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As an action item on the last conference call I agreed to draft
a list of activity factors for different applications in the usage scenarios.
First pass for discussion is below. The activity factor is the percent of time
(averaged over a long period) that the radio interface needs to transmit to
support the application and I added the typical time that a session would last.
I assumed a 110 Mbps capability and a MAC layer throughput efficiency of 70%. If
these assumptions are incorrect the numbers in the table can be scaled. If the
PHY bit rate is doubled, the activity factor is halved. Some applications will
use very little air time so the interference risk is low as in video
conferencing, audio or internet browsing. On the other hand a stream from a
digital camcorder uses nearly 80% of the full capacity of the air interface
during the viewing time, and is much more likely to cause interference to
another receiver within range.
Regards,
David
David
Baddeley
Motorola SPS
207 rte de Ferney
1218 Grand-Saconnex,
Geneva
Switzerland
Tel +41 22 7991 216
GSM: +41 (0)79
3100401
Table - PHY Layer utilization in
time
|
Application |
Ave. Data
Rate (Mbps) |
Peak Data
Rate (Mbps) |
QoS |
PHY Activity
Factor1 (%) |
Session
duration |
|
Digital
Video
Distribution |
|
|
|
|
|
|
SDTV
, DVD, MPEG-2 |
6 |
10 |
yes |
8 |
1.5
h |
|
Dig
Camcorder |
|
60 |
yes |
78 |
30
min |
|
HDTV |
20 |
25 |
yes |
25 |
1-3
h |
|
|
|
|
|
|
|
|
Digital
Image Transfer, |
|
77 |
no |
100 |
1-60
s |
|
High
Quality Audio |
1.5 |
2 |
yes |
2 |
1
h |
|
Data
Network (Printer, Internet) |
0.5 |
10 |
no |
1 |
1
h |
|
PC
Graphics Distribution |
4 |
100 |
yes |
5 |
1
h |
|
Video
Conferencing |
1 |
1.5 |
yes |
1 |
30
min |
1Estimated
average fraction of time the PHY emits assuming 110Mbps rate and that max
throughput = 0.7x(bit rate)