Slide thông tin di động đại học bách khoa hà nội chương12 mạng không dây wifi wemax

Wireless Landscape Wireless Technology Transmission Distance Speed WLAN 802.11a, g WLAN :: n*10 – 100 m 54/128 Mbps 2G digital cellular WWAN - Nationwide 14 Kbps 2.5G digital cellular W

Trường Đại học Bách Khoa Hà Nội

Khoa Điện tử Viễn thông

Thông tin di động Mobile Communications

in which radio waves, infrared

waves and microwaves, instead

of cables or wires, are used to

carry a signal to connect

communication devices

cell phones, portable PCs,

computer networks, location

devices, satellite systems and

handheld digital assistants

Wireless Landscape

Wireless

Technology

Transmission Distance

Speed

WLAN 802.11a, g WLAN :: n*10 – 100 m 54/128 Mbps

2G digital cellular WWAN - Nationwide 14 Kbps

2.5G digital cellular WWAN - Nationwide 384 Kbps

3G digital cellular WWAN - Nationwide 2-10 Mbps

WiMAX as a last-mile alternative for remote areas not currently served by DSL or cable

5

Wireless Technologies

PAN (Personal Area Network)

PAN (Personal Area Network)

LAN

(Local Area Network) LAN

(Local Area Network)

WAN

(Wide Area Network) WAN

(Wide Area Network)

MAN

(Metropolitan Area Network)

Bluetooth

Peer-to-Peer Device-to-Device Peer-to-Peer Device-to-Device Short

< 1 Mbps

802.11a, 11b, 11g HiperLAN2

802.11a, 11b, 11g HiperLAN2

Family, Office, and Enterprise Family, Office, and Enterprise Medium

2 - 54 Mbps

802.11 MMDS, LMDS 802.11 MMDS, LMDS

Last Mile Access Last Mile Access Medium–Long

75 Mbps

GSM, GPRS, CDMA, 2.5–3G GSM, GPRS, CDMA, 2.5–3G

PDAs, Mobile Phones, Cellular Access

PDAs, Mobile Phones, Cellular Access Long 9,6 Kbps – 2Mbps

 IEEE 802.11n : adding multiple-input multiple-output (MIMO)

Wi-Fi™ and IEEE 802.11 Standards

9

Unlicenced Frequency Bands

 Defined cable-free local area network with either fixed or mobile locations that

transmit at either 1 or 2 Mbps which was insufficient for most network applications

 A new standard was developed for sending packetsized data traffic over radio waves

in the unlicensed 2.4 Ghz band

 Unlicensed, means it does not have to be certified by the FCC, and devices could

possible share the bandwidth with other devices such as cordless phones, oven etc.

ISM : Industrial, Scientific and Medical

U-NII : Unlicenced National

Information Infrastructure

Frequency Bands

11Standard Selection

The Laws of Radio Dynamics:

Higher Data Rates = Shorter Transmission Range

Higher Power Output = Increased Range, but Lower Battery Life

Higher Frequency Radios = Higher Data Rates Shorter Ranges

Cordless Phones Microwave Ovens Wireless Video Bluetooth Devices

HyperLAN Devices

Standard Selection

13

Ad Hoc Topology

 Peer-to-Peer (Ad Hoc) Topology

 Can consist of 2 or more PCs with wireless network

adapters.

 Sometimes called an Independent BSS (IBSS)

 Limited range.

No AP is needed !

Cấu hình tùy biến (không phụ thuộc) IBSS

Ad Hoc Topology

15

Infrastructure Topology Cấu hình phụ thuộc - BSS

AP is needed !

Infrastructure Topology

17

Radio Signal Interference

Since the frequency is unlicensed, any device operating in the 2.4 GHz spectrum may cause network interference with a 802.11b wireless device Some devices that may prove troublesome include 2.4 GHz cordless phones, microwave ovens, adjacent public hotspots, and neighboring 802.11b wireless LANs

• 5 GHz client adapter (802.11a)

• PCI card for Desktop

• PCMCIA card for Laptop

(Personal Computer Memory Card

International Association )

• USB card for Desktop & Laptop

Optional 2.4GHz Antennas for Long Range

33 Km @ 11 Mbps

Note: Distances include 50 feet of low loss cable and 10 dB fade margin

WLAN Devices

Media Access Control

 DCF: Distributied Coordination Functions -> Contention Access

 PCF: Point Coordination Functions -> Contention - Free Access ( polling )

Hidden terminal problem

 B, A hear each other

 B, C hear each other

 A, C can not hear each other

means A, C unaware of their

interference at B

A’s signal strength

space

C’s signal strength

Signal fading:

 B, A hear each other

 B, C hear each other

 A, C can not hear each other interfering at B

Hidden Node

MAC::CSMA/CA

CarrierSense Multiple Access / Collision Avoidance

Tham số cấp phát tài nguyên mạng

NAV: Network Alocation Vector

B¾t ®Çu

Kiểm tra đường truyền

NNAV=0

?

Đường truyền rỗi

N

YY

ACK ?

Truyền khung

NY

Truyềnthµnh c«ng

Quay lui ngÉu nhiª n

25

IEEE 802.11 MAC Protocol: CSMA/CA

802.11 sender

1 if sense channel idle for DIFS then

transmit entire frame (no CD)

2 if sense channel busy then

start random backoff time

timer counts down while channel idle

transmit when timer expires

3 if no ACK, increase random backoff interval, repeat 2

data ACK

• Station can send RTS with reservation parameter after waiting for DIFS (reservation

determines amount of time the data packet needs the medium and the ACK related to it)

Every node receiving this RTS now has to set its NAV (Network Allocation Vector - it

specifies the earliest point at which the node can try to access the medium again.

• Acknowledgement via CTS after SIFS by receiver (if ready to receive)

• Sender can now send data and receive acknowledgement via ACK if data is received

without error.

IEEE 802.11 MAC Protocol: CSMA/CA

 Node 1 has to communicate with

address 2

address 4

address

seq control

IEEE 802.11 frame: addressing

Address 2: MAC address

of wireless host or AP

transmitting this frame

Address 1: MAC address

29

Internet router

AP

AP MAC addr H1 MAC addr R1 MAC addr

address 1 address 2 address 3

802 11 frame

R1 MAC addr AP MAC addr

dest address source address

address 2

address 4

address

seq control

Type Subtype AP To From AP More frag Retry Power mgt More data WEP Rsvd

Protocol

version

duration of reserved transmission time (RTS/CTS)

frame seq # (for reliable ARQ)

frame type (RTS, CTS, ACK, data)

 Basic Service Set (BSS)

 group of stations using the same radio frequency

Distribution System

Portal

802.x LAN

Access Point

ESS

WLAN network architecture

 2003: 802.16a standard (interest: 2-11GHz, NLOS point to

multi-point applications, upto 75MHz)

 2004: 802.16d ( upgrade of 802.16a, modifications and

interoperability )

 2005: 802.16e ( offers mobility at vehicular speed)

Some Technical Specs on WiMax

37

WIMAX TOWER WIMAX RECEIVER

41

802.16 Protocol Architecture

Transmission and physical, which can be mapped to two OSI

lowest layers: physical and data link.

802.16 Protocols Architecture

43

4 types of Scheduling Service

 Unsolicited Grant Service (UGS)

 Real-time, periodic fixed size packets (e.g T1 or VoIP)

 Restrictions on bw requests

 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 (e.g FTP)

 BS issues unicast polls regularly.

 Best Effort Service

 Never polled individually

Connections

 802.16/WiMAX is connection oriented

 For each direction, a connection identified with a 16 bit CID

 Each CID is associated with a Service Flow ID (SFID) that determines

the QoS parameters for that CID

WiMAX Wi-Fi

WiMAX

47

Intel WiMAX Vision

Broadband Access for Enterprise

Broadband Access @ Home

complementary

to DSL & Cable

Broadband Access for Public hotspots

complementary to 3G, EDGE & WiFi

802.16-e

FUTURE OF WiMAX

 WiMax will be deployed in three stages:

802.16-2004) provides fixed wireless connections

self-installing Subscriber Terminal (ST), linked to PC and to

antenna

IEEE 802.16e) will be integrated into commercial laptops

Key technologies are evolving to meet the Wireless

Broadband Requirements

802.11n (smart antennas) 802.11

802.16a/d (Fixed NLOS)

HRPDA

1x EVDO 1x EVDV Rel C 1x EVDV Rel D

GSM GPRS EDGE UMTS HSPA LTE 3GPP

MOBILE BROADBAND

DSL Experience Dial Up

802.16e (Mobile WIMAX)

+ E2E QOS

+ Access technology agnostic

+ Connect to legacy GSM/UMTS core (LTE)

WMAX/LTE Specifications

Motorola Confidential Proprietary, LTE CxO Overview, Rev 1

MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office All other product or service names are the property of their respective owners © Motorola, Inc 2007

HSDPA vs WiMAX Air Interface Performance

TDD, 70% DL (data)TDD, 50% DL (voice)Frequency Reuse

1 site, 1 sector reuse

3 sectors per site

1 site, 1 sector reuse

3 sectors per site

1 site, 1 sector reuse

3 sectors per site

BS Configuration

"Macro" BTS/Node B20W output

"BS2.2" w/o TxAA2W output

"BS2.2" w/o TxAA2W outputSystem Configuration

Web Browsing with TCP/IP (kbps) 1400 3200 1376

Sector Throughput (F/L)

Sector Throughput (R/L)

Voice Capacity (F/L) (Erlangs) 120 150 75 (est.)

Voice Capacity (R/L) (Erlangs) 80 120 60 (est.)

F/L Data Spectral Efficiency

Voice Spectral Efficiency (E/MHz)

802.16e

+ True high-speed mobile data

+ Full-motion HD video anywhere

+ Stream any content

+ Mobile peer2peer & Web 2.0

+ Quadruple play

+ Faster email access

+ Instantaneous web pages

Highly Responsive Multimedia

+ Improved user experience

+ Fast VoIP call set-up

+ Instantaneous web pages

+ Streaming fast buffering

+ Online mobile gaming

+ Spectral efficiencyBetter utilization of spectrum available

+ Low frequency, Advanced Receivers and Smart AntennaFor improved coverage and reduced cost of ownership

+ Increased CapacityMuch higher user and sector throughput for lower individual cost service delivery

+ Simpler RAN, IP Core &

Centralized service deliveryFewer nodes & interfaces (Node-B/RNC/Gateway)

One Network & IMS for all access technologies

+ Connect to legacy coresExisting network asset investment protection

+ 3GPP/2 Market tractionEconomy of scale

LTE/WIMAX VoIP cost*

UMTS rel.99 voice call cost

$

10%

3GPP subscribers 85% market share

Predicted LTE VoIP voice call cost* - Sound Partners Limited Research

Conventional multicarrier techniques

Orthogonal multicarrier techniques OFDM

57 All Sub carrier need to Orthogonal

OFDM Sub-carrier

CDMA Signal Channel Transfer Function

Frequency S(f)

CDMA & OFDM in Frequency-selective Channel

LTE (Long Term Evaluation)

 Supply Bandwidths from 1.25-20 MHz

 Subcarriers spacing 15kHz.

 Bit rate up to 100Mbps, and by using MIMO the

speed should reach 350Mbps !

8  3.84 MHz

23.04 MHz

6  3.84 MHz

15.36 MHz

4  3.84 MHz

7.68 MHz

2  3.84 MHz

3.84 MHz

1.92 MHz 1/2  3.84 MHz

Sampling

frequency

2048 1536

1024 512

256 128

FFT size

4.69 4.69

4.69 4.69

4.69 4.69

16.67 16.67

16.67 16.67

Lo

ng

LTE modulation Specification

3G/HSDPA vs WIMAX/LTE Network Architecture

Traditional Cellular Architecture

Gateway

CAPController

VoIP Gateway

or IMS

DataGateway

=

Wireless Industry Forecast

16.5

10.1 7.4

25.8 22.2

19.0 15.2 11.9 14.2

18.8

22.2

24.9 26.6 27.1

11.6

26.4 24.0 20.4 15.5

1.5 3.25.9

20.6

3.8 5.6

12.5

11.5 11.1 10.9 10.5

9.9 9.4

2.5 4.1

6.7 7.95.4 1.2

1.4 0.8 1.1 2.4

3.7 5.7 8.1 10.8 14.0

Source: H&N, Strategy & Technology , September 2007

 Declining growth expected for traditional cellular infrastructure (2006-2010)

 2009-10 growth driven by WiMAX 802.16e + LTE

 W-CDMA spending continues

in Western Europe, North America and Japan

 GSM remains strong in LAC, MEA, China and India

WW TAM by Technology $ (in billions)

World Total

76.4 75.7 75.0

Thank you !