# Book used is: Wireless Communications, Andrea Molisch, Wiley and Sons. The Problems are from the book, end of the chapter problems. This book has a solution manual. I could not find it in the web....

Book used is: Wireless Communications, Andrea Molisch, Wiley and Sons.
The Problems are from the book, end of the chapter problems. This book has a solution manual. I could not find it in the web.
Chapter 17: Multiple Access and the Cellular Principle - Problem1 and 2
1. An analog cellular system has 250 duplex channels available (250 channels in each direction).
To obtain acceptable transmission quality, the relation between reuse distance (D) and cell radius
(R) has to be at least D/R = 7. The cell structure is designed with a cell radius of R = 2km.
During a busy hour, the traffic per subscriber is on average one call of 2-minute duration. The
network setup is modeled as an Erlang-B loss system with the blocking probability limited to 3%.

1. Calculate the following:

(i) The maximal number of subscribers per cell.
(ii) The capacity of the network in Erlangs/km2. (Assume that the cell area is Acell = pR2.)
(b) The analog system above is modernized for digital transmission. As a consequence, the
channel separation has to be doubled – i.e., only 125 duplex are now available. However,
digital transmission is less sensitive to interference and acceptable quality is obtained for
D/R = 4. How is the capacity of the network affected by this modernization (in terms of
Erlangs/km2)?
(c) To increase the capacity of the network in B, the cells are made smaller, with a radius of
only R = 1 km. How much is capacity increased (in terms of Erlangs/km2) and how many
more BSs are required to cover the same area?
2. A system specifies a blocking level to be less than 5% for 120 users each with an activity level
of 10%. When a user is blocked, it is assumed to be cleared immediately – i.e., the system is
an Erlang-B system. Assume two scenarios: (i) one operator and (ii) three operators. How many
channels are needed for the two scenarios?

## Solution

David answered on Dec 20 2021
2. A system specifies a blocking level to be less than 5% for 120 users
each with an activity level of 10%. When a user is blocked, it is assumed
to be cleared immediately – i.e., the system is an Erlang-B system.
Assume two scenarios: (i) one operator and (ii) three operators. How
many channels are needed for the two scenarios?
Now 120 users
So T tr = 120 *0.1 = 12
One has to find Nc : Number of channels
It can be clearly observed that as the number of channels increases the
capacity to...
SOLUTION.PDF