Block Turbo Codes for 802.16 optional coding

Demonstrates that the current optional coding scheme does provide material gains, refuting claims made in C802.16a-02/59. [Results forthcoming] Purpose Defend BTC from claims made in C802.16a-02/59 Notice This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy and Procedures The contributor is familiar with the IEEE 802.16 Patent Policy and Procedures (Version 1.0) , including the statement “IEEE standards may include the known use of patent(s), including patent applications, if there is technical justification in the opinion of the standardsdeveloping committee and provided the IEEE receives assurance from the patent holder that it will license applicants under reasonable terms and conditions for the purpose of implementing the standard.” Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, of any patents (granted or under application) that may cover technology that is under consideration by or has been approved by IEEE 802.16. The Chair will disclose this notification via the IEEE 802.16 web site . 2002-07-02 IEEE C802.16a-02/73 1 Optional Coding Schemes for 802.16 Brian A. Banister Advanced Hardware Architectures Optional Coding This contribution demonstrates that the current optional coding scheme provides material gains over the mandatory coding scheme. The mandatory coding scheme performance is modeled using convolutional codes, using simulation points read off of the graphs in [1]. This paper further demonstrates that the claimed additional gains in [1] beyond the current optional coding scheme are immaterial. As the thrust of this paper is to respond to [1], there is no new text or changes necessary for the standard. Performance of Optional FEC Schemes In this section, we compare the performance of the current optional coding scheme, block turbo codes (BTCs), with parallel concatenated turbo convolutional codes (TCCs). Optimal log likelihood ratios (LLRs) are used by both the BTC and TCC. The TCC LLRs were computed in floating point precision and then quantized internally to the CRC software to 8 bits. The remainder of the processing occurs in 16 bit precision. The one exception to this is for the 64QAM example, where the I and Q values are quantized to 6 bits each, prior to the LLR computation. The BTC simulations assume 7 soft bits for each I and Q value. Bit error rate (BER) and packet error rate (PER) performance is compared for each coding scheme. While simulations are still in process, we will show that both the TCC and BTC are high performance FEC schemes. We will show that the BTC offers significant advantage over the mandatory coding, and that the TCC is an unnecessary addition to the standard, providing no useful gain over the BTC. [Results to be inserted here.] ConclusionWe propose that the BTC remain in the standard as the optional channel coding scheme. The BTC is a proventechnology with multiple vendor support, offering significant benefit to the physical layer. References[1] Brian Edmonston, “Convolutional turbo codes for 802.16,” IEEE C802.16a-02/59, May 15, 2002.