Current IP geoloation techniques can geolocate an IP address to a region approximately 700 square miles, roughly the size of a metropolitan area. We model geolocation as a pattern-recognition problem, and introduce techniques that geolocate addresses to within 5 miles inside a metropolitan area. We propose two complementary algorithms: The first algorithm, Pattern Based Geolocation (PBG), models the distribution of latencies to the target and compares it to those of the reference landmarks to resolve an address to within 5 miles in a metropolitan area. The second approach, Perturbation Augmented PBG (PAPBG), provides higher resolution by sending extra traffic in the network. While sending an aggregate of 600 Kbps extra traffic to 20 nodes for approximately 2 minutes, PAPBG geolocates addresses to within 3 miles.

Several new methods for vector quantization of image sequence were developed in this paper. The 3-d gradient operator1 and the newly developed stochastic gradient operator was used to estimate the motion vector on the present frame in a pixel-bypixel basis. Two new methods of block motion estimation using the pixel motion vectors were studied. The methods either use the pixel motion vectors directly on the moving block or calculate the block motion vector from the pixel motion vectors. Then for both of the methods, the differences between the prediction block and the moving block are vector quantized. The gradual deterioration of the image frames due to the incorrect matching of the code vectors and the difference blocks could be suppressed with the stochastic gradient operator and a simple smoothing filter for the prediction values. Good quality images for video conferencing applications could be obtained with the bit rate in the neighborhood of 0.15.

Several edge-adaptive dual-mode predictive coding systems are proposed for coding monochrome video signals. These algorithms use the pseudo-Laplacian edge detector to switch between the textural coding and the edge coding. The one-dimensional Song DM coder and the two-dimensional weighted average prediction DM coder were used for the textural coding. The edge coding was done with either a normal two-dimensional Song DM coder, Graham's DPCM schemes, or a DPCM coder developed by the authors. Nine different combinations of textural and edge coding techniques were developed and simulated. The bit rates of the various schemes were compared, and the range varied between 2.28-3.46 bits/pixel without further compression of the edge information bits or the correction bits. Subjective tests were carried out on images reconstructed according to these schemes. The results show that most of the pictures obtained with the techniques in this paper are superior to the pictures coded by the Song mode normal two-dimensional DM coder alone.