Abstract: In this application is described a method and a system for collecting streaming multi channel digital isochronous data from multiple independent digital signal sources. The method is used for collecting streaming multi channel digital isochronous data, e.g. audio data, in a standard wireless local area network transmission system where bandwidth is reserved for both contention-based traffic and contention free traffic and the audio data (10) formed by samples (9) is organized in audio frames (174) and sent to receivers (6) using multicasting, within consecutive beacon intervals (137). In accordance with the invention the contention free traffic (138) of the beacon interval (137) is adjusted to an optimum value, and the length of the beacon interval (137) is adjusted such that a required amount of audio data (9) can be sent to the receivers (6) with minimum system delay.