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IEEE 802.11 MAC/PHY layer modelling

We have proposed an analytical model named distance aware (DAW), that accounts for the positions of stations with respect to the access point while evaluating the performance of the IEEE 802.11 MAC layer (MAC/PHY modelling). In this model, given the position of one station, the DAW model computes the saturation throughput of wireless network, while conditioning on the positions of the other concurrent stations. This model is helpful to dimension 802.11 wireless access networks and to study their capacities and performances.

Accomplishments:

  • M.H. Manshaei, G. R. Cantieni, C. Barakat, T. Turletti, "Performance Analysis of the IEEE 802.11 MAC and Physical Layer Protocol", IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), June 2005, Taormina/Giardini Naxos.

IEEE 802.11 Rate Adaptation Mechanism

We have elaborated several rate adaptation mechanisms for the 802.11 standards (in particular, cross layer algorithms between MAC and PHY layer). After some practical experiments with available 802.11 wireless cards, we realized some important characteristics of the 802.11 systems that must be taken into account to design rate selection mechanisms.

Three mechanisms have been proposed in this field named, adaptive auto rare fallback (AARF), closed-loop adaptive rate allocation (CLARA), and adaptive multi rate retry (AMRR). AARF has very low complexity while obtaining performance similar to very complex rate selection mechanisms like RBAR, which requires incompatible changes to the 802.11 MAC and PHY protocols as well. CLARA is a culmination of the best attributes of the transmitter-based ARF and the RBAR control mechanisms with additional practical features to facilitate multipath fading channel sensing and feedback control signalling. AMRR has been implemented and evaluated on an AR5212-based device.

Accomplishments:

  • C. Hoffmann, M. H. Manshaei, T. Turletti, "CLARA: Closed-Loop Adaptive Rate Allocation for IEEE 802.11 WirelessLANs ",  IEEE International Conference on Wireless Networks, Communications, and Mobile Computing (WIRELESSCOM), June 2005, Maui, Hawaii.

  • M. Lacage, M.H. Manshaei, T. Turletti, "IEEE 802.11 Rate Adaptation: A Practical Approach", ACM International Symposium on Modeling, Analysis, and Simulation of Wireless and Mobile Systems (MSWiM), October 2004, Venice.

  • M. Lacage, M.H. Manshaei, T. Turletti, "IEEE 802.11 Rate Adaptation: A Practical Approach",  INRIA Research Report, No 5208, May 2004.

Multimedia Transmission over IEEE 802.11

We worked towards the optimization of real time multimedia transmission over IEEE 802.11 based networks. In particular, we have proposed a simple and efficient cross layer algorithm, named media oriented rate selection algorithm (MORSA), for dynamically selecting the transmission mode that considers both the channel conditions and characteristics of the media. An evaluation of this mechanism for mobile ad hoc networks (MONETs) has been provided using simulations with NS-2. The video quality obtained with a fine grain scalable video encoder based on a motion-compensated spatio-temporal wavelet transform has been analyzed as well. The transmission of a sample video flow over an 802.11a wireless channel was evaluated with MORSA and compared with the traditional approach in this part of my thesis.
 

Accomplishments:

Group Member Authentication in Wireless ad-hoc Networks

This project concerned the group member authentication in wireless ad-hoc networks. Our main contribution during this project was the analysis of secure group communication in MANETs and the elaboration and implementation of a group member authentication protocol. This protocol uses Zero Knowledge Proof for group membership verification, and Threshold Cryptography for managing a secret group key in MANETs. The protocol implementation showed possible communication model and relatively reasonable performance, and therefore this work would give opportunities for making significant and realistic contributions in the real use of secure group communication in MANETs.
 

Accomplishments:

  • H. Asaeda, M. Rahman, M. H. Manshaei, and Y. Fukuzawa, "Implementation of Knowledge-based Group Member Authentication in Mobile Ad-hoc Networks," in Proceeding of IEEE WCNC, Las Vegas, April 2006.

802.11a simulation with NS-2
 

Have a look to the Yans project aiming to improve simulation of wireless networks (towards the next generation of NS-2).
 

Accomplishments:

  • M.H. Manshaei, T. Turletti, "Simulation-Based Performance Analysis of 802.11a Wireless LAN", International Symposium on Telecommunications (IST), August 2003, Isfahan.