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- -*- Mode: text -*-
- ------------------
- About dei80211mr
- ------------------
- The dei80211mr library - nicknamed "multirate" for short - provides a
- 802.11 implementation for the Network Simulator Version 2. This
- implementations is derived from the 802.11 implementation included in
- NS 2.29 and aims at solving some known bugs as well as providing
- enhanced functionality.
- The dei80211mr library uses the Dynamic Library patch [2]. Thanks to
- the functionalities introduced by this patch, dei80211mr can be used
- with different versions of ns2. We have tested it with ns-2.29 and
- ns-2.31, and we expect it to work with future ns2 releases as well.
- -----------------------
- Authors
- ----------------------
- The dei80211mr library for the Network Simulator 2 has been developed
- by (in alfabetical order):
- Nicola Baldo (baldo@dei.unipd.it)
- Federico Maguolo (maguolof@dei.unipd.it)
- Simone Merlin (merlo@dei.unipd.it)
- At the time of this release (May 2007), all authors are with the
- Department of Information Engineering, University of Padova, Italy.
- --------------------------------------------------------------
- Improvements with respect to the 802.11 implementation in NS
- --------------------------------------------------------------
- - support for multiple PHY modes is included; in particolar,
- dei80211mr simulation of the different transmission rates, modulation
- and coding schemes defined in the IEEE802.11b/g standards.
- - a SINR-based packet level error model is introduced:
- + the RX Threshold variable which was used in the 802.11
- implementation included in standard NS to determine successful
- receptions has been removed. Instead, Packet Error Rate (PER) is
- used to determine random packet losses.
- + PER is calculated using pre-determined curves (PER
- vs SINR and packet size); the curves can be specified by the user
- via TCL. Some default curves for both 802.11g and 802.11b are provided.
- + SINR is calculated using received signal strength, noise and
- interference
- + interference is calculated using a gaussian model to account for
- all transmissions which happen simultaneously to the one which is
- considered for reception
- + noise power is set via TCL
- - the capture model, i.e. the determination of whether a packet can be
- received when there are other concurrent transmissions are
- simultaneously ogoing, is now embedded in the above mentioned
- interference model (no more Capture Threshold).
- - Some well-known bugs of the 802.11 implementation in NS have been
- resolved. With reference to [1], we solved the following bugs:
- + direct access denial
- + random backoff time
- + capture model (note: this is different from the point above since,
- as per the description in [1], it is actually a synchronization issue)
- - In the wireless channel, the affected nodes distance is no more
- determined using the CS threshold, but we used a fixed value in
- meters (distInterference_) which can be set at the beginning of the
- simulation. The reason is that, since we use a gaussian interference
- model, nodes well below the CS threshold often still provide a
- non-negligible contribution to interference. The default value for
- the affected nodes distance (distInterference_) is very
- conservative, so that all nodes are considered for interference
- calculation. This default value therefore yields accurate but
- computationally intensive simulations. The value can be adjusted via
- TCL to achieve different trade-offs between computational load and
- simulation accuracy.
- --------------------------------
- Origin of the name "dei80211mr":
- --------------------------------
- dei -> Developed at the Department of Information Engineering (DEI),
- University of Padova
- 80211 -> IEEE 802.11
- mr -> multirate
- -----------
- References:
- -----------
- [1] Ilango Purushotaman and Sumit Roy,
- "IEEE802.11 implementation Issues in Network Simulator 2",
- Dept. of Electrical Engineering, University of Washington, US
- http://ee.washington.edu/research/funlab/
- [2] Patch for Loading Dynamic Modules in ns-2,
- http://www.dei.unipd.it/~rossi/ns2-patch.html
- [3] ns-MIRACLE: Multi InteRfAce Cross Layer Extension for
- ns-2, http://www.dei.unipd.it/~rossi/miracle.html