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White Papers

  1. IETF-DRAFT: RTP Payload Format for MELPe Codec
    This document describes the RTP payload format for the Mixed Excitation Linear Prediction Enhanced (MELPe) speech coder algorithm with noise preprocessor (NATO Standard STANAG 4591).
  2. IEEE 802.15.3a: Reasons to use non-squared QAM constellations with independent I&Q in WPAN-systems
    This paper provides a rational for the use of non-squared constellations in PAN systems rather than only using different coding rates and squared constellations to increase the performance of the system.
  3. IEEE 802.11g and 802.11.NG: Use of Asymmetrical Advance coding for 802.11g and 802.11NG.
    This paper proposes the use of Asymmetrical Advanced Coding Techniques (AACT) for the 802.11g and the 802.11NG. Theses Asymmetrical Advance Coding Techniques have the main purpose of saving power in the mobile device.
  4. IEEE 802.16a:Method for using Concatenated Convolutional Turbo Codes in IEEE 802.16a.
    This paper proposes a method for using concatenated convolutional Turbo codes for802.16a. These concatenated convolutional turbo codes are optimized for each constellation size.
  5. IEEE 802.16a:Method for using non squared constellation and how to decoded them withindependent I and Q.
    This paper proposes a method for using non-squared constellations and how to decode them with independent I and Q.
  6. IEEE 802.16a:Method for using non-squared QAM constellations.
    This paper proposes a method for using non-square QAM constellations with independent I&Q. This method is based in the creation of non-separable I and Q constellations by combining constituent separable I and Q constellations.
  7. G.gen.bis: G.dmt.bis: G.lite.bis: Does it make sense a G.992.1.bis and G.992.2.bis without advance coding?
    This contribution presents discussion about if it makes sense to have a new recommendation without the advance coding improvement. This paper is in the same line that previous document AB-076 and also consider previous document IC-089.
  8. G.gen.bis: G.dmt.bis: G.lite.bis: Impulse noise response of Multi-level Turbo codes vs. Full turbo coding for different interleaver sizes.
    This contribution presents discussion about the use of multi-level and full turbo coding in an Impulse Noise Environment.
  9. G.gen.bis: G.dmt.bis: G.lite.bis: Are LDPC codes appropriated for ADSL modems?
    This contribution discuss the use of LDPC codes for ADSL modems.
  10. G.gen.bis: G.dmt.bis: G.lite.bis: Performance of full Turbo coding with variable interleaver with more protection to the information bits for G.992.1.bis and G.992.2.bis
    This contribution presents simulation results of the performance of full turbo coding with a variable interleaver size and protecting more the information bits than the parity bits for G.992.1.bis and G.992.2.bis.
  11. G.gen.bis: G.dmt.bis: G.lite.bis: G.vdsl: What means Turbo Coding for G.992.2.bis, G.992.1.bis and G.vdsl modems?
    This contribution presents a quantification of the impact of Turbo Codes for G.992.2.bis, G.992.1.bis and G.vdsl.
  12. G.gen.bis: G.dmt.bis: G.lite.bis: G.vdsl: General structure to support Trellis Code Modulation in the fast path, and a programmable Trellis Code Modulation, Multi-level and Full turbo code in the interleaved path of the transmitter of G.992.1 and G.992.2 with low computational burden and use the advantages of each technique in different environments.
    The present paper relates to a technique for implementation of a Trellis Code Modulation for the fast path and a configurable encoder, that allows the use of Trellis Code Modulation, Full Turbo code (FTC) or Multi-Level Turbo Code (MTC) for the interleaved path. Interleaver sizes are chosen as an integral number of DMT symbols. The assignment of parity/information bits for a better protection is also included.
  13. G.gen.bis: G.dmt.bis: G.lite.bis: G.vdsl: About the use of a fix interleaver size in Turbo Coding for high order constellations
    This contribution discuss the use of a fix interleaver size with high order constellations. The constellation used to illustrate the results is a b=14 bits constellation with 12 information bits and 2 parity bits.
  14. A configurable multilevel/full turbo encoder with 4, 8 or 16 state convolutional encoder in single, double or triple turbo coder configurations
    The present paper relates to a technique for implementation of a general configurable encoder that allows the following modes of operation: no coding (NC), Trellis Code Modulation (TCM), full turbo code (FTLC), multilevel turbo code (MTLC), in single, double or triple turbo encoder configurations, using 4, 8 or 16 state convolutional encoders, interleaver sizes as an integral number of DMT symbols, and assignment of parity/information bits for greater protection with QAM modulations in a DMT system.
  15. Size of the interleaver for the case of Turbo Codes
    In this paper VOCAL Technologies, Ltd. proposes that the size of the interleaver should be fixed to an integer number of DMT symbols to take the maximum advantage of the turbo code principle and to avoid degradation of the high order constellations.
  16. Euclidean distance, gain/loss and PAR considerations of the non-square QAM constellations with independent I and Q proposed in CF-038
    In the Clearwater meeting of Question 4 of Study Group 15, in January 2001, during the presentation and the discussion of document CF-038: G.gen: G.vdsl G.dmt.bis: G.lite.bis: Method for Using Non-Squared QAM Constellations with Independent I&Q for Receiver Soft-Decision Decoding Techniques, some members of the committee asked for details about the power of the proposed constellations with respect to the constellations of G.992.1 and the case of rectangular constellations with independent I and Q. This paper provides details about the Euclidean distance, gain/loss and PAR of the proposed constellations with respect to the constellations of G.992.1 and the case of rectangular constellations with independent I & Q, using as reference, the constellations of G.992.1.
  17. Method for using non-square constellations with independent I and Q for receiver soft Decision Decoding Techniques
    This paper proposes a method for using non-square QAM constellations with independent I&Q. This method is based in the creation of non-separable I and Q constellations by combining constituent separable I and Q constellations. This technique is applicable to any Receiver soft-Decision Decoding Technique, such as, Turbo codes or LDPC codes.
  18. Text to include a turbo Encode as mandatory in the transmitter for G.992.1 and G.992.2 following the proposal given in BA-020R1 and HC-073
    In this contribution VOCAL Technologies, Ltd. provides text and detailed information for the implementation of a Turbo Encoder as mandatory in the transmitter for G.992.1.bis and G.992.2.bis recommendations presented in BA-020R1 and HC-073.
  19. Turbo Codes 2000
    This document presents information about the implementation of turbo codes. Turbo coding represents a new and very powerful error control technique, which has started to have a significant impact in the late 90s, allowing communication very close to the channel capacity. The powerful error correction capability of turbo codes was recognised and accepted for almost all types of channels leading to increased data rates and improved Quality of Service. Turbo codes can operate at 0.1 dB from the Shannon capacity limit outperforming any other coding technique known today.
  20. Performance Results of the method provided in T1E1.4/2000-183
    A previous contribution T1E1.4/2000-217 presents performance results of the method described in T1E1.4/2000-183. These performance results presented in T1E1.4/200-217 are not totally correct. In this contribution we present the performance results of the technique described in T1E1.3/2000-183 as well as the performance results according to the ITU requirements provided in the ITU document BA-108R1.
  21. What is next in xDSL Turbo codes for xDSL modems
    Workshop Slides: Presentation for ITU Conference September 15, 2000 in Vienna, Switzerland.
  22. Results of the requirements requested in the Ad Hoc report (AB-118R1) for the proposed Turbo Codes for ADSL modems by VOCAL Technologies, Ltd. in BA-020R1
    In this paper we describe the results of the evaluation requested in the Coding Ad hoc report (BA-108R1) for the proposed Turbo Codes for ADSL modems by VOCAL Technologies, Ltd. in BA-020R1
  23. Comparison between coset “tone-base” turbo codes and “bit-base” turbo codes
    This paper describes a comparison of proposed coset “tone-base” turbo codes and proposed “bit-base” turbo codes for G.992.1bis and G.992.2bis error correction. Using three criteria, complexity, latency, and performance, we show that the proposed bit base turbo codes are superior to proposed coset “tone-base” turbo codes.
  24. New proposal of turbo codes for ADSL modems
    This paper describes a new technique for coding and decoding signals that use turbo codes with QAM modulation for error correction.
  25. New proposal of turbo codes for ADSL modems
    This paper describes a new technique for coding and decoding signals that use turbo codes with QAM modulation for error correction.
  26. Short-comings
    TR-30.1/SG16 is currently considering a revision to V.34 and V.90 to accommodate the modem-on-hold feature of the proposed V.92. Additionally support of a fast renegotiations may also be considered for these modem standards. In conjunction with these changes under consideration, it may also be desirable to address short-comings in the existing implementation of V.90. This is the subject of this presentation.
  27. Text to include a Turbo Encoder as mandatory in the transmitter for G.992.1.bis and G.992.2.bis.
    In this contribution VOCAL Technologies, Ltd. provides text and detailed information for the implementation of a Turbo Encoder as mandatory in the transmitter for G.992.1.bis and for G.992.2.bis. With this technique it is possible to reach longer loops (or work at higher bit rates in the same loop). We want to thank Dariush Divsalar from the Jet Propulsion Laboratory (Pasadena, CA) for his value comments for setup the decoder simulations used for the encoder proposed in this paper.
  28. G.gen.bis: Considerations about the power penalty of Reed-Solomon forward Error Correction in ADSL systems in regard to the use of inner encoders
    Previous presentations (NF-084 and BM-087), provide theoretical and simulated results comparing the uncoded ADSL data stream with Reed-Solomon FEC, with Reed-Solomon plus Trellis and Reed-Solomon and multiple concatenated Convolutional Codes (MCCC).In these presentations, the power penalty when using Reed-Solomon was not taking into account, because it did not affect the presentations’ conclusions, namely, that the use of inner coding, whether Trellis or MCCC, with Reed-Solomon provides better performance than the use of only Reed-Solomon.
    In this paper we present the mathematics for calculating the power penalty of error correction codes and apply this mathematics to Reed-Solomon FEC codes.
  29. G.gen: Comparison of simulation results for different Coding Techniques (Uncoded, Reed-Solomon, Reed-Solomon plus Trellis and Reed-Solomon plus Parallel Concatenated Convolutional Codes) for G.992.1.bis and G.992.2.bis
    In this contribution VOCAL Technologies, Ltd. proposes using Concatenated Convolutional Code technique for G.992.1.bis and G.992.2.bis recommendations. With this technique it is possible to reach longer loops (or works a higher bit rates in the same loop).
  30. G.dmt: Inclusion of a Serial Concatenated Convolutional Code in the G.992.1-bis
    In this contribution VOCAL Technologies, Ltd. proposes using Concatenated Convolutional Code technique for G.992.1 and G.992.2. This implementation is easy and only need a small change in the actual recommendation. With this technique it is possible to reach longer loops and to reduce the PAR due to a wider constellation.
  31. Inclusion of Concatenated Convolutional Codes in the ANSI T1.413 Issue 3
    In this contribution VOCAL Technologies, Ltd. proposes using Concatenated Convolutional Code technique for ANSI T1.413 Issue 3. This implementation is easy and only need a small change in the actual draft of the recommendation. With this technique it is possible to reach longer loops and to reduce the PAR due to a wider constellation.
  32. Text to include an optional Serial Concatenated Convolutional Codes in the next version of G.dmt (1)
    In this document we provide text for include an optional Serial Concatenated Convolutional Codes (SCCC) in G.dmt. The text proposed is a new point and an alternative to the Trellis Codes.
  33. Text to include an optional Serial Concatenated Convolutional Codes in the next version of G.dmt (2)
    In this document we provide text for include an optional Serial Concatenated Convolutional Codes (SCCC) in G.dmt. The text proposed is a new point and an alternative to the Trellis Codes.
  34. Text to include an optional Serial Concatenated Convolutional Codes in the next version of G.dmt (3)
    In this document we provide text for include an optional Serial Concatenated Convolutional Codes (SCCC) in G.dmt. The text proposed is a new point and an alternative to the Trellis Codes.
  35. Text to include an optional Concatenated Convolutional Codes in the ANSI T1.413 Issue 2
    In this document we provide text for include an optional Serial Concatenated Convolutional Codes (SCCC) in the T1.413 Issue2. The text proposed will be in a new point and will have a structure similar to the text of Trellis code version.
  36. Line Impairment: Detection of home’s bridge taps (ATU-R) and Crosstalk (ATU-C)
    From VOCAL Technologies, Ltd. point of view, frequency and time domain probing are very important functions that should be provided within T1.413. The lack of these features could impact the deployment of the xDSL modems especially for developing countries. xDSL modems will be sensitive to line impairments and cross-talk with other lines carrying ISDN, T1/E1 or even other xDSL modems. The reason to ask for including this facility in the T1.413 Issue 2 standard is to assure interoperability between the different companies’ designs.
  37. G.gen: Use of Parallel Concatenated Convolutional Codes PCCC (Turbo-Codes) for G.dmt and G.lite
    In this contribution VOCAL Technologies, Ltd. proposes using a Parallel Concatenated Convolutional Code (Turbo-Code) technique for G.dmt and G.lite recommendations. This implementation is easy and only need a small change in the actual draft of the recommendation. With this technique it is possible to reach longer loops and to reduce the PAR due to a wider constellation.
  38. G.dmt: Text to include an optional Parallel Concatenated Convolutional Codes (PCCC) in the Draft G.dmt Recommendation
    In this document we provide text for include an optional Parallel Concatenated Convolutional Codes (PCCC) in the Draft G.dmt Recommendation. The text proposed will be in a new point and will have a structure similar to the text of Trellis code version.
  39. G.hs: Loading Coil Detection
    xDSL modems are designed to operate between a Central Office and a customer premises. As such they use existing telephone network wiring between the Central Office and the subscriber. There are several modems in this class which function in generally similar manner. All of these modems transmit their signals usually above the voice band. As such, they are dependent on adequate frequency response above voice band. The telephone lines which are already in place generally have not been tested for adequate response in the intended frequencies of operation. In particular, prior to ISDN deployment, use of loading coils on long telephone lines has been common. Their intended purpose was to equalize the voice band frequency dependent signal propagation. Their effect on xDSL modems however is drastic. Because xDSL modems can not be expected to operate on loaded lines, here we propose a technique to identify their presence.
  40. G.hs: Loading Coil Location
    xDSL modems are designed to operate between a Central Office and a customer premises. As such they use existing telephone network wiring between the Central Office and the subscriber. There are several modems in this class which function in generally similar manner. All of these modems transmit their signals usually above the voice band. As such, they are dependent on adequate frequency response above voice band. The telephone lines which are already in place generally have not been tested for adequate response in the intended frequencies of operation. In particular, prior to ISDN deployment, use of loading coils on long telephone lines has been common. Their intended purpose was to equalize the voice band frequency dependent signal propagation. Their effect on xDSL modems however is drastic, because xDSL modems can not be expected to operate on loaded lines. We propose a technique to identify their location, to help the telephone company to locate and solve this problem.
  41. G.hs: Cross-talk Impairment Identification
    xDSL modems will be sensitive to impairments created from excessive cross-talk with other lines carrying ISDN, T1/E1 or even other xDSL modems. Some studies have indicated that xDSL operation may not be possible if another pair of wires in the same cable bundle is carrying ISDN or T1/E1. Since the wiring plant for a telephone operating company evolved over many years, it is unrealistic that the routing of these digital signals can be determined in advance when a customer orders xDSL service. We propose the addition of some relatively simple functions in a xDSL modem in order to aid with the determination of these potential problems.
  42. G.hs: Bridge taps detection and location
    As cable bundles are wired together at various distribution points, not all lead to a telephone line termination. Some wires simply “T- off” at points and can continue in multiple cables. For voice-band signals, such connection do not present any significant effect. However for high frequency signals such as for xDSL, the wires act as transmission lines and signals will propagate down both directions from a “T”. The line which is not terminated will create a reflection of the signal as the energy can not be absorbed which will in turn disrupt the signal quality. We propose an addition of an optional probing technique for the detection and location of these impairments.
  43. G.hs: Diagnosis of failed xDSL Modem Connections
    The deployment of xDSL modems requires telephone company plants and facilities coordination with the customer’s modem. As human resources can be very consumed at a high rate over large number of installations, it is a very critical goal to minimize truck roll and require as little installation support as possible, to let the customer initiate the entire procedure once the line has been provisioned at the Central Office. We believe that the primary reason for additional installation support is when the modems fail to connect. Secondary would be inadequate performance when the modems do connect.
  44. G.hs: Refined channel probing for G.hs
    V.8bis-style coding and transactions are proposed as additions to G.hs that would give forth the diagnostics for failed connections between ATUs. The G.hs procedures outlined would support the detection and location of impairments like loading coils, bridge taps and crosstalk among others.
VOCAL Technologies, Ltd.
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