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

To: samim anbarcioglu who wrote (5511)	12/16/2000 10:24:11 AM
From: John Walliker	Read Replies (1) \| Respond to of 197001

samim, Air interface means physical layer. While GPRS does have a physical layer, GPRS itself is not a physical layer, it is a service that uses the physical layer. However, GPRS does modify the GSM physical layer in some important ways. One of these is in the use of multiple timeslots which has a large impact on the thermal design of the handset transmitter circuits. Existing handsets allow the output stage to cool between each transmission pulse - this is not possible to the same extent with GPRS, so more efficient heatsinks are needed. John

To: samim anbarcioglu who wrote (5511)	12/16/2000 11:54:01 AM
From: Eric L	Respond to of 197001

Re: GPRS IS an Air Interface << GPRS itself is not a physical layer, it is a service that uses the physical layer >> Indeed GPRS is a bearer service and it is a data overlay of an existing network. It is also an air interface. You can call it whatever you like but in the context in which I originally used it (on another thread) that usage was correct. << In re: "GPRS involves overlaying a packet based air interface on the existing circuit switched GSM network" ... That sentence is simply incorrect >> Given your in depth knowledge of GSM & GPRS you might want to take that up with the author, Simon Buckingham of Mobile Lifestreams Limited who authored an extensive overview GPRS that can be linked from the GSMA web site. Using basic ITU-T definitions, telecommunication services can be divided into bearer services, teleservices, and supplementary services. The most basic teleservice traditionally supported by GSM is telephony. Voice telephony is supported in GSM using a circuit switched air interface. SMS data, and group 3 facsimile are bearer services, and they are also supported by this traditional circuit switched air interface. In an evolved GSM network with General Packet Radio Service packet switched data is supported by new bearer services AND a new packet switched air interface. The implementation of GPRS impacts on all three major components of the traditional GSM platform (MS, NS, BSS) and the mobile radio link. << The air interface that GPRS is designed on top of, is Time Division Multiple Access, which is what GSM uses as its air interface. >> To be more precise GSM is a combination of Time and Frequency Division Multiple Access (TDMA/FDMA). The FDMA part involves the division by frequency of the (maximum) 25 MHz bandwidth into 124 carrier frequencies spaced 200 kHz apart. One or more carrier frequencies are assigned to each base station. Each of these carrier frequencies is then divided in time, using a TDMA scheme. Samim, I post regularly on this thread and the Nokia thread. A discussion of an evolved GSM network or GPRS is more appropriate to the Nokia thread than this one. Lets take further discussions of this subject matter there please, so as not to interrupt the flow of discussion here which focuses on QUALCOMM & CDMA. Please note that the original comment that started this discussion was made by me on a thread devoted to investing theory, and it linked a post I made on another wireless thread. Earlier you commented, "GPRS is NOT an air interface. Anybody who says it is, does not what the hell he is saying." >> Perhaps I underestimate your knowledge of mobile wireless network architecture but you have failed to demonstrate to me, in any way shape or fashion, that you know what you are "saying". You may also want to reread (for better comprehension) the article I linked that discusses "GPRS: Architecture, Protocols, and Air Interface", and in particular the 3 sections that describe the GPRS air interface, noting the differences between the traditional GSM "A-interface" and the new air interface that supplements it for packet data services. I leave you to ponder Simon Buckingham's statement that *"GPRS involves overlaying a packet based air interface on the existing circuit switched GSM network".* I assume that we are in agreement that UMTS UTRA (W-CDMA),and the cdma2000 components, 1xRTT and 1xEV, are high speed/capacity air interfaces that will be used to deliver IP connectivity.? ... and so it is with GPRS, although in this case the packet data transmission rates provided by the air interface are lower. Prosperous investing, - Eric -