A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Access
description
Transcript of A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Access
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