FPGA Central

Yan Zhi Jie wrote in message

I'd like to introduce two different point of views
when we are considering such SM and SD in MIMO systems
as in your question.

> We also can switch between SM [Multiplexing] and SD [Diversity] in MIMO
> according the [Demmel] condition number.

First, one of those views [1] is regarding to
the Demmel condition number of MIMO channel matrix.
In there, it is interesting that SM is better method for MIMO
channel that has low Demmel condition number and
necessarily SD is better method otherwise. Thus,
feedback signaling to switch between them is proposed.

Another view [2] is that SD and SM are considered
to have fundamental trade-off. For example, SISO(1x1) system
has trade-off relationship as

SD = 1 - SM.

Furthermore, 2x2 MIMO system has

SD = (1-SM1) + 3*(1-SM2), such that
SM = SM1 + SM2,

where 0<=SM1<=SM2<=1. In this case, it emphasis that
the data transmission with lower rate (SM --> 0) provides
fundamentally more diversity order (SD --> 2x2=4).

In short, I told that we have two different views
regarding to SM and SD: 1) the idea of swathing by feedback signaling
2) the concept about the fundamental trade-off between twos.

[1] Robert W. Heath Jr and Arogyaswami J. Paulraj, Diversity Versus
Multiplexing in Narrowband MIMO Channels: A Tradeoff Based on Euclidean
Distance, Submitted to IEEE Transactions on Communications April 2001,
revised December 2002.

[2] L. Zheng and D. Tse, ``Diversity and Multiplexing: A Fundamental
Tradeoff in Multiple Antenna Channels'', IEEE Transactions on Information
Theory, vol. 49(5), May 2003.

--
Best regards,
James K. ([email protected])
- Any remarks, proposal and/or indicator to text would be greatly respected.
- Private opinions: These are not the opinions from my affiliation.