-
Article
1 - Statistical Analysis of Different Traffic Types Effect on QoS of Wireless Ad Hoc NetworksJournal of Information Systems and Telecommunication (JIST) , Issue 1 , Year , Winter 2015IEEE 802.11 based wireless ad hoc networks are highly appealing owing to their needless of infrastructures, ease and quick deployment and high availability. Vast variety of applications such as voice and video transmission over these types of networks need different net MoreIEEE 802.11 based wireless ad hoc networks are highly appealing owing to their needless of infrastructures, ease and quick deployment and high availability. Vast variety of applications such as voice and video transmission over these types of networks need different network performances. In order to support quality of service for these applications, characterizing both packets arrival and available resources are essential. To address these issues we use Effective Bandwidth/Effective Capacity theory which expresses packet arrival and service model statistically. Effective Bandwidth asymptotically represents arrival traffic specifications using a single function. Also, Effective Capacity statistically describes service model of each node. Based on this theory, at first we modeled each node’s service as an ON/OFF process. Then a new closed form of Effective Capacity is proposed which is a simple function and is dependent on a few parameters of the network. Afterward the performance of different traffic patterns such as constant bit rate, Poisson and Markov Modulated Poisson process are statistically evaluated in the case of both single and aggregate traffic modes. Using the proposed model we will show that traffic pattern affects QoS parameters even if all models have the same average packet arrival rate. We prove the accuracy of our model by a series of simulations which are run using NS2 simulator. Manuscript profile -
Article
2 - An Approach to Improve the Quality of Service in DTN and Non-DTN based VANETJournal of Information Systems and Telecommunication (JIST) , Issue 4 , Year , Autumn 2020Nowadays, with attention to soar in the number of network users, it is necessary to find new approaches to revolutionize network operation. Vehicular ad-hoc networks are bound to play a pivotal role in communication, therefore raising the traffic in the network, using o MoreNowadays, with attention to soar in the number of network users, it is necessary to find new approaches to revolutionize network operation. Vehicular ad-hoc networks are bound to play a pivotal role in communication, therefore raising the traffic in the network, using only WiFi is unlikely to address this problem. Vehicles could use SDN and other networks such as 4G as well as 5G to distribute traffic to different networks. Moreover, many approaches for handling different data types are inappropriate due to the lack of attention to the data separation idea. In this paper, we proposed a control scheme called Improve Quality of Service in DTN and Non-DTN (IQDN) which works based on vehicle communication infrastructure using SDN idea. IQDN separates data to Delay-Tolerant Data (DTD), and Delay-Intolerant Data (DID) where the former buffers in a vehicle till the vehicle enters an RSU range and sends DTD using IEEE 802.11p. DID packets are sent by cellular networks and LTE. To transmit DTD via IEEE 802.11p, the network capacity is evaluated by SDN. If that network has room to transmit the data, SDN sends a control message to inform the vehicle. Simulations show that sending data over RSU and LTE increases the throughput and decreases the congestion, so the quality of service improves. Manuscript profile -
Article
3 - روش جدیدی در بستهبندی نمونههای صوتی جهت مقابله با مشکل گمشدن بستههاNashriyyah -i Muhandisi -i Barq va Muhandisi -i Kampyutar -i Iran , Issue 16 , Year , Winter 2008این مقاله به معرفی روشی برای بستهبندی صدا جهت انتقال روی شبکه اینترنت میپردازد. هدف از این روش آن است که تا حد ممکن از کاهش کیفیت صدا بهدلیل گمشدن بستههای صوتی در شبکه جلوگیری شود. این روش اجازه بازسازی بستههای گمشده را در حین عبور از شبکه در گرههای فعال شبکه می Moreاین مقاله به معرفی روشی برای بستهبندی صدا جهت انتقال روی شبکه اینترنت میپردازد. هدف از این روش آن است که تا حد ممکن از کاهش کیفیت صدا بهدلیل گمشدن بستههای صوتی در شبکه جلوگیری شود. این روش اجازه بازسازی بستههای گمشده را در حین عبور از شبکه در گرههای فعال شبکه میدهد، لذا کیفیت صدای دریافتی در گیرنده بالاتر از روشهای عادی انتقال صدا روی اینترنت خواهد بود. کارآیی این روش بهوسیله شبیهسازی یک شبکه انتقال داده کاملاً غیر امن بههمراه یک گره فعال بررسی شده و نشان داده شده که کیفیت صدای دریافتی حتی با 50% بستههای گمشده نیز بسیار بهتر از روشهای دیگر انتقال صدا میباشد. Manuscript profile