RE: [10GBASE-T] question about the complexity reduction of MIMO
Bill,
The 7X reduction in complexity (10 Tops to 1.5 Tops) as claimed by your
MIMO realization is an important aspect of the technical feasibility of
10G-Base-T. Can you please provide sufficient details for the committee
to verify the claim?
Thanks,
...PJ
On Wed, 2003-01-22 at 15:17, Rao, Sailesh wrote:
> 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.