3 research outputs found
On the Optimal Transmission Scheme to Maximize Local Capacity in Wireless Networks
We study the optimal transmission scheme that maximizes the local capacity in
two-dimensional (2D) wireless networks. Local capacity is defined as the
average information rate received by a node randomly located in the network.
Using analysis based on analytical and numerical methods, we show that maximum
local capacity can be obtained if simultaneous emitters are positioned in a
grid pattern based on equilateral triangles. We also compare this maximum local
capacity with the local capacity of slotted ALOHA scheme and our results show
that slotted ALOHA can achieve at least half of the maximum local capacity in
wireless networks.Comment: This work has been presented in the 4th IFIP Wireless-Days conference
(WD 2011
An Overview of Local Capacity in Wireless Networks
This article introduces a metric for performance evaluation of medium access
schemes in wireless ad hoc networks known as local capacity. Although deriving
the end-to-end capacity of wireless ad hoc networks is a difficult problem, the
local capacity framework allows us to quantify the average information rate
received by a receiver node randomly located in the network. In this article,
the basic network model and analytical tools are first discussed and applied to
a simple network to derive the local capacity of various medium access schemes.
Our goal is to identify the most optimal scheme and also to see how does it
compare with more practical medium access schemes. We analyzed grid pattern
schemes where simultaneous transmitters are positioned in a regular grid
pattern, ALOHA schemes where simultaneous transmitters are dispatched according
to a uniform Poisson distribution and exclusion schemes where simultaneous
transmitters are dispatched according to an exclusion rule such as node
coloring and carrier sense schemes. Our analysis shows that local capacity is
optimal when simultaneous transmitters are positioned in a grid pattern based
on equilateral triangles and our results show that this optimal local capacity
is at most double the local capacity of ALOHA based scheme. Our results also
show that node coloring and carrier sense schemes approach the optimal local
capacity by an almost negligible difference. At the end, we also discuss the
shortcomings in our model as well as future research directions.Comment: This work has been accepted to appear in Springer Telecommunication
Systems journal. Part of this work was also presented at the Wireless Days
2011 and WMNC 201
Optimizing the Medium Access Control in Multi-hop Wireless Networks
We study the problem of geometric optimization of medium access control in
multi-hop wireless network. We discuss the optimal placements of simultaneous
transmitters in the network and our general framework allows us to evaluate the
performance gains of highly managed medium access control schemes that would be
required to implement these placements. In a wireless network consisting of
randomly distributed nodes, our performance metrics are the optimum
transmission range that achieves the most optimal tradeoff between the progress
of packets in desired directions towards their respective destinations and the
total number of transmissions required to transport packets to their
destinations. We evaluate ALOHA based scheme where simultaneous transmitters
are dispatched according to a uniform Poisson distribution and compare it with
various grid pattern based schemes where simultaneous transmitters are
positioned in specific regular patterns. Our results show that optimizing the
medium access control in multi-hop network should take into account the
parameters like signal-to-interference ratio threshold and attenuation
coefficient. For instance, at typical values of signal-to-interference ratio
threshold and attenuation coefficient, the most optimal scheme is based on
triangular grid pattern and, under no fading channel model, the most optimal
transmission range and network capacity are higher than the optimum
transmission range and capacity achievable with ALOHA based scheme by factors
of two and three respectively. Later on, we also identify the optimal medium
access control schemes when signal-to-interference ratio threshold and
attenuation coefficient approach the extreme values and discuss how fading
impacts the performance of all schemes we evaluate in this article.Comment: To be submitte