scholarly journals Improving WLAN Performance by Modifying an IEEE 802.11 Protocol

2011 ◽  
Vol 1 (1) ◽  
pp. 15-31 ◽  
Author(s):  
Nurul I. Sarkar
Keyword(s):  
Ieee 802.11 ◽  
Ad Hoc ◽  
Packet Delay ◽  
Distributed Coordination ◽  
Bandwidth Utilization ◽  
Medium Access ◽  
802.11 Dcf ◽  
Traffic Loads ◽  
802.11 Networks ◽  
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.

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.

Throughput Analysis of IEEE 802.11 DCF with Modified Binary Exponential Backoff in Mobile Ad Hoc Networks

2010 ◽  
Vol 2 (3) ◽  
pp. 61-70
Author(s):  
Rishipal Singh ◽  
D. K. Lobiyal
Keyword(s):  
Wireless Networks ◽  
Ieee 802.11 ◽  
Spread Spectrum ◽  
Ad Hoc ◽  
Distributed Coordination ◽  
Medium Access ◽  
Binary Exponential Backoff ◽  
802.11 Dcf ◽  
Hoc Networks ◽  
Coordination Function

In the design of wireless networks, the medium access protocols have a very large impact on the performance of the network. The IEEE 802.11 is widely accepted technology for the Wireless LANs and is used by wireless networks. This paper presents an analysis of the performance of Distributed Coordination Function (DCF) for IEEE 802.11 under modified Binary Exponential Backoff (BEB) Algorithm using Frequency Hoping Spread Spectrum (FHSS). In the modified algorithm, the size of Contention Window (CW) has been changed with the factor of for the first four collisions and the size becomes double thereafter in each subsequent collision. This paper also covers the effects of various parameters in modified BEB Algorithm.

scholarly journals Enhancing the Selection of Backoff Interval Using Fuzzy Logic over Wireless Ad Hoc Networks

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Radha Ranganathan ◽  
Kathiravan Kannan
Keyword(s):  
Fuzzy Logic ◽  
Ieee 802.11 ◽  
Ad Hoc ◽  
Distributed Coordination ◽  
Medium Access ◽  
Ieee 802.11 Dcf ◽  
802.11 Dcf ◽  
Effective Manner ◽  
Distributed Coordination Function ◽  
Coordination Function

IEEE 802.11 is the de facto standard for medium access over wireless ad hoc network. The collision avoidance mechanism (i.e., random binary exponential backoff—BEB) of IEEE 802.11 DCF (distributed coordination function) is inefficient and unfair especially under heavy load. In the literature, many algorithms have been proposed to tune the contention window (CW) size. However, these algorithms make every node select its backoff interval between [0, CW] in a random and uniform manner. This randomness is incorporated to avoid collisions among the nodes. But this random backoff interval can change the optimal order and frequency of channel access among competing nodes which results in unfairness and increased delay. In this paper, we propose an algorithm that schedules the medium access in a fair and effective manner. This algorithm enhances IEEE 802.11 DCF with additional level of contention resolution that prioritizes the contending nodes according to its queue length and waiting time. Each node computes its unique backoff interval using fuzzy logic based on the input parameters collected from contending nodes through overhearing. We evaluate our algorithm against IEEE 802.11, GDCF (gentle distributed coordination function) protocols using ns-2.35 simulator and show that our algorithm achieves good performance.

A Markov Model for the IEEE 802.11 DCF under Limit Load

2011 ◽  
Vol 48-49 ◽  
pp. 29-33
Author(s):  
Sheng Guo Gao
Keyword(s):  
Markov Model ◽  
Load Condition ◽  
Packet Delay ◽  
Limit Load ◽  
Local Area ◽  
Distributed Coordination ◽  
Medium Access ◽  
802.11 Dcf ◽  
Significant Research ◽  
Coordination Function

Wireless Local Area Networks (WLANs) have been attracted significant research during the last few years. The primary medium access control (MAC) technique of 802.11 is called distributed coordination function (DCF). DCF is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. This paper proposes a new Markov model to analyze the CSMA/CA protocol and average packet delay. This model covers the finite load condition and saturation condition. The close agreement between the theoretical results and simulation results using NS-2 under reaffirms the accuracy of the analytical model.

scholarly journals StegoFrameOrder—MAC Layer Covert Network Channel for Wireless IEEE 802.11 Networks

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6268
Author(s):  
Krzysztof Sawicki ◽  
Grzegorz Bieszczad ◽  
Zbigniew Piotrowski
Keyword(s):  
Ieee 802.11 ◽  
Radio Channel ◽  
Covert Channel ◽  
Distributed Coordination ◽  
Medium Access ◽  
Deterministic Algorithms ◽  
802.11 Networks ◽  
Ieee 802.11 Networks ◽  
Network Channel ◽  
Coordination Function

The proposed StegoFrameOrder (SFO) method enables the transmission of covert data in wireless computer networks exploiting non-deterministic algorithms of medium access (such as the distributed coordination function), especially in IEEE 802.11 networks. Such a covert channel enables the possibility of leaking crucial information outside secured network in a manner that is difficult to detect. The SFO method embeds hidden bits of information in the relative order of frames transmitted by wireless terminals operating on the same radio channel. The paper presents an idea of this covert channel, its implementation, and possible variants. The paper also discusses implementing the SFO method in a real environment and the experiments performed in the real-world scenario.

scholarly journals Performance Analysis of Synchronous Multi-Radio Multi-Link MAC Protocols in IEEE 802.11be Extremely High Throughput WLANs

2020 ◽  
Vol 11 (1) ◽  
pp. 317
Author(s):  
Taewon Song ◽  
Taeyoon Kim
Keyword(s):  
Ieee 802.11 ◽  
Markov Chain Model ◽  
Careful Consideration ◽  
Mac Protocols ◽  
Media Access Control ◽  
Chain Model ◽  
Distributed Coordination ◽  
Media Access ◽  
Medium Access ◽  
Coordination Function

The representative media access control (MAC) mechanism of IEEE 802.11 is a distributed coordination function (DCF), which operates based on carrier-sense multiple access with collision avoidance (CSMA/CA) with binary exponential backoff. The next amendment of IEEE 802.11 being developed for future Wi-Fi by the task group-be is called IEEE 802.11be, where the multi-link operation is mainly discussed when it comes to MAC layer operation. The multi-link operation discussed in IEEE 802.11be allows multi-link devices to establish multiple links and operate them simultaneously. Since the medium access on a link may affect the other links, and the conventional MAC mechanism has just taken account of a single link, the DCF should be used after careful consideration for multi-link operation. In this paper, we summarize the DCFs being reviewed to support the multi-radio multi-link operation in IEEE 802.11be and analyze their performance using the Markov chain model. Throughout the extensive performance evaluation, we summarize each MAC protocol’s pros and cons and discuss essential findings of the candidate MAC protocols.

A Novel Delay Model for IEEE 802.11

2012 ◽  
Vol 263-266 ◽  
pp. 1032-1036
Author(s):  
Chun Shi ◽  
Xian Hua Dai ◽  
Zheng Jie Deng ◽  
Shu Qian He
Keyword(s):  
Ieee 802.11 ◽  
Function Analysis ◽  
Full Time ◽  
Delay Model ◽  
Distributed Coordination ◽  
Node Number ◽  
802.11 Dcf ◽  
Real Performance ◽  
Coordination Function ◽  
Inter Frame

With the popularity of the IEEE 802.11 standards, many analytical delay studies for the Distributed Coordination Function (DCF) have been reported. In this paper, we analyze the additional idle durations that a tagged node needs to wait due to other nodes transmissions. Separating the distributed inter-frame space (DIFS) and extended inter-frame space (EIFS) durations from the full time of a successful transmission, we provide a correct function analysis of the DIFS and EIFS durations and build a more accurate delay model for the IEEE 802.11 DCF. The theoretical analysis and simulation results prove that the proposed delay model is coincident with the real performance when the node number increases.

ANALISIS PERBANDINGAN KINERJA TRANSPORT PROTOCOL PADA WIRELESS LAN DENGAN MENGGUNAKAN METODE DCF DAN DCF

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
I Gusti Ngurah Dwi Mulyartha ◽  
Nurain Silalahi ◽  
Nyoman Bogi A. K.
Keyword(s):  
Ad Hoc Network ◽  
Wireless Lan ◽  
Ad Hoc ◽  
Transport Protocol ◽  
Distributed Coordination ◽  
Mac Layer ◽  
Medium Access ◽  
Distributed Coordination Function ◽  
Infrastructure Network ◽  
Coordination Function

EEE 802.11 adalah protokol standar yang digunakan pada wireless LAN dan memiliki Medium Access Control (MAC) layer yang mendukung pengiriman data tak sinkron (asynchronous) untuk jaringan wireless baik pada infrastructure network dan ad hoc network. MAC menggunakan dua metode akses yaitu Point Coordination Function (PCF) dan Distributed Coordination Function (DCF), dimana DCF dikembangkan menjadi DCF+. Penelitian ini mensimulasikan ad hoc Network menggunakan perangkat bantu Borland Delphi dan dari hasil simulasi dianalisa performansi dari MAC dengan membandingkan parameter Throughput, Delay, Goodput dan Fairness antara metode DCF dan DCF+.

scholarly journals Enhancing MAC performance of DCF protocol for IEEE 802.11 wireless LANs

2017 ◽  
Vol 68 (1) ◽  
pp. 83-86
Author(s):  
Woo-Yong Choi
Keyword(s):  
Access Control ◽  
Medium Access Control ◽  
Ieee 802.11 ◽  
Wireless Lans ◽  
Medium Access Control Protocol ◽  
Distributed Coordination ◽  
Medium Access ◽  
Distributed Coordination Function ◽  
802.11 Wireless Lans ◽  
Coordination Function

Abstract The DCF (Distributed Coordination Function) is the basic MAC (Medium Access Control) protocol of IEEE 802.11 wireless LANs and compatible with various IEEE 802.11 PHY extensions. The performance of the DCF degrades exponentially as the number of nodes participating in the DCF transmission procedure increases. To deal with this problem, we propose a simple, however efficient modification of the DCF by which the performance of the DCF is greatly enhanced.

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