1,361 research outputs found
Multi-Round Contention in Wireless LANs with Multipacket Reception
Multi-packet reception (MPR) has been recognized as a powerful
capacity-enhancement technique for random-access wireless local area networks
(WLANs). As is common with all random access protocols, the wireless channel is
often under-utilized in MPR WLANs. In this paper, we propose a novel
multi-round contention random-access protocol to address this problem. This
work complements the existing random-access methods that are based on
single-round contention. In the proposed scheme, stations are given multiple
chances to contend for the channel until there are a sufficient number of
``winning" stations that can share the MPR channel for data packet
transmission. The key issue here is the identification of the optimal time to
stop the contention process and start data transmission. The solution
corresponds to finding a desired tradeoff between channel utilization and
contention overhead. In this paper, we conduct a rigorous analysis to
characterize the optimal strategy using the theory of optimal stopping. An
interesting result is that the optimal stopping strategy is a simple
threshold-based rule, which stops the contention process as soon as the total
number of winning stations exceeds a certain threshold. Compared with the
conventional single-round contention protocol, the multi-round contention
scheme significantly enhances channel utilization when the MPR capability of
the channel is small to medium. Meanwhile, the scheme automatically falls back
to single-round contention when the MPR capability is very large, in which case
the throughput penalty due to random access is already small even with
single-round contention
Selecting source image sensor nodes based on 2-hop information to improve image transmissions to mobile robot sinks in search \& rescue operations
We consider Robot-assisted Search Rescue operations enhanced with some
fixed image sensor nodes capable of capturing and sending visual information to
a robot sink. In order to increase the performance of image transfer from image
sensor nodes to the robot sinks we propose a 2-hop neighborhood
information-based cover set selection to determine the most relevant image
sensor nodes to activate. Then, in order to be consistent with our proposed
approach, a multi-path extension of Greedy Perimeter Stateless Routing (called
T-GPSR) wherein routing decisions are also based on 2-hop neighborhood
information is proposed. Simulation results show that our proposal reduces
packet losses, enabling fast packet delivery and higher visual quality of
received images at the robot sink
Maximum Multipath Routing Throughput in Multirate Wireless Mesh Networks
In this paper, we consider the problem of finding the maximum routing
throughput between any pair of nodes in an arbitrary multirate wireless mesh
network (WMN) using multiple paths. Multipath routing is an efficient technique
to maximize routing throughput in WMN, however maximizing multipath routing
throughput is a NP-complete problem due to the shared medium for
electromagnetic wave transmission in wireless channel, inducing collision-free
scheduling as part of the optimization problem. In this work, we first provide
problem formulation that incorporates collision-free schedule, and then based
on this formulation we design an algorithm with search pruning that jointly
optimizes paths and transmission schedule. Though suboptimal, compared to the
known optimal single path flow, we demonstrate that an efficient multipath
routing scheme can increase the routing throughput by up to 100% for simple
WMNs.Comment: This paper has been accepted for publication in IEEE 80th Vehicular
Technology Conference, VTC-Fall 201
- …