MITS5003 Wireless Networks and Communication

MITS5003 Wireless Networks and Communication


Part I: Encoding and error control

Sam is a computer science student and working on a new micro robot design. The robot

continuously sends every two seconds a status string comprising the accelerometer

reading (4 bits), ultrasound obstacle detection (6 bits), motor functionality (4 bits) and

battery power level (2 bits).

a) Calculate the data rate required for robot to remote controller communication

b) Explain 3 types of suitable encoding techniques could be used to encode the

status string.

c) At a certain instance, the sensors provided data as acceleration 5 m/s2,

obstacle at 48 cm, all motors working (i.e. motor functionality 1111), and

battery is 75%.

i. Write the status string in binary for this instance

ii. Represent the status string on ASK, FSK, and PSK encoding techniques

d) Calculate the CRC for the status string derived in c) with polynomial divisor


e) Briefly explain some other error control and flow control techniques that Sam

can use to ensure the accuracy of robot control

Part II: Multiplexing and multiple access

Multiplexing plays an important role in communication as it allows the combination of

multiple streams together. Different multiplexing techniques are used for various


a) Explain TDM, FDM and CDMA multiplexing techniques with suitable diagrams

b) Main air interface in the change from 3G to 4G and WiMAX. Explain how

OFDM is different from above techniques and the special feature of signals

used by OFDM

c) IEEE 802.11ac wireless LAN standard uses 40 MHz total bandwidth in OFDM


MITS5003 Wireless Networks and Communication

i. For 48 subscribers what should be the subcarrier bandwidth ( fb ) ?

ii. Propose a suitable subcarrier bit time of T to achieve orthogonality

iii. Explain how OFDM overcomes the issue of inter symbol interference


Part III: Wi-Fi

Prime Living is a real estate company based in Victoria and you work form them as a consultant

network engineer. The company has decided to open a new office in South Eastern suburbs and the

floor plan of the building is shown below. The office consists of 5 rooms and on average 8 employees

work at each room. The lounge is used by both staff and customers and on average about 25 devices

connect to Wi-Fi. The clients wants you to design the network for them with at least 100 Mbps data

rate for all wireless connections. As resources you’ve got one distribution system and few access

points of 10 m range.

10 m

10 m

10 m

10 m

10 m

10 m

10 m

5 m

10 m

5 m

Lounge and reception

MITS5003 Wireless Networks and Communication

a) Design the network specifying the locations of access points and distributions

system showing the backbone network.

b) Calculate the BSS and ESS sizes

c) Calculate the throughput for the DS

d) Recommend a suitable IEEE substandard for the network and give reasons for

your choice

e) Recommend suitable security strategies for the network

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