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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 (15256)	9/27/2001 12:24:16 PM
From: mightylakers	Respond to of 197227

BR and rkral, about TD-SCDMA sync. In CDMA(2000), all the basestations are time synced with a universal time reference so that each basestation can use a different time offset in the psudo random sequence they used for signal spreading. In CDMA(2000), all the basestations are using the same PN sequence but with different offsets. In WCDMA all the basestations are using different PN sequence with different time offset. But either way, a phone need to get sync up with the basestation so that it knows what PN sequence the serving basestation is using(in CDMA2k this is saved) and the time offset. Only after that a phone can talk and receive from the basestation. In TD-SCDMA, there will be no basestation side of syn, just like in WCDMA. What is does is to make the mobiles to transmitting at the fixed timeslots to reduce the interference level, although not by that much I believe. Because to have a synced transmission is important for reducing the walsh code inter symbol interference, for PN code it is not that significant. And on the reverse link the mobiles are not differentiated by the walsh code but rather by different PN codes. doesn't soft handoff become difficult or impossible? That's why WCDMA is having problem with HO performance. Because the mobile need to find more variables to determine what is in the adjacent cells, namely the time reference and PN code sequence.