames required when associating
‚new users’ in dense WLAN networks
MAC enhancements for probe response reduction
MAC enhancements for more efficient scanning
The increase of throughput at the level of 20-50%
The completion of IEEE 802.11ai standard – beginning of 2016 year
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IEEE 802.11ai: Fast Initial Link Setup
STA
11i
AP
AS
DHCP
Authentication
Association
STA
EAP
(PEAP/MSCHAPv2)
11ai
AP
AS
DHCP
Beacon/Probe Resp
Auth Req/Resp
Association & IP addr
EAPOL Key
DHCP
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IEEE 802.11aj, ak, aq
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IEEE 802.11aj
•
IEEE 802.11ak
•
IEEE 802.11aq
– The adoption of IEEE 802.11ad standard for the use in China in CMMW
(Chinese Milli-Meter Wave) band.
– The modification of PHY and MAC, which allows to use the WLAN network
in 59-64 GHz and 45 GHz frequency bands
– Maintains backward compatibility with 802.11ad when it operates in the
59-64 GHz frequency band
–
–
–
–
Integration of station based on IEEE 802.11 standard with 802.3 standard
The proper realization of bridging function between these interfaces
Joint standardization process with IEEE 802.1Qbz working group
The specification of protocols and procedures which are required in IEEE
802.11 standard for provisioning of internal connections as transit
connections based on IEEE 802.1Q standard
– The provisioning of sophisticated services (more sophisticated compared
to the regular Internet access)
– The methods for delivering to user (station) the list of available services
with their detailed description without the need of associating of IEEE
802.11 station to the AP - pre-association Service Discovery
– Container MAC protocol to carry upper layer service discovery protocols
(e.g. UPnP, Bonjour)
48
IEEE 802.11ax: High Efficiency WLANs
(HEW)
•
Focuses on per-user performance through
defining WLAN MAC and PHY enhancements
•
KPI metrics: average per station throughput and
area throughput (old – link throughput and
aggregate throughput)
•
Dedicated for dense WLAN networks
•
It uses the 5 GHz band to break the throughput of
10 Gbps
•
The usage of hybrid MIMO-OFDMA technique –
the division of radio channel for large number of
subchannels, and additionally the use of MIMO
technique
•
The transmission with limited power and increase
of directionality of transmission
•
The change of standard CCA (Clear Channel
Assessment) level – limitation of interferences
between neighboring networks and increase the
concurrent transmissions while reducing the
number of recognized collisions
49
IEEE 802.11ax: High Efficiency WLANs
(HEW)
•
The increase of Tx rate for transmission of control
frames
•
The usage of Piggy-backing
•
Simultaneous Transmit and Receive (STR)
•
The definition of dynamic header and usage of
shortened MAC addresses
•
The increase of effectiveness of corrupted frames
retransmission – different ARQ mechanism (HARQ is
considered)
•
The introduction of collisions detection instead of their
avoidance
•
The usage of a new medium access function called
CSMA/ECA (Carrier Sense Multiple Access / Enhanced
Collision Avoidance)
•
The introduction of dynamic channels bonding within
the DBCA (Dynamic Bandwidth Channel Access)
mechanism
•
The modification of techniques MIMO: MU-MIMO,
Massive MIMO, and Network MIMO
•
The completion of IEEE 802.11ax standard – 2019 year
50
IEEE 802.11ay, IEEE 802.11az
• IEEE 802.11ay
– Expected to develop mode of operation capable of supporting a
maximum throughput of 100 gigabits per second (measured at the
PHY), while maintaining or improving the power efficiency per station
– New Task Group - Initial Task Group Meeting May 2015
– July Session 14 presentations made
– Next Generation 60 GHz increases throughput, range and reliability
– Technical approaches are likely to include channel bonding and MIMO
• IEEE 802.11az
– IEEE Std 802.11-2007 includes support for timing measurement.
– When published, IEEE Std 802.11-2016/2017 will include “fine
timing measurement” that allows location to determined to ~3m
using 802.11n/802.11ac.
– The Next Generation Positioning study group will improve location
accuracy and scalability and will consider new usage such as
directionality
– New Task Group - Initial Task Group Meeting Sept 2015
51
Envisioning Future of Wi-Fi
• Will all Wi-Fi ecosystem be possible in the
future?
52
Future research directions
• drivers, environments & applications for
Wi-Fi “next gen” …
53
Future research directions
• Wi-Fi is still evolving today!
• Main directions of evolution
– Security
– Low power consumption
– Higher speed
– Longer range
– QoS
– Spectrum Sharing/ Cognitive Radio/ SDR
– Beamforming/ Smart Antennas
• Future vision
– More diversified services with spectrum heterogeneity
– Performance enhancement in dense environment
– Close interworking with cellular and
coexistence/interworking with other unlicensed band54
based connectivity technologies
Thank you very much for your attention
This presentation was prepared for educational purposes only.
It was compiled from other presentations and publications available in the Internet.
Most of charts, graphs, diagrams, pictures, and part of the text included in this
55
presentation are copyrighted.