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Re: stds-80220-requirements: Section 4.1.2 Spectral Efficiency





Hi Marianna,

I completely agree with you that the requirements document cannot 
hope to specify the many different parameters that feed into 
spectral efficiency. However (as I think Sameer pointed out) the 
target for spectral efficiency can mean different things depending 
on the "per cell" or "per sector" interpretation. Furthermore,
Faroukh made the timely comment that a baseline interpretation
would greatly simplify the work of the evaluation group. I therefore
see this area as one where the requirements document needs to be more 
specific to capture the true meaning of the requirement. I'm
certainly open to attempts to keep the requirement at a higher level.
Given that our PAR explicitly says "1 bit/sec/Hz/cell" I don't
see one right now. 

Also note that I have kept the requirement from explicitly mandating
that proposals be locked into a three sectored deployment model:

"Within this subsequent evaluation, proposals may submit respective
deployment models over and beyond the base configuration."


Mike 


On Thu, Nov 06, 2003 at 02:19:13PM +0200, Marianna Goldhammer wrote:
> Mike,
> 
> Both definitions are a mix of requirement / attempt to define conditions.
> 
> If you look at evaluation methodology used in 3GPP/2, there are tenths of
>  conditions influencing the spectral efficiency, still not addressing
>  sector/beam number and frequency planning issue.
> 
> I would propose to state in this document only the requirement. Should
>  be done a study to see which are the most appropriate deployment
>  architectures, for broadband data traffic, NOT limited by using the
> existing
>  cellular infrastructure (see Dan's e-mails).
> 
> And besides, the evaluation criteria should permit creative/advanced modes
>  of improving spectral efficiency. 
> 
> Marianna
> 
> -----Original Message-----
> From: Michael Youssefmir [mailto:mike@arraycomm.com]
> Sent: Thursday, November 06, 2003 9:45 AM
> To: Humbert, John J [NTWK SVCS]; stds-80220-requirements@ieee.org
> Cc: Michael Youssefmir
> Subject: stds-80220-requirements: Section 4.1.2 Spectral Efficiency
> 
> 
> 
> 
> Folks,
> 
> I was on tap for updating the text in this section
> to reflect the last requirements call. The general consensus on
> the call was to move forward with specifying a definition that
> would also lead to a baseline configuration for the evaluation
> group. (Please note previous recent text from Dan, Faroukh,
> and Samir on this section)
> 
> Current text
> 
> Sustained spectral efficiency is computed in a loaded multi-cellular network
> setting. It is defined as the ratio of the expected aggregate throughput
> (taking out all PHY/MAC overhead) to all users in an interior cell divided
> by the system bandwidth. The sustained spectral efficiency calculation
> shall assume that users are distributed uniformly throughout the network.
> 
> 
> [Downlink > 2 bps/Hz/sector]
> [Uplink >1 bps/Hz/sector]
> 
> Proposed Text
> 
> Sustained spectral efficiency is computed in a loaded multi-cellular network
> setting. It is defined as the ratio of the expected aggregate throughput
> (taking out all PHY/MAC overhead) to all users in a sector divided
> by the system bandwidth (the aggregate spectral allocation in use across
> the entire system). The sustained spectral efficiency calculation shall
> assume that users are distributed uniformly throughout the network
> and shall include a specification of the minimum expected data rate/user.
> 
> A fair comparison of the spectral efficiencies of different air interfaces
> can best be achieved for a single specified baseline configuration.  To
> facilitate the subsequent evaluation of different proposals for the 802.20
> air interface, the spectral efficiency of the 802.20 air interface shall
> be quoted as b/s/Hz/sector for a three sector baseline configuration.
> Within this subsequent evaluation, proposals may submit respective
> deployment models over and beyond the base configuration.
> 
> Consistent with the PAR requirement that is stated on a per cell basis and
> the definitions shown in Appendix A, the sustained spectral efficiency of
> the 802.20 air interface shall be greater than 1 b/s/Hz/sector.
> 
> Rationale
> 
> This proposal captures the need for a baseline comparison methodology
> for ease of evaluating various proposals. By establishing a baseline
> three sectored configuration, we also finesse the subtleties in
> the per cell or per sector nature of the definition of spectral
> efficiency.
> 
> [NOTE: The definition of "cell" in Appendix A states, "The term "cell"
> refers to  one single-sector base station or to one sector of a base
> station deployed with multiple cells."   As such, the PAR requirement of
> 1 bits/sec/Hz/cell is equivalent to 1 bits/sec/Hz/sector.
> The value established in the PAR and by the definition in the
> appendix through the definition: "Spectral efficiency: Spectral
> efficiency is measured in terms of bits/s/Hz/cell. (In the case
> of a sectorized configuration, spectral efficiency is given as
> bits/s/Hz/ sector.)"
> 
> The current text in the Requirements document -- Version 8c
> has:
>         downlink > 2 b/s/Hz/sector,  and
>         uplink > 1 b/s/Hz/sector
> 
> While these values are proposed in the current document. I could
> not find any  rationale for them on the list.  The Requirements Group
> still needs to agree on target values for spectral efficiency.
> ]
> 
> Mike
> 
> 
> 
> 
> 
>  
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