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Technology Stocks : Qualcomm Moderated Thread - please read rules before posting -- Ignore unavailable to you. Want to Upgrade?


To: rkral who wrote (20275)3/12/2002 6:46:11 PM
From: Eric L  Respond to of 197653
 
Ron,

<< The '3.84 MHz carrier bandwidth' number for WCDMA reminds me of a dilemma, at least for me. CDMA has a chip rate of 1.2288 Mcps and a channel spacing of 1.25 MHz, WCDMA has a chip rate of 3.84 Mcps and a channel spacing of 5 MHz. Why is the 'channel spacing:chip rate' ratio so much higher for WCDMA? It must have something to do with guardband requirements. Would a tech guru please shed light on this? >>

Hardly a tech guru but ...

... "actual "carrier spacing" for WCDMA is selectable on a 200khz grid between approximately 4.4 & 5 MHz, depending on interference between the carriers" - Peter Muszynski & Harri Holma , Chapter 3 "Introduction to WCDMA", in the Revised Edition of "WCDMA for UMTS" -

... expanded detail further into the book (which Qualcomm lifts from - earlier edition - for some of their charts) in sections related to multipath diversity, hierarchical cell structure, interference, etc..

- Eric -