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Articles by Johnny Koh
Total Records ( 2 ) for Johnny Koh
  David F.W. Yap , S.K. Tiong , Johnny Koh , D.P. Andito , K.C. Lim and W.K. Yeo
  Wireless Sensor Networks (WSN) is formerly created to support text-based data communication. However, by improving link level mechanism of WSN with Error Control Coding (ECC), reliable multimedia transmission could be realized. This paper addresses the performance issue of transferring multimedia data, particularly still image data, using real sensor motes platform. An X-ray image is transferred from one mote to other mote in one hop scenario. Forward Error Correction (FEC) and interleaving technique are used to design the code that capable of handling both erasure and noise in the received packet. The results show that erasure code can effectively combat the effect of random noise in one packet despite its number as well as recover small quantity of lost packet. Furthermore, the scheme can increase the image PSNR (Peak Signal to Noise Ratio) up to 18.41 dB as compared to the uncoded counterpart.
  Ayad Atiyah Abdulkafi , Tiong Sieh Kiong , Johnny Koh , David Chieng and Alvin Ting
  The concept of heterogeneous networks had been proposed as an alternative approach to provide higher capacity and coverage for cellular networks. Along with that, the aspect of “Energy Efficiency” had already received much attention lately due to ecological as well as economic reasons particularly for network operators. This study presented a systematic review on the topic of energy efficiency in heterogeneous cellular networks. The review was divided into three parts; first the typical metrics parameters used to measure energy efficiency and tradeoff relationships with respect to network performance were discussed. Next, the existing issues, approaches and challenges to provide energy efficiency in general cellular networks were addressed. Finally we looked into the current efforts on energy awareness in macro, micro, pico and femtocells. By means of discussions, we highlighted different heterogeneous network scenarios in which network planning and optimization techniques were (or not were) advantageous to provide essential understanding for successful deployment of green heterogeneous cellular networks.
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