A node of a data communication network which can transmit data at 4 different rates r, 2r, 3r& 4r uses the mechanism described below to control congestion: At any given time the nodeis transmitting data at one of the above rates. It is assumed that data is always available fortransmission. There is a congestion indication flag which is assumed to be independent of thestate of the node but indicates congestion in the whole network. The data transmission rate isrevised in regular intervals keeping to following rules:1. If the congestion flag is on, the data rate is reduced by two steps or to the lowest step (i.e.rate r) whatever the higher.2. If the flag is off, the rate is increased by one step or remains in the highest step.a) Draw the Markov chain indicating the states and transitions assuming that the flag ison with probability p. [30 marks]b) What happens if p=0 and if p=1? [10 marks]c) Calculate the state probabilities for p=0.6. [30 marks]d) What is the average transmission rate? [20 marks]e) Comment on the validity of the results in c) & d) if p varies with time. [10 marks]Q2.a) Jobs arrive at the rate of 1 job per unit time into an M/M/1-FIFO queue. What is themean queue length if the mean service time is 0.55 time units? [20 marks]b) Another M/M/1-FIFO queue has a server identical to that in a) and the same arrivalrate, but a longer mean service time of 0.85 time units. What is the mean queue lengthof this queue? [10 marks]c) Now, both streams of jobs are diverted to a third queue of type M/H2/1-FIFO with asingle server working at double the rate of those in a) and b).a. What is the total arrival rate? [10 marks]b. What is the mean service time of the jobs in this queue? [10 marks]c. What is the mean queue length of this queue? [30 marks]d. Analyse the pros and cons of this queue against the combination of queues ina) and b). [20 marks]

A node of a data communication network which can transmit data at 4 different rates r, 2r, 3r& 4r uses the mechanism described below to control congestion: At any given time the nodeis transmitting data at one of the above rates. It is assumed that data is always available fortransmission. There is a congestion indication flag which is assumed to be independent of thestate of the node but indicates congestion in the whole network. The data transmission rate isrevised in regular intervals keeping to following rules:1. If the congestion flag is on, the data rate is reduced by two steps or to the lowest step (i.e.rate r) whatever the higher.2. If the flag is off, the rate is increased by one step or remains in the highest step.a) Draw the Markov chain indicating the states and transitions assuming that the flag ison with probability p. [30 marks]b) What happens if p=0 and if p=1? [10 marks]c) Calculate the state probabilities for p=0.6. [30 marks]d) What is the average transmission rate? [20 marks]e) Comment on the validity of the results in c) & d) if p varies with time. [10 marks]Q2.a) Jobs arrive at the rate of 1 job per unit time into an M/M/1-FIFO queue. What is themean queue length if the mean service time is 0.55 time units? [20 marks]b) Another M/M/1-FIFO queue has a server identical to that in a) and the same arrivalrate, but a longer mean service time of 0.85 time units. What is the mean queue lengthof this queue? [10 marks]c) Now, both streams of jobs are diverted to a third queue of type M/H2/1-FIFO with asingle server working at double the rate of those in a) and b).a. What is the total arrival rate? [10 marks]b. What is the mean service time of the jobs in this queue? [10 marks]c. What is the mean queue length of this queue? [30 marks]d. Analyse the pros and cons of this queue against the combination of queues ina) and b). [20 marks]

Transmission data rate is decided by

what is the maximum data rate for a 3kHz channel that transmits data using 4 levels (binary) ?(only give the value in bits/second, don't put the unit)

what is the maximum data rate for a 10kHz channel that transmits data using 4 levels (binary) ?(only give the value in bits/second, don't put the unit)

The information to be communicated in a data communications system is the ________