Abstract: A method of assigning a unique IP address to a user of a mobile communication device in an OBS network allows for the dynamic assignment of IP addresses to users entering the OBS network. The OBS network includes a plurality of interconnected OBSs where each of the OBSs includes a user database including an OBS identifier, user identifier, assigned IP address, MAC hardware address, and beam identifier for each user in the network. The OBS network also includes a master ticketing authority that maintains a database of unique IP address that may be assigned to users entering the network, a gateway, a master routing database, and at least one mobile communication device in contact with an OBS. Users in the network are also authenticated through the transmittal of encrypted random numbers between a user authentication site and a mobile communication device.

Abstract: A pre-encoder look-up table (LUT) provides output symbols for a statistical coder in response to signals representing a prediction of a prediction signal in a differential pulse code modulation (DPCM) system. The normal prediction signal is used as one address to the LUT and the prediction of that normal signal is used as a second address. The average probability distribution of the signals is determined to construct the LUTs wherein the output symbols are assigned values corresponding to different average probabilities of occurrence of the signal to be processed to thereby reduce the entropy further without adding overhead control symbols to the transmission system.

Abstract: In a DPCM video digital data communication system, each scan line of a video frame is refreshed with PCM data over a refresh cycle comprising a plurality of frames. Refresh generators at the transmitter and at the receiver are synchronized with an initialization signal and with subsequent refresh cycle synchronizing signals. Also the scan lines and frames are synchronized with corresponding transmitted marker synchronizing signals. The refresh generators run asynchronously between marker synchronizing signals to select scan lines for refresh. The refresh generators each employ counters for counting a selected number M which is an integer having no factors in common with the number of scan lines of a frame to select scan lines for refresh which have different spatial positions in adjacent successive frames to avoid generating visible refresh artifacts.

Abstract: A digital television transmitter has a buffer that receives a low resolution low pass filtered signal. A high resolution high pass filtered signal is applied to the buffer only when the buffer can accept it without overflowing in accordance with a threshold signal. A controller provides a control signal that varies in accordance with an interframe difference motion indicator signal and the inverse of the occupancy of the buffer. A digital television receiver receives a digital television picture signal and preferably a transmitter buffer occupancy state signal. A low resolution low pass filtered signal is applied to an adder. A high resolution high pass filtered signal is applied to the adder in accordance with the buffer state and motion indication. The transmitter and receiver are useful in video teleconferencing.