{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# tutorial5 - slotted ALOHA In this problem we complete the...

This preview shows page 1. Sign up to view the full content.

EE3015 Tutorial 5 (Medium Access Control) 1. Suppose that the pure ALOHA protocol is used to share a 56 kbps satellite channel, and that frames are 2000 bits long. Find the maximum throughput of the system in frames/second. (Note: the throughput of pure ALOHA is 18.4%.) 2. Consider a broadcast channel with N nodes and a transmission rate of R bps. Suppose the broadcast channel uses polling (with an additional polling node) for multiple access control. There is a polling delay of d so that when a node completes its transmission, it takes d time units until the subsequent node is allowed to transmit. Within a polling round, a given node is allowed to transmit at most Q bits. What is the maximum throughput of the broadcast channel in bps? 3. In the lecture notes, we provided an outline of the derivation of the efficiency of
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: slotted ALOHA. In this problem, we complete the derivation. a) Recall that when there are N active nodes the efficiency of slotted ALOHA is Np (1 − p ) N − 1 . Find the value of p that maximizes this expression. b) Using the value of p found in (a), find the efficiency of slotted ALOHA by letting N approach infinity. Hint: (1 − 1/ N ) N approaches 1/ e as N approaches infinity. c) Compare your result in part (b) with the efficiency of pure ALOHA. Which protocol has a higher efficiency? Why? 4. Consider a slotted ALOHA system with two terminals, A and B. Terminal A transmits at the beginning of a time slot with probability 0.6, whereas terminal B transmits with probability 0.3. a) What is the throughput of terminal A? b) What is the throughput of terminal B?...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online