Network Protocol Trade-off for Strawman Missions Kawsu Sidibeh Surrey Space Centre, University of Surrey, UK ESA Wireless Study WP 1:II

Wireless technologies in context WPAN protocol Comparisons Agenda Wireless technologies in context WPAN protocol Comparisons WLAN & WMAN protocol Comparisons Recommendations & Conclusions WP1:II

Wireless Standards Date Rates and Deployment WP1:II

Wireless technologies By deployment : Wireless indoors: 802.15.4 (Industrial control and monitoring, Sensor networks, building automation and home control Wireless Indoors : 802.15.1( Wireless connectivity between devices such as phones, PDA, Laptops, headsets, etc. Wireless last mile : 802.11, 802.16 (WLAN connectivity, broadband internet access) Wireless overhaul/Backbone : 802.16 (MAN long range connectivity) By mobility Vehicular speeds up to 75 mph : 802.16e Supplement 802.11p delivers mobility up to 125mph Vehicular speeds up to 155 mph: mobile-Fi (802.20) WP1:II

Wireless Protocol Stacks ZigBEE/802.15.4 STACK BLUETOOTH STACK OSI Model 802.11 STACK 802.16 STACK WP1:II

General Comparison ZigBee vs Bluetooth ZigBee/IEEE 802.15.4 - General Characteristics Dual PHY (2.4GHz and 868/915 MHz)  Optimized for low duty-cycle applications (<0.1%) CSMA-CA channel access Yields high throughput (max 250Kbps) and low latency for low duty cycle devices like sensors and controls Low power (battery life multi-month to years) Multiple topologies: star, peer-to-peer, mesh Optional guaranteed time slot for applications requiring low latency Fully hand-shaked protocol for transfer reliability Bluetooth –General Characteristics PHY ( ISM Band 2.4 GHZ) Optimized for audio, graphic, FTP, ad hoc. Master-Slave Polling channel access 1 Mbps throughput Medium power consumption Max. 7 nodes per picocell Support TCP/IP connections High latency WP1:II

WPAN Protocol Comparison ZigBee Bluetooth Ultra Wide Band Data rate 20, 40, and 250 Kbps 1 Mbps 100-500Mbps Range 10-100 meters 10 meters <10 meters modulation DSSS FHSS N/A Bandwidth 2 MHz 1 MHz Very Large Network topology Ad-hoc, peer-to-peer, star or mesh (255+) Ad-hoc,Very small networks (7) Point-to-point MAC CSMA/CA Master-Slave: Polling Power consumption Very low (Design Goal) Medium low TCP/IP Support No Yes Latency Device Joining network in 30ms Device connection requires 1s Very low Protocol stack implementation ~ 32kb 256kb ? security 128 AES plus app. Layer security 64 and 128 bit encryption I/O SPI, Rs232, I2C UART, Rs232, I2C WP1:II

General comparison 802.11 Versus 802.16 Widely deployed Up to 54 Mbps on 20 MHz (802.11n supplement up to 300-500 Mbps) Up to 300 meters Qos support (802.11e supplement) Not adaptable to PHY conditions Smart antenna support (802.11n supplement) Weak security (enhanced in 802.11i) Up 100 Mph Mobility ( 802.11p supplement) Power control (Dose) 2.4 GHz and 5 GHz (licensed) 802.16 Experimentally deployed Up to 100 Mbps on 20MHz Up to 50,000 meters QoS support ( Built in the standard) Adaptable to PHY conditions Smart antenna support (both MIMO & AAS) Strong Security (built in the standard) Up to 75 Mph mobility( 802.16e) Space Time Coding (2 TX + 1 Rx) Power control (sleep & awake) 2-60 GHz (licensed & unlicensed) WP1:II

WLAN & WMAN Protocol Comparison Wi-Fi (802.11) Fixed WiMAX (802.16.2004) Mobile WiMAX (802.16e-2005) Data rate 1-25 Mbps 5-10 Mbps MAC CDMA/CA TDMA/DA TDMA\DA modulation OFDM OFDMA Range 300-10km 50 km 70 km Bandwidth Fixed, 20 MhZ/52 sub-carriers Variable; 1 to 28 Mhz/256 sub-carriers Mhz/2048 sub-carriers Spectral Efficiency 2.7 Mbps/Hz 3.1 to 3.8 Mbps/Hz EVM Required -25 dB -31dB Receive Noise Figure 10 dB max 7 dB max Duplexing TDD TDD, FDD, HFDD Mobility >100 mph, Ad hoc Fix 75 mph Transmit Dynamic range Transmit power fixed 50 dB range WP1:II

Recommendations & Conclusions ZigBee and Bluetooth for Intra-Satellite Links ZigBee for sensor networking, monitoring, control, etc on-board Bluetooth for cable replacement. Possibility of IR-UWB and Wi-Fi for high data rate requirements <1Mbps Wi-Fi and WiMAX for Inter-Satellite Links Wi-Fi directional or mesh deployments in close proximity links such as satellite clusters and formation flying. WiMAX deployment to cover last mile (>10 Km) for inter-satellite connectivity in LEO constellations such string of pearls. Possibility of using ZigBee-Pro (up to 1.6 km) for sensor networking in inter-satellite applications should be considered. WP1:II