Why Wireless is Different Herb Little Research In Motion

Why Wireless? Anytime, Anywhere computing RIM BlackBerry –Give customers access to their own data –Secure corporate and PIM –Always On, Always Connected

Why Wireless is Different Fundamental differences –Bandwidth –Error Rate –Latency and Variability –Power Constraints

Wireless Limitations Mobile device Network Regulatory

Device Limitations Power consumption –Idle: 300  A –CPU: 10 mA –Receiving: 50 mA –Transmitting: 1700 mA

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

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

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

Regulatory Limitations FCC, Industry Canada –Allocate spectrum –Responsible for device approval Specific Absorption Rate

Wireless vs. Wired Networks User expectations Error rates Throughput –Sensitive to protocol overhead –Compression Latency –Battery saving protocols –SAR

Wireless vs. Wired Networks Unknown network connectivity –Out of coverage –One way coverage Battery Life –Avoid chatty applications/protocols –No keep-alive messages

Wireless vs. Wired Networks Internet Protocols are typically not optimal for wireless networks –Too chatty –Too much overhead –Timeouts too tight

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