Developing
Applications on Top of Wireless
Standards
(CDMA, GSM, 3G, Wireless LAN,
Bluetooth and UWB)
Click
here to view and execute the
VisualSim model
This
shows the topology of a WiFi
network in VisualSim with the
Application processing for the
Access Node. The Task_Issue
block is the behavior block
that communicates with the hardware
and software resources.
Click here to view the interactive
VisualSim Block Diagram and
model
The
VisualSim model of the application
processing flow diagram shows
the behavior mapping to the
platform resources. These resources
can be on-chip or discrete components.
Modifying the parameters provides
the specific implementation.
Once
a technology has been standardized
by IEEE, ETSI, ITU or the industry
consortiums, companies providing solutions
for these market have to differentiate
on the applications offered. The standard
itself will be mass-produced by the
lowest cost provider. Wireless LAN
technologies such as 802.11 (WiFi),
Bluetooth and Ultra Wide Band (UWB)
got their beginnings in providing
a wire replacement for internet access
and digital data communications. The
transfer rate robustness, high performance
using embedded microprocessors and
dropping price points are making these
viable for audio and video applications
such as audio streaming, video conferencing,
and gaming. To accommodate the data
rate characteristics as a function
of distance on top of a Wireless network,
the issues associated with wireless
contention from other same network
users, and the added functionality
of audio or video processing must
be evaluated.
Evaluating
such applications are not simply an
issue of analyzing the hardware or
software platforms. The network and
protocols impacts can be drastic in
such issues are fragmentation, network
latency, throughput, contention and
time-jitter. Moreover the protocols
requirements must be consolidated
with the hardware and software of
the application.
This
example considers a set of applications
running on top of a Wireless LAN system.
The Wireless LAN protocol is based
on the model that is also available
from the demonstration
page. Please refer to the Wireless
Example System for more details on
the Wireless LAN protocol modeling.
The model has the hardware-software
defined at only the Access Point.
The current model can be easily modified
to add any application-specific instructions.
Moreover the protocols can also be
replaced with any other standard.
Model
Overview
A behaviour block called Task_Issue
has been added at the top-level for
the Access_Point. This block transfers
the request in the form of an incoming
Data Structure to the associated HW_SW_Proc
resource block just above. The communication
is made through the Virtual Connection
capability of VisualSim. The application
execution resource has been modeled
as a hierarchical block. The resource
is shown in the second Applets.
The
application has an Instruction Set
with four (4) instructions- Read,
Write, Block and Non-Block. The instructions
can be executed on a µProcessor
or custom ASIC. Both of these solutions
require access to the Cache and memory.
The ASIC and µP has been modeled
separately to accommodate for on-chip
cache modeling. The flow of data is
similar for both the ASIC and µP
flows as shown below:
Modifying
Parameters to create new scenarios
All the parameters available from
the Wireless LAN System are available
in this model. This includes frame
size, fragmentation limit, node frequency,
DIFS and SIFS delays, traffic rate
and Frame_Size_Bytes. In addition,
the following are available in the
HW_SW_Proc block:
