What is codeword-to-layer-mapping for spatial multiplexing ?

Question

I was looking out for some notes on LTE and saw this. I don't even have a minor idea what is this. But want to know if someone can explain me about this.

Comments

http://lteuniversity.com/get_trained/expert_opinion1/b/donhanley/archive/2011/09/20/codewords-and-layers-and-ports-oh-my.aspx

Answer 1

For Downlink Layer Mapping:

Just to give you more intuitive understanding of these table shown above, I represented two typical items as illustration.

Following illustration is the case where the number of codeword is 2 and number of layer is 4.

Following illustration is the case where the number of codeword is 2 and number of layer is 8.

For Uplink Layer Mapping: