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

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

3. Wireless Standards Date Rates and Deployment
WP1:II

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

5. Wireless Protocol Stacks
ZigBEE/ STACK
BLUETOOTH STACK
OSI Model
STACK
STACK
WP1:II

6. General Comparison ZigBee vs Bluetooth
ZigBee/IEEE 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

7. WPAN Protocol Comparison
ZigBee
Bluetooth
Ultra Wide Band
Data rate
20, 40, and 250 Kbps
1 Mbps
Mbps
Range
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

8. General comparison 802.11 Versus 802.16
Widely deployed
Up to 54 Mbps on 20 MHz (802.11n supplement up to 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 i)
Up 100 Mph Mobility ( p 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( e)
Space Time Coding (2 TX + 1 Rx)
Power control (sleep & awake)
2-60 GHz (licensed & unlicensed)
WP1:II

9. WLAN & WMAN Protocol Comparison
Wi-Fi
(802.11)
Fixed WiMAX
( )
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

10. 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