ellis@uunet.uu.net (John T Ellis) (02/11/91)
Digital cellular will increase capacity in the following manner. The first method under development (and actually being tested) is TDM - Time Division Multiplexing. The capacity increase on paper is 3:1 (3 times more than current analog). The other method being looked at is CDM - Code Division Multiplexing. On paper it is said to provide an increase of 20:1. The biggest problem with these new technologies is the size of the phone needed to implement them. Currently the phone designs call for some huge ie. garbage can, phone with an unbelievable power source. So ... digital cellular is a ways off. Motorola is currently working on a new technology called NAMPS - Narrow band Advanced Mobile Phone Service. This is an analog technology that will increase capacity of current analog systems 3:1. Hope this helps. John T. Ellis 708-632-7857 Motorola Cellular motcid!ellis@chg.mcd.mot.com
svoboda@uunet.uu.net (David Svoboda) (02/12/91)
One capacity limitation of current cellular is available bandwidth.
By lowering the bandwidth required by each speech channel, the total
capacity may be increased while maintaining the current total
bandwidth allotment of cellular. Assuming that a digital transmission
of raw PCM data would require roughly the same bandwidth as the
corresponding analog signal, the PCM speech data can be compressed by
DSP techniques to require less bandwidth.
In fact, as the US standard now stands, a souped-up LPC technique is
used to achieve a robust three to one capacity increase per RF channel
over analog.
Dave Svoboda, Motorola CID, RTSG, Arlington Heights, IL
uucp => {uunet|mcdchg|att}!motcid!svoboda
internet => svoboda@void.rtsg.mot.comdave@westmark.westmark.com (Dave Levenson) (02/12/91)
In article <74390@bu.edu.bu.edu>, telpc!tel@cdsdb1.att.com writes: > Could someone please post something describing how digital cellular will > increase capacity? My supervisor and others in my group were trying to > figure it out. The proposed digital standards would multiplex three voice channels on each radio channel, thus trippling the traffic capacity of each existing cell site with no increase in spectrum space. Dave Levenson Internet: dave@westmark.com Westmark, Inc. UUCP: {uunet | rutgers | att}!westmark!dave Warren, NJ, USA AT&T Mail: !westmark!dave Voice: 908 647 0900 Fax: 908 647 6857
af@sei.ucl.ac.be (Alain FONTAINE (Postmaster - NAD)) (02/15/91)
On 11 Feb 91 14:37:15 GMT John T. Ellis said: >The biggest problem with these new technologies is the size of the >phone needed to implement them. Currently the phone designs call for >some huge ie. garbage can, phone with an unbelievable power source. >So ... digital cellular is a ways off. Really? Did you see the size of a CD player two years before they were on sale? I mean, not only the player on top of the big table, but also the stuff hidden under the table... AF
meier@uunet.uu.net (Rolf Meier) (02/16/91)
In article <16804@accuvax.nwu.edu> John T Ellis <motcid!ellis@chg. mcd.mot.com> writes: > Digital cellular will increase capacity in the following manner. The > first method under development (and actually being tested) is TDM - > Time Division Multiplexing. The capacity increase on paper is 3:1 (3 > times more than current analog). The other method being looked at is > CDM - Code Division Multiplexing. On paper it is said to provide an > increase of 20:1. Neither of these methods increases the capacity of digital modulation compared to analog modulation. The REAL reason for capacity increase for digital modulation is that low bit-rate encoding (8 kb) has been proposed for digital cellular. In addition, digital modulation allows for better-defined cell boundaries, due to the increased "capture" quality of digital modulation. All the CDM proposals employ low-bit rate encoding. This confuses the issue when trying to compare it to other methods of modulation which may use 32 kb encoding. Rolf Meier Mitel Corporation