无线局域网_复习2018(new)
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CCEE
802.11a OFDM Parameters
Wireless LAN
Total Number of Frequencies: 64
Number of Subcarriers Used: 52
Number of Pilots: 4
Number of Data Subcarriers: 48
Destination Service Access Point (DSAP)
Source Service Access Point (SSAP) LLC Control field
Data field
CCEE
Distribution system of 802.11
Wireless LAN
Thnt to wireless networks are those dealing with these lower architectural layers, such as data encryption.
CCEE
NOTE
Wireless LAN
MAC sublayer and OSI reference model
Network Layers 802.2 logical control layer
802.3 CSMA /CD 802.5 token ring 802.11 Wireless LANs Other LANs
Network Layers Data Link layer
• MLME-GET.request Requests the value of a specific MIB attribute. • MLME-GET.confirm Returns the value of the applicable MIB attribute value that corresponds to a MLME-GET.request. • MLME-SET.request Requests that the MIB set a specific MIB attribute to a particular value. • MLME-SET.confirm Returns the status of the MLME-SET.request.
BSS1
ESS
BSS2
STA4 STA3 AP
Any device that contains an 802.11-conformed MAC and PHY interface to wireless medium
Any entity that has STA functionality and provides access to the DS.
The Protocol Stacks
Mobility of Stations
Interaction with other 802 Layers
802.11 consists of only PHY and MAC layers. 802.11 should appear the same to higher-layer (LLC) 802-style LAN. Mobility should be handled within the MAC layer.
STA1
STA2 AP
A system used to be interconnect a set of BSSs
DS
Protal
The logical point at which MAC service data units (MSDUs) from a non-IEEE802.11 LAN enter the DS of an ESS.
Mobile Station
Access Point
Mobile Station
Communication between stations must go through AP
Consume twice the bandwidth (than station to station directly) The AP can buffer the traffic from a mobile station which is in a very low power state.
复习
2018.6
IEEE 802.11
Wireless LAN
June 1997-- IEEE finalized the initial standard for wireless LANs: IEEE 802.11.
This standard specifies a 2.4GHz operating frequency with data rates of 1Mbps and 2Mbps. The initial 802.11 standard defines two forms of spread spectrum modulation: frequency hopping (802.11 FHSS) and direct sequence (802.11 DSSS).
CCEE
The AP use centralized control to guarantee the STAs’ QoS requirement AP acts as a Master during the contention free period
The Protocol Stacks
Wireless LAN
Higher utilization and settings resulting in higher rates of transmission will increase power consumption.
CCEE
Hardware Architecture
Wireless LAN
A set of STAs
CCEE
The Basic Service Set
Wireless LAN
A set of station that communicate with one another (maybe not directly) Two different modes
Ad Hoc Mode: Independent BSS (IBSS) Infrastructure Mode (BSS)
802.xLAN
A set of interconnect BSSs and integrated LANs as a single ESS. Stations within an ESS can communicate with each other through AP. Mobile stations may move from one BSS to another transparently to LLC.
CCEE
Network Security
Wireless LAN
Network security refers to the protection of information and resources from loss, corruption, and improper use. A wireless network provides a bit pipe, consisting of a medium, synchronization, and error control that supports the flow of data bits from one point to another.
Late 1999,-- IEEE published two supplements to the 802.11 standard: 802.11a and 802.11b.
IEEE 802.11b is a data rate extension of the initial 802.11 DSSS, providing operation in the 2.4GHz band at up to 11Mbps. Most wireless LANs implemented today comply with the 802.11b version of the standard. The 802.11a standard defines operation at up to 54Mbps using orthogonal frequency division multiplexing (OFDM) modulation in the roomy 5GHz frequency band. The 802.11a standard has a wide variety of high-speed data rates available: 6, 9, 12, 18, 24, 36, 48, and 54Mbps; it is mandatory for all products to have 6Mbps, 12Mbps, and 24Mbps rates.
Subcarrier Spacing: 312.5 kHz
-3 dB bandwidth:16.56 MHz
Channel spacing: 20 MHz
CCEE
IEEE 802.2 LLC Services
Wireless LAN
The LLC provides the following three services for a Network Layer protocol:
CCEE
IBSS
Wireless LAN
A set of stations that communicate with one another directly No connection to a wired network
Mobile stations only (NO AP) Short-lived network
Various physical layers IEEE 802
Physical layers OSI
CCEE
Note
Wireless LAN
The MAC layer includes a management information base (MIB) that stores parameters the MAC protocol needs to operate. MAC sublayer management entity (MLME) primitives:
The typical current draw of an IEEE 802.11b product is as follows:
Transmit: 350mA Receive: 250mA Sleep: less than 10mA
The aggregate power consumption of the wireless LAN device is dependent on utilization and configuration parameter settings.
Mobile Station
CCEE
BSS
Wireless LAN
Mobile Station
Includes an access point (AP)
The AP may have connection to the wired LAN All stations communicate with the AP The AP provides the local relay function for the BSS
Unacknowledged connectionless service Connection-oriented service
Acknowledged connectionless service
All three LLC protocols employ the same PDU format that consists of four fields:
802.11a OFDM Parameters
Wireless LAN
Total Number of Frequencies: 64
Number of Subcarriers Used: 52
Number of Pilots: 4
Number of Data Subcarriers: 48
Destination Service Access Point (DSAP)
Source Service Access Point (SSAP) LLC Control field
Data field
CCEE
Distribution system of 802.11
Wireless LAN
Thnt to wireless networks are those dealing with these lower architectural layers, such as data encryption.
CCEE
NOTE
Wireless LAN
MAC sublayer and OSI reference model
Network Layers 802.2 logical control layer
802.3 CSMA /CD 802.5 token ring 802.11 Wireless LANs Other LANs
Network Layers Data Link layer
• MLME-GET.request Requests the value of a specific MIB attribute. • MLME-GET.confirm Returns the value of the applicable MIB attribute value that corresponds to a MLME-GET.request. • MLME-SET.request Requests that the MIB set a specific MIB attribute to a particular value. • MLME-SET.confirm Returns the status of the MLME-SET.request.
BSS1
ESS
BSS2
STA4 STA3 AP
Any device that contains an 802.11-conformed MAC and PHY interface to wireless medium
Any entity that has STA functionality and provides access to the DS.
The Protocol Stacks
Mobility of Stations
Interaction with other 802 Layers
802.11 consists of only PHY and MAC layers. 802.11 should appear the same to higher-layer (LLC) 802-style LAN. Mobility should be handled within the MAC layer.
STA1
STA2 AP
A system used to be interconnect a set of BSSs
DS
Protal
The logical point at which MAC service data units (MSDUs) from a non-IEEE802.11 LAN enter the DS of an ESS.
Mobile Station
Access Point
Mobile Station
Communication between stations must go through AP
Consume twice the bandwidth (than station to station directly) The AP can buffer the traffic from a mobile station which is in a very low power state.
复习
2018.6
IEEE 802.11
Wireless LAN
June 1997-- IEEE finalized the initial standard for wireless LANs: IEEE 802.11.
This standard specifies a 2.4GHz operating frequency with data rates of 1Mbps and 2Mbps. The initial 802.11 standard defines two forms of spread spectrum modulation: frequency hopping (802.11 FHSS) and direct sequence (802.11 DSSS).
CCEE
The AP use centralized control to guarantee the STAs’ QoS requirement AP acts as a Master during the contention free period
The Protocol Stacks
Wireless LAN
Higher utilization and settings resulting in higher rates of transmission will increase power consumption.
CCEE
Hardware Architecture
Wireless LAN
A set of STAs
CCEE
The Basic Service Set
Wireless LAN
A set of station that communicate with one another (maybe not directly) Two different modes
Ad Hoc Mode: Independent BSS (IBSS) Infrastructure Mode (BSS)
802.xLAN
A set of interconnect BSSs and integrated LANs as a single ESS. Stations within an ESS can communicate with each other through AP. Mobile stations may move from one BSS to another transparently to LLC.
CCEE
Network Security
Wireless LAN
Network security refers to the protection of information and resources from loss, corruption, and improper use. A wireless network provides a bit pipe, consisting of a medium, synchronization, and error control that supports the flow of data bits from one point to another.
Late 1999,-- IEEE published two supplements to the 802.11 standard: 802.11a and 802.11b.
IEEE 802.11b is a data rate extension of the initial 802.11 DSSS, providing operation in the 2.4GHz band at up to 11Mbps. Most wireless LANs implemented today comply with the 802.11b version of the standard. The 802.11a standard defines operation at up to 54Mbps using orthogonal frequency division multiplexing (OFDM) modulation in the roomy 5GHz frequency band. The 802.11a standard has a wide variety of high-speed data rates available: 6, 9, 12, 18, 24, 36, 48, and 54Mbps; it is mandatory for all products to have 6Mbps, 12Mbps, and 24Mbps rates.
Subcarrier Spacing: 312.5 kHz
-3 dB bandwidth:16.56 MHz
Channel spacing: 20 MHz
CCEE
IEEE 802.2 LLC Services
Wireless LAN
The LLC provides the following three services for a Network Layer protocol:
CCEE
IBSS
Wireless LAN
A set of stations that communicate with one another directly No connection to a wired network
Mobile stations only (NO AP) Short-lived network
Various physical layers IEEE 802
Physical layers OSI
CCEE
Note
Wireless LAN
The MAC layer includes a management information base (MIB) that stores parameters the MAC protocol needs to operate. MAC sublayer management entity (MLME) primitives:
The typical current draw of an IEEE 802.11b product is as follows:
Transmit: 350mA Receive: 250mA Sleep: less than 10mA
The aggregate power consumption of the wireless LAN device is dependent on utilization and configuration parameter settings.
Mobile Station
CCEE
BSS
Wireless LAN
Mobile Station
Includes an access point (AP)
The AP may have connection to the wired LAN All stations communicate with the AP The AP provides the local relay function for the BSS
Unacknowledged connectionless service Connection-oriented service
Acknowledged connectionless service
All three LLC protocols employ the same PDU format that consists of four fields: