Digital Signal Processing Reference
In-Depth Information
Fig. 6.7
A smart radio design approach spans multiple layers with corresponding performance
metrics. The case study demonstrates the energy management methodology in the 802.11a WLAN
setting
Fig. 6.8
At design-time, a Cost, Resource and Quality profile is determined for each set of control
dimensions based on the system state. The optimal Cost-Resource-Quality trade-off is derived from
this mapping to give operating points used at run-time
respectively, and the generality of this mapping. A resource (respectively cost, qual-
ity) profile describes a list of potential resource (respectively cost, quality) alloca-
tion schemes resulting from each configuration point. These profiles are then com-
bined to give a Cost-Resource-Quality trade-off, which is essential for solving the
resource allocation problem (Fig.
6.8
). The Cost-Resource-Quality trade-off func-
tion represents the behavior of a specific system for one user in a given system
state.
Cost profile properties
•
The finite set of discrete control dimension configurations can be ordered by
their increasing cost.
•
The overall system cost,
C
net
, is defined as the weighted sum of costs of
all flows, where each flow can be assigned a certain weight depending on
its relative importance or to improve fairness [86]. Users may be assigned
higher weights for example when their battery capacity is low or when they
downscale their transmission rate by decreasing the video quality and get re-
warded for reducing the network congestion. Users with a higher weight will
typically be allowed to save more energy compared to other users:
C
net
=
i
=
1
ω
i
C
i
.
