1 Part 4 Wireless Network Wireless Technologies Wireless Networks Wireless Computer Networks Personal Mobile Networks Industry Use Wireless Networks

2 Wireless Technology Basics Medium: -- Air Types of Waves used for wireless communications Infrared Radio Wave Microwave Satellite Wired communication, directions fixed between sender and receiver Wireless communication, goes to all directions as long as there is an receiver configured with the right frequency

3 Comparison of wired and wireless comm. WiredWireless Bandwidth Depending on the media used, can be large Narrow in general, regulated by FCC (Federal Communication Commission, US government agency.) Signal receptionReliable due to dedicated link Unreliable, signal can be blocked, reflected SecurityHigh, difficult to tap in Everyone within the range can intercept the message InterferenceVery little Significant because all share the same medium: air MobilityNoYes Cost Changes dramatically in recent years. Depending on the technology. Keep tracking. ExpansionAdd wiresAdding relays, etc.

4 Comparison of Different Wireless Wave Bandwidth: a measure of frequency range and is typically measured in hertz. Central concept in data communication. Larger bandwidth = more channel to communicate simultaneously  faster

5 Multiplexing – Share communication channel TDMA – Time Division Multiple Access CDMA -- Code division multiple access Each can only talk in his assigned time slots. Have to agree upon when to talk. Both can talk together, using assigned codes, which insure that the two signals are orthogonal. So two can talk together. Complicated, but can be more efficient.

6 Wireless Computer Networks – Radio Frequencies Wireless Personal Area Networks (WPANs) Wireless Local Area Networks (WLANs) Extension: Wireless Mesh Network Wireless Metropolitan Area Networks (WMANs) Wireless Wide Area Networks (WWANs) Just Proposed. Wider…

7 Wireless Personal Networks Connecting Personal Devices Use Bluetooth Technologies Bluetooth = IEEE Can connect up to 8 devices within 10-meter area (~30 feet, yard) Transmission rate: ~1Mbps

8 Wireless LAN Wireless Local Area Network Mainly used for devices to communicate to Internet using “hotspots” – access points (APs) Technology: Wi-Fi = IEEE family Wireless-Fidelity: Industry standards for WLANs ~ 100 meters, 300 feet, 110 yards

9 Wi-Fi Family IEEE standards have a set of standards, use 2.4 GHz and 5 GHz frequency channel Faster due to multi-channeling Watch Microsoft video

10 Problems with Wi-Fi Roaming: currently hotspots are owned by a variety of vendors. Users cannot roam from hotspot to hotspot if use different Wi-Fi network Security: radio waves, easy to intercept, difficult to protect Survivability: currently intense competition. No viable and profitable business model yet.

11 Wireless MAN Wireless Metropolitan Area Networks Technology: Wi-Max = IEEE ~ 31 miles, 75 Mbps $349 per receiver Good for city-wide wireless deployment

12 Summary of RF Wireless Standards IEEE StandardA.K.ARangeSpeed WPANIEEE802.15Bluetooth~30 feet1Mbps WLANIEEE Wi-Fi~ 300 ft11~54Mbps WMANIEEE Wi-Max~ 30 miles75Mbps WWANIEEE802.20N/A>>30milesN/A

13 Computation: Company A is designing a new service used for travelers to download music to their handheld devices. They have the following choices of technologies to communicate between the music server and the personal handheld device. A) 10mbps Ethernet B) Bluetooth technology C) IEEE b D) IEEE g 1) Assume that the effective communication rate is 40% for all the above communication technologies. Also assume that the average size of a music file is 4MB per song. Estimate the time needed to download 15 songs. 2) Except for communication speed, discuss other pros and cons of implementing those technologies. Based on your discussion, give your choice. 3) Why Wimax is not being considered in this application?

14 Extension: Using Wi-Fi to Build WMAN Use Wi-Fi to create a Mesh Network What is mesh network? – discuss how to form a mesh using cables. Compare to the current WLAN with wireless-mesh Less number of access points Economical solution for rural area and developing countries Wired Network

15 Mobile Wireless Devices Use telephone network, satellite network, and other channels Wireless Application Protocols (WAP) Application level (5 th layer) protocol for small devices, Tiny screen Low bandwidth Minimal memory The new age of “M-Commerce”

16 Industry Wireless Applications Telemetry: sensor + antenna, measure remotely Used in dangerous, remote, inconvenient areas. Mesh: Wireless Sensor Networks RFID: Radio Frequency Identification Tags Future Fantasy: mote/dust

17 Business: Telemetry Services Information Right Where You Need It

18 After class reading A) The Road to WiMax To get more business information about WiMax development (Optional) blog your knowledge of WiMax and your opinions on the future of this technology. B) Network Applications How many major categories of network applications have been discussed in this material? Pick one category you are the most familiar with or the most interested in (based on your reading) and write a paragraph to discuss your understanding. Post your writing on the blog site.