Assignment title: Information
Assignment
Subject: Telecommunications System Modelling ECTE 962
You are responsible for the planning of roads in a small suburb shown in Figure below.
There are 4 intersections, labelled 1 to 4. The outside of this suburb has been represented
by areas 0 and 5. Each street segment is named based on the two intersections that it
connects to in the direction of traffic flow. For example, �12 is the road segment
connecting intersection 1 to intersection 2. The opposite direction would be called �21.
Similarly, �01connects the left-hand outside area 0 to intersection 1, and �35 connects the
intersection 3 to the outside area 5 at the bottom. Some example names for streets are
shown on the figure.
When cars arrive at an intersection, a percentage �� of them turn left, �� turn right, and
�� go straight. Also, a percentage �� will leave the street network (going home or to their
office). These percentages are the same for all intersections. At the edge of the suburb,
the turning cars will re-enter the suburb at the next available street and the ones going
straight are recycled back from the other end as shown in the Figure. This is meant to
model arrivals from other neighbouring suburbs to this area.
The cars arrive to the system (from houses or offices) at a rate of � in each street
segment (same rate for all segments) according to a Poisson process.
To model the queue at the intersection, you can use an �/�/� queue, where � is the
number of lanes in the street. The cars depart the intersection at the rate of � cars per
second for each lane. In other words, � is the service rate of each lane (each lane is a
server in the terminology of queueing theory). If � > 1 in any intersection, it means that
cars have more than one lane so this becomes a multi-server queue. Of course, making
streets wider to have more than one lane is very costly, so the aim is to identify the
minimum number of lanes that are sufficient to give a reasonable congestion delay for
the commuters. Your tasks are as follows:
1 2
3 4
0 0
5
5
Goes to
Goes to
Goes to1- Model this street network as a Jackson queuing network. Identify all relevant
parameters of the system. (10 Marks)
2- Write down the expressions for the total average delay (�) in the system, as well
as other relevant indicators such as the size of queues at intersections. Clearly
state any assumptions that you have to make. (10 Marks)
3- Discuss how � is related to �. It is expected that as � increases, then the
congestion delay is reduced. Is this correct? (5 Marks)
4- Solve this problem and obtain � (if a steady state solution exists) for the
following numerical example: � = 2, � = 8, �� = �� = 0.2, �� = 0.4, �� =
0.2, � = 2. Use Matlab for this purpose and attach your code. Discuss the
solution, if it exists or if you needed to make more assumptions in derivation. (10
Marks)
5- What range of values of � will result in a steady state solution for � = 1. (5
Marks)
You need to submit a hardcopy report for the above five tasks. Don't write an essay,
make it brief and clear. I expect the report to be a maximum of 3 pages (but it is ok if
you go a bit above this). Also attach the printout of your code and evidence that you
have run the code and obtained the results in part 4. You should also email me
([email protected]) the code (Matlab .m files) so that I can check.
Due Date:
Friday 21 October 2016. Submit with assignment cover sheet using SATS to EIS central
(4.G12). Late submissions will not be accepted.