Common use of Implementation Issues Clause in Contracts

Implementation Issues. We will onsider a given period T. To simplify, this period will be used both by the group leader or by the member of the group as a period to send their GKA messages. re eived IGROUP message for a duration kT. A node whi h has not re eived any message from a group leader for a duration kT with k ≥ 2 will suppose that there is no group leader and starts the pro edure to be ome a leader. Sin e a node may not have re eived a pa ket of the group leader be ause this pa ket has been lost, k must be sele ted so that the probability that k − 1 su essive transmissions of a GKA message are lost is small. Then, to be ome a group leader, the node sele ts a random integer ir between 1 and a given number l (ba ko window size) and initializes a timer at irtrtd, where trtd is a prede ned duration omputed to be at least the round trip delay of a message throughout the ad ho network. With su h a gure for trtd we an be sure that if two nodes draw di erent integers ir and ir′ , the node having sele ted the larger integer will re eive the IGROUP message of the other node and then will stop its ele tion pro ess. The ba ko window size l must be hosen with respe t to the total number of nodes in the network so that the probability that two nodes hoose the same integer is small. This ba k-o pro edure is performed to avoid possibly multiple group leader ▇▇▇▇▇▇▇▇▇, for instan e, when a group is set up or split into two subgroups.