How To Create A Simulator For Wireless Local Area Network (Ieee) And Wireless Network (Ipo) Networks

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1 ISSN : (Print) ISSN : (Online) Simulator to Analyze QoS for /a/g standards Rohit Sharma SUSCET, Tangori, Mohali, Punjab, India rohit9299@yahoo.com IJCST Vo l. 1, Is s u e 2, De ce m b e r 21 Abstract I have developed a simulator that simulates the behavior and performance of distinct wireless local area network standards, and in terms of few Quality of Service Parameters. Simulation measures the Quality of Service in terms of media access delay, network throughput, network bandwidth utilization and total packet delay. Simulator helps to predict which wireless standard is better for wireless communication in distinct wireless networks. In the presented work Simulator for /a/g standards operate under the distinct network topologies and same traffic scenarios. Simulator represents simulation results in the form of graphs. The simulation time taken by simulator is approximately is 15 seconds. Keywords,,, MAC Access Modes. I. Introduction Wireless network nodes communicate with each other by line of sight and mobile nodes with RF antennas. The major motivation and benefit from Wireless LANs [1] is increased mobility. The advantages for WLAN include cost-effective network setup for hard-to-wire locations such as older buildings and solidwall structures and reduced cost of ownership-particularly in dynamic environments requiring frequent modification, thanks to minimal wiring and installation costs per device and user. The standard IEEE [2] specifies two raw data rates of 1 and 2 Megabits per second (Mbps) to be transmitted via Infrared (IR) signals or by either Frequency hopping (FH) or Direct-Sequence Spread Spectrum (DSSS) in the Industrial Scientific Medical (ISM) frequency band at 2.4 GHz. The legacy IEEE was rapidly supplemented by. IEEE 82.11b has a maximum raw data rate of 11 Mbps and uses the same Carrier Sense Multiple Access network with Collision Avoidance (CSMA/CA) is a media access method. In case of the CSMA/CA protocol, can achieve throughput about 5.9 Mbps using Transmission Control Protocol (TCP) and 7.1 Mbps using User Datagram Protocol (UDP). Technically, the standard uses Complementary Code Keying (CCK) as its modulation technique, which is a variation of Code Division Multiple Access (CDMA) [3]. Technically, the IEEE 82.11b standard uses Complementary Code Keying (CCK) as its modulation technique, which is a variation of Code Division Multiple Access (CDMA). Both and were ratified in The standard uses the same core protocol as, operates in 5 GHz band and uses a 52-subcarrier Orthogonal Frequency Division Multiplexing (OFDM) [4] with maximum raw data rate of 54 Mbps. The data rate can be reduced to 48, 36, 24, 18, 12, 9 then 6 Mbps if required. It is not interoperable with, except if using equipment that implements both standards. In June 23, a third modulation standard was ratified i.e.. This extension works in the 2.4 GHz band like 82.11b but operates at a maximum raw data rate of 54 Mbps, or about 24.7 Mbps net throughput like 82.11a. hardware is compatible with hardware. However, the presence of an participant significantly reduces the speed of an network. The modulation scheme used in is OFDM for data rates of 6, 9, 12, 18, 24, 36, 48 and 54 Mbps, and reverts to like IEEE 82.11b CCK for 5.5 and 11 Mbps and Differential Binary Phase Shift Keying or Differential Quadrature Phase Shift Keying with DSSS (DBPSK/DQPSK+DSSS) for 1 and 2 Mbps. Even though operates in the same frequency band as, it can achieve higher data rates because of its similarities to. The maximum range of IEEE 82.11g devices is slightly greater that of IEEE82.11b devices, but the range in which a client can achieve the full 54 Mbps data rate is much shorter than that of which a client can reach 11 Mbps. The presented work examines the Quality of Service (QoS) parameters for, and that are extensions of the IEEE standard. To know which standard is best suited for a particular environment, I developed a simulator that simulates the various physical layer extensions of IEEE II. MAC Access Modes The IEEE protocol supports two modes or operations to control media access in the wireless network these are: A. Distributed Coordination Function. B. Point Coordination Function. A. Distributed Coordination Function The DCF uses the mechanism of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) [6] for contention based access. This function checks first to start transmission between various nodes in the wireless network. The stations use a random backoff after each frame to avoid collision. It can also use CTS/RTS clearing technique [5] to reduce the possibility of collisions in the wireless network. B. Point Coordination Function The PCF uses the contention free access or service, which uses the access point to control all activities in the cell. This function is based upon infrastructure wireless networks. The PCF allows nodes to transmit frames after a shorter interval, which increases the efficiency of the wireless network. III. Carrier Sensing Functions and Network Allocation Vector Carrier sensing uses two functions to determine medium is available in the wireless network. The carrier sensing functions in IEEE are: A. Physical Carrier Sensing Function B. Virtual Carrier Sensing Function A. Physical Carrier Sensing Function Physical carrier sensing (PCS) is one of the two main interference International Journal of Computer Science and Technology 91

2 IJCST Vo l. 1, Is s u e 2, De ce m b e r 21 mitigation (contention resolution) mechanisms defined in the PHY/MAC layers of WLANs. A node that intends to transmit first assesses the current channel state (this is generically termed as Clear Channel Assessment or CCA) [7] by comparing the measured on-air received energy against a predefined PCS threshold to determine if it should contend for channel access as per the CSMA/CA protocol. Each node samples the net energy level on-air and initiates channel access only if the detected value is below the threshold, indicating that the channel is free of significant ongoing transmissions. The PCS threshold effectively defines a carrier sensing range that denotes an area wherein a secondary transmitter is prevented from contending for access so as to not disrupt the reference transmission. B. Virtual Carrier Sensing Function The Virtual Carrier Sensing is provided by the Network Allocation Vector (NAV). In the wireless network a station waiting to transmit a packet will first transmit a short control packet called Request To Send (RTS) [8] which includes the source, destination and the duration of the following transaction (the packet and the respective ACK). If the medium is free, the destination station responds with a response control packet called Clear To Send (CTS) which includes the same duration information. All stations receiving either RTS and/or CTS, set their Virtual Carrier Sense indicator (called NAV, for Network Allocation Vector) [9], for the given duration and use this information together with the Physical Carrier Sense when sensing the medium. The mechanism reduces the probability of a collision on the receiver area by a station that is hidden from the transmitter to the short duration of the RTS transmission because the station hears the CTS and reserves the medium as busy until the end of the transmission. The duration information on the RTS also protects the transmitter area from collision during the ACK potentially caused from stations that are out of range of the acknowledgment station. Due the short frames of RTS and CTS, the method also reduces the overhead of collisions. If the packet is significantly bigger than the RTS, the packets can be transmitted without the RTS/CTS transaction. The station controls the process by RTS Threshold setting. The transmitting node or A, sends an RTS request to AP requesting to reserve a fixed amount of time necessary to transmit a frame of given length. When the medium is available, the AP broadcasts a CTS message that all stations can hear and B has the requested amount of air time. IV. Simulation Simulator is proposed software that analysis and compare three physical standards, and IEEE 82.11g on the user input parameters. In this research paper a Simulator named as Simabg is developed and designed that simulates physical standards of IEEE i.e. IEEE 82.11b, and. This simulator is developed and designed using Visual Basic tool, which is a programming language. The Visual Basic is used due to its simplicity and has capability to develop Graphical User Interface (GUI) applications. The typical features of Simulator named Simabg are as follows: 1. It supports different data rates in terms of, and standards. 92 International Journal of Computer Science and Technology ISSN : (Print) ISSN : (Online) 2. It analysis and compare three protocol standards of IEEE 82.11, which shows MAC layer performance in terms of Media Access Delay, Network Throughput, Network Bandwidth Utilization and Total Packet Delay. 3. Support of the new CTS-to-Self virtual carrier sense and protection mechanism: This means that a node can support RTS/CTS protection mechanism or new defined specification in i.e. CTS-to-Self virtual sense mechanism for better network performance. 4. Support for specifying RTS threshold value. 5. It supports Exponential Distribution for Packet Length Distribution and Packet Generation Rate Distribution processes. 6. Simulator is easy to operate and Graphical User Interface. The following metrics are used to compare the standards in the proposed simulator: 1. Media Access Delay (msec): The delay of a packet from the time it is picked from the transmitter until it is successfully received from the receiver. This statistic contains the delay due to retransmission attempts and the transmission delay. 2. Network Throughput (bps): The number of successfully transmitted bits per second by a node in a specific time interval. 3. Network Bandwidth Utilization (percentage): The percentage of the channel capacity the node occupied. 4. Total Packet Delay (msec): It is the sum of the media access delay and the queuing delay. It considers the total delay from the birth of a packet until its reception from the receiver. A. Configuring the Simulator Simulator Simabg includes three physical standards IEEE 82.11b, and used in wireless Local Area Networks. The physical layer elements that can be config.d include: MAC Layer Configuration Event Configuration Statistical Results Configuration Physical Layer Configuration Data Rate Configuration Packet Generation Rate Configuration Packet Length Configuration 1. MAC Layer Configuration The MAC layer (Fig-1) parameters that can be config.d in the simulator are: Access Mechanism: Simulator Simabg is designed to use one of the three access mechanism, which are Basic access, RTS/CTS or CTS-to-self. CTS-to-Self is a new protection mechanism only supported by standard. RTS Threshold: It is used to specify the RTS threshold in bits. In case packet larger than RTS threshold then the protection mechanism will be enabled. If packet length is equal to or smaller than RTS threshold then no protection mechanism will be enabled. It can support only integer values. The minimum and maximum values of RTS bits are and 2347 respectively. Simulator assigns by default 5 bits to RTS, In case user assigns wrong value like alphanumeric, negative value and greater than maximum value. To enable protection mechanism always, set the

3 ISSN : (Print) ISSN : (Online) RTS threshold to zero. IJCST Vo l. 1, Is s u e 2, De ce m b e r 21 form the network to be simulated. The presented simulator named Simabg can simulate only 1 nodes in the wireless network. Fig. 1: MAC, Event and Statistical Results Configuration Fig. 2: Network Configuration for 2. Event Configuration The Even configuration (Fig.1) includes following components: Simulation Time: This option sets the time period for which simulation will be run for the analysis and comparative study of three wireless physical standards. It is measured in seconds. Collected Vales per Statistics: This option is approximately equivalent to the Simulation Time. It specifies the time period taken by per statistics run in the simulator. In this simulator named Simabg, the Collected Values per Statistics kept approximately equal to the Simulation Time measurements. 3. Statistical Results Configuration The Statistical Configurations (Fig.1) used in the simulator to predict comparative analysis of, and standards. Statistical Results Configuration includes following components: Media Access Delay (msec): This option is used to get statistical results regarding media access delay of the nodes in the wireless network. Network Throughput (bps): This option is used to get statistical results regarding throughput of the nodes in the wireless network. Network Bandwidth Utilization (percentage): This option is used to get statistical results regarding Bandwidth Utilization of the nodes in the wireless network. Total Packet Delay (msec): This option is used to get statistical results regarding total packet delay of the nodes in the wireless network. 4. Physical Layer Configuration The simulation supports the selection of one of the available physical layers for wireless network. Physical layer (Fig. 2, Fig. 3 & Fig. 4) components that can be config.d include: Physical layer extension of IEEE standard: One of the physical layer extensions among, IEEE 82.11a and can be chosen. Number of nodes: It specifies the number of nodes that Fig. 3: Network Configuration for Fig. 4: Network Configuration for 5. Data Rate Configuration The Simulator supports one of the available data rates for available physical layer extensions. The data rate components (Fig. 2, Fig. 3 & Fig. 4) that can be config.d include: International Journal of Computer Science and Technology 93

4 IJCST Vo l. 1, Is s u e 2, De ce m b e r 21 Date Rate configuration for : Under this configuration, simulator can choose one of the data rates out of 1 Mbps, 2 Mbps, 5.5 Mbps and 11 Mbps. Date Rate Configuration for : Under this configuration, simulator can choose one of the date rates out of 6 Mbps, 9 Mbps, 12 Mbps, 18 Mbps, 24 Mbps, 36 Mbps, 48 Mbps and 54 Mbps. Date Rate Configuration for : Under this configuration, simulator can choose one of the date rates out of 6 Mbps, 9 Mbps, 12 Mbps, 18 Mbps, 24 Mbps, 36 Mbps, 48 Mbps and 54 Mbps. 6. Packet Generation Rate Configuration The Packet Generation Rate Configuration (Fig-2, Fig-3 & Fig-4) includes components as: Packet Generation Rate Distribution: This simulator considers exponential distribution for packet generation. Packet Generation Rate Mean: This option used to set the mean value of packet generation rate in packets per second. 7. Packet Length Configuration The Packet Length Configuration (Fig-2, Fig-3 & Fig-4) considers the following components: Packet Length Distribution: This simulator considers exponential distribution to obey packet length rules. Packet Length Mean: This option represent the mean value of the packet length in bits. The maximum value the protocol supports is bits. V. Simulation Results Simulator named Simabg can analyze and evaluate the performance of, and standards under the same network topology and traffic scenarios, in terms of Quality of Service (QoS) parameters such as: Media Access Control Network Throughput Network Bandwidth Utilization Total Packet Delay A. Simulation Parameters The various parameters used to simulate the four metrics (Media Access Delay, Network Throughput, Network Bandwidth Utilization and Total Packet Delay) for comparing and analyzing standards under consideration are kept same until or unless a standard lacks support for a particular parameter. The different simulation parameters used in simulator to evaluation are shown in Table-1. B. Performance Evaluation Metrics The performance measures used in the simulator are mentioned with results obtained after simulation, evaluation and comparative analysis of physical standards. Table-1 Simulation Parameters. Parameter Value Simulation Time Number of values per statistic 15 sec 149 (Assumed to be approximately equal to 15 sec) Access Mechanism RTS/CTS for & CTS-to-Self for IEEE 82.11g RTS Threshold P a c k e t Distribution L e n g t h Mean Packet Length Packet Generation Rate Distribution M e a n P a c k e t Generation Rate Number of Nodes to 2347 bits and default value in exceptional cases is 5 bits. Exponential Distribution (Fixed in Simulator) 8 bits Exponential Distribution (Fixed in Simulator) 8 Packets/Sec 1 (Fixed in Simulator) Data Rate 11 Mbps for IEEE 82.11b 54 Mbps for and 1. Media Access Delay Media Access Delay as name specifies is a delay caused by the network from picking a packet from the transmitter until the reception of packet by the receiver. Fig.-5 illustrates the Media Access Delay for, and IEEE 82.11g standards. Delay (msec) Media Access Delay Wireless Nodes Fig. 5: Media Access Delay ISSN : (Print) ISSN : (Online) After simulation process, Simulator predicts graph that indicates media access delay of the is quite lesser than standard, though being comparable to the. This means that performs better transmission in the wireless local area network due to shorter delays. The outcome shown in the above Fig. predicts mean Media Access Delays for 1 nodes, the number of nodes remained fixed throughout the life time of the simulator Simabg. The Media Access Delay is mathematically expressed as: 94 International Journal of Computer Science and Technology

5 ISSN : (Print) ISSN : (Online) Media Access Delay = Transmission Time / Successful Transmission Network Bandwidth Utilization IJCST Vo l. 1, Is s u e 2, De ce m b e r Network Throughput The network throughput considers number of bits successfully transmitted by a node in the specific time interval. The Fig.-6 illustrates the network throughputs for, IEEE 82.11a and standards. Network Throughput Bandwidth Utilization Time (sec) Throughput (kbps) Time (sec) Fig. 6: Network Throughputs. The Network Throughput is mathematically expressed as: Network Throughput = (Number of bits successfully transmitted by node i ) / Time Interval After analysis and comparative study, the simulator predicts graph that indicates the network throughput of is higher than the and standards. It can be easily explained as a consequence of the RTS/CTS exchange signaling, which adds some extra overhead to the network. However the difference between the throughputs of and is not much. Arithmetically speaking, the calculated mean difference between the throughputs of and is about 5%, however, mean difference between the throughputs of IEEE 82.11a and is approximately 3%. This predicts that nodes transmitting bits under the wireless standard IEEE 82.11g are much faster, efficient and productive. 3. Network Bandwidth Utilization The Network Bandwidth Utilization represents the percentage of the channel capacity is occupied by the node in the wireless network. The Fig.-7 illustrates the Network Bandwidth Utilization for the, and standards respectively. Fig. 7: Network Bandwidth Utilization The Network Utilization considers the nodes throughput in bits per second divided with the nodes data rate. Therefore, the Total network Bandwidth Utilization is the sum of the Bandwidth Utilization of the nodes. The graph predicted by the simulator Simabg indicates that the has higher network utilization against the other two physical layer extensions i.e. and IEEE 82.11a. As the data rate for the /g and IEEE 82.11b is used to be maximum i.e. 54 Mbps and 11 Mbps, therefore above graph justifies the behavior of the three physical extensions under consideration because Network Bandwidth Utilization is inversely proportional to the Data Rate. It is easily comprehensible that higher the data rate lesser will be the time for which the channel is being utilized in the wireless network and vice-versa. The Network Bandwidth Utilization is mathematically expressed as: Network Utilization = (Throughput of node i ) / (Data Rate of node i ) 4. Total Packet Delay The Total Packet Delay is the total delay from the birth of a packet until its reception by the receiver. The Queuing Delay is expressed as the delay from the birth of a packet until the transmitter picks it up for transmission; it means the time or which packet waits in the packet pool or queue. The Total Packet Delay is the sum of Media Access delay and Queuing Delay. The Total Packet Delay is mathematically is expressed as: Total Packet Delay = Media Access Delay + Queuing Delay Delay (msec) Total Packet Delay Time (sec) Fig. 8: Total Packet Delay International Journal of Computer Science and Technology 95

6 IJCST Vo l. 1, Is s u e 2, De ce m b e r 21 The simulators predictions regarding Total Packet Delay are shown in Fig.-8. The graph predicted by simulator indicates that the total packet delay is high for as compared to and standards. This could be explained that the contribution of media access delay is much high to the total packet delay as compared to the queuing delay. The analysis and comparative study through simulator predicts that is better standard to be utilized in the wireless local area network. VI. Conclusion Simabg Simulator is the proposed wireless system designed to analyze and compare different routing physical standards of IEEE (, and ) on certain parameters such as Media Access Delay, Network Throughput, Network Bandwidth Utilization and Total Packet Delay. The observations based upon simulation environment and input parameters as mentioned below: has shortest delays. It means that media access delay for is lowest in comparison to its rival protocol and. However there is a very small difference when it is compared with. Also as the major contribution to the total packet delay is media access delay rather than queuing delay, therefore the total packet delay for is considerably lower than and almost same as. The RTS/CTS exchange signaling adds extra overhead to the network. Therefore the network throughput of IEEE 82.11g is greater than the other two standards under consideration. Thereby, making as the best choice for the networks that require high throughput. The Network Bandwidth Utilization is maximum for IEEE 82.11b as compared to the other two wireless standards due to the considerable difference in the data rates offered by these standards. The presented work in this research paper is focused on the different wireless Physical Layer Extensions of IEEE standard, named, and IEEE 82.11g. I hereby presented a simulator named Simabg for comparing, simulate and evaluate, and standards under same network topology and same network traffic scenario. The simulator runs after taking the inputs on different parameters and shows a graphical result of four parameters (Media Access Delay, Network Throughput, Network Bandwidth Utilization and Total Packet Delay). This can be used as a very good educational tool to understand the behavior of these standards. The conclusion driven through this research work is that standard is much better than both and standards, if we employ standard in the real wireless local area network. Moreover is backward compatible to standard, with higher data rate speed and range. These protocols, and are popularly pronounced in the wireless network as Wi-Fi (Wireless Fidelity). ISSN : (Print) ISSN : (Online) Conference on Wireless Technology: Current Issues and Applications, 14th July 27, RCM, Bhubaneswar, India. [2] Kumar M., Parmanand, Sharma S. C., Singh S. P., Performance of QoS Parameter in Wireless Adhoc Network (). Proceeding of the WCECS, Vol. I, 2th-22nd Oct 29, San Francisco, USA. [3] Katarzyna K., Marek N., Luca V., Andrzej R. P., Simulation Study of 82.11e in the Presence of Hidden Terminals a Star Topology Case. UE-funded NoE CONTENT project no [4] Choi S., Pavon J., 82.11g CP: A Solution for and 82.11b Inter-Working. [5] Bai Y., Yu Y., Chen L., Enhanced Protection Mechanism for Improving Co-existence of and Wireless LANs. IEEE, 29. [6] Bruno R., Conti M., Gregori E., IEEE 8211 Optimal Performanes: RTS/CTS Mechanism vs Basic Access. IEEE, 22. [7] Sidhu G. S., Sidhu P. K., Sidhu S. S., QoS Issues of Media Access Delay and Throughput in WLAN. [8] Acharya R., Vityanathan V., Chellaih P. R., WLAN QoS Issues and IEEE 82.11e QoS Enhancement. International Journal of Computer Theory and Engineering, Vol. 2, N.1, Feb, 21. [9] Zyren J., Godfrey T., Wentink M., Network Behavior in a Mixed Environmet. Intersil Americas Inc., 23. Rohit Sharma M.C.A, M.Phil CS, M.Tech CSE. Designation: Assistant Professor Contact Information: Dept. of Information Technology, SUSCET, Tangori. References [1] Puthal D. K., Sahoo Bibhdatta, Performance Evaluation of MC DCF scheme in WLAN. Proceeding International 96 International Journal of Computer Science and Technology