1. Date:16 February, 2009 Abstract: This contribution contains OFDMA preamble proposal for EV-DO Rev. C Notice Contributors grant a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner’s name any Organizational Partner’s standards publication even though it may include all or portions of this contribution; and at the Organizational Partner’s sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner’s standards publication. Contributors are also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution. This document has been prepared by contributors to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on Contributors. Contributors specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of Contributors other than provided in the copyright statement above. OFDMA Preambles for EV-DO Rev. C Recommendation : Review and Adopt Source: Shu Wang VIA Telecom Contact:shuwang@via-telecom.comshuwang@via-telecom.com C30-20090511-031

2. OFDMA Preambles for DO Rev. C Shu Wang shuwang@via-telecom.com VIA Telecom

3. Proposal Highlights Embedded OFDM Preamble for  Single-User Packets  DO Rev. A/B style Multiuser Packet. Coded OFDM Preamble encoded via a tail-biting convolutional coding code with inverted CRC bits for  OFDMA Multiuser Preamble  Multiuser MIMO

4. Introduction CDM DO capacity is known to be interference limited.  Though CDM with IC is capacity-approaching, the implementation is challenging, especially on FL. OFDMA helps bring new dimensions in optimizing DO network.  Frequency selectivity gain for better packing efficiency.  Subband interference avoidance for better cell-edge user experience.  Additional scheduling flexibility for improving the balance between VoIP capacity and sector throughput. For implementing OFDMA in DO Rev. C, OFDMA multiuser packet preamble design and proposals are discussed and proposed here.

5. Considerations for OFDM Preamble Design There is a tradeoff between control overhead and achievable throughput. For OFDM or single-user MIMO/OFDM transmission, it is recommended to signal the AT(s) through the pattern of OFDM/MIMO pilots. For OFDMA or multiuser MIMO transmission, additional packing information/overhead is recommended be sent through OFDM preamble tones.  The similar design was adopted in UHDR-DO.  Preamble coding can be adaptive based on DRC feedback from ATs.

6. Embedded OFDM Preamble for Single-User Packets It is recommended to use the same or similar design previous adopted in UHDR-DO. The details can be found in  C30-20060731-046  C30-20060731-044R2

7. Coded OFDM Preamble (1/2): Modulation MACID is used to determine the location of the OFDM tones for preamble.  Orthogonal Preamble among ATs: The set of preamble tones for different ATs’ preamble are almost disjoint  The power of preamble tones, T/P in particular, are adjusted based on AT’s DRC feedback

8. Coded OFDM Preamble (2/2): Coding Except the first 8-bit MAC ID, the rest 2~44-bit preamble is repeated, encoded via tail-biting convolutional coding with inverted CRC bits  The encoded symbols are scrambled, modulated, and mapped to the 32 - 176 tones selected based on the previous procedure.  The modulation can be BPSK or QPSK, depending on DRC feedback.  The repetition number can be 2 or 4, depending on DRC feedback.  A tail-biting convolutional coding with inverted CRC bits is used. Power gain for preamble, pilot and traffic are configurable The additional coding gain is designed to decrease the false alarm rate and detection missing rate.

9. Coded OFDM Preamble Structure (1/2) OFDMA MUP puts the subpackets of multiple users into subbands.  Up to 4 subbands per 1.2288MHz carrier. Subband pattern or Tx power can be preconfigured per sector. OFDMA is friendly to inter-cell interference management.  Subband Tx power may be differentiated for either higher spectral efficiency, lower latency and interference management. Similar to the case of single-subband OFDM SUP, both OFDM common pilots and preambles are distributed inside the whole 1.2288MHz carrier for achievable frequency diversity.

10. Coded OFDM Preamble Structure (2/2) OFDMA multiuser packeting is flexible with more scheduling flexibility.  For each subband, layered transmission can be used. The power imbalance between two superimposed OFDM layers can help the signal demodulation by receivers.  bad-channel users successfully decode the base layer message.  good-channel users decode both layers with successive IC or joint demodulation.

11. Summary For the purpose of “ significantly improve performance and operating efficiency of existing infrastructure and devices through incremental low cost upgrades ”, MIMO-OFDMA with antenna selection is proposed for DO Rev. C OFDMA multiuser packeting with coded preamble design can help increase the spectral efficiency of DO networks.  Coded OFDM Preamble  The 2-bit compatible rate field within the 10-bit DO preamble is encoded via a tail-biting convolutional coding code with inverted CRC bits  OFDMA Multiuser Packeting  One 1.2288MHz carrier is divided into 4 subbands with 0.3096MHz each.  For each subband, layered modulation can be used.