[e2e] Opportunistic Scheduling.

[Detlef Bosau]

Hi to all.

Some weeks ago, I asked some questions about this topic on the e2e-list. 
  Perhaps, the TCCC list might be more appropriate. However, I´m not 
quite sure. So, if I´m completely wrong here, I would appreciate if 
someone can please give me a hint.

I refer to systems like the Qualcomm 1xEV-DO wireless system, i.e. to 
systems with a high data rate TDM downlink from a base station (BS) to 
several (mobile) terminals (UE) and dedicated CDMA uplinks from the UE 
to BS.

To my understanding, at BS there is one queue per UE. All queues are 
served in turn and the question is which scheduling mechanism is 
appropriate.

Now, there is a huge amount of literature about this issue and perhaps I 
cannot place all of my questions into this one post, but let me please 
ask the following few.

1. In uplink direction, CDMA is used. To my understanding, the use of 
CDMA requires a rather precise channel state model at least for the 
purpose of propper power control. So the question is: Can I reasonably 
assume a channel model on each terminal which particularly allows the 
terminal to identify periods of "locally high SNR", i.e. periods of 
constructive interference when Rayleigh fading is considered, and 
periods of "locally low SNR", i.e. periods with destructive interference 
respectively?

To my understanding, each terminal issues a "data rate control" message 
once in a time slot and the content of this message could be derived 
from such a channel model.

Is this correct?

2. When I look at the "opportunistic scheduling" algorithm as used e.g. 
by Jalali, Padovani and Pankaj, I honestly do not understand how the 
rationale of Kelly´s "Charging and Rate Control for Elastic Traffic" 
paper does apply to this algorithm.

Could someone please give me some hints on this one?

Thanks

Detlef