Fast Retransmission Mechanism for VoIP in IEEE e wireless LANs

Size: px
Start display at page:

Download "Fast Retransmission Mechanism for VoIP in IEEE 802.11e wireless LANs"

Transcription

1 Fast Mechanism for VoIP in IEEE e wireless LANs Gyung-Ho Hwang and Dong-Ho Cho Division of Electrical Engineering, Department of Electrical Engineering and Computer Science, KAIST, Guseong-dong Yuseong-gu Daejeon, Korea Abstract The IEEE wireless LANs provide cheap and high data rate mobile service. The voice service through wireless LANs has became important issue. The new IEEE e standard provides a framework to support quality of service(qos) according to the traffic types. The enhanced distributed channel access(edca) mechanism, that is contention-based access, has several access parameters which are able to give higher access probability to the high priority service. Since the real time service such as voice of IP(VoIP) has a delay constraint to guarantee a QoS, the fast collision resolution is required. In this paper, we review the IEEE e standard and propose a new fast retransmission mechanism for s to reduce the delay and improve the channel utilization by eliminating overhead time for backoff procedure. The simulation results show that the proposed scheme reduces the delay and dropping probability of s. I. INTRODUCTION Wireless LAN is very fascinate technology providing mobility and convenience. In the current world market, the IEEE compliant wireless LAN equipments are dominant. IEEE wireless LANs equipments have been extensively deployed in the recent years in many different environments. Moreover, many hotspots are covered with wireless LANs by mobile service providers. The current devices provide the best effort service with the transmission data rate up to 54Mbps at 2.4GHz and 5GHz bands. The main MAC protocol of IEEE is CSMA/CA that is a quite old protocol. But this protocol has got an attention since the IEEE wireless LAN is deployed[1]. The original DCF scheme does not support QoS, that is, it does not have any concept for the different priorities. So, the IEEE e task group(tg) was organized to make a scheme for providing QoS. The IEEE e draft provides a framework that can differentiate QoS between traffic categories according to their priority[2]. Since the IEEE e is organized, there have been many researches on the differentiation of quality of service(qos) in CSMA/CA-based original DCF scheme. In [7], the performance of the EDCA was simulated using three traffic types. But the access parameters were fixed and the effects of the parameters were not presented. Kuo et al. [8] provided an analytical model to study the expected bandwidth for each traffic class in EDCA scheme. Yamada et al. [9] presented a contention window control scheme to suppress the delay fluctuation of the real-time traffic, where the contention window size at retransmission is monotonically decreased in case that a queue has large waiting time. Romdhani et al. [10] proposed adaptive contention widow size control method in EDCA scheme, where the increase and the decrease factors of contention window size varies according to the service classes in case of retransmission. In [12], Hiraguri et al. proposed priority access scheme for s. But this proposed method is actually similar to current e EDCA scheme. The EDCA method is based on the original DCF scheme and it can differentiate the service classes by using a different access parameters. The support of voice over IP(VoIP) in wireless LANs should be the cutting edge issue because the price of wireless LAN equipments becomes lower and there is no wireless technology to provide such a high data rate like IEEE a. When VoIP is implemented in wireless LANs, the quality of voice service should be guaranteed. The rest of this paper is organized as follows. First of all, we describe the MAC protocol of the IEEE e wireless LANs focusing on EDCA scheme. Next, we propose the fast retransmission mechanism for s in case that VoIP and data traffics collide and we evaluate the performance of the proposed scheme compared with original IEEE e scheme using extensive simulation. Finally, conclusions and further works are presented. II. IEEE E EDCA SCHEME There are two main schemes for QoS support in the IEEE e standard. The hybrid coordination function(hcf), which is a coordination function of IEEE e, has two access schemes: HCF contention-based channel access, that is named as EDCA and HCF-controlled channel access. Generally, real time service such as voice call, is served through controlled or reservation-based channel access schemes. However, we can give a priority to real time traffic even in contention-based channel access scheme with IEEE e EDCA scheme. Moreover, in ad-hoc mode where there is no centralized control unit, the stations use the EDCA scheme to communicate s. In EDCA scheme, each user has several queues for different prioritized traffics and an access category(ac) is assigned to each traffic.

2 Each data frame has a specific priority and the MAC frame header contains its priority. In e standard, a station can have four ACs. Each frame arriving at the MAC with a priority is mapped into an AC as shown in Table. I where some abbreviations are referred from [5]. The main difference between EDCA and the DCF scheme is that each AC has its own IFS called as arbitrary IFS(AIFS), and minimum and maximum of contention window size. Namely, each AC has AIF S[AC], CWmin[AC] and CWmax[AC]. The AIF S[AC] is as follows. AIF S[AC] =AIF SN[AC] aslott ime + asif ST ime (1) Fig. 1 illustrates the EDCA scheme. The AIF SN[AC], CWmin[AC] and CWmax[AC] are announced by the QoS access point(qap) in the EDCA parameter set information element within beacons and probe response frames. But in adhoc mode where there is no AP, the stations use the default parameters. The default parameters in IEEE b physical layer are shown in Table II, where the AIFS s difference between AC VO and AC BE is 1 slot length. Therefore, the first slot after AIFS for voice packet, that is represented as AIF S v, is dedicated to voice traffic. DIFS/ AIFS Busy Medium PIFS SIFS AIFS[j] AIFS[i] DIFS Defer Access Slot time Contention Window Slots Fig. 1. EDCA Scheme in IEEE e Next Frame The smaller AIF S and CW values make the higher access probability. Therefore, the QAP can adapt these parameters according to traffic conditions. The new concept of a transmission opportunity(txop) is defined with a starting time and a maximum duration. When the medium is determined to be available under the EDCA TABLE I USER PRIORITY TO ACCESS CATEGORY MAPPINGS Priority UP 802.1D AC Designation Designation lowest 1 BK AC BK Background 2 - AC BK Background 0 BE AC BE Best Effort 3 EE AC VI Video 4 CL AC VI Video 5 VI AC VI Video 6 VO AC VO Voice highest 7 NC AC VO Voice rules, the station can transmit packets during TXOP. The duration of a TXOP in EDCA is limited by a TXOP limit distributed in beacon frames. Hence, the TXOP value is very important parameter that could determine the radio resource usage. However, we consider no TXOP concept in this paper and the EDCA-TXOP is defined as one packet transmission. III. VOICE OF IP PACKETS We consider the G.711 codec for generation of voice packets which has source bit rate of 64Kbps. The contains vocoder frame and many protocol headers. In case of IPv4, the RTP/UDP/IP header is 320 bits (40bytes) when the header compression is not used. If the header compression is used, the RTP/UDP/IP header is 16bits. We do not consider the header compression and the voice activity detection(vad). Therefore, we consider the voice traffic generating ( ) bits per 20 msec. The structure of in IEEE wireless LAN is shown in Fig.2. We set the delay bound of wireless access for s to 20 msec. This allows sufficient delay margin for the backbone network for an end-to-end delay budget. The QoS of VoIP traffic is defined as the loss rate of voice packets, P loss which is less than 1%. The P loss is defined as following. P loss = P overdelay + P retrylimit (2) where P overdelay is the dropping probability of voice packet in case that elapsed time for wireless access exceeds a predefined delay bound, and P retrylimit is the discarding probability of voice packet due to retry limit. PHY Preamble + Header 20byte 8byte 12 byte Depends on Codec & VAD MAC Header IP UDP RTP Voice Payload Fig. 2. VoIP Packet in wireless LAN MAC FCS IV. FAST RETRANSMISSION MECHANISM FOR VOIP To reduce the delay of s and collision probability, we propose a new fast retransmission scheme. Basically, the access probability of s can be adjusted by assigning AIF S, CW min and CW max. However, there still exist collisions and retransmissions are needed. To satisfy the delay constraints of s, the retransmission should be executed as quickly as possible. Moreover, the packets are discarded in case that the number of retransmission exceeds the pre-defined retry limit. Therefore, the collision probability should be minimized. TABLE II DEFAULT EDCA PARAMETERS IN IEEE B PHY Parameters AC VO AC VI AC BE AC BK AIFSN CWmin CWmax

3 First, let us consider the general situation where the VoIP packets collided with data packets. Normally, the length of is small compared with data packet. Consequently, user to transmit s may detect busy channel after completing its transmission if there is a longer data packet that is transmitted simultaneously. Using this information, the VoIP user can retransmit the packet without performing a backoff procedure. Fig.3 shows the general EDCA mechanism in case that two packets collide. The station A transmits a and station B transmits a longer data packet. If there s a collision between these two packets, the station A and station B should wait for Ack timeout interval. But, in view of station A, the ack timeout timer may expire during the data packet transmission and it can detect busy channel. If the ack timeout timer expires before completing data packet transmission, the station A starts backoff procedure as soon as the channel becomes idle. The station B performs a normal backoff procedure in this case. For other listening stations, there are a few situations. The station C listens a data packet s preamble but the frame check sequence is failed due to collision. So, the station C waits for EIFS time. On the contrary, the station D only detects the collision as busy signal. Therefore, the station D just waits for AIFS time before starting backoff procedure when it has pending voice or data packets. If it has pending s, the station D will wait for AIF S v time before decreasing backoff counter. Considering above all situations, the new fast retransmission is presented in Fig.4. The main motivation of this scheme is that the collision probability between VoIP and data packets is higher than collision probability between s because generally the concurrent number of VoIP sessions is small in one cell. The station A detecting the busy signal after transmitting its own, retransmits the after AIF S v time without backoff procedure. If either VoIP or data packets are received correctly, the station A can detect the Ack frame and the retransmission does not occur. Since voice traffic has delay bound, we should restrict the number of retransmission. We set the retry limit to three in this paper. As shown in Fig. 4, the first retransmission is done after channel becomes idle. The first slot after AIF S v is only dedicated to voice packets. Therefore, the collision with data packets does not appear. In case that the first retransmission fails, the second retransmission performs the original backoff procedure. Failing of the first retransmission indicates that there is a collision between s. When the station A detects no busy channel and ack timeout timer expires, original backoff procedure follows because it means that there may be other VoIP transmission of the same length. We apply this new fast retransmission scheme to only VoIP packets because the data users with small packet size may have high access probability and it can affect the delay of s against providing QoS. V. EVALUATION AND DISCUSSION For the performance evaluation, we use the OPNET tool. The simulation parameters are shown in the Table III. We consider only the ad-hoc mode where there is no AP. We use two access categories for performance evaluations. One is packet voice traffic that is delay sensitive service and the other is data traffic that is best effort service. Namely, both AC VO and AC BE in Table I are considered. The VoIP traffic has constant inter-arrival time of 20msec. The best effort traffic has exponential inter-arrival time with 12msec on the average that makes 1Mbps data load. We used the IEEE b physical specification which is widely deployed in wireless LAN equipments which supports up to 11Mbps data rate. The control packet such as ACK frame is also transmitted using the same data rate as data packet. s are able to be retransmitted up to 3 times and the retry limit for data packets is set to 7. The delay bound is 20 msec. When two or more packets collide, other receiving stations detect the transmissions as busy signal or frame check sequence(fcs) error according to receiving conditions. If the receiver detects busy signal, it starts the backoff procedure after detecting idle channel during AIF S time. But in case of FCS error, the receiver should wait for EIFS time. In this simulation, we give each case a half probability, that is, a half of listening stations experience FCS error due to the collision, which could be seen in the station C shown in Fig. 3 and a half of listening stations recognize the collision as just busy signal which could be seen in the station D shown in Fig. 3. The performances of the proposed scheme are shown in Fig.5 to Fig.8. We evaluate the performance with fixed VoIP users as increasing the number of data users. Fig.5 shows the average delay of s. The average delay means the elapsed time from arrival at MAC queue of the higher layer packet to correctly received time, that it, the sum of queueing delay and MAC transmission delay. As the number of data users increases, the delay also increases because the probability of collision with data packets becomes high. But the proposed fast retransmission scheme has shorter delay since the first retransmission is fast and avoids collision with data packets. In fact, the data user is saturated when the number of stations is over 5 which means that the data users always have a packet to transmit. The case of 10 voice users TABLE III PARAMETERS USED IN SIMULATIONS Parameters Symbol Value PHY(Data rate) 11Mbps Slot time T slot 20µsec SIFS time T sifs 10µsec AIFS for VoIP T aifs,v 50µsec AIFS for Data T aifs,d 70µsec Propagation delay T prodely 1µsec Delay Bound T delaybound 20µsec size L voip 200 byte Data packet size L data 1500 byte

4 EDCA mechanism Station A Detect BUSY signal Station B Data packet AIFS_d Listening Station C FCS error Wait EIFS time Listening Station D BUSY signal AIFS Data/VoIP Packet Fig. 3. s s collision with Data packets in EDCA scheme Fast Mechanism Station A Detect BUSY signal No First No ACK & Detect BUSY signal Normal Second Collided with other VoIP packet No BUSY signal Station B Data packet Fig. 4. Fast Mechanism for s has longer delay than that of 5 voice users, which is analogical. We classify the dropping rate into two types. One is due to retry limit and the other is due to delay bound. The dropping rate of s due to retry limit is shown in Fig. 6. The fast retransmission scheme has lower dropping rate since the first retransmission makes collision probability low and reduces the number of retransmissions. Fig. 7 shows the dropping rate of s due to delay bound. In simulation, the s are discarded in cases that either waiting time in queue or delay of received VoIP packet exceeds the pre-defined delay bound. Like Fig.6 the proposed scheme shows better performance. We consider that the sum of two dropping rates determines the QoS of VoIP service and use 1% packet loss as QoS constraint. Satisfying the constraint, the original scheme supports about 15 data users but fast retransmission scheme is able to support 40 data users in case that 5 voice users exist. Finally, we evaluate the channel utilization of data packets, which means the used time for successfully transmitted data packets over total simulation time, which is shown in Fig. 8. The channel utilization decreases as the number of data users increases because the collision probability becomes high which wastes the channel resource. The data utilization with 5 voice users is much higher than that with 10 voice users. One interesting point is that the voice users affect the data utilization severely though the voice traffic itself is not high load. The proposed scheme shows more data utilization than the original scheme because of low collision probability. VI. CONCLUSIONS AND FURTHER WORKS In this paper, we reviewed the IEEE e standard and proposed a new fast retransmission mechanism for VoIP packets to reduce the delay and dropping rate of s. The proposed scheme eliminates overhead time for backoff procedure in case of collision between VoIP and data packets. The simulation results showed that the proposed scheme has better performance compared with original e EDCA scheme in view of delay and dropping rate. Since there is

5 Fig. 5. Average delay of s Fig. 7. Dropping rate of s due to Delay Bound Fig. 6. Dropping rate of s due to Retry Limit Fig. 8. Channel Utilization of Data Packets not a centralized control unit performing AP s function in adhoc mode, it is difficult to guarantee the QoS of VoIP service. We are going to research on providing guaranteed service on s in ad-hoc mode. REFERENCES [1] Part11:Wireless Medium Access Control(MAC) and Physical Layer(PHY) specifications, IEEE Std, [2] Part11:Wireless Medium Access Control(MAC) and Physical Layer(PHY) specifications; Medium Access Control(MAC) Enhancement for Quality of Service(QoS), IEEE e/D8.0, Feb [3] Part11:Wireless Medium Access Control(MAC) and Physical Layer(PHY) specifications; High-speed Physical Layer in the 5Ghz Band, IEEE a Std, Sep [4] Part11:Wireless Medium Access Control(MAC) and Physical Layer(PHY) specifications; High-speed Physical Layer Extension in the 2.4Ghz Band, IEEE b Std, Sep [5] Part3: Media Access Control (MAC) bridges, ANSI/IEEE 802.1D Std, [6] Yang Xiao, -based Priority Schemes for IEEE , Proc. IEEE ICC 2003, pp , [7] Sunghyun Choi, Javier del Prado, Sai Shankar N and Stefan Mangold, IEEE e Contention-Based Channel Access(EDCF) Performance Evaluation, Proc. IEEE ICC 2003, pp , [8] Yu-Lian Kuo, Chi-Hung Lu, Eric Hsiao-Kuang Wu, Gen-Huey Chen and Yi-Hsien Tseng, Performance Analysis of the Enhanced Distributed Coordination Function in the IEEE e, Proc. IEEE VTC fall 2003, [9] Hiroyuki Yamada, Hiroyuki Morikawa and Tomonori Aoyama, Decentralized Control Mechanism Suppressing Delay Fluctuation in Wireless LANs, Proc. IEEE VTC fall 2003, [10] Lamia Romdhani, Qiang Ni and Thierry Turletti, Adaptive EDCF: Enhanced Service Differentiation for IEEE Wireless Ad-Hoc Networks, Proc. IEEE WCNC 2003, pp , [11] Stefan Mangold, Sunghyun Choi, Guido R. Hiertz, Ole Klein and Bernhard Walke, Analysis of IEEE e for QoS Support in Wireless LANs, IEEE Wireless Communications, pp , Dec [12] Takefumi Hiraguri, Takeo Ichikawa, Masataka Iizuka and Masahiro Morikura, Novel multiple access protocol for Voice over IP in Wireless LAN, Proc. IEEE ISCC 02, 2002.

Performance Comparison of Dual Queue and EDCA for VoIP over IEEE 802.11 WLAN

Performance Comparison of Dual Queue and EDCA for VoIP over IEEE 802.11 WLAN Performance Comparison of Dual Queue and for VoIP over IEEE 8. WLAN Jeonggyun Yu and Sunghyun Choi Multimedia & Wireless Networking Laboratory (MWNL), School of Electrical Engineering, Seoul National University,

More information

Enhanced TXOP scheme for efficiency improvement of WLAN IEEE 802.11e

Enhanced TXOP scheme for efficiency improvement of WLAN IEEE 802.11e Enhanced TXOP scheme for efficiency improvement of WLAN IEEE 802.11e Jakub Majkowski, Ferran Casadevall Palacio Dept. of Signal Theory and Communications Universitat Politècnica de Catalunya (UPC) C/ Jordi

More information

Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks

Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks 1 Mr. Praveen S Patil, 2 Mr. Rabinarayan Panda, 3 Mr. Sunil Kumar R D 1,2,3 Asst. Professor, Department of MCA, The Oxford College of Engineering,

More information

II. IEEE802.11e EDCA OVERVIEW

II. IEEE802.11e EDCA OVERVIEW The 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'7) CACITY IMPROVEMENT OF WIRELESS LAN VOIP USING DISTRIBUTED TRANSMISSION SCHEDULING Kei Igarashi,

More information

Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh

Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh, Ph.D. benveniste@ieee.org Mesh 2008, Cap Esterel, France 1 Abstract Abundant hidden node collisions and correlated channel access

More information

Enhancing WLAN MAC Protocol performance using Differentiated VOIP and Data Services Strategy

Enhancing WLAN MAC Protocol performance using Differentiated VOIP and Data Services Strategy IJCSNS International Journal of Computer Science and Network Security, VOL.9 No.12, December 2009 89 Enhancing WLAN MAC Protocol performance using Differentiated VOIP and Data Services Strategy S.Vijay

More information

Philippe Klein. avb-phkl-802-11-qos-overview-0811-1

Philippe Klein. avb-phkl-802-11-qos-overview-0811-1 802.11 QoS Overview Philippe Klein IEEE Plenary Meeting Nov 08 Dallas, TX avb-phkl-802-11-qos-overview-0811-1 Disclaimer This presentation is not a highly detailed technical presentation but a crash course

More information

Enhancement of VoIP over IEEE 802.11 WLAN via Dual Queue Strategy

Enhancement of VoIP over IEEE 802.11 WLAN via Dual Queue Strategy Enhancement of VoIP over IEEE 802.11 WLAN via Dual Queue Strategy + Multimedia & Wireless Networking Laboratory School of Electrical Engineering Seoul National University jgyu@mwnl.snu.ac.kr, schoi@snu.ac.kr

More information

QOS PROTECTION FOR IEEE 802.11E IN WLAN WITH SHARED EDCA AND DCF ACCESS

QOS PROTECTION FOR IEEE 802.11E IN WLAN WITH SHARED EDCA AND DCF ACCESS QOS PROTECTION FOR IEEE 802.11E IN WLAN WITH SHARED EDCA AND DCF ACCESS Jakub Majkowski, Ferran Casadevall Palacio Dept. of Signal Theory and Communications Universitat Politècnica de Catalunya (UPC) C/

More information

2 BACKGROUND. J. Yu and S. Choi

2 BACKGROUND. J. Yu and S. Choi Comparison of Modified Dual Queue and for VoIP over IEEE.11 WLAN JEONGGYUN YU AND SUNGHYUN CHOI Multimedia & Wireless Networking Laboratory (MWNL) School of Electrical Engineering and INMC, Seoul National

More information

An Experimental Study of Throughput for UDP and VoIP Traffic in IEEE 802.11b Networks

An Experimental Study of Throughput for UDP and VoIP Traffic in IEEE 802.11b Networks An Experimental Study of Throughput for UDP and VoIP Traffic in IEEE 82.11b Networks Sachin Garg sgarg@avaya.com Avaya Labs Research Basking Ridge, NJ USA Martin Kappes mkappes@avaya.com Avaya Labs Research

More information

Attenuation (amplitude of the wave loses strength thereby the signal power) Refraction Reflection Shadowing Scattering Diffraction

Attenuation (amplitude of the wave loses strength thereby the signal power) Refraction Reflection Shadowing Scattering Diffraction Wireless Physical Layer Q1. Is it possible to transmit a digital signal, e.g., coded as square wave as used inside a computer, using radio transmission without any loss? Why? It is not possible to transmit

More information

Video Transmission over Wireless LAN. Hang Liu Hang.liu@thomson.net

Video Transmission over Wireless LAN. Hang Liu Hang.liu@thomson.net Video Transmission over Wireless LAN Hang Liu Hang.liu@thomson.net Page 1 Introduction! Introduction! Wi-Fi Multimedia and IEEE 802.11e for QoS Enhancement! Error Control Techniques Page 2 Introduction!

More information

An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e

An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e Jahanzeb Farooq, Bilal Rauf Department of Computing Science Umeå University Sweden Jahanzeb Farooq, 2006 (tipputhegreat@hotmail.com) Chapter

More information

CSMA/CA. Information Networks p. 1

CSMA/CA. Information Networks p. 1 Information Networks p. 1 CSMA/CA IEEE 802.11 standard for WLAN defines a distributed coordination function (DCF) for sharing access to the medium based on the CSMA/CA protocol Collision detection is not

More information

then, we require that, in order to support the offered load, (1)

then, we require that, in order to support the offered load, (1) Capacity of an IEEE 802.11b Wireless LAN supporting VoIP To appear in Proc. IEEE Int. Conference on Communications (ICC) 2004 David P. Hole and Fouad A. Tobagi Dept. of Electrical Engineering, Stanford

More information

IEEE 802.11E ENHANCEMENT FOR VOICE SERVICE

IEEE 802.11E ENHANCEMENT FOR VOICE SERVICE V OICE OVER WIRELESS LOCAL AREA N ETWORK IEEE 802.11E ENHANCEMENT FOR VOICE SERVICE PING WANG, HAI JIANG, AND WEIHUA ZHUANG, UNIVERSITY OF WATERLOO Wired network IP phone Gateway router Access point Motivated

More information

IEEE 802.11e WLANs / WMM. S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd.

IEEE 802.11e WLANs / WMM. S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd. IEEE 802.11e WLANs / WMM S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd. Outline A short review of 802.11 MAC Drawbacks of 802.11 MAC Application

More information

VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN

VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN 1144 PAPER Special Section on Internet Technology and its Architecture for Ambient Information Systems VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN Yasufumi

More information

Enhancement of VoIP over IEEE 802.11 WLANs by Adapting Transmitting Interval

Enhancement of VoIP over IEEE 802.11 WLANs by Adapting Transmitting Interval Enhancement of VoIP over IEEE 82.11 WLANs by Adapting Transmitting Interval Zhuo Chen, Lingyun Wang, and Xinbing Wang School of Electronic, Information and Electrical Engineering Shanghai Jiao Tong University

More information

FORTH-ICS / TR-375 March 2006. Experimental Evaluation of QoS Features in WiFi Multimedia (WMM)

FORTH-ICS / TR-375 March 2006. Experimental Evaluation of QoS Features in WiFi Multimedia (WMM) FORTH-ICS / TR-375 March 26 Experimental Evaluation of QoS Features in WiFi Multimedia (WMM) Vasilios A. Siris 1 and George Stamatakis 1 Abstract We investigate the operation and performance of WMM (WiFi

More information

Can I add a VoIP call?

Can I add a VoIP call? Can I add a VoIP call? Sachin Garg Avaya Labs Basking Ridge, NJ 07920 Email: sgarg@avaya.com Martin Kappes Avaya Labs Basking Ridge, NJ 07920 Email: mkappes@avaya.com Abstract In this paper, we study the

More information

A TCP-like Adaptive Contention Window Scheme for WLAN

A TCP-like Adaptive Contention Window Scheme for WLAN A TCP-like Adaptive Contention Window Scheme for WLAN Qixiang Pang, Soung Chang Liew, Jack Y. B. Lee, Department of Information Engineering The Chinese University of Hong Kong Hong Kong S.-H. Gary Chan

More information

How To Configure the WLAN with QoS

How To Configure the WLAN with QoS How To Configure the WLAN with QoS Introduction This How to Note explains how to configure Quality of Service (QoS) in a wireless Local Area Network to prioritize traffic under busy conditions. There is

More information

PLUS-DAC: A Distributed Admission Control Scheme for IEEE 802.11e WLANs

PLUS-DAC: A Distributed Admission Control Scheme for IEEE 802.11e WLANs -DAC: A Distributed Admission Control Scheme for IEEE 8.e WLANs Kiran Kumar Gavini, Varsha Apte and Sridhar Iyer Kanwal Rekhi School of Information Technology Indian Institute of Technology Bombay, Powai,

More information

802.11. Markku Renfors. Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak

802.11. Markku Renfors. Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak 802.11 Markku Renfors Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak Contents 802.11 Overview & Architecture 802.11 MAC 802.11 Overview and Architecture

More information

DUE to the high performance versus price ratio, IEEE

DUE to the high performance versus price ratio, IEEE Improving WLAN VoIP Capacity Through Service Differentiation Deyun Gao, Member, IEEE, Jianfei Cai, Senior Member, IEEE, Chuan Heng Foh, Member, IEEE, Chiew-Tong Lau, Member, IEEE, and King Ngi Ngan, Fellow,

More information

Adapting WLAN MAC Parameters to Enhance VoIP Call Capacity

Adapting WLAN MAC Parameters to Enhance VoIP Call Capacity Adapting WLAN MAC Parameters to Enhance VoIP Call Capacity Gráinne Hanley, Seán Murphy and Liam Murphy Dept. of Computer Science, University College Dublin Belfield, Dublin 4, Ireland hanleyg@gmail.com,

More information

TCP in Wireless Networks

TCP in Wireless Networks Outline Lecture 10 TCP Performance and QoS in Wireless s TCP Performance in wireless networks TCP performance in asymmetric networks WAP Kurose-Ross: Chapter 3, 6.8 On-line: TCP over Wireless Systems Problems

More information

Advanced Wireless LAN VoIP Technology

Advanced Wireless LAN VoIP Technology Wireless LAN VoIP QoS Advanced Wireless LAN VoIP Technology A technical overview is given of an optimal access point selection method and an autonomous distributed scheduling MAC method that take QoS into

More information

Extended-rtPS Algorithm for VoIP Services in IEEE 802.16 systems

Extended-rtPS Algorithm for VoIP Services in IEEE 802.16 systems Extended-rtPS Algorithm for VoIP Services in IEEE 802.16 systems Howon Lee, Taesoo Kwon and Dong-Ho Cho Department of Electrical Engineering and Computer Science Korea Advanced Institute of Science and

More information

Admission Control for VoIP Traffic in IEEE 802.11 Networks

Admission Control for VoIP Traffic in IEEE 802.11 Networks Admission Control for VoIP Traffic in IEEE 802.11 Networks Sachin Garg Avaya Labs Basking Ridge, NJ 07920 Email: sgarg@avaya.com Martin Kappes Avaya Labs Basking Ridge, NJ 07920 Email: mkappes@avaya.com

More information

No Ack in IEEE 802.11e Single-Hop Ad-Hoc VoIP Networks

No Ack in IEEE 802.11e Single-Hop Ad-Hoc VoIP Networks No Ack in IEEE 802.11e Single-Hop Ad-Hoc VoIP Networks Jaume Barceló, Boris Bellalta, Anna Sfairopoulou, Cristina Cano, Miquel Oliver Abstract This paper analyzes the impact of the No Ack policy in VoIP

More information

Department of Computer Science Columbia University

Department of Computer Science Columbia University Towards the Quality of Service for VoIP traffic in IEEE 82.11 Wireless Networks Sangho Shin Henning Schulzrinne Email: sangho, hgs@cs.columbia.edu Department of Computer Science Columbia University 28

More information

Aspects of Coexistence Between WiFi and HSDPA

Aspects of Coexistence Between WiFi and HSDPA (Cross-layer design and network planning for B3G systems) Aspects of Coexistence Between WiFi and HSDPA Orlando Cabral Valdemar Monteiro 2005, it - instituto de telecomunicações. Todos os direitos reservados.

More information

Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - III

Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - III Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - III CS: 647 Advanced Topics in Wireless Networks Drs. Baruch Awerbuch & Amitabh Mishra Department of Computer Science Johns Hopkins

More information

Collision of wireless signals. The MAC layer in wireless networks. Wireless MAC protocols classification. Evolutionary perspective of distributed MAC

Collision of wireless signals. The MAC layer in wireless networks. Wireless MAC protocols classification. Evolutionary perspective of distributed MAC The MAC layer in wireless networks The wireless MAC layer roles Access control to shared channel(s) Natural broadcast of wireless transmission Collision of signal: a /space problem Who transmits when?

More information

802.11 standard. Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale

802.11 standard. Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale 802.11 standard Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale IEEE 802.11 Requirements Design for small coverage (e.g. office, home) Low/no mobility High data-rate applications Ability to

More information

Capacity Evaluation of VoIP in IEEE 802.11e WLAN Environment

Capacity Evaluation of VoIP in IEEE 802.11e WLAN Environment Capacity Evaluation of VoIP in IEEE 802.11e WLAN Environment Abdelbasset Trad, Farukh Munir INIA, Planete Project 4 oute des Lucioles, BP-93 06902 Sophia-Antipolis, France Email: {atrad, mfmunir}@sophia.inria.fr

More information

PROVIDING STATISTICAL QOS GUARANTEE FOR VOICE OVER IP IN THE IEEE 802.11 WIRELESS LANS

PROVIDING STATISTICAL QOS GUARANTEE FOR VOICE OVER IP IN THE IEEE 802.11 WIRELESS LANS V OICE OVER WIRELESS LOCAL AREA N ETWORK PROVIDING STATISTICAL QOS GUARANTEE FOR VOICE OVER IP IN THE IEEE 82.11 WIRELESS LANS HONGQIANG ZHAI, JIANFENG WANG, AND YUGUANG FANG, UNIVERSITY OF FLORIDA The

More information

Design of QoS and Admission Control for VoIP Services over IEEE 802.11e WLANs

Design of QoS and Admission Control for VoIP Services over IEEE 802.11e WLANs Design of QoS and Admission Control for VoIP Services over IEEE 802.11e WLANs Pei-Yeh Wu, Jen-Jee Chen, Yu-Chee Tseng, and Hung-Wei, Lee Abstract Supporting telephone services using wireless LAN as the

More information

Virtual PCF: Improving VoIP over WLAN performance with legacy clients

Virtual PCF: Improving VoIP over WLAN performance with legacy clients Virtual PCF: Improving VoIP over WLAN performance with legacy clients by Usman Ismail A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master

More information

Introduction VOIP in an 802.11 Network VOIP 3

Introduction VOIP in an 802.11 Network VOIP 3 Solutions to Performance Problems in VOIP over 802.11 Wireless LAN Wei Wang, Soung C. Liew Presented By Syed Zaidi 1 Outline Introduction VOIP background Problems faced in 802.11 Low VOIP capacity in 802.11

More information

VoIP in 802.11. Mika Nupponen. S-72.333 Postgraduate Course in Radio Communications 06/04/2004 1

VoIP in 802.11. Mika Nupponen. S-72.333 Postgraduate Course in Radio Communications 06/04/2004 1 VoIP in 802.11 Mika Nupponen S-72.333 Postgraduate Course in Radio Communications 06/04/2004 1 Contents Introduction VoIP & WLAN Admission Control for VoIP Traffic in WLAN Voice services in IEEE 802.11

More information

A Software Architecture for Simulating IEEE 802.11e HCCA

A Software Architecture for Simulating IEEE 802.11e HCCA A Software Architecture for Simulating IEEE 802.11e HCCA Claudio Cicconetti, Luciano Lenzini, Enzo Mingozzi, Giovanni Stea Dipartimento di Ingegneria dell'informazione University of Pisa, Italy IPS-MoMe

More information

Measuring the Performance of VoIP over Wireless LAN

Measuring the Performance of VoIP over Wireless LAN Measuring the Performance of VoIP over Wireless LAN Keshav Neupane, Student Victor Kulgachev, Student Department of Computer Science Northern Kentucky University Highland Heights, KY, USA, 41099 neupanek1@nku.edu

More information

Improving WLAN VoIP Capacity through Service Differentiation

Improving WLAN VoIP Capacity through Service Differentiation IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. X, NO. XX 1 Improving WLAN VoIP Capacity through Service Differentiation Deyun Gao, Member, IEEE, Jianfei Ca Member, IEEE, Chuan Heng Foh, Member, IEEE,

More information

Optimum Parameters for VoIP in IEEE 802.11e Wireless LAN

Optimum Parameters for VoIP in IEEE 802.11e Wireless LAN Optimum Parameters for VoIP in IEEE 82.11e Wireless LAN Ryo Kitahara NTT DoCoMo 3-5 Hikari-no-oka, Yokosuka City Kanagawa Prefecture, Japan kitaharar@nttdocomo.co.jp Shingo Morita Waseda University 3-4-1

More information

Wiereless LAN 802.11

Wiereless LAN 802.11 Tomasz Kurzawa Wiereless LAN 802.11 Introduction The 802.11 Architecture Channels and Associations The 802.11 MAC Protocol The 802.11 Frame Introduction Wireless LANs are most important access networks

More information

Modeling and Simulation of Quality of Service in VoIP Wireless LAN

Modeling and Simulation of Quality of Service in VoIP Wireless LAN Journal of Computing and Information Technology - CIT 16, 2008, 2, 131 142 doi:10.2498/cit.1001022 131 Modeling and Simulation of Quality of Service in VoIP Wireless LAN A. Al-Naamany, H. Bourdoucen and

More information

Solutions to Performance Problems in VoIP over 802.11 Wireless LAN 1

Solutions to Performance Problems in VoIP over 802.11 Wireless LAN 1 1 Solutions to Performance Problems in VoIP over 802.11 Wireless LAN 1 Wei Wang, Soung C. Liew Department of Information Engineering The Chinese University of Hong Kong Victor O. K. Li Department of Electrical

More information

ECE 358: Computer Networks. Homework #3. Chapter 5 and 6 Review Questions 1

ECE 358: Computer Networks. Homework #3. Chapter 5 and 6 Review Questions 1 ECE 358: Computer Networks Homework #3 Chapter 5 and 6 Review Questions 1 Chapter 5: The Link Layer P26. Let's consider the operation of a learning switch in the context of a network in which 6 nodes labeled

More information

QoS-aware MPDU Aggregation of IEEE 802.11n WLANs for VoIP Services

QoS-aware MPDU Aggregation of IEEE 802.11n WLANs for VoIP Services QoS-aware MPDU Aggregation of IEEE 802.11n WLANs for VoIP Services Shinnazar Seytnazarov and Young-Tak Kim Department of Information and Communication Engineering, Graduate School, Yeungnam University

More information

An End-to-End Measurement-Based Admission Control Policy for VoIP over Wireless Networks

An End-to-End Measurement-Based Admission Control Policy for VoIP over Wireless Networks An End-to-End Measurement-Based Admission Control Policy for VoIP over Wireless Networks Ala Khalifeh Department of EECS University of California, Irvine [akhalife]@uci.edu Abstract in this paper, we present

More information

Throughput Analysis of WEP Security in Ad Hoc Sensor Networks

Throughput Analysis of WEP Security in Ad Hoc Sensor Networks Throughput Analysis of WEP Security in Ad Hoc Sensor Networks Mohammad Saleh and Iyad Al Khatib iitc Stockholm, Sweden {mohsaleh, iyad}@iitc.se ABSTRACT This paper presents a performance investigation

More information

802.11 Wireless LAN Protocol CS 571 Fall 2006. 2006 Kenneth L. Calvert All rights reserved

802.11 Wireless LAN Protocol CS 571 Fall 2006. 2006 Kenneth L. Calvert All rights reserved 802.11 Wireless LAN Protocol CS 571 Fall 2006 2006 Kenneth L. Calvert All rights reserved Wireless Channel Considerations Stations may move Changing propagation delays, signal strengths, etc. "Non-transitive"

More information

Optimization of VoIP over 802.11e EDCA based on synchronized time

Optimization of VoIP over 802.11e EDCA based on synchronized time Optimization of VoIP over 802.11e EDCA based on synchronized time Padraig O Flaithearta, Dr. Hugh Melvin Discipline of Information Technology, College of Engineering and Informatics, National University

More information

Wi-Fi CERTIFIED for WMM - Support for Multimedia Applications with Quality of Service in Wi-Fi Networks Wi-Fi Alliance September 1, 2004

Wi-Fi CERTIFIED for WMM - Support for Multimedia Applications with Quality of Service in Wi-Fi Networks Wi-Fi Alliance September 1, 2004 Wi-Fi CERTIFIED for WMM - Support for Multimedia Applications with Quality of Service in Wi-Fi Networks Wi-Fi Alliance September 1, 2004 2004 Wi-Fi Alliance. All rights reserved. Wi-Fi is a registered

More information

Dynamic Traffic Prioritization in 802.11e Networks

Dynamic Traffic Prioritization in 802.11e Networks 1 Dynamic Traffic Prioritization in 802.11e Networks William Spearman, James Martin, James Westall Abstract The IEEE 802.11 family of standards defines a collection of widely used local wireless network

More information

CSE331: Introduction to Networks and Security. Lecture 6 Fall 2006

CSE331: Introduction to Networks and Security. Lecture 6 Fall 2006 CSE331: Introduction to Networks and Security Lecture 6 Fall 2006 Open Systems Interconnection (OSI) End Host Application Reference model not actual implementation. Transmits messages (e.g. FTP or HTTP)

More information

CS6956: Wireless and Mobile Networks Lecture Notes: 2/11/2015. IEEE 802.11 Wireless Local Area Networks (WLANs)

CS6956: Wireless and Mobile Networks Lecture Notes: 2/11/2015. IEEE 802.11 Wireless Local Area Networks (WLANs) CS6956: Wireless and Mobile Networks Lecture Notes: //05 IEEE 80. Wireless Local Area Networks (WLANs) CSMA/CD Carrier Sense Multi Access/Collision Detection detects collision and retransmits, no acknowledgement,

More information

Impact of Randomness on MAC Layer Schedulers over High Speed Wireless Campus Network in IEEE802.11e

Impact of Randomness on MAC Layer Schedulers over High Speed Wireless Campus Network in IEEE802.11e ISSN (Online): 2409-4285 www.ijcsse.org Page: 8-13 Impact of Randomness on MAC Layer Schedulers over High Speed Wireless Campus Network in IEEE802.11e M. K. Alam 1, S. A. Latif 2, M. Akter 3 and M. Y.

More information

Asia-Pacific Advanced Network

Asia-Pacific Advanced Network Frame aggregations in the wireless LANs: A review paper Presented by: Anwar Saif Asia-Pacific Advanced Network Wireless communication 2009 Abstract The overhead induced by the IEEE 802.11 PHY and MAC layer

More information

Wi-Fi Capacity Analysis for 802.11ac and 802.11n: Theory & Practice

Wi-Fi Capacity Analysis for 802.11ac and 802.11n: Theory & Practice Wi-Fi Capacity Analysis for 802.11ac and 802.11n: Theory & Practice By Timo Vanhatupa, Ph.D. Senior Research Scientist at Ekahau Contents Introduction Why capacity matters with Wi-Fi... 3 Part 1: Modeling

More information

Railway Freight Dispatching Telephone System Based on VoIP in Wireless Networks

Railway Freight Dispatching Telephone System Based on VoIP in Wireless Networks International Conference on Computer, Communications and Information Technology (CCIT 2014) Railway Freight Dispatching Telephone System Based on VoIP in Wireless Networks Jun Xiao1, Feng Liu1, 2 1 2 School

More information

Frame Burst Adjusting for Transmitting Video Conference in Gigabit Ethernet

Frame Burst Adjusting for Transmitting Video Conference in Gigabit Ethernet Frame Burst Adjusting for Transmitting Video Conference in Gigabit Ethernet Han-Chieh Chao and Yao-Chung Chang Institute of Electrical Engineering National Dong Hwa University Hualien, Taiwan E-mail: hcc@cc.ndhu.edu.tw

More information

Design of QoS and Admission Control for VoIP Services Over IEEE 802.11e WLANs *

Design of QoS and Admission Control for VoIP Services Over IEEE 802.11e WLANs * JOURNAL OF INFORMATION SCIENCE AND ENGINEERING 24, 1003-1022 (2008) Design of QoS and Admission Control for VoIP Services Over IEEE 802.11e WLANs * PEI-YEH WU 1, JEN-JEE CHEN 1, YU-CHEE TSENG 1,2 AND HUNG-WEI

More information

Efficient MAC Protocol for Heterogeneous Cellular Networks (HC-MAC)

Efficient MAC Protocol for Heterogeneous Cellular Networks (HC-MAC) Vol.2, Issue.2, Mar-Apr 2012 pp-078-083 ISSN: 2249-6645 Efficient MAC Protocol for Heterogeneous Cellular Networks (HC-MAC) 1 Y V Adi Satyanarayana, 2 Dr. K Padma Raju 1 Y V Adi Satyanarayana, Assoc. Professor,

More information

Wireless Network Measurement: VoIP and 802.11e

Wireless Network Measurement: VoIP and 802.11e Wireless Network Measurement: VoIP and 82.11e by Ian Dangerfield, B.A Masters Thesis Hamilton Institute National University of Ireland Maynooth Maynooth Co. Kildare December 27 Research Supervisor: Dr.

More information

CS263: Wireless Communications and Sensor Networks

CS263: Wireless Communications and Sensor Networks CS263: Wireless Communications and Sensor Networks Matt Welsh Lecture 4: Medium Access Control October 5, 2004 2004 Matt Welsh Harvard University 1 Today's Lecture Medium Access Control Schemes: FDMA TDMA

More information

ECE 428 Computer Networks and Security

ECE 428 Computer Networks and Security ECE 428 Computer Networks and Security 1 Instructor: Sagar Naik About the Instructor Office: EIT 4174, ECE Dept. Other courses that I teach ECE 355: Software Engineering ECE 453/CS 447/ SE 465: Software

More information

Performance Evaluation of VoIP Services using Different CODECs over a UMTS Network

Performance Evaluation of VoIP Services using Different CODECs over a UMTS Network Performance Evaluation of VoIP Services using Different CODECs over a UMTS Network Jianguo Cao School of Electrical and Computer Engineering RMIT University Melbourne, VIC 3000 Australia Email: j.cao@student.rmit.edu.au

More information

Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation

Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation Changsu Suh, Young-Bae Ko, and Jai-Hoon Kim Graduate School of Information and Communication, Ajou University, Republic of Korea

More information

A Slow-sTart Exponential and Linear Algorithm for Energy Saving in Wireless Networks

A Slow-sTart Exponential and Linear Algorithm for Energy Saving in Wireless Networks 1 A Slow-sTart Exponential and Linear Algorithm for Energy Saving in Wireless Networks Yang Song, Bogdan Ciubotaru, Member, IEEE, and Gabriel-Miro Muntean, Member, IEEE Abstract Limited battery capacity

More information

A Multiplex-Multicast Scheme that Improves System Capacity of Voice-over-IP on Wireless LAN by 100% *

A Multiplex-Multicast Scheme that Improves System Capacity of Voice-over-IP on Wireless LAN by 100% * A Multiplex-Multicast Scheme that Improves System Capacity of Voice-over-IP on Wireless LAN by 100% * Wei Wang, Soung C. Liew, Qixiang Pang Department of Information Engineering The Chinese University

More information

Local Area Networks transmission system private speedy and secure kilometres shared transmission medium hardware & software

Local Area Networks transmission system private speedy and secure kilometres shared transmission medium hardware & software Local Area What s a LAN? A transmission system, usually private owned, very speedy and secure, covering a geographical area in the range of kilometres, comprising a shared transmission medium and a set

More information

IEEE 802 LANs. LAN: Local Area Network What is a local area network?

IEEE 802 LANs. LAN: Local Area Network What is a local area network? IEEE 802 LANs LAN: Local Area Network What is a local area network? A LAN is a network that resides in a geographically restricted area LANs usually span a building or a campus 1 Characteristics of LANs

More information

Professor, Dept. of Computer Science and Engineering, Sri Siddhartha Institute of Technology, Tumkur,

Professor, Dept. of Computer Science and Engineering, Sri Siddhartha Institute of Technology, Tumkur, Computing For Nation Development, March 10 11, 2011 Bharati Vidyapeeth s Institute of Computer Applications and Management, New Delhi Techniques to Improve Performance of VoIP over 802.11e WLAN D. Ramesh

More information

Configuring QoS in a Wireless Environment

Configuring QoS in a Wireless Environment Configuring QoS in a Wireless Environment This chapter describes how to configure quality of service (QoS) on your Cisco wireless interface. With this feature, you can provide preferential treatment to

More information

Lecture 17: 802.11 Wireless Networking"

Lecture 17: 802.11 Wireless Networking Lecture 17: 802.11 Wireless Networking" CSE 222A: Computer Communication Networks Alex C. Snoeren Thanks: Lili Qiu, Nitin Vaidya Lecture 17 Overview" Project discussion Intro to 802.11 WiFi Jigsaw discussion

More information

Voice over WLAN (VoWLAN) A wireless voice alternative?

Voice over WLAN (VoWLAN) A wireless voice alternative? Voice over WLAN (VoWLAN) A wireless voice alternative? Trond Ulseth Paal Engelstad Abstract Voice over WLAN (VoWLAN) is a natural evolution of VoIP. It is also a potential supplement or a potential competitor

More information

An Efficient Transmission Scheme for Short Message Service in IEEE 802.16 Systems

An Efficient Transmission Scheme for Short Message Service in IEEE 802.16 Systems An Efficient Transmission Scheme for Short Message Service in IEEE 802.16 Systems Sung-Min Oh* and Jae-Hyun Kim* *Ajou University, School of Electrical and Computer Engineering smallb01@ajou.ac.kr and

More information

Yalda Hakki (yha17@sfu.ca) Rosy Johal (rja2@sfu.ca) Renuka Rani (rra7@sfu.ca) www.sfu.ca/~rra7

Yalda Hakki (yha17@sfu.ca) Rosy Johal (rja2@sfu.ca) Renuka Rani (rra7@sfu.ca) www.sfu.ca/~rra7 ENSC 427: Communication Networks Spring 2010 Final Project Presentation Yalda Hakki (yha17@sfu.ca) Rosy Johal (rja2@sfu.ca) Renuka Rani (rra7@sfu.ca) www.sfu.ca/~rra7 1 Introduction Overview and Motivation

More information

COMPARATIVE STUDY OF VARIOUS VOIP APPLICATIONS IN 802.11A WIRELESS NETWORK SCENARIO

COMPARATIVE STUDY OF VARIOUS VOIP APPLICATIONS IN 802.11A WIRELESS NETWORK SCENARIO COMPARATIVE STUDY OF VARIOUS VOIP APPLICATIONS IN 802.11A WIRELESS NETWORK SCENARIO Sutanu Ghosh Faculty of Electronics and Communication Engineering, Dr. Sudhir Chandra Sur Degree Engineering College

More information

Comparative call Capacity analysis of VOIP in IEEE802.11b WLAN Environment

Comparative call Capacity analysis of VOIP in IEEE802.11b WLAN Environment Comparative call Capacity analysis of VOIP in IEEE802.11b WLAN Environment Jitendra Jakhar 1, Sankit R Kassa 2, Tejpal 3 PG Student, Electronics & Communication Engineering Department, SBCET, Jaipur, Rajasthan,

More information

Performance Evaluation of Wired and Wireless Local Area Networks

Performance Evaluation of Wired and Wireless Local Area Networks International Journal of Engineering Research and Development ISSN: 2278-067X, Volume 1, Issue 11 (July 2012), PP.43-48 www.ijerd.com Performance Evaluation of Wired and Wireless Local Area Networks Prof.

More information

Performance Evaluation of AODV, OLSR Routing Protocol in VOIP Over Ad Hoc

Performance Evaluation of AODV, OLSR Routing Protocol in VOIP Over Ad Hoc (International Journal of Computer Science & Management Studies) Vol. 17, Issue 01 Performance Evaluation of AODV, OLSR Routing Protocol in VOIP Over Ad Hoc Dr. Khalid Hamid Bilal Khartoum, Sudan dr.khalidbilal@hotmail.com

More information

2004-08-18 IEEE C802.16e-04/351r1

2004-08-18 IEEE C802.16e-04/351r1 Project Title Date Submitted IEEE 802.16 Broadband Wireless Access Working Group Extended rtps, for VoIP services 2004-08-18 Source(s) Howon Lee, Dong-Ho Cho, Taesoo Kwon, Ki-Ho

More information

Performance evaluation of QoS in wireless networks using IEEE 802.11e

Performance evaluation of QoS in wireless networks using IEEE 802.11e Performance evaluation of QoS in wireless networks using IEEE 802.11e Laio B. Vilas Boas, Pedro M. C. Massolino, Rafael T. Possignolo, Cintia B. Margi and Regina M. Silveira Abstract The increase demand

More information

Performance Evaluation of Priority based Contention- MAC in Mobile Ad-Hoc Networks

Performance Evaluation of Priority based Contention- MAC in Mobile Ad-Hoc Networks International Journal of Computer Applications (975 7) Volume 5 No.1, June 11 Performance Evaluation of Priority based Contention- MAC in Mobile Ad-Hoc Networks Soni Sweta Arun Nahar Sanjeev Sharma ABSTRACT

More information

802.11 Arbitration. White Paper. September 2009 Version 1.00. Author: Marcus Burton, CWNE #78 CWNP, Inc. marcus.burton@cwnp.com

802.11 Arbitration. White Paper. September 2009 Version 1.00. Author: Marcus Burton, CWNE #78 CWNP, Inc. marcus.burton@cwnp.com 802.11 Arbitration White Paper September 2009 Version 1.00 Author: Marcus Burton, CWNE #78 CWNP, Inc. marcus.burton@cwnp.com Technical Reviewer: GT Hill, CWNE #21 gt@gthill.com Copyright 2009 CWNP, Inc.

More information

Supporting VoIP Services in IEEE 802.11e WLANs

Supporting VoIP Services in IEEE 802.11e WLANs Supporting VoIP Services in IEEE 802.11e WLANs Jeonggyun Yu, Munhwan Choi, Daji Qiao, and Sunghyun Choi Samsung Electronics Co., LTD, Suwon, Korea The School of Electrical Engineering and INMC, Seoul National

More information

EECS 122: Introduction to Computer Networks Multiaccess Protocols. ISO OSI Reference Model for Layers

EECS 122: Introduction to Computer Networks Multiaccess Protocols. ISO OSI Reference Model for Layers EECS 122: Introduction to Computer Networks Multiaccess Protocols Computer Science Division Department of Electrical Engineering and Computer Sciences University of California, Berkeley Berkeley, CA 94720-1776

More information

2004-11-04 IEEE C802.16e-04/522. IEEE 802.16 Broadband Wireless Access Working Group

2004-11-04 IEEE C802.16e-04/522. IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16> Project Title Date Submitted IEEE 802.16 Broadband Wireless Access Working Group Extended rtps for VoIP services 2004-11-04 Source(s) Re: Abstract Howon Lee, Jee-young Song, Taesoo

More information

Management of IEEE 802.11e Wireless LAN for Realtime QoS-Guaranteed Teleconference Service with Differentiated H.264 Video Transmission

Management of IEEE 802.11e Wireless LAN for Realtime QoS-Guaranteed Teleconference Service with Differentiated H.264 Video Transmission Management of IEEE 82.11e Wireless LAN for Realtime QoS-Guaranteed Teleconference Service with Differentiated H.264 Video Transmission Soo-Yong Koo, Byung-Kil Kim, Young-Tak Kim Dept. of Information and

More information

... neither PCF nor CA used in practice

... neither PCF nor CA used in practice IEEE 802.11 MAC CSMA/CA with exponential backoff almost like CSMA/CD drop CD CSMA with explicit ACK frame added optional feature: CA (collision avoidance) Two modes for MAC operation: Distributed coordination

More information

HEARW P: EnHanced MEdium Access ContRol Protocol for Wireless Voice over IP

HEARW P: EnHanced MEdium Access ContRol Protocol for Wireless Voice over IP HEARW P: EnHanced MEdium Access ContRol Protocol for Wireless Voice over IP inem Coleri, Mustafa Ergen, Ahmad Bahai {csinem,ergen}@eecs.berkeley.edu, Ahmad.Bahai@nsc.com 1 OBJECTIVE This paper describes

More information

Announcements : Wireless Networks Lecture 9: MAC. Outline. History. Page 1

Announcements : Wireless Networks Lecture 9: MAC. Outline. History. Page 1 Announcements 18-759: Wireless Networks Lecture 9: 80.11 Peter Steenkiste Departments of Computer Science and Electrical and Computer Engineering Spring Semester 016 http://www.cs.cmu.edu/~prs/wirelesss16/

More information

Improving Performance for CSMA/CA Based Wireless Networks

Improving Performance for CSMA/CA Based Wireless Networks Improving Performance for CSMA/CA Based Wireless Networks A dissertation submitted for the degree of Doctor of Philosophy by Tianji Li, BSc., MSc. Supervisor: Prof. Douglas Leith Hamilton Institute National

More information

PERFORMANCE ANALYSIS OF WLAN STANDARDS FOR VIDEO CONFERENCING APPLICATIONS

PERFORMANCE ANALYSIS OF WLAN STANDARDS FOR VIDEO CONFERENCING APPLICATIONS PERFORMANCE ANALYSIS OF WLAN STANDARDS FOR VIDEO CONFERENCING APPLICATIONS Lachhman Das Dhomeja 1, Shazia Abbasi 1, Asad Ali Shaikh 1, Yasir Arfat Malkani 2 1 Institute of Information and Communication

More information