diff --git a/auracast/auracast_config.py b/auracast/auracast_config.py
index f9b70f5..09cb5e1 100644
--- a/auracast/auracast_config.py
+++ b/auracast/auracast_config.py
@@ -3,16 +3,34 @@ from bumble.profiles import bap
 from dataclasses import dataclass
 
 # Define some base dataclasses to hold the relevant parameters
+@dataclass
+class AuracastQoSConfig:
+    iso_interval_us: int = 10000
+    number_of_retransmissions:int = 4
+    max_transport_latency_ms:int = 43 # TODO: varies from the default value in bumble (was 65)
+
+qos_config_mono_high_rel = AuracastQoSConfig() #highest rel + lowest latency
+qos_config_mono_medium_rel = AuracastQoSConfig( 
+    iso_interval_us = 10000,
+    number_of_retransmissions = 3,
+    max_transport_latency_ms = 65
+)
+qos_config_mono_low_rel = AuracastQoSConfig( #highest latency
+    iso_interval_us = 10000,
+    number_of_retransmissions = 2,
+    max_transport_latency_ms = 65
+)
+
 @dataclass
 class AuracastGlobalConfig:
+    qos_config: AuracastQoSConfig
     device_name: str = 'Auracaster'
     transport: str = ''
     auracast_device_address: hci.Address = hci.Address('F0:F1:F2:F3:F4:F5')
     auracast_sampling_rate_hz: int = 24000
     octets_per_frame: int = 60 #48kbps@24kHz # bitrate = octets_per_frame * 8 / frame len
     frame_duration_us: int = 10000
-    presentation_delay_us: int = 40000 
-
+    presentation_delay_us: int = 40000
 
 @dataclass
 class AuracastBigConfig:
@@ -24,7 +42,7 @@ class AuracastBigConfig:
     broadcast_program_info: str = 'Some Announcements'
     broacast_wav_file_path: str = './auracast/announcement_48_10_96000_en.wav'
 
-global_base_config = AuracastGlobalConfig()
+global_base_config = AuracastGlobalConfig(qos_config=AuracastQoSConfig())
 
 # Instanciate some example configurations
 broadcast_de = AuracastBigConfig(
diff --git a/auracast/multicast.py b/auracast/multicast.py
index 9d9ab7c..5310978 100644
--- a/auracast/multicast.py
+++ b/auracast/multicast.py
@@ -16,7 +16,7 @@
 # Imports
 # -----------------------------------------------------------------------------
 from __future__ import annotations
-
+import pprint
 import asyncio
 import contextlib
 import logging
@@ -43,7 +43,7 @@ from bumble.profiles import bass
 import bumble.device
 import bumble.transport
 import bumble.utils
-from bumble.device import Host
+from bumble.device import Host, BIGInfoAdvertisement
 
 import auracast_config
 
@@ -184,7 +184,7 @@ async def run_broadcast(
                     )
                 ],
             )
-            logging.info('Setup Advertising')
+            logger.info('Setup Advertising')
             bigs[f'big{i}']['broadcast_audio_announcement'] = bap.BroadcastAudioAnnouncement(conf.broadcast_id)
             advertising_set = await device.create_advertising_set(
                 random_address=conf.broadcast_random_address,
@@ -224,10 +224,10 @@ async def run_broadcast(
                 bigs[f'big{i}']['advertising_set'] ,
                 parameters=bumble.device.BigParameters(
                     num_bis=1,
-                    sdu_interval=global_config.frame_duration_us,
+                    sdu_interval=global_config.qos_config.iso_interval_us,
                     max_sdu=global_config.octets_per_frame, # is this octets per frame ?
-                    max_transport_latency=65,
-                    rtn=4,
+                    max_transport_latency=global_config.qos_config.max_transport_latency_ms,
+                    rtn=global_config.qos_config.number_of_retransmissions,
                     broadcast_code=(
                         bytes.fromhex(conf.broadcast_code) if conf.broadcast_code else None
                     ),
@@ -243,6 +243,10 @@ async def run_broadcast(
 
             bigs[f'big{i}']['frames_iterator'] = itertools.cycle(frames)
 
+            logging.debug(f'big{i} parameters are:')
+            logging.debug('%s', pprint.pformat(vars(big)))
+            logging.debug(f'Finished setup of big{i}.')
+
         await asyncio.sleep(3) # Wait for advertising to set up
 
         LOOP_FINITE_PKGS = -1 # set -1 to loop infinitely
@@ -293,7 +297,10 @@ def broadcast(global_conf: auracast_config.AuracastGlobalConfig, big_conf: List[
 
 # -----------------------------------------------------------------------------
 if __name__ == "__main__":
-    logging.basicConfig(level=logging.INFO)
+    logging.basicConfig(
+        level=logging.INFO,
+        format='%(module)s.py:%(lineno)d %(levelname)s: %(message)s'
+)
 
     global_conf = auracast_config.global_base_config
 
@@ -301,8 +308,11 @@ if __name__ == "__main__":
 
     #global_conf.transport='serial:/dev/serial/by-id/usb-SEGGER_J-Link_001050076061-if02,1000000,rtscts' # transport for nrf53dk
 
-    global_conf.transport='serial:/dev/serial/by-id/usb-SEGGER_J-Link_001057705357-if02,1000000,rtscts' # transport for nrf54l15dk
+    #global_conf.transport='serial:/dev/serial/by-id/usb-SEGGER_J-Link_001057705357-if02,1000000,rtscts' # transport for nrf54l15dk
 
+    global_conf.transport='serial:/dev/ttyACM1,115200,rtscts'
+
+    global_conf.qos_config = auracast_config.qos_config_mono_high_rel # TODO: low rel, actually advertising seems to work again- maybe then the problem is hci->controler
 
     bigs = [
         auracast_config.broadcast_de,
@@ -315,7 +325,12 @@ if __name__ == "__main__":
     global_conf.octets_per_frame = 40 # 32kbps@16kHz
 
     # Note: 24kHz is only working with 2 streams - so this may be a host->controller interface bottleneck
-    # TODO: use thread usage debugger on controller to check actual cpu load
+    # use thread usage debugger on controller to check actual cpu load - not much load
+
+    # TODO; I dont think hci is really the bottleneck. probably limited airtime is the problem. Analyze this somehow.
+    # Advertising is still 1Mbit phy - use 2Mbit
+    # Check is the sdu interval (iso interval?) may really be varied - does not seem to work really 
+    # # sdu per frame also needs to be adjusted somehow? is this even compatible with lc3?
 
     broadcast(
         global_conf,