Information Technology Reference
In-Depth Information
T
ABLE
IV
I
NPUT
P
ARAMETERS
Parameter
Value (default/range)
Number of objects on broadcast
5,120
Average number of classes along hierarchy
8
Percentage distribution of number of object in inheritance hierarchy
25
,
25
,
25
,
25%
Percentage distribution of number of objects in aggregation hierarchy
40
,
30
,
20
,
10%
Distribution of object size [S
,
M
,
L
,
VL]
16, 512, 3K, 6K bytes
Distribution of the object sizes in inheritance hierarchy
VL
,
L
,
M
,
S
S
,
M
,
L
,
VL
Distribution of the object sizes in aggregation hierarchy
Percentage of classes to be retrieved (default/range)
70% / [10-100%]
Average number of objects to retrieve per class
2
Fan-out in index tree
5
Average number of objects with distinct key attribute per class
60% of objects per class
Size of air-channel page
512 bytes
Broadcast data rate
1 M bits/sec
Power consumption active mode
130 mW
Power consumption doze mode
6.6 mW
Power consumption (switching channels)
13 mW
broadcast is searched.
Table V
shows the degradation factor of the average response
time due to the inclusion of an index in the broadcast. The factor is proportional to
the ratio of the size of the index blocks to that of the entire broadcast. However, this
degradation comes at the expense of drastic improvement in the energy consumption.
As can be seen there is a great deal of benefit, ranging from a factor of 17.5 to 19, in
including an index.
The simulator generated the response time for different broadcast organizations
(
Fig. 22
). From the figure, one could conclude that for both the inheritance and
aggregation cases, the response time of the hierarchical organization remained al-
most constant. This is due to the fact that regardless of the number of classes and
the location of the initial probe all accesses have to be directed to the beginning
of the index (at the beginning of the broadcast). The slight increase is attributed
T
ABLE
V
R
ESPONSE
T
IME
D
EGRADATION AND
E
NERGY
I
MPROVEMENT
D
UE TO
I
NDEXING
Aggregation/
Hierarchical
Aggregation/
Single
Inheritance/
Hierarchical
Inheritance/
Single
Response time degradation
1.17
1.05
1.1
1.02
Energy improvement
17.5
18.9
18.4
19
