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 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.


The dei80211mr library for the Network Simulator 2 has been developed
by (in alfabetical order):

Nicola Baldo         (
Federico Maguolo     (
Simone Merlin        (

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 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


[1] Ilango Purushotaman and Sumit Roy, 
"IEEE802.11 implementation Issues in Network Simulator 2", 
Dept. of Electrical Engineering, University of Washington, US

[2] Patch for Loading Dynamic Modules in ns-2,

[3] ns-MIRACLE: Multi InteRfAce Cross Layer Extension for