OFDM over FHSS Constellation detection
Not a definite answer, but here's some analysis on the data:

strct=load('/tmp/mozilla_mmatthe0/fhss_1.mat'); 
FHSS_1=strct.fhss_1;

start = 14653;
Ns = 3650;
Ncp = Ns/8;
N_total = round(Ns + Ncp);

symind = 10;

X1 = FHSS_1(start+symind*N_total+(1:Ns));
subplot(211);
plot(mag2db(abs(fft(X1))))

fstart = 2593;
fend = 2701;
xlim([fstart-50, fend+50]);

QAM = X1(fstart:fend);

subplot(223);
plot(QAM, 'x-')
axis equal;

subplot(224);
delta = QAM(1:end-1) ./ QAM(2:end);
hold off;
plot(abs(delta)); hold on;
plot(angle(delta), 'k-');
plot(abs(QAM), 'r-');
legend({'abs(delta)', 'angle(delta)', 'abs(QAM)'});




My observations: 


the SNR seems to be fairly high (the noise floor in the spectrum is much below the signal part)
There seems to be a strong correlation between adjacent symbols along the subcarriers. I mean, when drawing the constellation symbols along the subcarriers, and connecting the adjacent subcarriers with a line (i.e. a normal "plot", I get a somehow spiral (bottom left figure).  


My conclusion: The QAM symbols are highly structured. This does not seem like a data transmission. Instead, it appears to be something like a preamble/synchronization sequence, and these dont need to follow a given constellation. So, the answer might be, that there is no constellation behind.

This answer is to start some discussion on the data. It's not definite.