Performance Analysis of FTP, HTTP and Database for IEEE802.11, IEEE802.11a, IEEE802.11b and IEEE802.11g using OPNET Simulator

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1 Performance Analysis of FTP, HTTP and Database for IEEE802.11, IEEE802.11a, IEEE802.11b and IEEE802.11g using OPNET Simulator Almutaz Ali Mohammed 1, Ibrahim Elimam Abdalla 2 Faculty of Engineering, Neelain University, Khartoum Sudan Abstract: WLAN is the most exceedingly accepted broadband wireless technology that can offer a high transmission rate; Wi-Fi provides its users with option of connecting to the Internet from any place without wires. This paper presents a performance analysis of WLAN in a simulated office for different applications (FTP, Database and HTTP) for various WLAN standards(802.11b, a, g, infrared and frequency hopping), OPNET 14.5 tool was used to design the network that consists of a number of access points each of them supports different WLAN technology standards, deployed to serve the needs of workstations that work with same AP standard with maximum data rate adopted by this standard. From the simulation, we focused to find out some metrics namely Database, FTP and HTTP download - upload response times, WLAN load, WLAN delayed, WLAN throughput, Media access delay, TCP abort and queuing size. Keywords WLAN, response time, Opnet, HTTP, FTP. I. INTRODUCTION Wi-Fi is a short name for Wireless Fidelity. Generally, Wi-Fi refers to any type of IEEE Wireless Local Area Network (WLAN), it s a technology that allows electronic devices to connect to a wireless network, and mainly that using the 2.4 GHz and 5 GHz radio bands. Technically Wi-Fi is point to communications standard for WLAN (Wireless Local Area Networks) that has various standards known IEEE and identified by extensions. In Wi-Fi protocols there are several physical layers and features described in the specifications. The latest new physical layer called VHT (Very High Throughput) and it is defined in the IEEE ac standard amendment. The PHY is responsible for such things as modulation, encoding schemes and error correction [1]. Wireless LAN technologies studied and simulated for development and performance evaluation reasons. OPNET Modeler is the most commonly used simulation tool, it is considered as first class discrete event simulator in the networking research. In this paper, the performance results of FTP, HTTP and Database for IEEE802.11, IEEE802.11a, IEEE802.11b and IEEE802.11g WLAN was presented by using OPNET. II. IEEE AND AMENDMENTS A) STANDARD: The most widely used standard IEEE is developed by IEEE in This standard introduce physical layer (PHY) and Medium Access Control (MAC) as sub-layer, The PHY layer that actually handles data transmission between nodes, might use Direct Sequence Spread Spectrum (DSSS), Frequency Hopping Spread Spectrum (FHSS), or infrared (IR). IEEE provides data rates of either 1 Mbps or 2 Mbps [5]. B) A STANDARD: Is the first of the variety of standards that are in use today, published in It uses (OFDM) Orthogonal Frequency Division Multiplexing to offer data rates up to 54 Mbps in the 5 GHz bands. The OFDM signal used for a includes 52 subcarriers, 48 of these were used for the data transmission and four as pilot subcarrier [2]. C) B STANDARD: Was the first wireless LAN standard to be widely adopted and built-in to many laptops, computers and other forms of equipment. The standard for b was approved by the IEEE in July 1999 and the idea for wireless networking quickly held on with many Wi-Fi hotspots, b has a maximum data rate of ISSN: Page 57

2 11 Mbps and uses the same media access method defined in the original standard, it requires less access points than a for the coverage of large area [3]. D) G STANDARD: In order to offer the higher speed of while operating on the 2.4 GHz band, a new standard was introduced known as g using the CSMA/CA transmission scheme. The four layer options defined in the g specifications are: - ERP-DSSS-CCK: This layer is the same as that used in b standard, Direct sequence spread spectrum used along with CCK - complementary code keying. - ERP-OFDM: this is a new physical layer comes for g where OFDM is used to enable the provision of high data rates at 2.4 GHz. - ERP-DSSS/PBCC: in this option the physical layer was introduced to be used with b and it provides the same data rates as the DSS/CCK layer, but with g the data rates expanded to offer 22 and 33 Mbps, it uses DSSS technology for the modulation jointly with PBCC coding for the data. - DSSS-OFDM: This layer is new to g, it uses a combination of DSSS and OFDM, here the payload is transmitted using OFDM, while the packet header is transmitted using DSSS [4]. III.SIMULATION MODEL This section presents the system model that was used in this study. Figure.1 displays the layout of the system which was designed to study the performance of different WLAN standards. Figure.1 Network Model The network consists of 5 workstations, 5 access points(ap) connected through a switch as one network, each workstation is connected to a certain AP by configuring a unique BSS identifier. The AP and workstation which have the same BBS identifier configured in WLAN PHY, to use the same standard with same data rate which in this case the maximum data rates introduced and adopted by WLAN standard. Application Configuration: Three applications defined for FTP, HTTP and database, described as high load, heavy browsing, and high load in order with the type of service (best effort) for all. IV.PERFORMANCE METRICS A) THROUGHPUT This parameter is known in networking as the measurement of the actual data packets which are transmitted from one place to another or processed in a specified amount of time. B) RESPONSE TIME: Response time is the total amount of time it takes to respond to a request for service when applied to a system, it is the interval between a user-request (command) and the receipt of a response, result, or feedback from the system. The service can be anything from HTTP request to loading a full web page or database query [9]. C) TCP ABORTS RST: TCP is a bi-directional protocol. This means that during a connection close sequence both sides need to say we have done sending, the connection remain up until both sides have performed that, or one side sends a TCP RST packet. RST is an abortive close use the RST (Reset) message. If either side issues an RST sent, this means the entire connection aborted and the TCP can throw away any data queued which has not been sent or received by any of the applications[6]. D) LOAD:Describes the amount of data (traffic) being carried by the network or the link. E) DELAY: Delay affects transfer of information that can occur at any level in the packet transferring from end to end, delay is the time taken to generate the packet by the source up to delivering it to the destination end. So this is the time that a packet takes to go across the network, Sometimes this delay is called the latency. F) QUEUE SIZE: Queuing theory is a tool to study of waiting lines or queues to simplify locating the cause for bottlenecks, Queue size and waiting time are parameters to describe the system performance since ISSN: Page 58

3 waiting time known as queuing delay and queue size reflect system or network scale. When a network node is carrying more data than it can handle is called congestion [7]. G) MEDIA ACCESS DELAY: - According to the OPNET it s a total of queue and contention delays of data packets received by WLAN MAC from higher layers. For each packet the delay marked when the packet sent to the physical layer for the first time. Many real-time applications have largest tolerable delay that is a respective reason to consider the average access delay being studied [8]. V. SIMULATION RESULTS The performance of the WLAN network that supports WLAN standard ( b, a, g, infrared and frequency hopping) has been analyzed and studied for Database, FTP and HTTP applications, output results presented by using Discrete Event Simulator OPNET. Figure.4: Average HTTP Objet response time Figure 5: Average HTTP Page response Time Figure.2: Average FTP Download response time Figure.3: Average FTP uploads response time A) Response time: Figure 2 and Figure 3 show the response time of FTP in both directions upload and download and reflect that (IR) and (FH) have the highest response time values (in seconds) in both directions while g and a have the lowest response time values, in both upload and download g is better in download response time (approximately 18 sec) than a. For the HTTP response time Figure 4 illustrates the object response time, hence object with a has the lowest response time value and the same behavior in page response time as in Figure (FH) has the highest value of object and page response time value. There is a matching in the performance between object and page response time in ISSN: Page 59

4 term of trend not values. Figure 13 presents the DB query response time, a has the good performance by being less response time in DB query and (IR) take the representative of the one with high response time (approximately 0.25 sec). Figure 8: Average WLAN Delay Figure 6: Average TCP Connection Abort (RST RCVD) Figure 9: Average WLAN Media Access Delay Figure 7: Average WLAN Queue Size packet B) TCP abort-queue size:- Figure 6 presents the TCP connection Abort with (RST RCVD) workstation that supports a has the highest abort (RST RCVD) value while (FH) reflects the lower value. In Figure 7 Queue size (FH) shows the greatest value of packet queue size and a presents the less value. C) Delay:- Figure 8 presents WLAN delay, a offers the best value of delay which is considered as the lowest one and its value is close to zero, (FH) shows the highest value, while b and g present close value trend in WLAN delay. Figure 9 WLAN media access delay a present again as lowest value, while this time (IR) has the lower one. Figure 12 WLAN delay for access point devices, The AP that supports a has the least delay value. Since the (IR) has the greatest value, But in the workstation delay Figure 8, (FH), presents the highest value of delay. ISSN: Page 60

5 D) Throughput-WLAN load:- throughput for a and b shows the close trend while (IR), g and (FH) are having the similar trend as Figure 10 displays, the load as Figure 11 shows minimum load value for (FH), b and a show close trend as maximum values. While g and (IR) reflect close pattern and in between values when compared with all the studied standards. Figure 10: Average WLAN Throughput Figure 13: Average DB Query Response Time Fig.11 Average WLAN Load Figure 12: Average AP WLAN Delay VI.SUMMARY AND CONCLUSION In this paper, a based WLAN Network with a working protocol of IEEE (IR), IEEE (FH), IEEE a, IEEE b and IEEE g were simulated using OPNET simulator for FTP, HTTP and DB applications. The main point of the study was to analyze the performance of these standards to see how they behaved in the network in term of delay, media access delay, queue size, response time, load, TCP abort and throughput. Results obtained reflect that when the data-rate in a wireless network increased, the Delay, Media access delay and Queue size decreases, Even for HTTP it was observed that if data-rate increases the response time decreases. REFERENCES [1] Aitizaz Uddin Syed,Very High Throughput (VHT) Multi-User Multiple Input Multiple Output (MU-MIMO) Communication in ac, Master Research Simon Frasor University -Spring [2] David D. Coleman, David A. Westcott, WLAN Troubleshooting and Design Official Study Guide Fourth Edition, Copyright 2014 by John Wiley & Sons, Inc., Indianapolis, Indiana ISBN: [3] Charlotte Abrahamsson and Mattias Wessman, Bachelor Thesis in Computer Science, Thesis no: BCS-2004:05, May 2004, School of Engineering Blekinge, Institute of Technology, Box 520 SE Ronneby Sweden. [4] Dimitris Vassis, George Kormentzas, Angelos Rouskas, and Ilias Maglogiannis, the IEEE g Standard for High Data Rate WLANs - University of the Aegean. [5] Pejman Roshan, Jonathan Leary, Wireless LAN Fundamentals, Publisher- Cisco Press Pub Date: December 23, 2003, ISBN: [6] ISSN: Page 61

6 [7] [8] OPNET Modeler 14.5 Documentation. [9] ISSN: Page 62