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Dave et al:
Do you have any recommendations on were to set the target values for SSE?
6220 Sprint Parkway
Mailstop KSOPHD0504 - 5D276
Overland Park, KS 66251-6118
PCS (816) 210-9611
-----Original Message-----
From: Dave James (OAK Global) [mailto:djames@oak-global.com]
Sent: Tuesday, December 02, 2003 12:08 AM
To: Humbert, John J [NTWK SVCS]; 'Requirements Reflector'
Subject: RE: RE: stds-80220-requirements: Spectral Efficiency (4.1.2)
John et al:
A few points that relate to the market needs, the Requirements that are linked to this:
- I have consistently held the view that the issue of high physical speed is over-cooked here, reflected to some extent in the PAR, I have to say. It is not that it is totally needless to accommodate speeds like 180 kph, it is the weighting that we ascribe that concerns me .
- like the offered traffic, the speeds in practice are distributed over a fair range. But IMHO the speeds are generally skewed markedly for target markets to ambulant + modest vehicular speeds. In fact in many cases the user is essentially nomadic e.g. usage is often FWA - like but with advantage as per RLANs of no antenna directionality - and using appropriate technology thriving in a high-multipath etc., non LoS environments i.e. anywhere….
We can all think of special cases, but I think we should be careful about excess bias placed on higher physical speeds. As I mentioned at ABQ mtg., WAN + LAN makes a great combination looking ahead (.11 + .20) with suitable handover featured, but that does NOT mean that our .20 design should be compromised in its primary characteristics by skewing the overall AI approach to pander too much to high physical speeds. To a great extent markets are there today for what I refer to as ADSL/cable untethered (portable) e.g. portable wireless DSL, so to speak (PWDSL) I,e decent wired world experience now made un-wired, and not too much attention paid to comparison with conventional cellular legacy market and design thinking.
This is another reason I have got so frustrated over all the pre-occupation on mail traffic over the issue of detailed discussion of FDD extant spectrum for PCS. As I mentioned at ABQ, there are plenty of great applications in a number of bands internationally, we seem to endlessly drift into comparison with 3G and detailed usage of PCS bands. We are not 'addressing' 2G, 2.5G, 3G here surely.
I take note of your points, but again I see a danger in being overly specific about exactly how to specify UL, DL SE etc under all conditions and situations. Before we know it, we will have a 'camel = horse as designed by committee' syndrome. As we know, too, it is the overall combination of data rates, coverage, capacity and other parameters that is the key and not just one or two in isolation. We can bury ourselves in statistical simulations here, so for example, just to be clear: what constraints are we suggesting for the associated range and say traffic here for item 1) ? We need simple scenarios and sets of criteria. But proposals can surely also explain in due course more of the pros and cons of different arrangements and feature sets We surely don't mean such SEs as computed at the highest range and worst traffic mix and worst channel conditions and extremas for X ...and for Y…, true ?
BR, Dave
-----Original Message-----
From: Humbert, John J [NTWK SVCS] [mailto:owner-stds-80220-requirements@majordomo.ieee.org] On Behalf Of Humbert, John J [NTWK SVCS]
Sent: 01 December 2003 21:01
To: Requirements Reflector
Subject: RE: stds-80220-requirements: Spectral Efficiency (4.1.2)
Below is a proposal that addresses the remaining issues from the plenary meeting:
1) Set the target values to
Downlink: 2 bits/Hz/sector at 3 km/hr
Uplink: 1 bits/Hz/sector at 3 km/hr
Downlink: 1 bits/Hz/sector at 180 km/hr
Uplink: 0.5 bits/Hz/sector at 180 km/hr
Rational
1) The requirements for UL and DL data rates are not the same and it is assumed that both will use the same system bandwidth. If the same calculation for SE is applied to both the UL and the DL the UL will not have the same spectral efficiency as the DL. Also, if the two are blended together then it is possible for a proposal to have poor spectral efficiency in one direction masked by very good spectral efficiency in the other direction.
2) It is necessary to specify the SE at a given speed because the SE depends on the modulation used and the highest order modulation that can be transmitted is dependant on the speed of the mobile
3) Higher target values are needed because the SE degrades in a non-linear fashion, SE should be optimized across a range of speeds not for a particular speed.
4) The values for the 3 km/hr are set based achieving targets that are significantly better than what can be achieved by other technologies in the near future. (See the presentation from plenary)
John J. Humbert
6220 Sprint Parkway
Mailstop KSOPHD0504 - 5D276
Overland Park, KS 66251-6118
PCS (816) 210-9611