128 DSQ (Double Square QAM)

http://www.freepatentsonline.com/7515642.html
LDPC (Low Density Parity Check) coded 128 DSQ (Double Square QAM) constellation modulation and associated labeling

12. The communication device of claim 10, wherein: the 8 regions of the 128 DSQ constellation, each region being indicated by the 3 uncoded bits, are selected according to a mapping admitting at most two bit positions to be different for adjacent regions; the 16 constellation points within each region of the 8 regions of the 128 DSQ constellation are selected according to a two-dimensional Gray code mapping

5bit中3bit(8 regions,3 uncoded bits)を固定、2bitを可変(most two bit positions to be different)とした2信号(Double Square)による7bit(3+2+2)表現と理解した。
10GBASE-T Coding and Modulation:128-DSQ + LDPC
http://grouper.ieee.org/groups/802/3/an/public/sep04/ungerboeck_2_0904.pdf
めも

https://internet.watch.impress.co.jp/docs/column/nettech/1086947.html

128DSQは図2のように、この64QAMを2つ重ねた形で、2つのシンボルを利用して7bitの信号を送り出す。

うーん簡略化しすぎな気もするが、まあいいか。