A novel error concealment method using a Kalman filter is presented in this paper. In order to successfully utilize the Kalman filter, its state transition and observation models that are suitable for the video error concealment are newly defined as follows. The state transition model represents the video decoding process by a motion-compensated prediction. Furthermore, the new observation model that represents an image blurring process is defined, and calculation of the Kalman gain becomes possible. The problem of the traditional methods is solved by using the Kalman filter in the proposed method, and accurate reconstruction of corrupted video frames is achieved. Consequently, an effective error concealment method using the Kalman filter is realized. Experimental results showed that the proposed method has better performance than that of traditional methods.

Research and development of a multi-degree colorless, directionless and contentionless reconfigurable optical add-drop multiplexer (CDC-ROADM) has recently been attracting a lot of attention. A large-scale transponder aggregator (TPA) is indispensable for providing high-capacity flexible connections to optical networks. In this paper, we report our study of the requirements for the TPA, which is a key technology for achieving flexible optical networks. To meet the requirements, we have developed an 848 TPA prototype based on Si photonics technology. This prototype was made with a few 88 Si optical switches and designed to be used with a commercial ROADM system. The 88 Si optical switches are made by integrating 152 Mach Zehnder (MZ) Thermo Optoelectronic (TO) 22 optical switch elements. A double gate structure is introduced to achieve the high extinction ratio (ER) required for optical communication. To the best of our knowledge, this is the world's first Si-TPA that can be used with a commercial ROADM system. By evaluating the basic optical characteristics utilizing real-time 100 Gbps digital coherent detection as one of today's practical technologies and a 4.4 THz spectral bandwidth 20 Tbps super-channel with digital coherent detection, as a promising future technology, we have confirmed that our prototype Si-TPA has the potential for practical use and future extensibility.