List of Articles WLAN

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  1 - SRR shape dual band CPW-fed monopole antenna for WiMAX / WLAN applications
  Zahra Mansouri Ramezan Ali Sadeghzadeh Maryam  Rahimi Ferdows Zarrabi
  10.7508/jist.2015.01.007
  CPW structure is became common structure for UWB and multi band antenna design and SRR structure is well-known kind of metamaterial that has been used in antenna and filter design for multi band application. In this paper, a SRR dual band monopole antenna with CPW-fed f More

  CPW structure is became common structure for UWB and multi band antenna design and SRR structure is well-known kind of metamaterial that has been used in antenna and filter design for multi band application. In this paper, a SRR dual band monopole antenna with CPW-fed for WLAN and WiMAX is presented. The prototype antenna is designed for wireless communication such as WLAN and WIMAX respectively at 2.4 GHz and 5 GHz. The HFSS and CST microwave studio are used to simulate the prototype antenna for two different FEM and time domain method and they have also been compared with the experimental results. The total size of the antenna is 60mm×55mm×1.6mm and it is fabricated on FR-4 low cost substrate. The antenna is connected to a 50 Ω CPW feed line. Its bandwidth is around 3% for 2.45 GHz (2.4-2.5 GHz) and 33% for 5.15GHz (4.3-6 GHz).Its limited bandwidth in 2.4 GHz frequency is benefit for power saving at indoor application. The antenna has 2-7 dBi gain in the mentioned bands with an Omni-directional pattern. The antenna experimental result shows good similarity to simulation kind for return loss and pattern. Here, the effect of parasitic SRR on current distribution has been studied in presence and absence of parasitic element. The simulation of polarization is confirmed that the antenna has linear polarization. Here comparison between antenna return losses in absence of each parasitic element is presented. Manuscript profile
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  2 - A Game Theory Based Dynamic Transmission Opportunity Adjustment in WLANs
  Mahdieh Ghazvini Kamal Jamshidi Naser Movahedinia
  10.7508/jist.2019.01.002
  IEEE 802.11e is standardized to enhance real time multimedia applications’ quality of service (QoS). This standard introduces two access mechanisms called Enhanced distributed channel access (EDCA) and HCF Controlled Channel Access (HCCA) as well as four Access Categor More

  IEEE 802.11e is standardized to enhance real time multimedia applications’ quality of service (QoS). This standard introduces two access mechanisms called Enhanced distributed channel access (EDCA) and HCF Controlled Channel Access (HCCA) as well as four Access Categories (ACs) for different types of applications. Each AC has four adjustable parameters : Arbitrary Inter-Frame Space Number(AIFSN), minimum Size of Contention Window(CWmin), maximum size of Contention Window (CWmax), and TXOP_limit. A TXOP_limit (TXOP) is time interval, in which a wireless station can transmit a number of frames consecutively, without releasing the channel and any further contention with other wireless stations. TXOP improves network throughput as well as service differentiation. Proper TXOP adjustment can lead to better bandwidth utilization and QoS provisioning. This paper studies the determination of TXOP in EDCA mode of IEEE 802.11e using a game theory based approach called GDTXOP. Based on GDTXOP, each wireless node chooses its appropriate TXOP according to its queue length and media access delay. OPNET simulator simulated the proposed method and its accuracy is evaluated and verified. The results of the simulation indicate that tuning TXOP appropriately improves both channel utilization for all levels of traffic priority and fairness. This improvement does not impair the quality of high-priority traffics. The proposed approach improves channel utilization, while preserving fairness and efficiency in WLANs and minimizing selfishness behaviours of stations in a distributed environment. Simulation results show the proposed method improves fairness while not disrupting the quality of service. Manuscript profile
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  3 - Broadband Printed Microstrip Antenna Loaded by Wideband AMC Structure for MIMO Systems
  حسین  ملک پور شهرکی Ali Abolmasoumi
  In this paper, a wideband printed antenna over an artificial magnetic conductor (AMC) surface is introduced which can be utilized for wireless applications such as WLAN, WiMAX, and multiple-input multiple-output (MIMO) systems. In the proposed structure, a planar AMC su More

  In this paper, a wideband printed antenna over an artificial magnetic conductor (AMC) surface is introduced which can be utilized for wireless applications such as WLAN, WiMAX, and multiple-input multiple-output (MIMO) systems. In the proposed structure, a planar AMC surface as the antenna ground plane is used to direct the radiation pattern of the antenna, and enhancing the impedance bandwidth. The proposed antenna design is composed of a pair of printed microstrip elements fed by an E-shape feed line for coupling the elements. The bandwidth of the designed antenna includes from 4.94 GHz to 6.9 GHz with a return loss of less than -10dBforlinear polarization in C-band. The rhombic-shape AMC unit cell indicates the bandwidth of 5.24-7.15 GHz for the ±90˚ reflection phase. By adding the AMC surface into the printed antenna, a wideband structure with acceptable miniaturization and gain enhancement to 7.25 dBi is achieved. The simulated results of the antenna’s impedance properties are performed by using full-wave simulators of HFSS and CST. Also, two-element array of the proposed design are investigated for different polarizations. Based on the obtained results, the operating bandwidth includes the frequency range from5.18GHz to 6.81 GHz and the isolation between the array elements is less than -22 dB. For this purpose, the antenna arrays can be applied for MIMO systems. Manuscript profile