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          Spectrum Efficiency

          I understand the need and desire for rohc in cellular systems as this is where the majority of the near-term use and revenue will come from.  I am interested in seeing the developments be useful for both aeronautic and space-based networks if possible.  That is, I believe we should attempt to ensure that the compression techniques can be utilized other communications networks as well as for cellular.  I believe this is already stated in the charter. 

          I would like the group to reconsider the definition of spectrum efficiency in draft-ietf-rohc-rtp-01.txt and whatever other drafts may use this definition.  I believe this definition is overly cellular specific and somewhat inaccurate.

          ?Spectrum efficiency

              Radio resources are limited and expensive. Therefore they must be
              used efficiently to make the system economically feasible. In
              cellular systems this is achieved by maximizing the number of users
              served within each cell, while the quality of the provided services
              is kept at an acceptable level. A consequence of efficient spectrum
              use is a high rate of errors (frame loss and residual bit errors),
              even after channel coding with error correction.?

          I suggest the following:

          Spectrum Utilization (Cellular)

              Radio resources are limited and expensive. Therefore they must be
              used efficiently to make the system economically feasible. In
              cellular systems this is achieved by maximizing the number of users
              served within each cell, while the quality of the provided services
              is kept at an acceptable level.


          I suggest removing the following statement, as I believe this is more a statement of the way cellular system maximize the revenue producing aspects of spectral utilization.

              ?A consequence of efficient spectrum
              use is a high rate of errors (frame loss and residual bit errors),
              even after channel coding with error correction.?


          I believe this may be a better definition for spectrum efficiency:

          Spectrum efficiency

          The amount of useful information that can be transmitted over a given spectrum (bandwidth) over a given period of time.  For modem designers, spectrum efficiency is defined as the amount of bits per second per bandwidth.  For packet communications systems, bandwidth efficiency can be defined as the amount of useful user packet transmitted per second per bandwidth  excluding overhead.  The difference being that one can have a network with good spectral efficiency at layer at two that results in a poor spectral efficiency when considering layer three.  For a given BER, burst errors are more desirable than a binomial distribution of errors when considering packet communications.



          Will Ivancic


          from: http://www1.ietf.org/mail-archive/web/rohc/old-archive/msg00579.html

          posted on 2005-06-22 13:07 weidagang2046 閱讀(549) 評論(0)  編輯  收藏 所屬分類: Communication


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