A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Acces

s

IEEE 802.16 WirelessMAN

Carl Eklund

Roger B. Marks

Kenneth L. Stanwood

Stanley Wang

資訊工程學系碩士在職專班

學號 : 492515019

姓名 : 何俊慶

Agenda

• Why IEEE 802.16 wirelessMAN ?• IEEE 802.16 Standard

– 802.16– 802.16a– 802.16b

• IEEE 802.16 theory– Physical Layer– MAC Layer– BS SS initial

• Conclusion• References

What are WMANs?

• WMAN: Wireless Metropolitan Area Network.

• They are meant to provide wireless access for large residential areas.

• They are designed to provide Broadband Wireless Access (BWA) services.

• BWA offers integrated high-speed links supporting data, voice and video communication.

Applications

• It comprises a “Last Mile” solution. It is a suitable cost-effective solution to replace copper and fiber last mile connections.– Buildings equipped with subscriber and base stations,

SS & BS– Users connect to SS via conventional network technol

ogies (e.g. 802.3, 802.11)– BSs connected directly to backbone

• Lowers barriers to entry for new ISPs increasing competition

“Last Mile” solution

LAN MAN WANPAN

IEEE-802.16 2.5G,GSM/TDMA/ CDMA 3G,GPRS/WCDMA

Personal Area802.15/Bluetooth

Wireless LAN802.11x/HiperLAN

Wireless MANIEEE-802.16

WPAN WLAN WWAN

Wireless LAN Technology

WMAN

What technologies can we choose from?

• sample wireless applications (source: Cisco 2002)

PAN LAN MAN WAN

standards BlueTooth

802.15

802.11

802.11b

802.11a

802.11g

802.16

(MMDS

LMDS)

CDMA,

G2.5-3,

GSM

speed < 1Mb/s 1 to 54Mb/s 128Kb/s to 100Mb/s+

10 to 384Kb/s

range Short medium medium-long long

applications P2p enterprise last mile mobile phones

Wireless Technologies

WMAN Standards

General Overview

• Standard for wireless metropolitan area networks (WirelessMAN™)

• Supports a variety of services such as IP, voice over IP, and streaming video

• Protocol independent supporting ATM & packet based protocols

Standardization of Wireless Networks

• Wireless networks are standardized by IEEE.

• Under 802 LAN MAN standards committee.Application

Presentation

Session

Transport

Network

Data Link

Physical

ISOOSI7-layermodel

Logical Link Control

Medium Access (MAC)

Physical (PHY)

IEEE 802standards

IEEE 802.16 Standard

• P802.16 — Air interface for fixed BWA systems at 10-66 GHz– Common MAC definition– Point-to-multipoint (PMP) operation– 2 to 134 Mbps– Bandwidth on Demand system– Requires directional line-of-sight (LOS) propagation

IEEE 802.16 Standard

• P802.16a — 2-11 GHz licensed bands– Point-to-multipoint BWA system– 3 physical layer specs: Single Carrier, 256-point OFDM,

2048-point multi-user OFDMA– the standard tackles the Non-Line-of-Sight

applications

• P802.16b — License-Exempt Bands, with a focus on 5-6 GHz– Wireless High-Speed Unlicensed Metropolitan Area Net

works (WirelessHUMAN)– Primary focus is 5-6 GHz (UNII band)

IEEE 802.16 Theory

802.16 protocol layer

802.16 Physical Layer

• Data rates determined by exact modulation and encoding schemes

• TDMA and OFDMA

Channel Size

(MHz)

Bit Rate

(Mbps)

QPSK

Bit Rate

(Mbps)

16-QAM

Bit Rate

(Mbps)

64-QAM

20 32 64 96

25 40 80 120

28 44.8 89.6 134.4

Bit Rate Shifting in 802.16

Bit rate shifting is achieved using adaptive modulation. When you are near to the BS, you are offered high speed, when you’re far, reliability decreases, hence you’re offered lower speed.

802.16 MAC

• WirelessMAN operates at MAC sub-layer of Data Link Layer

• MAC layer is further subdivided into three layers– Convergence sub-layer (CS)– Common part sub-layer (CPS)– Privacy sub-layer

IEEE 802.16 MAC layer function

• Transmission scheduling : – Controls uplink and downlink transmissions so that

different QoS can be provided to each user

• Link initialization– Scans for a channel, synchronizes the SS with the

BS, performs registration, and various security issues.

• Support for integrated voice/data connections– Provide various levels of bandwidth allocation

802.16 MAC: Privacy Sub-Layer

• Provides secure communication– Data encrypted with cipher clock chaining

mode of DES

• Prevents theft of service– SSs authenticated by BS using key

management protocol

802.16 MAC: CPS Layer

• Performs typical MAC functions such as addressing– Each SS assigned 48-bit MAC address– Connection Identifiers used as primary address after

initialization

• MAC policy determined by direction of transmission– Uplink is TDMA– Downlink is TDM

802.16 MAC: CS Layer

• Interoperability requires convergence sub-layer to be service specific – Separate CS layers for ATM & packet

protocols

• CS Layer:– Receives data from higher layers– Classifies data as ATM cell or packet– Forwards frames to CPS layer

802.16 MAC Layer

FDD map relevance

802.16 MAC Layer

TDD map relevance

Physical Layer

Downlink subframe structure

Physical Layer

Upnlink subframe structure

BS SS initial

Transition to a more robust burst profile

BS SS initial

Transition to a less robust burst profile

802.16 MAC Layer

Generic MAC header format

802.16 MAC Layer

802.16 MAC Layer

Bandwidth Request header format

802.16 MAC Layer

Conclusion

WMAN Advantage

• 支援可變長度資料封包傳輸• 提供品質保證 QoS, 包含頻寬需求與延遲控制、封包分級、動態連結建立

• 提供安全傳輸服務• 提供數種傳輸速度• 提供封包分割重整與 TCP/IP 相連時提供通透性連接 ,可直接到任何網際網路

• 建制容易 ,升級更新容易 ,成本低

References

REFERENCES

[1] IEEE 802.16-2001,”IEEE Standard for Local Metropolitan Area Networks - Air Interface for Fixed Brodband Wireless Access System.”Apr.8,2002

[2] IEEE P802.16a/D3-2001:”Draft Amendment to IEEE Standard for Local and Metropolitan Area Networks – Air Interface for Fixed Wireless Access Systems – Medium Access Control Modifications and Additional Physical Layers Specifications for 2-11 GHz”Mar.25,2002

[3] IEEE 802.16.2-2001,”IEEE Recommended Practice for Local and Metropolitan Area Networks – Coexistence of Fixed Broadband Wireless Access Systems,”Sep.10,2001