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<br />DRAFT 2.0 <br />04/30/97 <br /> <br />Khursheed Khan <br />St. Paul, Minnesota <br /> <br /> <br />Frequency and Time Domain Representations of FDM A, <br />TDM A, CDM A: unlike FDM A or TDM A, CDM A has multiple <br />users simultaneously sharing the same ""ide-band channel <br />(Qualcomm CDM A Engineering Handbook) <br /> <br />In a CDMA system, once the speech is processed and about to be transmitted over <br />the airwaves, it is "spread" by unique sequences of numbers (codes) which are <br />particular to different users. This spreading of each user's voice conversation by unique <br />codes is a means to lower the signal energy of each individual user's transmission and <br />to spread the energy across the 1.23 MHz of bandwidth allocated to each provider (for <br />transmission) in a specific market. One can notice instantly that the bandwidth of a <br />CDMA channel (1.23 MHz) is much larger than the corresponding bandwidth of a <br />logical FDMA channel (0.025 MHz or 25 KHz). Also, since everyone uses the same <br />frequency band, there are techniques particular to CDMA system implementation which <br />are used to decode this coded voice call at the intended destination. It is mentioned <br /> <br />4 <br />