Why channel broadcast? It should be more like channel on demand, but probably in that case the zapping time is more relevant. But considering a phisical access channel like ADSL2+ it has to be channel on demand because with ~~20Mbps forget Channel broadcast (for the usual number of channels)... So considering this you have a ...

What are the issues relating to channel setup time. Does it depend on the bandwidth of the access or is it only related with video decoder setup (reset and refill of buffers...etc)?