IEEE 802.16 WirelessMAN For Broadband Wireless Metropolitan Area Networks.

IEEE 802.16 WirelessMAN

For Broadband Wireless Metropolitan Area Networks

IEEE 802The LAN/MAN Standards Committee

• Wired:– 802.3 (Ethernet)– 802.17 (Resilient Packet Ring)

• Wireless:– 802.11: Wireless LAN

• Local Area Networks– 802.15: Wireless PAN

• Personal Area Networks {inc. Bluetooth}– 802.16: WirelessMANTM

• Metropolitan Area Networks– 802.20:

• Vehicular Mobility (new)

IEEE 802.16 Projects

• Air Interface (PHYs with common MAC)– 802.16: 10-66 GHz– 802.16a: 2-11 GHz

• Coexistence– IEEE 802.16.2 (10-66 GHz)– P802.16.2a: amendment

• with 2-11 GHz licensed

Properties of IEEE Standard 802.16

• Broad bandwidth– Up to 134 Mbit/s in 28 MHz channel (in 10-66 GHz air interface)

• Supports multiple services simultaneously with full QoS– Efficiently transport IPv4, IPv6, ATM, Ethernet, etc.

• Bandwidth on demand (frame by frame)• MAC designed for efficient used of spectrum• Comprehensive, modern, and extensible security• Supports multiple frequency allocations from 2-66 GHz

– ODFM and OFDMA for non-line-of-sight applications• TDD and FDD• Link adaptation: Adaptive modulation and coding

– Subscriber by subscriber, burst by burst, uplink and downlink• Point-to-multipoint topology, with mesh extensions• Support for adaptive antennas and space-time coding• Extensions to mobility are coming next.

Point-to-MultipointWireless MAN: not a LAN

• Base Station (BS) connected to public networks• BS serves Subscriber Stations (SSs)

– SS typically serves a building (business or residence)– provide SS with first-mile access to public networks

• Compared to a Wireless LAN:– Multimedia QoS, not only contention-based– Many more users– Much higher data rates– Much longer distances

Scope of 802 Standards

PHY Considerations

• Line of Sight (because of 10-66 GHz)– Negligible multi-path

• Broadband Channels– Wide channels (20, 25, or 28 MHz)– High capacity – Downlink AND Uplink

• Multiple Access– TDM/TDMA– High rate burst modems

• Adaptive Burst Profiles on Uplink and Downlink• Multiple duplex schemes

– Time-Division Duplex (TDD)– Frequency-Division Duplex (FDD) [including Burst FDD]

• Support for Half-Duplex Terminals

Adaptive Burst Profiles

• Burst profile– Include transmission parameters such as modulation

and FEC• Dynamically assigned according to link

conditions– Burst by burst, per subscriber station– Trade-off capacity vs. robustness in real time

• Roughly doubled capacity for the same cell area • Burst profile for downlink broadcast channel is

well- known and robust– Other burst profiles can be configured “on the fly”– SS capabilities recognized at registration

Framing Structure

• Frame length: 0.5, 1, or 2 ms

• Allocation process is done in terms of PSs– PS = Physical Slot = 4 Modulation Symbols– Depending on modulation, a PS contains 1, 2,

or 3 bytes

DL-MAP specifies when physical layer transitions (modulation and FEC) occur within the downlink subframe

UL-MAP specifies bandwidth allocations And burst profiles on the uplink

UL-MAP within the frame control grants bandwidth and burst profiles to specific SSs.

Initial ranging for transmit time advance and power adjustments

MAC Requirements

• Provide Network Access• Address the Wireless environment

– e.g., very efficient use of spectrum

• Broadband services– Very high bit rates, downlink and uplink– A range of QoS requirements– Ethernet, IPv4, IPv6, ATM, ...

• Likelihood of terminal being shared– Base Station may be heavily loaded

• Security• Protocol-Independent Engine

– Convergence layers to ATM, IP, Ethernet, ...

• Support PHY alternatives– Adaptive mod, TDD/FDD; single-carrier, OFDM/OFDMA, etc

802.16 MAC: Overview

• Point-to-Multipoint• Metropolitan Area Network• Connection-oriented• Supports difficult user environments

– High bandwidth, hundreds of users per channel– Continuous and burst traffic– Very efficient use of spectrum

• Protocol-Independent core (ATM, IP, Ethernet, …)• Balances between stability of contentionless and efficien

cy of contention-based operation• Flexible QoS offerings

– CBR, rt -VBR, nrt-VBR, BE, with granularity within classes• Supports multiple 802.16 PHYs

Definitions

• Service Data Unit (SDU)– Data units exchanged between adjacent layers

• Protocol Data Unit (PDU)– Data units exchanged between peer entities

• Connection and Connection ID– a unidirectional mapping between MAC peers over th

e airlink (uniquely identified by a CID)

• Service Flow and Service Flow ID– a unidirectional flow of MAC PDUs on a connection th

at provides a particular QoS (uniquely identified by a SFID)

MAC Addressing

• SS has 48-bit IEEE MAC Address

• BS has 48-bit Base Station ID– Not a MAC address– 24-bit operator indicator

• 16-bit Connection ID (CID)– Used in MAC PDUs

Possible Consideration

• QoS– In GPC, if the amount of the connections are v

ery high, then SS should not request BW for each connection, which is resource consuming.

– In GPSS, SS should aggregate all the connections that are with different services, and request BW from BS.

• Scheduling problem?

• Mesh topology support