Why Wireless is Different

1
Why Wireless is Different

• Herb Little
• Research In Motion

2
Why Wireless?

• Anytime, Anywhere computing
• RIM BlackBerry
• Give customers access to their own data
• Secure corporate email and PIM
• Always On, Always Connected

3
Why Wireless is Different

• Fundamental differences
• Bandwidth
• Error Rate
• Latency and Variability
• Power Constraints

4
Wireless Limitations

• Mobile device
• Network
• Regulatory

5
Device Limitations

• Power consumption
• Idle 300 ?A
• CPU 10 mA
• Receiving 50 mA
• Transmitting 1700 mA

6
Device Limitations

• Battery technology
• Getting better
• Power saving protocols
• Devices go to sleep for long periods
• Half duplex vs. Full duplex radios
• Turnaround time

7
Device Limitations

• Transmitter strength vs. Receiver sensitivity
• One way coverage
• CPU cycles
• Compression, cryptography
• Commercial and marketing pressures
• Price, form factor, features

8
Network Limitations

• RF link bandwidth
• Bandwidth vs. Transmit power
• Bandwidth vs. Error control
• Mobitex 8kbps
• Shared
• 1200 baud in file transfer tests

9
Regulatory Limitations

• FCC, Industry Canada
• Allocate spectrum
• Responsible for device approval
• Specific Absorption Rate

10
Wireless vs. Wired Networks

• User expectations
• Error rates
• Throughput
• Sensitive to protocol overhead
• Compression
• Latency
• Battery saving protocols
• SAR

11
Wireless vs. Wired Networks

• Unknown network connectivity
• Out of coverage
• One way coverage
• Battery Life
• Avoid chatty applications/protocols
• No keep-alive messages

12
Wireless vs. Wired Networks

• Internet Protocols are typically not optimal for
  wireless networks
• Too chatty
• Too much overhead
• Timeouts too tight

13
Summary

• Wireless is different
• Internet protocols are not optimal for wireless
  networks
• Efficient applications can be achieved
• understand the device and network limitations
• tailor solutions