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802.11 frame: addressing

6. 4. 2. 2. 6. 6. 6. 2. 0 - 2312. frame control. duration. address 1. address 2. address 3. address 4. payload. CRC. seq control. 802.11 frame: addressing. Address 3: used only in ad hoc mode. Address 1: MAC address of wireless host or AP to receive this frame.

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802.11 frame: addressing

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  1. 6 4 2 2 6 6 6 2 0 - 2312 frame control duration address 1 address 2 address 3 address 4 payload CRC seq control 802.11 frame: addressing Address 3: used only in ad hoc mode Address 1: MAC address of wireless host or AP to receive this frame Address 3: MAC address of router interface to which AP is attached Address 2: MAC address of wireless host or AP transmitting this frame

  2. router AP Internet R1 MAC addr AP MAC addr source address dest. address 802.3frame AP MAC addr H1 MAC addr R1 MAC addr address 3 address 2 address 1 802.11 frame 802.11 frame: addressing H1 R1

  3. 6 4 2 2 6 6 6 2 0 - 2312 frame control duration address 1 address 2 address 3 address 4 payload CRC seq control 2 2 4 1 1 1 1 1 1 1 1 Protocol version Type Subtype To AP From AP More frag Retry Power mgt More data WEP Rsvd 802.11 frame: more frame seq # (for reliable ARQ) duration of reserved transmission time (RTS/CTS) frame type (RTS, CTS, ACK, data)

  4. Compared to 802.11 provides a communications path between a subscriber site and a core network 802.16 hooks up buildings Distances involves several kilometers Signal strength varied widely among buildings Each cell have many more users than 802.11 More bandwidth should be allocated, at high frequency band Signal is more sensitive to weather Downlink: time slots Uplink: request-approval-release Guaranteed slots best effort slots. Wireless MAN: 802.16

  5. 802.16

  6. Used to wirelessly transfer data among devices. Original goal: get ride of the serial cable or USB cable. Upload picture from you cellular phone to desktop PC Wireless headphone… Short-range radio frequency (RF) technology Operates at 2.4 GHz Interfere with 802.11 Effective range of Bluetooth devices is 32 feet (10 meters). Data at the rate of 1 Mbps Compared to 802.11 Slow,Low Power, and Short range Master / slave architecture, no collision Bluetooth: 802.15

  7. Wireless Cellular Network • Primary for voice communication • Connected to ground telephone network. • Infrastructure-based network • Mobile station, Base station, mobile switching center, • Large coverage: a cell could span several miles long. • 1G, 2G, and 3G • Accessing technology: FDMA, TDMA, CDMA • Frequency reuse • How to reduce interference among cells, while maximize number of subscriber? • Issues: • Continuous service • No call dropping • Smooth handoff • Able to support reasonable concurrent subscribers: to make enough revenue. • Support data service

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