enb_amarisoft: add option to enable and configure DL AWGN channel

expose option to enable DL AWGN noise and make SNR configurable

Change-Id: Ib248e87e5abd855d4c974eab42ec40828c6e1d40
diff --git a/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl b/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl
index 09532cc..7896ecb 100644
--- a/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl
+++ b/src/osmo_gsm_tester/templates/amarisoft_enb.cfg.tmpl
@@ -38,6 +38,13 @@
   /* RF driver configuration */
   include "amarisoft_rf_driver.cfg",
 
+% if enb.enable_dl_awgn:
+  channel_dl: {
+    type: "awgn",
+    snr: ${enb.dl_awgn_snr}
+  },
+% endif
+
   mme_list: [
     {
       s1ap_bind_addr: "${enb.addr}",