Consider the following Aloha systems. (a) A group of N users share a 56 kbps pure Aloha channel. Each user generates at a Poisson rate of one 1000-bit packet every 100 sec, even if the previous one has not yet been sent. What is the maximum value of N (Hint: The pure Aloha maximum channel utilization is 18.4%)? (b) Ten thousand airline reservation stations are competing for the use of a single slotted Aloha channel. The average station makes 18 requests/hour. A slot is 125 μsec. What is the approximate total channel load (requests per slot)?

Consider the following Aloha systems. (a) A group of N users share a 56 kbps pure Aloha channel. Each user generates at a Poisson rate of one 1000-bit packet every 100 sec, even if the previous one has not yet been sent. What is the maximum value of N (Hint: The pure Aloha maximum channel utilization is 18.4%)? (b) Ten thousand airline reservation stations are competing for the use of a single slotted Aloha channel. The average station makes 18 requests/hour. A slot is 125 μsec. What is the approximate total channel load (requests per slot)?

Operations Research : Applications and Algorithms

4th Edition

ISBN:9780534380588

Author:Wayne L. Winston

Publisher:Wayne L. Winston

Chapter20: Queuing Theory

Section20.10: Exponential Queues In Series And Open Queuing Networks

Problem 8P

See similar textbooks

Similar questions

2. Consider a bus-topology network with five stations. A reservation access method is used. Each station has infinite data to transmit. Each reservation slot has 10 microseconds (note that 1 microsecond = 106 second). For each station, one data transmission sends 1000 bits. The transmission rate over the medium is 10 Mbps. For a station, which is its throughput (in unit "Mbps")?
Frames of 1000 bits are sent over a 106 bps duplex link between two hosts. The propagation time is 25 ms. Frames are to be transmitted into this link to maximally pack them in transit (within the link). 1.1 What is the minimum number of bits (1) that will be required to represent the sequence numbers distinctly? Assume that no time gap needs to be given between transmission of two frames.
A digitized voice channel is made by digitizing a 4-kHz bandwidthanalog voice signal. We need to sample the signal at twice the highestfrequency. We assume that each sample requires 16 bits. What is therequired bit rate?
A TCP connection is established through 10 wireless hops in an acoustic underwater ad hoc network. Assume that each hop is 100 meter in the average, acoustic signals travel 1500 meter per second, 10 kilobit data can be sent per second over a link, the source node has one megabyte of data to send, the receiver window size is 64 kilobytes, the maximum segment size is 1 kilobyte and the average processing delay for routing at each node is one millisecond. Assume also that the following segments do not reach the destination: 67, 112, 137. What would be the average utilization of the links for this connection if there is not another communications through them? Explain an alternative approach to increase the bandwidth utilization?
Suppose a frame (F) experiences collision forth time on a shared Ethernet link of I Mbps: What is the maximum possible value of K in this case Suppose maximum value of K is taken, compute backoff bit time for frame F Convert bit time into absolute time (second or fraction of a second)
Consider the following scenario: Frames of 12000 bits are sent over a 400kbps channel using a satellite whose propagation delay is 270ms. Acknowledgements are always piggybacked onto data frames. (That is, in the case of stop-and-wait, the next frame cannot be transmitted until the entire frame containing the acknowledgement is received.) Five-bit sequence numbers are used. What is the maximum achievable channel utilization for (a) Stop-and-wait. (b) Protocol 5 (i.e., Go Back N). (c) Protocol 6 (i.e., Selective Repeat)
If a two port bridge was used in a heavy load standard Ethernet network such that the traffic is going through it. If each station is theoretically given a capacity of5Mbpsand the number of stations in each LAN segment is equal, then the number of stations in each LAN is:
A communication satellite orbits the earth at distance of 30000 miles with each mile having a propagation speed of 5 x 10^(-6) seconds. The data rate of the satellite link is 1 Mb/s. Suppose a data frame is 1250 bytes and that ACKs have negligible processing and transmission times. With the Stop-and-Wait protocol, what is the maximum utilization possible.Discuss ways in which the utilization can be improved. Remember that the satellite is far away and therefore outline the disadvantages to any scheme you propose that may improve the utilization.
Given a link with a maximum transmission rate of 34.1 Mbps. Only two computers, X and Y, wish to transmit starting at time t = 0 seconds. Computer X sends filex (19 MiB) and computer Y sends fileY (222 KiB), both starting at time t = 0. • Statistical multiplexing is used, with details as follows • Packet Payload Size = 1000 Bytes • Packet Header Size = 24 Bytes (overhead) • Ignore Processing and Queueing delays • Assume partial packets (packets consisting of less than 1000 Bytes of data) are padded so that they are the same size as full packets. • Assume continuous alternating-packet transmission. • Computer X gets the transmission medium first. At what time (t = ?) would Filey finish transmitting? Give answer in milliseconds, without units, and round to one decimal places (e.g. for an answer of 0.013777 seconds you would enter "13.8" without the quotes) 1.6
A telephone modem is used to connect a personal computer to a host computer. The speed of the modem is 56 kbps, the one-way propagation delay is 100 ms, the packet size is 256 bytes, and the probability of an error in a packet is 10^-4. Find the efficiency of stop-and-wait ARQ. What window size N is needed to keep the channel busy when there are no transmission errors. For this window size finds the efficiency of the go-back-N and selective repeat protocols. Note: Correct and detailed answer will be Upvoted else downvoted
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. 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 dpoll. 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?
The Syldavia TGV is equipped with a computer network with CSMA/ CD-type access protocols. The signal travels at 200,000 kilometers per second. Each transmitted frame is 300 bytes. Speed is 1 Gbit/s. Knowing that the size of each truck that makes up this TGV is 24 m, A:how many trucks can we have at most so that the CSMA/CD protocol can work properly (detailed calculations)? B:If a TGV consists of eight cars travelling at 250 km/h, how far does it travel (collision-free) before the rear of the train receives the frame sent by the head of the train?