3 sheets of handwritten notes, WHATEVER WE WANT amir's paper! 802.11 wifi stuff 802.11: FHSS, DSSS, IR, PHY b: DSSS, CCK a: DSSS, OFDM g: OFDM, PHY n: OFDM, PHY, MIMO types and adv talking about n part and MIMO multi in multi out spatial multiplexing, strong multipath channel transmission, inc bw and range, 2+ antennas, more cap over SISO large scale path loss: around corners and choke points beam forming (ooooh): controls directionality of tx, reduces interference, inc gain, save power, inc qual of nets and sigs spatial multiplexing: data divided between multiple antennas and sent over different spatial channels no additional bandwidth or power how does it work? advantages? ipv6 fun IP is apparently layer 5 128bit addresses better extension of options in header no header checksum auth and privacy caps ipsec encryption can use AES128, DES-CBC, 3DES-CBC this is at the IP layer instead of at tcp or application layer and now TCP is at layer 6 current tech allows tunneling of IPv6 traffic more about 802.11 from holtster... uses ISM band in 2.4ghz original uses FHSS and DSSS (direct sequence spread spectrum) 75 sub chans in 2.4ghz band DSSS allows higher throughput DSSS uses chipping to avoid interference (redundant bit patterns) barker sequence, 11 bits to rep a chip BPSK used for 1mbps rate, QPSK for 2mbps CCK (complementary code keying) for higher speeds dyn rate shifting, decreases speed for further distance and now bluetooth jinliu wang short range wireless comms personal area network devices classified according to range, 1/2/3 100m/10m/1m respectively basic unit is piconet one dev is a master, rest are slaves scatternet formed from multiple piconets slaves share clock of master uses 2.4ghz band 1mbps rate gfsk (gaussian freq shift keying) uses FHSS uses chips as well pattern only known to slaves and master carrier changes 1600 times a sec different chans in diff freqs 79 hopping chans of 1mhz 23 hopping chans of 1mhz low power consumption low cost easy to utilize high inherent net security can sometimes replace other techs like IR mobile phone accessories game console controllers mobile device sync p2p functionality on mobile devices scott hodges on OFDM (orthog freq div multiplexing) purpose higher data rate based on fdm serial modulation equalization in freq domain technobabble advantages digital domain instead of analog ISI reduced or elim flat fading disadv sensitivity to freq offsets sensitivity to phase noise large peak amp power ratio idea for it in 1966 data transmitted in parallel on diff freqs uses cyclic prefix for guard band freqs chosent to be ortho for given symbol period due to ortho, LTI channel reduces cross talk more efficient use of bw uses FFT and IFFT cyclic prefix maintains rx carrier sync, elims ISI, combats time dispersion comprehensive exam slight emphasis on recent material near 7 problems few to none written answer questions nothing complex with raised cosine, but need to know about rolloff factor possible equalizer problem yes to autocorrelation, convolution