This document proposes a channel allocation algorithm to address the problem of asymmetric channel sensing and reserving in 802.11ac networks. It analyzes how contention parameters and packet length impact performance and cause unfairness. The algorithm models channel allocation as a graph coloring problem and uses a heuristic approach to eliminate the "hidden channel" problem while maximizing utilization. Simulations show it lowers packet error rates and increases throughput and fairness compared to other allocation schemes.
Cooperative load balancing and dynamic channel allocation for cluster based m...
A channel allocation algorithm for reducing the channel sensing reserving asymmetry in 802.11ac networks
1. A Channel Allocation Algorithm for Reducing the Channel
Sensing/Reserving Asymmetry in 802.11ac Networks
Abstract:
The major goal of IEEE 802.11ac is to provide very high throughput (VHT)
performance while at the same time guaranteeing backward compatibility.
To achieve this goal, 802.11ac adopts the channel bonding technique that
makes use of multiple 20MHz channels in 5GHz band. Due to the
heterogeneity of bandwidth that each device exploits, and the fixed total
transmission power in the standards, a problem called ‘Hidden Channel’
arises. In this paper, we first analyze the problem and show how the
contention parameters and transmission time affect collision probability
and fairness in some deployment scenarios.
Then, we propose a heuristic channel allocation algorithm that aims to
avoid such problematic situations effectively. Through simulations, we
demonstrate that our proposed channel allocation algorithm lowers the
packet error rate (PER) compared to uncoordinated and RSSI (Received
Signal Strength Indicator) based allocation schemes and increases the
network-wide throughput as well as the throughput of a station that
experiences poor performance. This implies improved fairness
performance among transmission pairs with various channel bandwidths.
2. Existing System:
The quality of the transmission could vary significantly causing unfairness.
Further, the fixed transmission power and the difference in CCA sensitivity
and bandwidth usage lead to asymmetric sensing/reserving situations
between two devices.
This implies that a transmission from a device may not be sensed by
another device while it is sensed in the other direction, so channel
reservation is successful only in one direction. We call this problem the
Hidden Channel (HC) problem throughput this paper. The HC problem
has basically originated due to the heterogeneity of the channel and
bandwidth usage.
Proposed System:
We analyze the asymmetric channel sensing/reserving situation from the
perspective of downlink communication, and illustrate via numerical
results how the contention parameters and the packet length impact
performance.
We use graph coloring to model the channel allocation problem, and prove
that the problem is NP-hard.
3. We present a heuristic algorithm that aims to eliminate the HC problem
while maximizing channel utilization.
We evaluate the performance of our heuristic algorithm with simulations.
To the best of our knowledge, this is the first work that explicitly deals with
channel allocation to alleviate the HC problem in 802.11ac networks.
Hardware Requirements:
• System : Pentium IV 2.4 GHz.
• Hard Disk : 40 GB.
• Floppy Drive : 1.44 Mb.
• Monitor : 15 VGA Colour.
• Mouse : Logitech.
• RAM : 256 Mb.
Software Requirements:
• Operating system : - Windows XP.
• Front End : - JSP
• Back End : - SQL Server
Software Requirements:
4. • Operating system : - Windows XP.
• Front End : - .Net
• Back End : - SQL Server
