At the WAVES lab, we use real channel traces for our experimental
evaluations. The trace collections are performed over various wireless
settings and using different standards according to the nature of
experiment. Here is one of the examples. If you are interested in using
these traces or collaboration in future experiments please
contact me. The leader of this project was
Shirish Karande.
IEEE80211b Trace
Collection
Five wireless receivers were used to simultaneously collect
error traces on an 802.11b WLAN. These receivers are placed in different
locations in a room (see the figure). The access
point (AP) is located across the hallway from the room. A wired sender is
used to send multicast packets with a predetermined payload on the WLAN;
multicasting disabled MAC layer retransmissions. Each trace comprised of
one million packets with
a payload of 1,000 bytes each. At the physical layer, the auto rate
selection feature of the AP was disabled and for each experiment the AP was
forced to transmit at a fixed data rate.
Each trace collection experiment was repeated for different
physical layer (PHY) data rates (i.e., 2Mbps, 5.5 Mbps
and 11Mbps). For a specific PHY data rate, we have collected traces
using four transmission rates: 500kbps, 750kbps,
900kbps and 1024kbps respectively. We collected 41 traces over
different receivers.
We used Prism 2.5 Chipset WiFi adapter which allows us to modify the
receiver's MAC layer device to pass corrupted packets to higher layers. To
capture packets at high transmission rates, packet dissectors were
implemented inside the device drivers. These packet dissectors ensured that
only packets pertinent to our wireless experiment are processed, while all
other packets are dropped. In addition to a packet header and payload
information, for each packet two additional parameters (1)
Signal strength (S), (2)
Silence Value (N) were logged at the
receivers. These parameters are used to calculate the
Signal to Silence Ratio (SSR) value (SSR =
S - N) observed with each packet.
Note: The description of
other projects will be added after the trace collection is finalized.
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This site was last updated
01/19/09
