Explaining Cell Splitting in Wireless Telephone Systems

Question 1:
With the help of diagram/s explain the concept of cell splitting. (3 marks)
It is an approach of splitting the frequency broadcasting area of a congested cell in wireless
telephone system into a number of smaller cell sites. Each of the small or sub-splitted cell is
connected with its own base station. Therefore the antenna size is also reduced for each
station (Campbell, 2017). The relation is as follws:
C=MKN= M × S,
Where the term C is the Cell Capacity,
M defines cluster number,
K represents number of channel,
N is cell number present in cluster,
S, the cluster capacity.
It offers several advantages as below:
 Increase in Signal to interference factor
 Reduces hands off
 Improves cell capacity
 Size of cluster is decreased
Question2:
1. Find reuse distance if the radius of each is cell is 2km (2 marks)
Radius of each cell, R is given as 2 km
D
R = √3 × N

D=R × √3 × N
Putting the values of R as 2 and N as 12 in the above expression, we get,D=12
The reuse distance is calculated as 12 km.
2. If each channel is multiplexed among eight (8) users how many calls can be
simultaneously processed by each cell if only 10 channels per cell are reserved
for control, assuming a total bandwidth of 30 MHz is available and each simplex
channels consist of 25 kHz. (3 marks)
Frequency BW of single duplex channel is given as, 2× BW of single simplex channel
=Twice of 25 kHz i.e. 50 kHz
Channel no. in total cell becomes ( 30 ×103 )
50 −10 ×12 = 600-120 = 480
Channels present in each cell = 480
12 =40
Number of calls present in each cell becomes 8 × 40 = 320
3. If each user keeps the traffic channel busy for an average of 5% time and an
average of 60 requests per hour are generated, what is the Erlang value? (3
marks)
Request rate, r is 60 / 3600 = 0.0167 Requests/sec.
Holding time can be obtained as, (5 × 3600) % = 180 sec
Erlang value becomes, 0.0167×180 = 3
Question 3:
1. You are working as Network Design Engineer with local service provider and
your manager has asked you to propose the design for the below cellular
architecture shown in figure 1. In your design provide the following
information; Base station sites locations, Antenna specification, mention the area
type considering the cell size (suburban, urban, rural etc) and justify you design.
(8 marks)
The proposed model is based on the cell splitting and cell sectoring. The below figure. 3
shows the proposed model of the wireless mobile communication system. Here the cell is
subdivided based on user numbers to increase the channel capacity. It can be observed from
figure shown below; the entire zone is divided in several hexagonal shape cell zones. Each of
these cells will contain a single Base Station. Each base station will have its own frequency
channel. So, the number of channel will also increase. As the frequencies will be distributed

based on the cell splitted structure, there will be no additional interference in the channel
(Chidiebere, 2018). By controlling the transmitting power of the BS, the coverage area can
also be achieved depending on the radius of the cell.
Cell splitting model of the given figure.
A coverage area of single transmitter and the Path loss model obtaining by the signal can be
roughly determined by the size of cell. This conception can be used for modelling the cell
structure.
Antenna Design:
For each cell communication we will be needed one antenna. The sub-division
of cell in a number of small cells causes in the reduction of antenna size. The