Sharif Digital Repository

In this letter, we explore blind interference alignment (BIA) for the K-user single-input and single-output interference channel. We show that if we implement the structure of reconfigurable antennas at the receivers, by increasing the number of reception modes, the chance of finding proper channel conditions to align most part of interference signals will increase. Throughout this letter, we use the antenna structure of media-based modulation as reconfigurable antenna structure of the receivers. In this method, the receivers try to find proper channel states to align interference signals in an opportunistic manner. The results of this letter show that our proposed method has higher capacity... 

Infrared indoor wireless communications using nondirected links are subject to severe multipath distortion which causes intersymbol interference (ISI). To lessen multipath distortion effect and thereby to improve the system performance, in this paper, we consider a new time-hopping based multiple access scheme for this channel, in which one pulse is transmitted in each bit interval. The position of the pulse is determined based on the output of a low rate error correcting code along with the user's dedicated PN code. We evaluate the multiple access performance of the system for correlation receiver considering background noise, dark current, and thermal noise. We compare the performance of... 

Low-complexity error concealment techniques for missing macroblock (MB) recovery based on the boundary matching principle are extensively studied and evaluated. In this paper, an improved boundary matching algorithm (BMA) using adaptive search is presented to conceal channel errors in inter-frames of video images. The proposed scheme adaptively selects proper candidate regions to conceal the artifact of a lost block. The candidate regions are examined based on analyzing motion activity of the neighboring MBs. Simulations show that the proposed scheme outperforms both on PSNR and visual quality obviously of about 1-4dB compared to existing methods  

The emerging multimedia applications of Wireless Sensor Network (WSNs) impose new challenges in design of algorithms and communication protocols for such networks. In the view of these challenges, error control is an important mechanism that enables us to provide robust multimedia communication and maintain Quality of Service (QoS). Despite the existence of some good research works on error control analysis in WSNs, none of them provides a thorough study of error control schemes for multimedia delivery. In this paper, a comprehensive performance evaluation of Automatic Repeat Request (ARQ), Forward Error Correction (FEC), Erasure Coding (EC), link-layer hybrid FEC/ARQ, and cross-layer hybrid... 

In recent years, the demand for video transmission over wireless communication networks is growing very fast. The H.264 video compression standard which offers high quality at low bit rates, is a suitable codec for applications that require efficient video transmission over wireless networks. While the compressed videos are transmitted through error-prone networks, error robustness becomes an important issue. In this paper, a joint source-channel Lagrange optimization method in which the distortion of the decoder is estimated without using feedback which can be used for both multicast and point-to-point applications is proposed. The experimental results show that the new algorithm has a good...