19-04-2011, 12:49 PM
Presented by:
Sridhar Iyer
WiMAX.ppt (Size: 252.5 KB / Downloads: 147)
WiMAX:
IEEE 802.16 - Wireless MANs
Wireless networks
Wireless PANs (Bluetooth – IEEE 802.15)
– very low range
– wireless connection to printers etc
Wireless LANs (WiFi – IEEE 802.11)
– infrastructure as well as ad-hoc networks possible
– home/office networking
– Multihop Ad hoc Networks
– useful when infrastructure not available, impractical, or expensive
– military applications, emergencies
WiMAX
Goal: Provide high-speed Internet access to home and business subscribers, without wires.
Base stations (BS) and subscriber stations (SS)
Centralized access control to prevents collisions
Supports applications with different QoS requirements
WiMAX is a subset of IEEE 802.16 standard
IEEE 802.16 standards
802.16.1 (10-66 GHz, line-of-sight, up to 134Mbit/s)
802.16.2 (minimizing interference between coexisting WMANs)
802.16a (2-11 Ghz, Mesh, non-line-of-sight)
802.16b (5-6 Ghz)
802.16c (detailed system profiles)
P802.16e (Mobile Wireless MAN)
Physical layer
Allows use of directional antennas
Allows use of two different duplexing schemes:
– Frequency Division Duplexing (FDD)
– Time Division Duplexing (TDD)
Support for both full and half duplex stations
Adaptive Data Burst profiles
– Transmission parameters (e.g. Modulation, FEC) can be modified on a frame-by-frame basis for each SS
– Profiles are identified by ”Interval Usage Code”
Time Division Duplexing (TDD)
Media Acces Control (MAC)
Connection oriented
– Connection ID (CID), Service Flows
– Channel access: decided by BS
– UL-MAP
– Defines uplink channel access
– Defines uplink data burst profiles
– DL-MAP
– Defines downlink data burst profiles
– UL-MAP and DL-MAP are both transmitted in the beginning of each downlink subframe
TDD Downlink subframe
Uplink subframe
Uplink periods
Initial Maintenance opportunities
– Ranging - to determine network delay and to request power or profile changes
– Collisions may occur in this interval
– Request opportunities
– SSs request bandwith in response to polling from BS
– Collisions may occur in this interval
– Data grants period
– SSs transmit data bursts in the intervals granted by the BS
– Transition gaps between data intervals for synchronization
– Bandwidth request
SSs may request bandwidth in 3 ways:
– Use the ”contention request opportunities” interval upon being polled by the BS
– Send a standalone MAC message called ”BW request” in an allready granted slot
– Piggyback a BW request message on a data packet
Bandwidth allocation
BS grants/allocates bandwidth in one of two modes:
– Grant Per Subscriber Station (GPSS)
– Grant Per Connection (GPC)
Decision based on requested bandwidth and QoS requirements vs available resources
Grants are notified through the UL-MAP
Bandwidth Request-Grant Protocol
Scheduling services
Unsolicited Grant Service (UGS)
– Real-time, periodic fixed size packets (e.g. VoIP)
– No periodic bandwith requests required
Real-Time Polling Service (rtPS)
– Real-time, periodic variable sizes packets (e.g MPEG)
– BS issues periodic unicast polls
Non-Real-Time Polling Service (nrtPS)
– Variable sized packets with loose delay requirements (FTP)
– BS issues unicast polls regularly (not necessarily periodic)
– Can also use contention requests and piggybacking
Best Effort Service
– Never polled individually
– Can use contention requests and piggybacking
Sridhar Iyer
WiMAX.ppt (Size: 252.5 KB / Downloads: 147)
WiMAX:
IEEE 802.16 - Wireless MANs
Wireless networks
Wireless PANs (Bluetooth – IEEE 802.15)
– very low range
– wireless connection to printers etc
Wireless LANs (WiFi – IEEE 802.11)
– infrastructure as well as ad-hoc networks possible
– home/office networking
– Multihop Ad hoc Networks
– useful when infrastructure not available, impractical, or expensive
– military applications, emergencies
WiMAX
Goal: Provide high-speed Internet access to home and business subscribers, without wires.
Base stations (BS) and subscriber stations (SS)
Centralized access control to prevents collisions
Supports applications with different QoS requirements
WiMAX is a subset of IEEE 802.16 standard
IEEE 802.16 standards
802.16.1 (10-66 GHz, line-of-sight, up to 134Mbit/s)
802.16.2 (minimizing interference between coexisting WMANs)
802.16a (2-11 Ghz, Mesh, non-line-of-sight)
802.16b (5-6 Ghz)
802.16c (detailed system profiles)
P802.16e (Mobile Wireless MAN)
Physical layer
Allows use of directional antennas
Allows use of two different duplexing schemes:
– Frequency Division Duplexing (FDD)
– Time Division Duplexing (TDD)
Support for both full and half duplex stations
Adaptive Data Burst profiles
– Transmission parameters (e.g. Modulation, FEC) can be modified on a frame-by-frame basis for each SS
– Profiles are identified by ”Interval Usage Code”
Time Division Duplexing (TDD)
Media Acces Control (MAC)
Connection oriented
– Connection ID (CID), Service Flows
– Channel access: decided by BS
– UL-MAP
– Defines uplink channel access
– Defines uplink data burst profiles
– DL-MAP
– Defines downlink data burst profiles
– UL-MAP and DL-MAP are both transmitted in the beginning of each downlink subframe
TDD Downlink subframe
Uplink subframe
Uplink periods
Initial Maintenance opportunities
– Ranging - to determine network delay and to request power or profile changes
– Collisions may occur in this interval
– Request opportunities
– SSs request bandwith in response to polling from BS
– Collisions may occur in this interval
– Data grants period
– SSs transmit data bursts in the intervals granted by the BS
– Transition gaps between data intervals for synchronization
– Bandwidth request
SSs may request bandwidth in 3 ways:
– Use the ”contention request opportunities” interval upon being polled by the BS
– Send a standalone MAC message called ”BW request” in an allready granted slot
– Piggyback a BW request message on a data packet
Bandwidth allocation
BS grants/allocates bandwidth in one of two modes:
– Grant Per Subscriber Station (GPSS)
– Grant Per Connection (GPC)
Decision based on requested bandwidth and QoS requirements vs available resources
Grants are notified through the UL-MAP
Bandwidth Request-Grant Protocol
Scheduling services
Unsolicited Grant Service (UGS)
– Real-time, periodic fixed size packets (e.g. VoIP)
– No periodic bandwith requests required
Real-Time Polling Service (rtPS)
– Real-time, periodic variable sizes packets (e.g MPEG)
– BS issues periodic unicast polls
Non-Real-Time Polling Service (nrtPS)
– Variable sized packets with loose delay requirements (FTP)
– BS issues unicast polls regularly (not necessarily periodic)
– Can also use contention requests and piggybacking
Best Effort Service
– Never polled individually
– Can use contention requests and piggybacking