WiMAX By: Ankit Rakha MSE, CS JHU-'07

What is WiMAX ??

Think about how you access the Internet today….

3 options !!

Broadband access Wi-Fi access Dial-up access

WiMAX or Worldwide Interoperability of Microwave Access, is a wireless Internet service designed to cover wide geographical areas serving large number of users at low cost. WiMAX is the synonym given to the IEEE 802.16 standard defining wide area wireless data networking .

Typical Network Ranges WAN IEEE 802.16e IMT-2000(3G) (Nationwide) Wide Area Network MAN IEEE 802.16-2004 ETSI HiperMAN/WiMAX (50 Km) Metropolitan Area Network LAN IEEE 802.11 (a,b,g) (150 m) Local Area Network PAN IEEE 802.15 Bluetooth (10m) Personal Area Network

A WiMAX system consists of two parts : A Transmitter A single WiMAX tower can provide coverage to a very large area – as big as 3,000 sq. miles A Receiver The receiver and antenna could be a small box or PCMCIA card or they could built into a laptop as the way Wi-Fi access is today.

WiMAX WiMAX WiMAX

HOW DOES IT WORK ? WiMAX uses microwave radio technology to connect computers to the internet in place of wired connections such as DSL or cable modems. It works very much like cell phone technology in that reasonable proximity to a base station is required to establish a data link to the Internet. Users within 3 to 5 miles of the base station will be able to establish a link using NLOS technology with data rates as high as 75 Mbps. Users up to 30 miles away from the base staion with an antenna mounted for LOS to the base station will be able to connect at data rates approaching 280 Mbps.

Forms of Wireless Service NLOS (Non Line of Sight) Wi-Fi sort of service LOS ( Line of Sight)

WiMAX Fixed WiMAX (IEEE 802.16-2004) Ex: ETSI HiperMAN Optimized for Fixed and nomadic applications in LOS and NLOS environment 10-66 GHz licensed frequency bands (LOS) Licensed and license-exempt sub 11 GHz bands (LOS & NLOS) Mobile WiMAX (IEEE 802.16e) Ex: WiBro Optimized for Portable and mobile applications in NLOS environment Sub 6 GHz bands

Customer Premise Equipment Central Office, Network Management, VOIP Server etc. Customer Premise Equipment Traffic Aggregation PtP Wireless Backhaul Wireless PMP Access Base Station

Air Interface for Fixed Broadband Wireless Access System IEEE 802.16 Air Interface for Fixed Broadband Wireless Access System MAC and PHY specifications for 10-66 GHZ (LOS) One PHY: Single Carrier Connection oriented, TDM/TDMA MAC, QOS, Privacy IEEE 802.16 a Amendment to 802.16, MAC Modifications and additional PHY Specifications for 2-11 Ghz (NLOS) Three PHYs: OFDM, OFDMA, Single Carrier Additional MAC functions: OFDM and OFDMA PHY support, Mesh topology support, ARQ IEEE 802.16d Combines both IEEE 802.16 and 802.16a Some modifications to the MAC and PHY IEEE 802.16e Amendment to 802.16-2004 MAC modifications for limited mobility

The different flavors of WiMAX 802.16 REVd 802.16 e Fixed Outdoor Applications Indoor Broadband access for residential users ( High Speed Internet, VoIP,…) CPE External box connected to PC with built-in antenna Limited Mobility Applications “Portable” Broadband access for consumers Always Best Connected CPE PC Card Fixed Outdoor Applications E1/T1 service for enterprises Backhaul for Hotspots Limited residential Broadband access CPE External box connected to PC with outside antenna

System for 802.16 WiMAX

A TYPICAL WiMAX AND WiLAN DEPLOYMENT Non-Line-of-sight, point-to-multipoint Or point-to-point backhaul : 802.16a Non-line-of-sight, Point-to-multipoint: 802.16a 802.11 Telco core network or Private (fiber) network Internet Backbone Access Point

WiMAX Point-To-Point backhaul WiMAX PTP backhaul ISP PoP Wi-Fi Hotspots

Point to Multipoint application WiMAX point-to-multipoint Wire line or Wireless backhaul ISP PoP WiMAX Base Station Homes with outdoor/indoor WiMAX receiver

WiMAX as the backbone of meshed networks WiMAX may enjoy a complementary relationship with Wi-Fi due to differences in the reach of each of the networks . WiMAX connections can be used to provide backhaul connections to Wi-Fi hotspots over longer distances. WiMAX could also play a key role in connecting Wi-Fi hotspots in a mesh-type network to quickly increase coverage and capacity. Wi-Fi WiMAX

Factors affecting WiMAX performance (throughput and range) Frequency Band on which it is operating Channel Bandwidth Duplexing Scheme (TDD or FDD) Modulation (BPSK, QPSK, 16-QAM or 64-QAM) and Code Rate Antenna Types Whether LOS or NLOS Transmit Power Receiver Sensitivity The no. of users per base station sector.

Standard Family Primary Use Radio Tech Downlink (Mbps) Uplink (Mbps) 802.16 e WiMAX Mobile Internet MIMO-SOFDMA 70 Quoted speeds only achievable at very short ranges, more practically 10 Mbps at 10 km. HIPERMAN OFDM 56.9 WiBro OFDMA 50 Mobile range (900 m) iBurst iBurst802.20 HC-SDMA 64 3-12 km UMTS W-CDMA HSDPA + HSUPA UMTS/3GSM Mobile Phone CDMA/FDD .384 3.6 5.76 HSDPA downlink widely deployed. Roadmap shows HSDPA up to 28.8 Mbps downstream in the future. Currently, users can expect typical download speeds of 1-2 Mbps but around 200 kbps uplink speeds. UMTS-TDD CDMA/TDD 16 Reported speeds according to IPWireless using 16QAM modulation similar to HSDPA+HSUPA LTE UMTS UMTS/4GSM General 4G OFDMA/MIMO/SCFDMA HSOPA >100 >50 Still in development !xRTT CDMA 2000 CDMA 0.144 Obsoleted by EV-DO EV-DO 1x Rev.0 EV-DO 1x Rev.A EV-DO Rev.B 2.45 3.1 4.9xN 0.15 1.8 1.8xN Rev B note: N is the number of 1.25 MHz chunks of spectrum used . Not yet deployed.

Relationship with other Wireless Technologies Mobile-Fi Wi-Fi WiMAX Max. Speed 2 Mbps 16 Mbps 54 Mbps 100 Mbps Coverage Several Miles 300 feet 50 miles Airwave Licensed Unlicensed Either Advantages Range, Mobility Speed, Mobility Speed, Price Speed, Range Disadvantages Slow, Expensive High Price Short Range Interference issues

Security Issue Every WiMAX traffic is encrypted using DES (Data Encryption Standard) or AES (Advanced Encryption Standard) for securing its transmission over the air. The encryption keys are distributed from the BS to the SSs using PKM ( Privacy Key Management) protocol to ensure that only authorized SSs can receive the keys. Every WiMAX user device is authenticated using a digital certificate or SIM ( Subscriber Identity Module). This way, WiMAX keeps user traffic from eavesdropping and protects operator or service provider from becoming a victim of bandwidth theft by unauthorized users.

5) Providing Nomadic connectivity. USES 1) Connecting Wi-Fi hotspots with each other and to other parts of the internet. 2) Providing a wireless alternative to cable and DSL for last km broadband access. 3) Providing a high-speed mobile data and telecommunications services (4G). 4) Providing a diverse source of Internet connectivity as a part of business continuity plan. 5) Providing Nomadic connectivity.

What are the Advantages ? What are the disadvantages ? A Single WiMAX main Station can serve hundreds of users. Endpoints install within days instead of the weeks required for wired connections. Data rates as high as 280 Mbps and distances of 30 miles are possible. Users can operate mobile within 3-5 miles of a base station at data rates up to 75 Mbps. No FCC radio licensing is required. Less expensive than DSL or coaxial cable. What are the disadvantages ? Line-of-Sight is required for long distance (5-30 mile) connections. Heavy rains can disrupt the service. Other wireless electronics in the vicinity can interfere with the WiMAX connection and cause a reduction in data throughput or even a total disconnect.

Advantages over Wi-Fi Analysis The WiMAX specification provides symmetrical bandwidth over many kilometers and range with stronger encryption and typically less interference. Wi-Fi is short range has WEP or WPA encryption and suffers from interference as in metropolitan areas there are many users. The fastest Wi-Fi connection can transmit up to 54 Megabits per second under optimal conditions. WiMAX can handle up to 70 Megabits per second. The biggest difference isn’t speed; its distance. WiMAX outdistances Wi-Fi by miles. Analysis WiMAX is not competing other, it is wireless cable replacement technology, which competes with wired operators.

Future developments and IEEE 802.20 MBWA is a technology developed by IEEE 802.20. It is the future technology standard for true wireless broadband or 4G and so far iBurst is the only pre-selected solution with over a dozen commercial deployments worldwide.