Presentation on theme: "Frame control duration address 1 address 2 address 4 address 3 payloadCRC 226662 6 0 - 2312 4 seq control 802.11 frame: addressing Address 2: MAC address."— Presentation transcript:
frame control duration address 1 address 2 address 4 address 3 payloadCRC seq control frame: addressing Address 2: MAC address of wireless host or AP transmitting this frame 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 3: used only in ad hoc mode
Internet router AP H1 R1 AP MAC addr H1 MAC addr R1 MAC addr address 1 address 2 address frame R1 MAC addr AP MAC addr dest. address source address frame frame: addressing
frame control duration address 1 address 2 address 4 address 3 payloadCRC seq control Type From AP Subtype To AP More frag WEP More data Power mgt RetryRsvd Protocol version frame: more duration of reserved transmission time (RTS/CTS) frame seq # (for reliable ARQ) frame type (RTS, CTS, ACK, data)
Wireless MAN: Compared to –provides a communications path between a subscriber site and a core network – hooks up buildings –Distances involves several kilometers –Signal strength varied widely among buildings –Each cell have many more users than 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.
Bluetooth: 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 Effective range of Bluetooth devices is 32 feet (10 meters). Data at the rate of 1 Mbps Compared to –Slow,Low Power, and Short range –Master / slave architecture, no collision
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