Research of Link Adaptation Technology and Solutions in Wireless Communication Network

2013 ◽  
Vol 336-338 ◽  
pp. 1757-1760
Author(s):  
Lu Cao ◽  
Ying Xu ◽  
Tian Lei Wang

With the rapid growth of the demand for wireless data services, it becomes a hotspot in the field of mobile communication to maximize data transfer rate on the limited bandwidth. Link adaptation technology has a strong advantage in improving the data transfer rate and the spectrum utilization rate, thus becoming one of the key technologies in current and future mobile communication systems. This paper aims to study the adaptive technology of the wireless link, emphasizing on the basic principles and existing implementations of the adaptive modulation and coding (AMC) and the hybrid-automatic repeat request (HARQ) which are both mainstream link adaptive technologies. Finally, a new link adaptation technology implementation is given by combining the advantages of AMC and HARQ.

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Shaila Ghanti ◽  
G. M. Naik

Embedded systems are extensively used in home automation systems, small office systems, vehicle communication systems, and health service systems. The services provided by these systems are available on the Internet and these services need to be protected. Security features like IP filtering, UDP protection, or TCP protection need to be implemented depending on the specific application used by the device. Every device on the Internet must have network interface. This paper proposes the design of the embedded Secured Ethernet Interface System to protect the service available on the Internet against the SYN flood attack. In this experimental study, Secured Ethernet Interface System is customized to protect the web service against the SYN flood attack. Secured Ethernet Interface System is implemented on ALTERA Stratix IV FPGA as a system on chip and uses the modified SYN flood attack protection method. The experimental results using Secured Ethernet Interface System indicate increase in number of genuine clients getting service from the server, considerable improvement in the data transfer rate, and better response time during the SYN flood attack.


Author(s):  
BIMA BIMA ◽  
LITA LIDYAWATI ◽  
ARSYAD RAMADHAN DARLIS

ABSTRAKAntena merupakan perangkat yang memiliki peranan yang sangat penting dalam sistem komunikasi tanpa kabel (wireless). Pada penelitian ini akan diimplementasikan reflektor antena wajanbolik yang beroperasi pada frekuensi CDMA 2000 1x EVDO 1900 MHz. Antena ini menggunakan  reflektor dari wajan, dengan waveguide dari pipa paralon yang dilapisi dengan lakban alumunium, dan penerima sinyal menggunakan USB modem adapter. Antena ini ditujukan untuk menjadi media bantu  dalam  memperkuat  penerimaan sinyal  EVDO dan memaksimalkan dan kecepatan transfer data. Antena ini memberikan gain sebesar 15,530 dB berdasarkan pengukuran dan 15,156 dB berdasarkan teoritis. Pengujian menggunakan wajanbolik menunjukkan adanya peningkatan level sinyal modem yang terendah sebesar 4 dB pada pengukuran dengan kondisi indoor di siang hari serta tertinggi sebesar 19 dB pada pengukuran dengan kondisi outdoor di malam hari. Hasil dari pengujian pun menunjukkan peningkatan kecepatan transfer data rata – rata sebesar 42 KBps sampai dengan 269 KBps dibandingkan pengukuran tanpa wajanbolik.Kata kunci: Reflektor, Waveguide, Wajanbolik, USB adapter, EVDO.  ABSTRACTThe antenna is a device that has a very important role in wireless communication systems (wireless). In this research will be implemented wajanbolik reflector antenna which operates at frequencies of CDMA 2000 1x EVDO 1900 MHz. This antenna uses a reflector of the pan, with the waveguide of the pipe is coated with aluminum duct tape, and a signal receiver using a USB modem adapter. This antenna is intended to be a media aids in strengthening the EVDO and signal reception to maximize data transfer speeds. This antenna give a gain of 16.015 from measurement dBi and 15.156 dBi based on theory. Tests using wajanbolik showed an increase in the level of modem signals a low of 4 dB in measurement with indoor conditions during the day and 19 dB at the peak of measurements with outdoor conditions at night. Results of testing also showed an increase in average data transfer rate is 42 KBps up to 269 KBps compared to measurements without wajanbolik.Keywords:  Reflector, Waveguide, Wajanbolic, USB adapter, EVDO.


2002 ◽  
Vol 41 (Part 1, No. 3B) ◽  
pp. 1804-1807 ◽  
Author(s):  
Gakuji Hashimoto ◽  
Hiroki Shima ◽  
Kenji Yamamoto ◽  
Tsutomu Maruyama ◽  
Takashi Nakao ◽  
...  

2021 ◽  
Vol 1 (132) ◽  
pp. 136-144
Author(s):  
Volodymyr Khandetskyi ◽  
Dmutro Sivtsov ◽  
Kostjantun Panin

Analysis of new technologies IEEE 802.11ac/ax of wireless networks showed that increasing their noise immunity is an actual task. The article studies the efficiency of fragmented data frames transmission. Comparison of the efficiencies in the case of retransmission of the corrupted original frame and in the case of its fragmentation in a wide range of the physical data transfer rates is carried out.


1989 ◽  
Vol 66 (12) ◽  
pp. 6138-6143 ◽  
Author(s):  
Harukazu Miyamoto ◽  
Toshio Niihara ◽  
Hirofumi Sukeda ◽  
Masahiko Takahashi ◽  
Takeshi Nakao ◽  
...  

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 70
Author(s):  
Hirayama ◽  
Fujimura ◽  
Umegaki ◽  
Tanaka ◽  
Shimura

Holographic memory is currently attracting attention as a data storage system capable of achieving a data transfer rate of about 105~106105~106 times that of an optical disc such as Blu-ray disc. In conventional holographic memory, data is generally recorded by optical writing using volume holograms. However, a volume hologram has the problem not only that it is required to have high mechanical accuracy of a system and low coefficient of thermal expansion of a recording medium, because reconstruction tolerance is extremely low, but also that duplicating time efficiency is poor because whole data cannot be recorded at once. In this paper we proposed surface holographic memory that achieved a high data transfer rate, stable readout performance, and collective duplication by expressing holograms with fine surface asperity. Furthermore, the theoretical formulas of recording and reconstruction processes in the proposed system were derived and the reconstruction characteristics of the hologram were evaluated by numerical simulation. As a result, the proposed method generated reconstructed image readout with sufficient signal for a single page recording. However, the reconstructed image had noise, which was particular to a surface holographic memory.


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