Telecommunication Modelling and Simulation
Unit Learning Outcomes covered in this assessment
a. Design, analyse and evaluate wireless mobile communication systems;
b. Research and analyse recent developments, and relate them to the principles of mobile network design and network management;
c. Apply engineering techniques, tools and resources to plan and model cellular networks;
Question 1:
(a) Discuss the reasons why multiple antennas are sometimes mounted at the same height on the same antenna tower.
(b) Assume that an eNodeB uses two sets of antennas which are mounted one set above the other on the same antenna tower. Discuss what should be the minimum vertical separation between the two sets of antennas for proper system functioning.
Question 2
The size of Melbourne city in the Victorian State of Australia is about 9,990 square kilometers. Assume that a telecommunications operator called Telstra has 100% mobile cellular coverage of entire Melbourne. Compute the maximum number of cell sites that Telstra needs to cover the entire area if it uses:
(a) micro-cells, each of radius 500 m.
(b) macro-cells, each of radius 20 km.
(c) Use CelPlanner software to illustrate your design. Assume that each cell has a hexagonal shape.
Question 3
A cellular system which uses microcells of radius 500 m and the cluster size of 3 requires the minimum signal-to-interference ratio (SIR) of 24 dB.
(a) Compute the average reuse distance D for the path loss exponent of (i) 2 and (ii) 4.
(b) Compute the worst-case reuse distance D for path loss exponents of (i) 2 and (ii) 4.
Assume in all cases that the CCI far outweighs all other types of noise in the system.
Question 4
Assume an operator has acquired a 20-MHz bandwidth from a local radio frequency spectrum regulator to roll out a mobile cellular network based on LTE-Advanced technology using a cluster size of C=4. In LTE, the smallest unit of frequency resource which can be allocated to one user is called a physical resource block (RB). One RB occupies 180 kHz of frequency, lasts 0.5 ms in time, and it is made of either twelve 15-kHz OFDM subcarriers or twenty-four 7.5-kHz OFDM subcarriers. The operator divides the 20 MHz into 100 RBs occupying 18 MHz. The remaining 2-MHz bandwidth is used as guard bands. Place the traffic channels in the cells such that both the ACI within a cluster and CCI (co-channel interference) between clusters are minimized. Explain your cellular system design (i.e., cell planning and frequency planning) using appropriate diagrams.
Question 5
A cell in a mobile cellular network serves a number of users, each of which on the average generates a single call of duration 3 minutes during the busy hour. Each blocked call is not queued but cleared. The grade of service of the network is 2%. The number of duplex traffic channels assigned to the cell is 21.
(a) Compute the maximum number of users that the cell can serve at the same time if no sectoring is used.
(b) How many users can the cell serve simultaneously if the cell is divided into:
(i) 3 sectors each covering 120o?
(ii) 6 sectors each covering 60o?
Assume that channels are shared equally among the sectors of a given cell.
(c) Compare the trunking efficiencies of the three cases studied above.
Question 6
A mobile system serving a large city has the following parameters:
- base station antenna height above ground is 200 m
- mobile station antenna height is 2.2 m
- operating frequency is 0.8 GHz.
Compute the largest radius that a cell in the mobile system can be in order to keep the total link path loss within 70 dB.
Assume that as the cellular system designer, the only path loss model available to you is the Okumura- Hata path loss model.
Question 7
(a) Explain the purpose of multiple access schemes in cellular mobile networks.
(b) Differentiate between multiplexing and multiple access schemes as used in cellular mobile networks.
(c) Explain in detail how the multiple access schemes (MACs) CP-OFDMA, OFDMA, SCMA, NOMA and DFT-spread OFDM differ from each other. These are potential MACs for 5G mobile.