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1 - EBG Structures Properties and their Application to Improve Radiation of a Low Profile Antenna
Masoumeh Rezaei Abkenar Pejman Rezaei
10.7508/jist.2013.04.006

In this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure More

In this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure, which has more compact electrical dimensions, is analyzed and its electromagnetic properties are derived. Results show that resonant frequency of this novel structure is about 15.3% lower than the basic structure with the same size. Moreover, the novel EBG structure has been used as the ground plane of antenna. Its application has improved radiation of a low profile dipole antenna. The antenna performance over the new EBG ground plane is compared with the conventional mushroom-like EBG structure. Simulation results show that using this slot loaded EBG surface, results in 13.68dB improvement in antenna return loss, in comparison with conventional mushroom-like EBG, and 33.87dB improvement in comparison with metal ground plane. Besides, results show that, EBG ground planes have increased the input match frequency bandwidth of antenna. Manuscript profile
Open Access Article
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2 - Statistical Analysis of Different Traffic Types Effect on QoS of Wireless Ad Hoc Networks
Mahmood Mollaei Gharehajlu Saadan Zokaei Yousef Darmani
10.7508/jist.2015.01.002

IEEE 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 More

IEEE 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
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3 - Analysis of Imperfect Space Channel for the Next Generation Satellite Networks
pedram hajipour ali shahzadi
10.7508/jist.2017.20.004

An efficient space data management is imperative in guaranteeing the best performance with a fair distribution of next generation satellite networks. Therefore, one of the major challenges of implementing this kind of future satellite networks is evaluation any untruste More

An efficient space data management is imperative in guaranteeing the best performance with a fair distribution of next generation satellite networks. Therefore, one of the major challenges of implementing this kind of future satellite networks is evaluation any untrusted error for the best Quality of Service (QoS). Therefore, Bit Error Rate (BER) criteria based on the type of space channel which it can be defined prefect or imperfect state between satellites and ground stations seems to be a major challenge for space communication. In this paper, the authors provide a bandwidth sharing algorithm for a proposed future satellite networks under multi-beam prototype. This structure has many antennas in transmitter and receiver sides (satellite and ground stations) which they will be communication together based on space data. Using the above framework, the coverage probability and MIMO capacity for a typical multi-beam satellite system is compared with a single antenna for satellite and multi-antenna for area side coverage based on input parameters such as path loss and Signal to Noise Ratio (SNR), respectively. Finally, the bit error rate based on imperfect channel estimation is obtained by employing 4-QAM and QPSK digital modulations and the number of antennas followed by a comparative analysis. Manuscript profile

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