IEEE--ICET 2006 2 nd International Conference on Emerging Technologies Peshawar, Pakistan, 13-14 November 2006 1-4244-0502-5/06/$20.00©2006 IEEE 532 Performance Analysis of MPEG-4 Encoding For Low Bit-Rate Mobile Communications S.M. Majad Ashraf Khan 1 , Faqir Zarrar Yousaf 2 1 N-W.F.P. University of Engineering and Technology, Peshawar, Pakistan, majid@nwfpuet.edu.pk 2 Communication Networks Institute, University of Dortmund, Germany, faqir.yousaf@uni-dortmund.de Abstract: The transport of Multimedia applications over mobile networks with an effective QoS poses a challenge due to noise, high error probability and lower data rates, the factors inherent to mobile environments. Due to better compression techniques and the ability to support wide range of data rates, and its independence from transport, network and physical layer technologies, MPEG-4 (Motion Picture Expert Group 4) has become the coding technique of choice for the transport of multimedia applications over mobile networks. This paper reports the work on the performance analysis of the transport of video frames over mobile networks using MPEG-4 video coding techniques. Keywords: MPEG-4, Mobile Communication, Low bit rate. 1. INTRODUCTION The concept of providing multimedia services to end-user has gained popularity in the last couple of years due to major breakthrough in the access technologies and the exponential growth of the Internet since1990. The same is the case for the mobile networks too. The very first mobile network to offer some sort of data service was GSM, which can only support the data rate of 9.6kbps, the operator offer short message service (SMS) at this rate. But with the passage of time as the number of user grows, they put new demands on the network which eventually results into the high speed circuit switched data (HSCD) which can offer data rate up to 44kbps, but it was an expensive solution and quality was not very good. Also the biggest multimedia service like audio with/and video cannot be delivered with much efficiency. This paper is organized as follows. In section 1 we discuss the MPEG4 technology in reference to the characteristics and limitations of the mobile communication environment. In section 2 we highlight the principle features of MPEG4 making it suitable mobile applications. In section 3 we present some simulation results and conclusions are presented at the end in section 4. 2. MOBILE NETWORKS AND MPEG4 2.1. Performance Issues in Mobile Environments When we look on the mobile environment where data rates are not so high and also the environment is somewhat noisy we have to consider the following factors: Channel adaptation: The bandwidth of the air channel is never constant owing to the random variation in its characteristics due to environmental factors. This has a direct effect on the overall link delay causing congestion and buffer starvation in receivers and is especially detrimental to real time video services. Therefore the algorithm used for video coding must be capable of adapting to the variable nature of the channel. Robust encoding: The error probability of a wireless medium is in the range of 10 -3 , thereby warranting robust encoding to protect the channel from errors. Power efficiency: The mobile terminals operate at low powers and are served by batteries. Therefore in every mobile system a proper power control method is used to save the power demands of the terminal and in order to have fair access to all the mobile users. The algorithms or encoder/decoder must be power efficient. This lead to that encoder/decoder complexity should be reasonable at the mobile terminal, as complexity is directly related to delay and power consumption. Error handling: The encoder and decoder must be able to implement the error detection and corrections techniques. There are two methods suggested for this approach; Forward Error Correction (FEC) and Automatic Repeat Request (ARQ), where the latter is not deemed suitable for real time applications. So the main idea is to implement simple FEC techniques with low complexity. There is another