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To: Clarksterh who wrote (2780)	10/27/1999 11:23:00 PM
From: wonk	Respond to of 13582

...Another mystery is why HDR boasts of 2.4Mbps peak only. Why is the average lower? This help? CDMA/HDR: A Bandwidth Efficient High Speed Wireless Data Service for Nomadic Users Paul Bender, Peter Black, Matthew Grob, Roberto Padovani,Nagabhushana Sindhushayana and Andrew Viterbi QUALCOMM, Incorporated TABLE I Data Rate Pckt Lgth FEC rate Modulation (bps) (Bytes) (Bits/symbol) 76.8 128 _ QPSK 102.6 128 _ QPSK 153.6 128 _ QPSK 204.8 128 _ QPSK 307.2 128 _ QPSK 614.4 128 _ QPSK 921.6 192 3/8 QPSK 1228.8 256 _ QPSK 1843.2 384 _ 8PSK 2457.6 512 _ 16QAM Figure 4 shows the bit-exact simulated performance of some of the modes from Table I on an AWGN channel and Table III summarizes the SNR required to achieve a 1% packet error rate. TABLE III Data Rate [kbps] Ec/Nt [dB] 76.8 -9.5 102.6 -8.5 153.6 -6.5 204.8 -5.7 307.2 -4.0 614.4 -1.0 921.6 1.3 1228.8 3.0 1843.2 7.2 2457.6 9.5 Slight problem for the system designer with the varying Ec/Nt, though. ww

To: Clarksterh who wrote (2780)	10/28/1999 3:31:00 AM
From: qdog	Respond to of 13582

Well, I haven't really given it much thought, other than I knew that the hype surrounding data wasn't informationally being fully disseminated, but now I'm curious and will have to sit down to ponder this in more depth. The top of my head answer, which is coming from the hip, on the original GSM/CDMAOne probably evolves around component capabilities at the time or something to do with the interconnect to the wired infrastructure. Originally, GSM was to emulate ISDN, hence I would think that horizontal type thinking was present through its evolution. Now most designs are looking to interface to ATM networks. I'm sure the factors are probably a combination of things. Peak infers perfect. Its debatable that it will be achieved in a mobile environment. Fixed maybe, but even that is debatable, perfect that is.