01-01-2013, 12:51 PM
Wireless Fidelity
Wireless.pptx (Size: 442.86 KB / Downloads: 38)
INTRODUCTION
Wi-Fi is the name of a popular wireless networking technology that uses radio waves to provide wireless high-speed internet and network connections.
A common misconception is that the term Wi-Fi is short for "wireless fidelity,".
Wi-Fi is simply a trademarked term meaning IEEE 802.11x.
The Wi-Fi alliance, the organization that owns the Wi-Fi (registered trademark) term specifically defines Wi-Fi as any "wireless local area network (WLAN) products that are based on the IEEE 802.11 standards."
Initially, Wi-Fi was used in place of only the 2.4GHz 802.11b standard,
however the Wi-Fi Alliance has expanded the generic use of the Wi-Fi term to include any type of network or WLAN product based on any of the 802.11 standards, including 802.11b, 802.11a, dual-band, and so on
WORKING
Wi-Fi works with no physical wired connection between sender and receiver by using radio frequency (RF) technology, a frequency within the electromagnetic spectrum associated with radio wave propagation.
When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space.
The cornerstone of any wireless network is an access point (AP).
The primary job of an access point is to broadcast a wireless signal that computers can detect and "tune" into.
In order to connect to an access point and join a wireless network, computers and devices must be equipped with wireless network adapters
Wi-Fi Certified and indicates the radio frequency band used (2.5GHz for 802.11b, 802.11g, or 802.11n, and 5GHz for 802.11a
A device that can use Wi-Fi (such as a personal computer, video-game console ,smartphone, tablet, or digital audio player) can connect to a network resource such as the Internet via a wireless network access point.
Such an access point (or hotspot) has a range of about 20 meters (65 feet) indoors and a greater range outdoors
Protocol Architecture
Convergence layer functions:
Encapsulate PDU framing of upper layers into native 802.16 MAC/PHY frames
Map upper layer’s addresses into 802.16 addresses
Translate upper layer QoS parameters into native 802.16 MAC format
Adapt time dependencies of upper layer traffic into equivalent MAC service
Physical Layer: Downlink
Continuous downstream mode
For continuous transmission (audio/video)
Simple TDM scheme is used for channel access
Frequency division duplex (FDD)
Burst downstream mode
For bursty transmission (IP-based traffic)
DAMA-TDMA scheme for channel access
FDD with adaptive modulation, frequency shift division duplexing (FSDD), time division duplexing (TDD)
Radio Link Control
Power control and paging
Transition among burst profiles
Downlink burst profile change
Subscriber station monitors downlink quality
Requests a new profile
Granted if base station judges possible
Uplink profile change
Base station monitors the uplink signal quality
Specifies the new profile’s usage code when granting subscriber bandwidth in a frame
Layers Definitions
The ISO 18000-7:2004 defines physical and data link layers [ISO4D].
The physical layer defines the modulation used in air communications and band frequencies.
The data link layer defines the communications protocol, dataheader,commands,data, collision treatment, broadcast communication and point-to-point communication.
Wireless.pptx (Size: 442.86 KB / Downloads: 38)
INTRODUCTION
Wi-Fi is the name of a popular wireless networking technology that uses radio waves to provide wireless high-speed internet and network connections.
A common misconception is that the term Wi-Fi is short for "wireless fidelity,".
Wi-Fi is simply a trademarked term meaning IEEE 802.11x.
The Wi-Fi alliance, the organization that owns the Wi-Fi (registered trademark) term specifically defines Wi-Fi as any "wireless local area network (WLAN) products that are based on the IEEE 802.11 standards."
Initially, Wi-Fi was used in place of only the 2.4GHz 802.11b standard,
however the Wi-Fi Alliance has expanded the generic use of the Wi-Fi term to include any type of network or WLAN product based on any of the 802.11 standards, including 802.11b, 802.11a, dual-band, and so on
WORKING
Wi-Fi works with no physical wired connection between sender and receiver by using radio frequency (RF) technology, a frequency within the electromagnetic spectrum associated with radio wave propagation.
When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space.
The cornerstone of any wireless network is an access point (AP).
The primary job of an access point is to broadcast a wireless signal that computers can detect and "tune" into.
In order to connect to an access point and join a wireless network, computers and devices must be equipped with wireless network adapters
Wi-Fi Certified and indicates the radio frequency band used (2.5GHz for 802.11b, 802.11g, or 802.11n, and 5GHz for 802.11a
A device that can use Wi-Fi (such as a personal computer, video-game console ,smartphone, tablet, or digital audio player) can connect to a network resource such as the Internet via a wireless network access point.
Such an access point (or hotspot) has a range of about 20 meters (65 feet) indoors and a greater range outdoors
Protocol Architecture
Convergence layer functions:
Encapsulate PDU framing of upper layers into native 802.16 MAC/PHY frames
Map upper layer’s addresses into 802.16 addresses
Translate upper layer QoS parameters into native 802.16 MAC format
Adapt time dependencies of upper layer traffic into equivalent MAC service
Physical Layer: Downlink
Continuous downstream mode
For continuous transmission (audio/video)
Simple TDM scheme is used for channel access
Frequency division duplex (FDD)
Burst downstream mode
For bursty transmission (IP-based traffic)
DAMA-TDMA scheme for channel access
FDD with adaptive modulation, frequency shift division duplexing (FSDD), time division duplexing (TDD)
Radio Link Control
Power control and paging
Transition among burst profiles
Downlink burst profile change
Subscriber station monitors downlink quality
Requests a new profile
Granted if base station judges possible
Uplink profile change
Base station monitors the uplink signal quality
Specifies the new profile’s usage code when granting subscriber bandwidth in a frame
Layers Definitions
The ISO 18000-7:2004 defines physical and data link layers [ISO4D].
The physical layer defines the modulation used in air communications and band frequencies.
The data link layer defines the communications protocol, dataheader,commands,data, collision treatment, broadcast communication and point-to-point communication.