RFC 3550 specifies that the time interval between receiver RTCP reports include a randomization factor to avoid having all the receivers send at the same time. If all the receivers sent in the same 5% subinterval of their reply time interval, the arriving upstream RTCP traffic would rival the downstream RTP traffic.

(a) Video receivers might reasonably wait to send their reports until the higher-priority task of processing and displaying one frame is completed; this might mean their RTCP transmissions were synchronized on frame boundaries. Is this likely to be a serious concern?

(b) With 10 receivers, what is the probability of their all sending in one particular 5% subinterval?

(c) With 10 receivers, what is the probability half will send in one particular 5% subinterval? Multiply this by 20 for an estimate of the probability half will all send in the same arbitrary 5% subinterval. Hint: In how many ways can we choose 5 receivers out of 10?