doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 1 80MHz Tone Allocation Authors: Date:

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 2 Introduction Functional requirements as per the spec framework document [1]: R3.1.A (Channelization): The draft specification shall include support for 80 MHz PHY transmission. Possible preambles for 80MHz OFDM have been discussed in [2, 3]. This presentation will focus on a possible data and pilot tone mapping for 80MHz VHT data.

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 3 Tone Allocation Legacy preamble portion (LLTF/LSIG) needs to be repeated across each of the 20MHz sub-bands –(6+5) guard tones in each 20MHz legacy portion, therefore (6+5) guard tones in 80MHz. –Spectrum mask and filter design will have to conform to (6+5) guard tones anyway Propose to use (6 + 5) guard tones, 3 DC tones in 80MHz Data/Pilot Tones 6 Guard Tones5 Guard Tones3 DC Tones Freq Subcarrier Index

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 4 Location of pilot subcarriers The n spec mandates that –LSIG of 20MHz packets have pilots at {±7, ±21} and Repetition of the LSIG sequence across 80MHz –LSIG in an 80MHz 11ac packet will have pilots at location pairs belonging to {±11, ±25, ±39, ±53, ±75, ±89, ±103, ±117}. Not desirable to change pilot positions between the legacy (11a/n) and VHT parts of the packet. –Some implementers may average pilots across and legacy preamble (SIG fields) and VHT data. For simple receiver design, better to pick 80MHz pilots among these 16 tones.

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 5 Number of pilot subcarriers Simulations show that the performance gap between using 8 and 10 pilots is small. (See backup slides) Reducing the number of pilots to 6, however, results in a ~1dB loss in performance in some scenarios (See backup slides) We propose that 11ac packets use 8 pilots during 80MHz VHT-DATA portion. –Can be chosen such that they are maximally separated, with indices {±103, ±75, ±39, ±11}

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 6 References 1.IEEE /0992r3, R. Stacey et al., Proposed Specification Framework for TGac 2.IEEE /0070r1, H. Zhang et al., ac Preamble 3.IEEE r0, Y. Tu et. Al., Proposed TGac Preamble

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 7 Simulation Results 1

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 8 Simulation Results 2

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 9 Strawpolls

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 10 Strawpoll #1: Do you support to add to the specification frame work document (IEEE /0992r9) –3.x Data Formats 3.x.2 OFDM Modulation: The draft specification shall have 3 DC tones at (0, ±1) in 80MHz VHT data field. –Yes –No –Abstain

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 11 Strawpoll #2: Do you support to add to the specification frame work document (IEEE /0992r9) –3.x Data Formats 3.x.2 OFDM Modulation: The draft specification shall have 5 null tones at the upper tone edges (tone indices 123, 124, 125, 126, 127) and 6 null tones at the lower tone edges (tone indices -128, -127, - 126, -125, -124, -123) of the 80MHz VHT data. –Yes –No –Abstain

doc.:IEEE /0370r1 Submission May 17, 2010 Sudhir Srinivasa et al.Slide 12 Strawpoll #3: Do you support to add to the specification frame work document (IEEE /0992r9) –3.x Data Formats 3.x.1 Pilot Subcarriers: The draft specification shall have 8 pilot tones, with the positions {±103, ±75, ±39, ±11}, for 80MHz VHT data. –Yes –No –Abstain