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To: mmeggs who wrote (19714)	12/14/1998 2:45:00 PM
From: Clarksterh	Read Replies (2) \| Respond to of 152472

mmeggs - There is no "backwards compatibility" to IS-41 or GSM, as these are both TDMA based systems. No. Just FYI. IS-41 is a spec on the communication between different ground components. It is almost completely independent of the air interface. The confusing point is that 'GSM' in normal usage encompasses both an air interface and a ground interface (although there is actually a separate spec for the GSM ground interface it is rarely talked about separately from GSM as a whole.). Clark

To: mmeggs who wrote (19714)	12/15/1998 1:32:00 AM
From: Ramus	Read Replies (2) \| Respond to of 152472

mmeggs, Your logic is correct here. In fact, I thought I would give you a little direct evidence showing that W-CDMA is not as robust or state of the art as CDMA-2000. This is not my opinion or the opinion of the CDG. These are the conclusions of the people who wrote the ETSI UTRA W-CDMA proposal and the CDMA-2000 proposal<gg>. In response to question A1.3.1.5.2 in part "what is the information capacity per cell"... to break this down we can look at the Erlangs/MHz/Cell for the Uplink and Downlink Erlangs/MHz/Cell RL / FL W-CDMA 26.1/21.4 see page 131 of proposal CDMA-2000 29/36.7 see page 241 of proposal *higher numbers mean higher capacity This is for voice services and means that the CDMA-2000 Cell can support more voice calls than W-CDMA. Now, consider that this is based on an 8kbps vocoder rate for W-CDMA and a 9.6kbps vocoder rate for CDMA-2000. This means that the CDMA-2000 cell supports more users and they are using a higher data rate. This implies that the CDMA-2000 cell has an even greater data capacity than the W-CDMA cell. The really neat thing to realize is that the CDMA-2000 cell uses 10% less spectrum than the W-CDMA cell in doing this. Plus, with the ability to mix and match 1XRTT and 3XRTT the CDMA-2000 system will be much more efficient and versatile than W-CDMA in any spectrum allocation. What? This can't be true can it? Why? Well here are some reasons. Question A1.4.9 asked about signaling overhead. "Describe the estimated fixed signaling overhead" In other words, some of the system capacity will be used for internal use...to configure the system. W-CDMA states:2.8% up to 25% in downlink and 5.9 to 33% in uplink. CDMA-2000 states: about 5% (do you suppose 2.5% each for UL/DL) Another possible reason is the use of asynchronous signaling in W-CDMA. It is well known that asynchronous signaling yields higher bit error rates(reduced system capacity) than synchronous signaling (as used in IS-95 and CDMA-2000). And another possible reason: The W-CDMA proposal stipulates the use of concatenated Reed-Solomon/convolutional coding. And mentions that more state of the art "Turbo" coding schemes are under consideration but are not implemented. The CDMA-2000 proposal specifies the use of "Turbo" codes and specifically describes their implementation. This item struck me when I first read it. W-CDMA is being touted as a new technology that is leading the pack into 3G. On the contrary, This type of concatenated Reed-Solomon/convolutional coding scheme was (to my knowledge) first used in deep space probes going back to the 1960's. I worked at a company some years ago ( building V-sat data modems) where concatenated Reed-Solomon/Viterbi convolutional coding was used. In fact, DirectTV which was developed in the early 90's uses this type of coding scheme. On the other hand Turbo codes represent the state of the art. I can't imagine why ETSI UTRA W-CDMA would consider using anything less than Turbo codes. Especially when they tout W-CDMA as being so advanced. So mmeggs, your conclusions are correct "ergo ipso facto, no reason cdma2000 cannot be THE converged standard." Walt

To: mmeggs who wrote (19714)	12/15/1998 10:24:00 AM
From: Raymond	Respond to of 152472

mmeggs "P.S. Your example of why 3g systems are "not just broader pipes" applies equally to both W-CDMA and cdma2000, no? How will W-CDMA overcome this problem where cdma2000 inherently won't?" I haven't said that cdma2000 will not overcome it.They will of course make the necessary changes in the IS41 core networks to accommodate cdma2000 if that is chosen as a standard.What I am saying that it's very difficult to merge the IS-41 and GSM standards so you could use exactly the same signals from the mobile when accessing GSM core networks and IS-41 networks.I think that in this area you need to have some sort of dual mode mobile anyhow. /R