Design and analysis of differentiated quality of service using multicarrier energy allocation. - Page 15 |
Save page Remove page | Previous | 15 of 178 | Next |
|
small (250x250 max)
medium (500x500 max)
Large (1000x1000 max)
Extra Large
large ( > 500x500)
Full Resolution
All (PDF)
|
This page
All
|
It is apparent that to transmit multimedia data with varying amounts of distortion,
data classes must have unique amounts of energy allocated to them. That is, classes
that have targets on the order of 1e¡3 require less energy than those with distortions
on the order of 1e¡6. One manner in which to transmit discrete classes is in a time-
division multiplex (TDM) sense, where classes can be allocated to timeslots. However,
this causes variation in transmit energy. This variation causes a °uctuation about
the operating point of the RF power ampli¯er (PA) causing a subsequent reduction in
the e±ciency of the device. For optimal e±ciency, the solution is to have a constant
envelope signal that can be driven at the ampli¯er saturation point. However, as
multicarrier modulation is not constant envelope, the next best solution is to maintain
uniform energy per slot, and simultaneously reduce the instantaneous energy within
a timeslot. Here, the focus is on reducing the inter-timeslot variation. Multiclass
allocation has this capability. With this method, multiple classes are all allocated in
the same timeslot, and their energy sum is the total energy per slot. Because there
is no variation in total energy, e±ciency is improved by driving the PA closer to the
saturation point.
1.2 Review of Previous Work
Early loading research [41],[8] was derived from an information theoretic point of view
and was targeted towards channel capacity considerations. These methods provide a
theoretical limit with regard to what is possible from a transmission point of view.
However, channel capacity specify a particular type of modulation. This in an issue
5
Object Description
Description
| Title | Design and analysis of differentiated quality of service using multicarrier energy allocation. - Page 15 |
| Repository email | cisadmin@lib.usc.edu |
| Full text | It is apparent that to transmit multimedia data with varying amounts of distortion, data classes must have unique amounts of energy allocated to them. That is, classes that have targets on the order of 1e¡3 require less energy than those with distortions on the order of 1e¡6. One manner in which to transmit discrete classes is in a time- division multiplex (TDM) sense, where classes can be allocated to timeslots. However, this causes variation in transmit energy. This variation causes a °uctuation about the operating point of the RF power ampli¯er (PA) causing a subsequent reduction in the e±ciency of the device. For optimal e±ciency, the solution is to have a constant envelope signal that can be driven at the ampli¯er saturation point. However, as multicarrier modulation is not constant envelope, the next best solution is to maintain uniform energy per slot, and simultaneously reduce the instantaneous energy within a timeslot. Here, the focus is on reducing the inter-timeslot variation. Multiclass allocation has this capability. With this method, multiple classes are all allocated in the same timeslot, and their energy sum is the total energy per slot. Because there is no variation in total energy, e±ciency is improved by driving the PA closer to the saturation point. 1.2 Review of Previous Work Early loading research [41],[8] was derived from an information theoretic point of view and was targeted towards channel capacity considerations. These methods provide a theoretical limit with regard to what is possible from a transmission point of view. However, channel capacity specify a particular type of modulation. This in an issue 5 |
