Wireless WAN: WLL & Wimax Module W.Wan.5 WLL: Wireless Local Loop

W.wan.5-2 WLL: Wireless Local Loop

Access network Æ Local loop (subscriber loop) Wired systems Wireless WAN: WLL & WiMax ¾ Twisted pair Æ coaxial cable Æ optical fiber Wireless systems Module W.wan.5 ¾ WLL (Wireless Local Loop)

Dr.M.Y.Wu@CSE Dr.W.Shu@ECE Shanghai Jiaotong University University of New Mexico Shanghai, China Albuquerque, NM, USA

WLL architecture: Last-mile solution Source: Stalling2nd

W.wan.5-3 W.wan.5-4 WLL: Wireless Local Loop WLL: Why better?

Scope of wireless coverage Lower cost ¾ PAN, 10m, 1Mbps are less expensive due to cost of cable installation that’s ¾ LAN, 100m, 10Mbps avoided ¾ MAN, 25km, 1-75Mbps Easy to install WLL = Wireless + MAN can be installed in a small fraction of the time required for a new wired system Narrowband – offers a replacement for existing telephony services Selective installation Broadband – provides high-speed two-way voice and data radio units installed for subscribers who want service at a service given time Stationary or mobile? ¾ while with a wired system, cable is laid out in anticipation of serving every subscriber in a given area Fixed Æ Portable Æ Mobil

WLL mainly uses millimeter wave frequencies (2 GHz LOS: Line-of-sight to about 30 GHz) Higher Frequencies range: up to 66 GHz Good things Fixed dish antenna points straight at WiMax tower from a rooftop or pole. ¾ There are wide unused frequency bands available above 25 GHz Service is stronger and more stable, capable to send a lot of data ¾ At these high frequencies, wide channel bandwidths can be used, with fewer errors. providing high data rates At higher frequencies, less interference and more bandwidth ¾ Small size transceivers and adaptive antenna arrays can be used NLOS: Non-line-of-sight Not so good things (propagation): Lower Frequency range: 2-11 GHz ¾ Free space loss increases with the square of the frequency; losses A small antenna on computer connects to a tower. are much higher in millimeter wave range Lower wavelength transmissions are not as easily disrupted by ¾ Attenuation effects due to rainfall and atmospheric or gaseous physical obstructions. absorption are large They are better able to diffract, or bend around obstacles. ¾ Multipath losses can be quite high In general, >10GHz can be LOS, <10GHz can be LOS or NLOS

W.wan.5-7 W.wan.5-8 MDS: Multipoint Distribution Service MDS: Multipoint Distribution Service

PMP: Point to Multipoint Distribution Two commonly used WLL: LMDS & MMDS: A single antenna transceiver is used to link to many users LMDS: Local multipoint distribution service Appeals to larger companies with greater bandwidth Contrast to cellular system demands ¾ Broadband instead of telecommunication oriented, data oriented MMDS: Multichannel multipoint distribution ¾ Mostly stationary (fixed) instead of mobile users, so no handoff service Also referred to as wireless cable ¾ Cells do not overlap, frequency can be reused Used mainly by residential subscribers and small ¾ Classified as MAN instead of WAN in scope businesses

28GHz in USA, 40GHz in Europe, millimeter-wave spectrum 2.5GHz licensed, and 5.8GHz unlicensed, centemeter-wave High frequency, smaller cell spectrum Lower frequency, larger cell size (50 km), equipment less expensive size (2 km), LOS Relatively lower data Relatively high data rates (27-36Mbps) rates (155Mbps) MMDS signals with larger Capable of providing wavelengths can travel video, telephony, farther without losing and data significant power Relatively low cost in MMDS signals don't get comparison with blocked as easily by objects cable alternatives and are less susceptible to rain absorption OFDM can improve data rate

W.wan.5-11 W.wan.5-12 LMDS & MMDS IEEE802 suite

Spectrum allocations in USA IEEE 802 --- PAN/LAN/MAN Standards Wired Frequency, GHz Allocations ¾ 802.3 (Ethernet) 2.1500—2.1620 MMDS, licensed, 2 bands of 6 MHz each Wireless 2.4000—2.4835 ISM, unlicensed ¾ 802.11: Wireless LAN WiFi 2.5960—2.6440 MMDS, licensed, 8 bands of 6 MHz each ¾ 802.15: Wireless PAN 2.6500—2.6800 MMDS, licensed Bluetooth 5.7250—5.875 ISM-UNII, unlicensed, used for MMDS too ¾ 802.16: Wireless MAN 24.000—24.250 ISM, unlicensed WiMAX 27.500—31.300 LMDS, licensed, ¾ 802.20: Vehicular Mobility ? MobilFi ISM = Industrial, Scientific, and Medical Downloads (free 6 months after publication) UNII = Unlicensed National Information Infrastructure http://standards.ieee.org/getieee802

WiMAX = WLL + Standardization Technology considerations Use point-to-multipoint architecture with stationary rooftop Licensed vs unlicensed or tower-mounted antennas LOS vs NLOS Æ Worldwide interoperability for Microwave Access WiMAX Half-duplex vs full-duplex Standard: IEEE 802.16 P2P, P2MP, Mesh Frequency spectrum Fixed, portable, mobile ¾ 10-66 GHz, LMDS, Cost performance LOS, licensed ¾ ¾ 2-11 GHz, MMDS, throughput = channel bandwidth (Hz) X bits/Hz NLOS, licensed & unlicensed Last-mile tech? Last-mile technology: metropolitan area in scale ¾ WiFi backhaul Can serve as backhaul for wireless LANs (802.11) ¾ T1 replacement ¾ 3G/4G replacement?

W.wan.5-15 W.wan.5-16 WiMAX/802.16 vs WiFi/802.11 WiMAX/802.16 vs 3G

WiMAX/802.16 Technology WiFi/802.11b/g 2-11 GHz Spectrum 2.4 GHz WiMAX/802.16 Technology 3G Licensed, unlicensed unlicensed Wireless broadband Broadband Mobile broadband < 50 km (typical 5km) Range < 200m Laptop centric Client Phones & laptops Outdoor LOS & NLOS Coverage Indoor short range Fixed to portable mobility Roaming / mobility 5bps/Hz peak Data rate 2.7bps/Hz peak LOS or NLOS Channels NLOS < 100Mbps in 20 MHz < 54Mbps in 20MHz Optimized for data Services Optimized for voice Hundreds CPE Scalability Tens CPE WiMAX Æ potential 4G??? On demand: A/V,data QoS No Connection oriented Connection type Connectionless TDD/FDD Full duplex No TDMA Multiple access CSMA/CA