Microsoft Word CellBreathing

2.
 
Related Work 
In this article, the terms Mobile Station (MS), User Equipment (UE) and Mobile Node 
(MN) have been used interchangeably but all mean a user device to connect to the 
network. The coverage area of the cell is dependent upon the density of MSs. As the 
density of MSs increases, the cell breaths and connection of the border users drops as the 
result of cell breathing [Kay Loeng 2005]. One way to deal with this problem is to plan 
multiple overlapping cells (an overlap of 20 to 30 percent). As the cell breaths, the 
border users either get disconnected or get connected to the neighboring cells if they are 
already in Soft Handover state. However this is done at the expense of additional base 
stations thereby increasing the cost of the network. 
The other already proposed solution is to plan cells in such a manner that a highly 
loaded cell is always surrounded by lightly loaded cells [Jalali 1998]. But exactly 
predicting traffic a priori is very difficult and resources in lightly loaded cells are wasted 
for most of the time. Another solution in the literature is to assign plural frequencies to a 
base station [Bergenlid 2001]. One frequency among the plural frequencies can be 
defined as Maximum Coverage Frequency and the coverage of this frequency is kept 
constant i.e. cell coverage from this frequency is not allowed to breath. On the other 
hand, Cell Breathing is allowed on the remaining frequencies. As the coverage from the 
Maximum Coverage Frequency is held constant, border users are given service from this 
frequency; as a result disconnections because of Cell Breathing are prevented. The issue 
related to this solution is that plural frequencies will always be assigned to a Base Station 
which may be considered as a wastage of the most valuable and precious resource 
(bandwidth) in the cellular network. Moreover, there is no mechanism to assign 
Maximum Coverage Frequency to the border users.