added reference octave script for lte-x2-handover-measures test

src/lte/test/reference/lte_link_budget_x2_handover_measures.m

@@ -0,0 +1,54 @@
+clear all;
+close all;
+
+%% LTE from theory to practice
+%% Table 22.7 Reference sensitivity.
+
+f = 2160e6;  % carrier freq Hz, EARFCN = 500 (downlink)
+nrbs = 25; % tx bandwdith configuration in number of RBs
+bw = nrbs * 180000; % bandwidth in Hz, note that this is smaller than
+		    % the nominal Channel Bandwdith, see TS 36.101 fig 5.6-1
+kT = -174; % noise PSD in dBm / Hz
+n = kT + 10*log10(bw);  % noise power dBm
+p = 20;  % tx power dBm
+txPsd = p - 10*log10(bw); % power / bandwidth in linear units
+nf = 9; % receiver noise figure in dB
+
+pW = 10.^((p-30)./10); % tx power in W
+nW = 10.^((n+nf-30)./10); % noise power in W
+
+%%d = logspace (0,5,100);
+x = linspace (0,4000,100);
+g1 = gain_freespace(abs (x-1000),f); % propagation gain from
+				% eNB 1
+g2 = gain_freespace(abs (x-2000),f); % propagation gain from
+				% eNB 2
+
+sinr1 = 10.*log10 (pW .* g1 ./ (nW + pW .* g2)); %dB
+sinr2 = 10.*log10 (pW .* g2 ./ (nW + pW .* g1)); %dB
+
+# semilogy (x, g1, ";eNB 1;", x, g2, ";eNB 2;");
+# xlabel ("X-coordinate of UE");
+# ylabel ("gain (linear)");
+# title ("gain X2 handover measures");
+
+hox200mps=200*8.41193; # speed * handover time
+hox150mps=150*10.7719; # speed * handover time
+
+figure;
+plot (x, sinr1, ";eNB 1;",
+      x, sinr2, ";eNB 2;",
+      [hox150mps hox150mps], [min(sinr1), max(sinr1)], ";HO point at 150 m/s;",
+      [hox200mps hox200mps], [min(sinr1), max(sinr1)], ";HO point at 200 m/s;");
+xlabel ("X-coordinate of UE");
+ylabel ("SINR (dB)");
+title ("LTE link budget X2 handover measures");
+myaxis = axis;
+myaxis(3:4) = [-20 20];
+axis (myaxis);
+
+grid on;
+print ("lte_link_budget_x2_handover_measures.png", "-dpng");
+      
+
+