151661
20190316234853.0
REP_WORK
Understanding and Tackling the Root Causes of Instability in Wireless Mesh Networks: (extended version)
2010
2010
19
Reports
A journal paper version of this work is under submission in the IEEE/ACM Transactions on Networking
We investigate, both theoretically and experimentally, the stability of CSMA-based wireless mesh networks, where a network is said to be stable if and only if the queue of each relay node remains (almost surely) finite. We identify two key factors that impact stability: the network size and the so-called "stealing effect", a consequence of the hidden node problem and non-zero transmission delays. We consider the case of a greedy source and prove, by using Foster's theorem, that 3-hop networks are stable, but only if the stealing effect is accounted for. We also prove that 4-hop networks are, on the contrary, always unstable (even with the stealing effect) and show by simulations that instability extends to more complex linear and non-linear topologies. To tackle this instability problem, we propose and evaluate a novel, distributed flow-control mechanism, called EZ-flow. EZ-flow is fully compatible with the IEEE 802.11 standard (i.e., it does not modify headers in packets), can be implemented using off-the-shelf hardware, and does not entail any communication overhead. EZ-flow operates by adapting the minimum congestion window parameter at each relay node, based on an estimation of the buffer occupancy at its successor node in the mesh. We show how such an estimation can be conducted passively by taking advantage of the broadcast nature of the wireless channel. Real experiments, run on a 9-node testbed deployed over 4 different buildings, show that EZ-flow effectively smoothes traffic and improves delay, throughput, and fairness performance.
Aziz, Adel
149125
242765
Starobinski, David
Thiran, Patrick
103925
240373
1372321
n/a
http://infoscience.epfl.ch/record/151661/files/aaziz-ToN10_extended_1.pdf
LCA
252614
US00024
LCA3
252454
U10431
oai:infoscience.tind.io:151661
report
IC
GLOBAL_SET
149125
149125
103925
EPFL-REPORT-151661
EPFL
PUBLISHED
REPORT