rajala,
Major claims requires major proofs.
Capacity in RF communication systems usually refers to the data rate measured in bits per second that can be sent. The late Claude Shannon captured the entire problem in a single equation relating data rate, bandwidth and noise. Modern bandlimited systems compress the source material before modulation. This leads to an apparent increase in capacity. There has been a long history of work on voice compression with the challenge that the final measurement of performance is subjective. Voice quality is, in general, inversly related to compression ratio. Higher ratios of compression lead to lower voice quality.
So, AMR is a new compression scheme, and leads to less bits sent for voice users. This would not have any effect on the number of voice users that could be supported. Ahh wait, from the documents it appears what will happen is the users will signal to reduce their timeslots. This has been the challenge for GSM, improved compression had NO benefit until it cut the number of timeslots needed.
GSM systems use time slots with time guard bands. Due to light speed delay it has been impossible to reassign these time slots for transmitters with no voice data. Data users, with less sensitivity to latency, could reassign the slots.
So, again, what capacity are you referring to?
Paul
"AMR codecs (4.75 - 12.2kHz, GSM EFR=12.2kHz)"
(love this one: from uwcc.org)
"A new revelation from the carrier were plans to introduce Adaptive Multirate Codec technology in its GSM base stations and handsets, which is expected to quadruple GSM voice capacity similar to the expected increases from the CDMA migration path. VoiceStream announced a deal with Nortel Networks to develop similar technology for its network."
And no doubt you won't appreciate this one from the five principles
W-CDMA is expected to use the Adaptive Multi-Rate (AMR) codec, which uses a degenerate and less effective method than true variable rate vocoding. The AMR transmission rates can be adapted to the channel and source conditions by using signaling, a far slower and cruder method of control. In contrast, the true variable rate codec canadapt its rate on a frame-by-frame basis without the need for signaling while incorporating the advantages of seamless channel control. This flexibility of variable rate vocoding permits the rate to be instantaneously lowered when the source contains greater redundancy, increasing capacity. Furthermore, the mobile station using variable rate vocoding can autonomously reduce its transmission rate to increase range when at the edge of coverage. |
