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*To*: "'William Jones'" <wjones@solarflare.com>, "P.J. Sallaway" <pj@myricanetworks.com>*Subject*: RE: [10GBASE-T] question about the complexity reduction of MIMO*From*: "Rao, Sailesh" <sailesh.rao@intel.com>*Date*: Wed, 22 Jan 2003 16:17:31 -0700*Cc*: xichen@marvell.com, stds-802-3-10gbt@ieee.org*Sender*: owner-stds-802-3-10gbt@majordomo.ieee.org

Bill, On Page 20 of your January tutorial presentation, you show that the DSP complexity of the receiver in your proposal will be >40X the DSP complexity of 1000BASE-T receivers in the market, assuming scalar operations. It would be very difficult to justify the technical feasibility of your proposal on this basis. On Page 25, you are claiming that there are MIMO realizations possible that would render the complexity of the Matrix-Vector multiplication (with a 4X4 matrix, and a 4X1 vector) needed for your receiver to be equal to 1.5X that of a 1000BASE-T scalar operation, and therefore the DSP complexity of your receiver is only 6X that of commercial 1000BASE-T receivers. Aside from the matrix-scalar distinction, since the 4X1 vector in your receiver uses 4 10-level symbols ranging over [-9, +9] and since the 1000BASE-T scalar uses 5-level symbols ranging over [-2, +2], this appears too good to be true. Can you please clarify your claims? Regards, Sailesh. -----Original Message----- From: William Jones [mailto:wjones@solarflare.com] Sent: Tuesday, January 21, 2003 10:10 PM To: P.J. Sallaway Cc: xichen@marvell.com; stds-802-3-10gbt@ieee.org Subject: RE: [10GBASE-T] question about the complexity reduction of MIMO PJ, Answering your question first, the metric used in the tutorial was operations/second. Regarding your comment, I agree that the complexity of a realization is a concern for the group, but, not the realization itself. This distinction avoids excessive consideration for vendor dependent issues which was what I was trying to get at. So, I think it is not whether MIMO can achieve a 4x or 16x reduction, but rather, that there exists at least one possible realization of a particular technology that can achieve an acceptable level of complexity. In the tutorial, we made the comparison to a multi-port 1000BASE-T part. One can then argue feasibility by extension to a realized solution. This leads to a question for the group. What strategy or steps are needed to get to an agreement on technical feasibility? Bill -----Original Message----- From: P.J. Sallaway [mailto:pj@myricanetworks.com] Sent: Tuesday, January 21, 2003 10:24 AM To: William Jones Cc: xichen@marvell.com; stds-802-3-10gbt@ieee.org Subject: RE: [10GBASE-T] question about the complexity reduction of MIMO Bill, I believe the complexity of a practical realization is important to the group as we look at the feasibility of 10 gigabits/second over Cat-5 and the role that different line codes play. I am curious as to what complexity measure you are using when discussing the 16x reduction using MIMO. Is it power dissipation for a given technology? Multiplies per second? Gate count? Thanks, ...PJ On Mon, 2003-01-20 at 13:44, William Jones wrote: > Xiaopeng > > I would claim the maximum is a 16x reduction. So, a practical realization is in the range 4x to 16x. Our approach is somewhere around 7x. Note, a MIMO realization is not unique. But, this is not a concern for the study group. > > Bill > > -----Original Message----- > From: xichen@marvell.com [mailto:xichen@marvell.com] > Sent: Monday, January 20, 2003 10:24 AM > To: William Jones > Cc: stds-802-3-10gbt@ieee.org > Subject: [10GBASE-T] question about the complexity reduction of MIMO > > > > Bill, > > I have a quick question about MIMO. In your presentation, you stated that > the MIMO architecture can help to reduce the DSP complexity from 10 to 1.5. > > For a 4x4 MIMO system, the maximum complexity reduction is 4 times if I am > not wrong. In this extreme case, a one-channel DSP engine can be reused > for 4 channels without any modification. However even in such a case, the > DSP complexity is still 2.5. > > Xiaopeng > > -- P.J. Sallaway <pj@myricanetworks.com> Myrica Networks Inc.

**Follow-Ups**:**RE: [10GBASE-T] question about the complexity reduction of MIMO***From:*"P.J. Sallaway" <pj@myricanetworks.com>

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