Packets are communicated between a first device and a second device, over a primary data channel, according to an interval. The first device receives over the primary data channel a request from the second device to establish a secondary data channel. The request includes secondary connection parameters including an offset relative to events on the primary data channel, and a sub-interval relative to the interval. Acknowledgement is exchanged and the first and second devices communicate over the secondary data channel according to the secondary connection parameters.