scholarly journals Channel Assignment Mechanism for Multiple APs Cochannel Deployment in High Density WLANs

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jianjun Lei ◽  
Jianhua Jiang ◽  
Fengjun Shang
Keyword(s):  
Channel Assignment ◽  
Loss Rate ◽  
Time Slot ◽  
Local Area ◽  
Network Capacity ◽  
Vertex Coloring ◽  
Distributed Coordination ◽  
Slot Allocation ◽  
Distributed Coordination Function ◽  
Coordination Function

In Wireless Local Area Networks (WLANs), cochannel deployment can bound channel access delay and improve network capacity due to mitigating the collision and interference among different Access Points (APs). In this paper, we present a network model and an interference model for multiple APs cochannel deployment and propose a channel assignment mechanism which formulates the channel assignment problem into a time slot allocation problem. Meanwhile, we assign the channel based on the vertex coloring algorithm and make extra polls by utilizing the time slot reservation strategy to improve the channel assignment. Furthermore, we optimize the polling list of APs through classifying the clients to improve the channel utilization. The simulation results show that our proposed algorithm can improve the performance in terms of network throughput, transmission delay, and packet loss rate compared with the DCF (Distributed Coordination Function) and TMCA algorithms.

Enhanced Distributed Coordination Function of MAC for VoIP Services Using IEEE802.11 Networks

2012 ◽  
Vol 433-440 ◽  
pp. 2304-2309
Author(s):  
B. Suvarna Vignan ◽  
B. Lalu Naick
Keyword(s):  
Mac Protocol ◽  
Local Area ◽  
Contention Window ◽  
Collision Probability ◽  
Network Simulator ◽  
Distributed Coordination ◽  
Medium Access ◽  
Packet Collision ◽  
Distributed Coordination Function ◽  
Coordination Function

Voice over Internet Protocol (VoIP) is an important service with strict Quality-of-Service (QoS) requirements with in wireless local area networks. The popular Distributed Coordination Function (DCF) of IEEE802.11 Medium Access Control (MAC) protocol adopts Multiplicative Increase and linear Decrease procedure to reduce the packet collision probability in WLANs. In DCF, the size of contention window is doubled upon a collision regardless of the network loads. This paper presents an enhanced DCF scheme to improve the QoS of VoIP in WLANs. This scheme applies a threshold of the collision rate to switch between two different functions for increasing the size of contention window based on the status of network loads. The performance of this scheme investigated and compared to the original DCF using the network simulator NS-2. Under the high traffic loads the packet loss probability decreases with the enhanced DCF compared to the original DCF. Some other parameters like throughput and access delay is decreased with the enhanced DCF.

scholarly journals Latency and Jitter Analysis for IEEE 802.11e Wireless LANs

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Sungkwan Youm ◽  
Eui-Jik Kim
Keyword(s):  
Local Area ◽  
Ieee 802.11E ◽  
Distributed Coordination ◽  
Mac Layer ◽  
Medium Access ◽  
Distributed Coordination Function ◽  
Packet Latency ◽  
Coordination Function ◽  
The Voice

This paper presents a numerical analysis of latency and jitter for IEEE 802.11e wireless local area networks (WLANs) in a saturation condition, by using a Markov model. We use this model to explicate how the enhanced distributed coordination function (EDCF) differentiates classes of service and to characterize the probability distribution of the medium access control (MAC) layer packet latency and jitter, on which the quality of the voice over Internet protocol (VoIP) calls is dependent. From the proposed analytic model, we can estimate the available number of nodes determining the system performance, in order to satisfy user demands on the latency and jitter.

Improving WLAN Performance by Modifying an IEEE 802.11 Protocol

2013 ◽  
pp. 15-32
Author(s):  
Nurul I. Sarkar
Keyword(s):  
Ieee 802.11 ◽  
Ad Hoc ◽  
Packet Delay ◽  
Distributed Coordination ◽  
Bandwidth Utilization ◽  
Medium Access ◽  
802.11 Dcf ◽  
802.11 Networks ◽  
Distributed Coordination Function ◽  
Coordination Function

One of the limitations of the IEEE 802.11 distributed coordination function (DCF) protocol is its low bandwidth utilization under medium-to-high traffic loads resulting in low throughput and high packet delay. To overcome performance problems, traditional IEEE 802.11 DCF (“DCF”) protocol is modified to the buffer unit multiple access (BUMA) protocol. The BUMA protocol achieves a better system performance by introducing a temporary buffer unit at the medium access control (MAC) layer to accumulate multiple packets and combine them into a single packet (with a header and a trailer) before transmission. This paper provides an in-depth performance evaluation (by simulation) of BUMA for multiuser ad hoc and infrastructure networks. Results obtained show that the BUMA is more efficient than that of DCF. The BUMA protocol is simple and its algorithm (software) can be upgraded to 802.11 networks requiring no hardware changes. The BUMA protocol is described and simulation results are presented to verify the performance.

Distributed Approach for QoS Guarantee to Wireless Multimedia

2007 ◽  
pp. 195-201
Author(s):  
K. Chetan ◽  
P. Venkataram ◽  
R. Sircar
Keyword(s):  
Ieee 802.11 ◽  
Wireless Multimedia ◽  
Distributed Coordination ◽  
Access Method ◽  
Qos Guarantee ◽  
Distributed Approach ◽  
Research Areas ◽  
Distributed Coordination Function ◽  
Active Research ◽  
Coordination Function

Providing support for QoS at the MAC layer in the IEEE 802.11 is one of the very active research areas. There are various methods that are being worked out to achieve QoS at MAC level. In this article we describe a proposed enhancement to the DCF (distributed coordination function) access method to provide QoS guarantee for wireless multimedia applications.

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