Computer Networks:

1.Consider two nodes, A and B, that use the slotted ALOHA protocol to contend for a channel. Suppose each node has an infinite number of packets to send. Node A attempts to transmit a packet in each time slot with probability Pa, while node B attempts to transmit a packet in each time slot with probability Pb. The first slot is numbered slot 1, the second slot is numbered slot 2, and so on.

a. What is the probability that node A succeeds for the first time in slot 3?

b. What is the throughput of node A

c. What is the throughput of this two-node system

2.Consider a broadcast channel with N nodes and a transmission rate of R bps. Suppose the broadcast channel uses pollingwithaadditional polling node for multiple access. Suppose the amount of time from when a node completes transmission until the subsequent node is permitted to transmit (that is, the polling delay) is D seconds. Suppose that within a polling round, a given node is allowed to transmit at most Q bits. What is the maximum throughput of the broadcast channel?