© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved. © The McGraw-Hill Companies, Inc. Wireless Network Technologies Asst. Prof. Chaiporn Jaikaeo, Ph.D. Computer Engineering Department Kasetsart University, Bangkok, Thailand Adapted from the notes by Lami Kaya

2 Electromagnetic Spectrum Government regulations make specific ranges of the electromagnetic spectrum available for communication A license is required to operate transmission equipment in some parts of the spectrum and other parts of the spectrum are unlicensed RF range

3 ISM Bands Industrial, Scientific, and Medical frequency band Can operate without FCC licenses Tx output power  1 watt Eliminate cost and time consuming for licenses 26 MHz 902 MHz 928 MHz 915 MHz* 100 MHz 2.40 GHz 2.50 GHz 2.45 GHz 150 MHz GHz GHz 5.8 GHz * Region 2 onlyRegion 2

4 Taxonomy of Wireless Networks

5 Wireless LANs and Wi-Fi IEEE provides most of the standards which are categorized as IEEE A group of vendors who build wireless equipment formed the Wi-Fi Alliance A non-profit organization that tests and certifies wireless equipment using the standards Alliance has received extensive marketing Most consumers associate wireless LANs with the term Wi-Fi

6 IEEE Standards StandardMax Speed Frequency Band Original Mbps2.4 GHz a54 Mbps5 GHz b11 Mbps2.4 GHz g54 Mbps2.4 GHz n600 Mbps 2.4 GHz and 5 GHz ac1.3 Gbps5 GHz

7 Wireless LAN Modes Ad hoc Wireless hosts communicate amongst themselves without a base station Infrastructure based A wireless host only communicates with an access point, and the access point relays all packets AP

8 8 Wireless LAN Architecture The three building blocks of an infrastructure wireless LAN are: Access Points (AP) An interconnection mechanism Such as a switch or router used to connect access points A set of wireless hosts Also called wireless nodes or wireless stations

9 Wireless LAN Architecture BSS – Basic Service Set

10 Overlap and Association If a pair of APs are too far apart A dead zone will exist between them If a pair of APs are too close together An overlap will exist A wireless host is required to associate with a single AP

WiFi Channels Channels in 2.4 GHz band are largely overlapping 11 Source: Wikipedia

12 Wireless MAN - WiMAX IEEE standards for wireless Metropolitan Area Network (WMAN) A group of companies formed WiMAX Forum to promote use of the technology Two main versions Fixed WiMAX Mobile WiMAX WiMAX = Worldwide Interoperability for Microwave Access

13 WiMAX Overview ISP Internet Backbone Line of sight transmission Non line of sight transmission Home WLAN Cell-like WiMAX towers

14 Wireless WAN – Cellular Systems Originally designed to provide voice services to mobile customers Currently being used to provide data services and Internet connectivity Source: Wikipedia

15 Cellular Coverage Perfect cellular coverage occurs if each cell is a hexagon because the cells can be arranged in a honeycomb In practice, cellular coverage is imperfect Ideal Realistic

16 Frequency Reuse Each cell in a given shape is assigned a unique frequency Not assign the same frequency to any pair of adjacent cells

17 Evolution of Cellular Systems 1G – analog cellular networks Began in the late 1970s, and extended through the 1980s Originally called cellular mobile radio telephones used analog signals to carry voice 2G – digital cellular networks Began in the early 1990s Uses digital signals to carry voice Standard: GSM (Global System for Mobile Communications) Circuit-switched voice communications Packet-switched data communications GPRS – General Packet Radio Services EDGE – Enhanced Data rates for GSM Evolution Source: Wikipedia

18 Evolution of Cellular Systems 3G – high-speed mobile broadband Began in the 2000s Focuses on the addition of higher-speed data services Standards: UMTS/HSPA  Europe and most of Asia CDMA2000  North America and South Korea 4G – high-speed all-IP-based mobile broadband Began around 2008 Standards: LTE (3GPP Long-Term Evolution) WiMAX Source: Wikipedia

19 Personal Area Networks (PANs) A PAN technology provides communication over a short distance It is intended for use with devices that are owned and operated by a single user between a wireless headset and a cell phone between a computer and a nearby wireless mouse or keyboard among appliances in home E.g., Bluetooth (IEEE ), ZigBee (IEEE )