High-speed wireless access

workablejeansMobile - Wireless

Nov 21, 2013 (3 years and 4 months ago)

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1

Recent Developments


Introduction


Ultra
-
Wide
-
Band Radio
Communication (UWB) and
WiMedia


Wireless Fidelity System
(WiFi) and WiMax


Optical Wireless Networks



Advances in 802.11


The Meghadoot Architecture

2

Ultra
-
Wide
-
Band Radio Communication


UWB is a technology developed to transfer large amounts of data
wirelessly over short distances over a very wide spectrum of
frequencies in a short period of time.


The amount of spectrum occupied by a UWB signal, i.e. the bandwidth of
the UWB signal is at least 25% of the center frequency. For example, a
UWB signal centered at 2 GHz would have a minimum bandwidth of 500
MHz and the minimum bandwidth of a UWB signal centered at 4 GHz
would be 1 GHz. The most common technique for generating a UWB signal
is to transmit pulses with durations less than 1 nanosecond.


UWB technology has the capacity to handle the very high bandwidths
required to transport multiple audio and video streams.


UWB will be ideally suited for transmitting data between consumer
electronics (CE), PC peripherals, and mobile devices within short range at
very high speeds while consuming little power.


This technology operates at a level that most systems interpret as noise and,
as a result, does not cause interference to other radios such as cell phones,
cordless phones or broadcast television sets.

3

Ultra
-
Wide
-
Band Radio Communication

4

UWB Advantages


Extremely Difficult to Intercept
-

LPI/LPD. Wideband pulsed
radar spreads the signal and allows more users access to a limited
amount of scarce frequency spectrum.


Multipath Immunity
-

A low path loss and low energy density
minimizes interference to other services. UWB is very tolerant of
interference, enabling operation within buildings, urban areas, and
forests.


Precision Network
-
wide timing
-

Real
-
time, continuous position
location down to a centimeter of resolution results in precision
geolocation systems.


Low Cost
-

Requires minimal components resulting in small size
and weight


Low Power
-

Typical consumption is in microwatts

5

UWB Applications


Communications

-

High Speed WLANs, Mobile Ad
-
Hoc wireless
networks, Groundwave Communications, Handheld and Network
Radios, Intra
-
home and Intra
-
office communication. Stealthy
communications provide significant potential for military, law
enforcement, and commercial applications.


Sensor Networks
-

Ground penetrating Radar that detects and
identifies targets hidden in foliage, buildings or beneath the
ground. Intrusion Detection Radars, Obstacle Avoidance Radars,
and Short
-
range motion sensing.


Tracking/Positioning
-

Precision Geolocation Systems and high
-
resolution imaging. Indoor and outdoor tracking down to less than
a centimeter. Good for emergency services, inventory tracking,
and asset safety and security.

6

WiMedia


WiMedia refers to high data
-
rate, wireless multimedia networking
applications operating in a wireless personal area network
(WPAN).


The WiMedia brand is defined and supported by the WiMedia
Alliance.


The initial WiMedia radio technology will be based on
ultrawideband (UWB) as defined by the MultiBand OFDM
Alliance (MBOA) SIG's PHY and MAC specifications.


The primary goals of the WiMedia Alliance are


to enable coexistence of multi
-
protocol applications (UWB, 1394 and
TCP/IP among others) and



to enable true multi
-
vendor interoperability by establishing procedures for
ensuring devices from different manufacturers coexist within the common
UWB radio platform.

7

UWB Standards


802.15.3a is a group working on UWB standards but could not
decide between the two approaches


multiband OFDM (MOFDM)
from the TI/Intel
-
led MBOA group, or direct sequence code
division multiple access (DS
-
CDMA) from Motorola.


Multiband OFDM Alliance SIG (MBOA
-
SIG) and WiMedia
Alliance have merged to create UWB industry specifications and
certification programs for consumer electronics, mobile and PC
applications.


Advantages of the MultiBand OFDM proposal:


based on
proven OFDM technology: u
sed in IEEE 802.11a and 802.11g


Achieves data rates of
53 to 480 Mbps


Support for
4 to 16 simultaneous piconets



Spectrum easily sculpted for
international regulatory domain compliance


easily
extensible

for future range/rate improvements


Refer to MBOA at http://www.multibandofdm.org/.

8

Objectives of MBOA


To develop, publish, and promote the best overall solution for
global UWB standardization


As a formal SIG, publish detailed system specification in May 2004


To support the development of a robust UWB ecosystem


Support industry efforts to develop upper layer protocols and interfaces


Provide a forum for vendors of antennas, RF modules, and test and
measurement equipment


Work in harmony with IEEE, WiMedia, CEA, 1394
-
TA, Wireless
-
USB WG


To ensure the standardization of UWB solutions with the best
coexistence characteristics possible and to continue work with
worldwide regulatory agencies to provide education and seek
specific approval of MBOA
-
based technology


To enable a single worldwide standard for high bit rate UWB
applications with optimum time
-
to
-
market and maximum benefit
to the broadest number of end consumers

9

Wireless Fidelity Systems (WiFi)


Wireless Fidelity (WiFi) is the standard for the high
-
speed
wireless LAN.


A Wi
-
Fi network can be used to connect computers to each other,
to the Internet, and to wired networks (which use IEEE 802.3 or
Ethernet).


Wi
-
Fi networks operate in the unlicensed 2.4 and 5 GHz radio
bands, with an 11/54 Mbps (802.11b/g) or 54 Mbps (802.11a) data
rate Any Wi
-
Fi product uses the same radio frequency (for
example, 2.4GHz for 802.11b/g, 5GHz for 802.11a).


The Wi
-
Fi Alliance (
http://www.wi
-
fi.org/
)


A global, non
-
profit industry association of more than 200 member
companies devoted to promoting the growth of wireless Local Area
Networks (WLANs).


With the aim of enhancing the user experience for mobile wireless devices,
the Wi
-
Fi Alliance's testing and certification programs ensure the
interoperability of WLAN products based on the IEEE 802.11 specification.

10

WiMax


WiMAX is an acronym that stands for
W
orldwide
I
nteroperability
for
M
icrowave
Acc
ess.


The WiMAX Forum is an industry
-
led, non
-
profit corporation
formed to promote and certify compatibility and interoperability of
broadband wireless products.


The WiMax forum supports the industry
-
wide acceptance of the
IEEE 802.16 and ETSI HiperMAN wireless MAN standards.

11

Optical Wireless Networks


Optical wireless communication enables communication using
infrared ray.


Operates outdoor up to 5 Km and indoor a few meters.


Advantages:


Abundance of unregulated bandwidth: 200 THz in the 700


1500 nm range


No multipath fading: Intensity modulation and direct detection


Higher capacity per unit volume


Cost effective at rates near 100 Mbps


Small cell size


At 800


890 nm and 1550 nm absorption effects are minimal.


Disadvantages:


Multipath dispersion


Limited range


Difficult to operate outdoor


High power requirement


SNR can vary significantly with the distance


costly

12

Advances in IEEE 802.11


Multimode 802.11 enables dynamically to use 802.11a/b/g.


The 802.11e defined an extension of the 802.11 standard for
quality of service (QoS).


The 802.11f developed specifications for implementing access
points and distribution systems.


The 802.11h developed the MAC layer standard that comply with
European regulations for 5 GHz wireless LAN.


The 802.11i group is working on mechanisms for enhancing
security in the 802.11 standard.


The 802.11j task group is working on mechanisms for enhancing
security in the 802.11 MAC physical layer protocols to
additionally operate in the newly available Japanese 4.9 GHz and
5 GHz bands.


The 802.11n defines standardized modifications to the 802.11
MAC and physical layers to allows at least 100 Mbps.

13

Meghadoot


The meghadoot architecture is a packet
-
based wireless network
architecture for low
-
cost rural community networks.


The major goals of the Meghadoot project are


Develop a fully distributed packet
-
based hybrid wireless network that can
carry voice and data traffic


Provide a low
-
cost communication system in the rural regions


Provide a low
-
cost communication network for urban environment


Meghadoot uses a routing protocol called infrastructure
-
based ad
hoc routing protocol (IBAR).


The end user equipment in Meghadoot is an IEEE 802.11 enabled
device.


Meghadoot is aimed at deploying an 802.11 phone in rural areas,
using Voice over Wireless IP (VoWIP) that promises to free them
from their telephone handsets.


VoWIP is an emerging technology that enables IP voice to be sent
over an 802.11 wireless LAN.

14

Final Thoughts


Wireless networks are widespread in our daily life.


Fourth generation (4G) WWAN communications systems that are
characterized by high
-
speed data rates at 20+ Mbps, suitable for
high
-
resolution movies and television. It describes two different
but overlapping ideas.


High
-
speed wireless access

with a very high data transmission speed, of the
same order of magnitude as a local area network connection (20 Mbps and
up). It can integrate wireless LAN technologies like Wi
-
Fi, as well as other
potential successors of the current 3G mobile telephone standards.


Pervasive networks
. A user is simultaneously connected to several wireless
access technologies and can seamlessly move between them. These access
technologies can be Wi
-
Fi, UMTS, EDGE or any other future access
technology. Included in this concept is also smart
-
radio technology to
efficiently manage spectrum use and transmission power as well as the use
of mesh routing protocols to create a pervasive network .


A cell phone could be an integral part of all wireless standards.