Apple Computer Inc. v. Burst.com, Inc.

Filing 116

Declaration of Leeron Kalay in Support of 115 Reply Memorandum In Support of Motion for Summary Judgment of Invalidity filed byApple Inc.. (Attachments: # 1 Exhibit A# 2 Exhibit B# 3 Exhibit C# 4 Exhibit D# 5 Exhibit E# 6 Exhibit F)(Related document(s) 115 ) (Brown, Nicholas) (Filed on 6/21/2007)

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Apple Computer Inc. v. Burst.com, Inc. Doc. 116 Att. 3 Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 1 of 7 Exh. C Dockets.Justia.com Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 2 of 7 Digital Telephony Second Edition John Bel/amy Vice President of Engineering AMBIT Systems Inc Carrollton , Texas A Wiley- Interscience Publication JOHN WILEY & SONS, INC. New York. Chichester. Brisbane. Toronto. Singapore i.e'b, Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 3 of 7 In recognition of the importance of preserving what has been written , it is a policy of John Wiley & Sons, Inc. to have books of enduring vahle published in the United States printed on acid-free paper , and we exert our best efforts to that end. Copyright (!:;) 1991 John Wiley & Sons , Inc. All rights reserved. Published simultaneously in Canada. Reproduction or translation of any part of this work beyond that permitted by Section 107 or 108 of the 1976 United States Copyright Act without the permission of the copyright owner is unlawful. Requests for permission or further information should be addressed to the Permissions Department , John Wiley & Sons, life. Librll1')' of Congress Cataloging- in-Publication Data: Bellamy, John , 1941- Digital telephony / John Bellamy. - 2nd ed. em. (Wiley series in telecommunications) A Wiiey-Interscience publication. Includes bibliographical references and index. 1. Digital telephone systems. TK5103. B44 1990 621.385- dc20 ISBN 0-471- 62056- I. Title. II. Seri.:s. 90-37906 CIP Printed in the United States of America 109 8 7 6 5 Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 4 of 7 130 VOICE DIGITIZATION Frequency domain voice coders provide improved coding efficiencies by encoding the most important components of the spectrum on a dynamic basis. As the sounds change different portions (formants) of the frequency band are encoded. The period between formant updates is typically 10 to 20 msec. Instead of using periodic spectrum measurements , some higher quality vocoders continuously track gradual changes in the spectral density at a higher rate. Frequency domain vocoders often provide lower bit rates than the time domain coders, but typically produce more unnatural sounding speech. DIFFERENTIAL PULSE CODE MODULATION Differential pulse code modulation (DPCM) is designed specifically to take advantage of the sample- to-sample redundancies in a typical speech waveform. Since the range of sample differences is less than the range of individual samples fewer bits are needed to encode difference samples. The sampling rate is often the same as for a comparable PCM system. Thus the bandlimiting filter in the encoder and the smoothing filter in the decoder are basically identical to those used in conventional PCM systems. A conceptual means of generating the difference samples for a DPCM coder is to store the previous input sample directly in a sample-and- hold circuit and use an analog subtractor to measure the change. The change in the signal is then 27 is more complicated , however, because the previous input value quantized and encoded for transmission. The DPCM structure shown in Figure reconstructed by a feedback loop that integrates the encoded sample differences. In essence , the feedback signal is an estimate of the input signal as obtained by integrating the encoded sample differences. Thus the feedback signal is obtained in the same manner used to reconstruct the waveform in the decoder. The advantage of the feedback implementation is that quantization errors not accumulate indefinitely. If the feedback signal drifts from the input signal , as a result of an accumulation of quantization errors , the next encoding of the difference signal automatically compensates for the drift. In a system without Bandlimiting filter Differentiator Analog Sampler quantizer encoder Input AID Encoded difference samples DIA Previous input estimate Accumulator Figure 3.27. Functional block diagram of differential PCM. -= Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 5 of 7 DIFFERENTIAL PULSE CODE MODULATION 131 feedback the output produced by a decoder at the other end of the connection might accumulate quantization errors without bound, As in PCM systems, the analog-to-digital conversion process can be uniform or companded. Some DPCM systems also use adaptive techniques (syllabic companding) to adjust the quantization step size in accordance with the average power level of the signal. (See reference (9) for an overview of various techniques, Example 3.4. Speech digitization techniques are sometimes measured for quality by use of an 800-Hz sine wave as a representative test signal. Assuming a uniform PCM system is available to encode the sine wave across a given dynamic range, determine how many bits per sample can be saved by using a uniform DPCM system, SolutioD. In essence, the solution is obtained by determining how much smaller the dynamic range of the difference signal is in comparison to the dynamic range of the signal amplitude, Assume the maximum amplitude of the sine wave is so that x(t) sin(2n' 800t) The maximum amplitude of the difference signal can be obtained by differentiating and multiplying by the time interval between samples: A, (2n)' (800)' cos(2n' 800t) 628A lL\x(t)lmax = . (2n) , (800) , The savings in bits per sample can be determined as logz (O, ~28 = 0.67 bits Example 3.4 demonstrates that a DPCM system can use i bit per sample less than a PCM system with the same quality, Typically DPCM systems provide a fun I bit reduction in code word size. The larger savings is achieved because , on average, speech waveforms have a lower slope than an 800 Hz tone (see Figure 25), 1 DPCM Implementations Differential PCM encoders and decoders can be implemented in a variety of ways depending on how the signal processing functions are partitioned between analog and digital circuitry. At one extreme the differencing and integration functions can be implemented with analog circuitry, while at the other extreme Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 6 of 7 232 DIGITAL SWITCHING As is demonstrated shortly, the number of crosspoints defined in Equation 1 can be significantly lower than the number of crosspoints required for single stage switches. First , however , we must detennine how many center stage arrays are needed to provide satisfactory service. Nonblocking Switches One attractive feature of a single stage switch is that it is strictly nonblocking. If the called party is idle , the desired connection can always be established by selecting the particular crosspoint dedicated to the particular input/output pair. When crosspoints are shared, however, the possibility of blocking arises. In 1953 Charles Clos (2) of Bell Laboratories published an analysis of three-stage are required to switching networks showing how many center stage arrays provide a strictly nonblocking operation. His result demonstrated that if each is equal to individual array is nonblocking, and if the number of center stages 2n - 1, the switch is strictly nonblocking. The condition for a non blocking operation can be derived by first observing that a connection through the three-stage switch requires locating a center stage array with an idle link from the appropriate first stage and an idle link to the appropriate third stage. Since the individual arrays themselves are nonblocking, the desired path can be set up any time a center stage with the appropriate idle links can be located. A key point in the derivation is to observe that since each - 1 of these inlets can be busy when the inlet inlets, only first-stage array has is greater than corresponding to the desired connection is idle. If - 1, it follows that , at most - 1 links to center stage arrays can be busy. Similarly, at - 1 links to the appropriate third-stage array can be busy if the outlet of most the desired connection is idle. 7) if all - 1 busy The worst case situation for blocking occurs (as shown in Figure 5. links from the first-stage array lead to one set of center stage arrays, - 1 busy links to the desired third-stage array come from a separate and if all set of center stage arrays. Thus these two sets of center stage arrays are exists , the appropriate input and output links must be idle , and that center stage 1) + (n connection. Hence if can be used to unavailable for the desired connection. However , if one more center stage array set up the (n of - 1) + 1 = is strictly nonblocking. Substituting this value into Equation 5.1 reveals that for a strictly nonblocking operation of a three 2n - 1 the switch stage switch: 2N(2n - 1) + (2n - 1) (:r (5.2) As expressed in Equation 5. , the number of cross points in a nonblocking three-stage switch is dependent on how the inlets and outlets are partitioned into subgroups of size n. Differentiating Equation 5. 2 with respect to nand setting the resulting expression equal to 0 to detennine the minimum reveals Case 3:06-cv-00019-MHP Document 116-4 Filed 06/21/2007 Page 7 of 7 SPACE DIVISION SWITCHING 233 Figure 5,7, Nonblocking three-stage switching matrix. (N /2)1/2 that (for large N) the optimum value of is Substituting this value of into Equation 5,2 then provides an expression for the minimum number of crosspoints of a nonblocking three-stage switch, NAmin) = 4N(JiN - 1) (5.3) = total number of inlets/outlets, Table 5, 1 provides a tabulation of N (min) for various sized nonblocking three-stage switches and compares the values to the number of crosspoints in a single stage square matrix, Both switching structures inherently provide fourwire capabilities, a requirement for digital switches because voice digitization implies four-wire circuits, where TABLE Crosspoint Requir8m8nts of Nonblocking Switches .t Number of Lines Number of Corosspoints for Three- Stage Switch It 128 512 048 192 32, 768 131 072 Number of Crosspoints for Single- Stage Switch 680 63.488 516 096 2 million 33 million 268 million 16, 256 261, 632 2 million 67 million 1 billion 17 billion

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