Useful Information
N = i2 + ij + j2 Pr = Pt Gt Gr ht2 hr2 / D4 Ao = r * h Ab = Ao * B Ao = Ab + Ac U = Ac / N	Giga (G) = 109 Mega (M) = 106 kilo (k) = 103 milli (m) = 10-3 micro (m) = 10-6 nano (n) = 10-9 Speed of light in a vacuum: c = 300,000 km/sec

Show your work on mathematical problems so that if you have part of the solution correct, you can earn partial credit.

This exam has a total of 44 points.

1. [8] In a CDMA system, handsets A, B and C are assigned the following chips:

0 = 010100111

1 = 111101001

1 = 101011010

What chipped stream will the tower receive when the handsets intend to send the following data ?

A intends to send 1 0 0 1

B intends to send 1 1 1 0

C intends to send 0 0 0 1

ANS ________________________________________________________________________

2. A cellular system has a total of 110 reuse groups with 13 cells per group. There are three channels in each cell for users to make calls. The entire system has 2,760 Erlangs of traffic intensity for the entire system (evenly distributed among all cells in the full system). In the system, the average call is 3 minutes 15 seconds.

a. [2] What is the blocking rate (B) in a cell, assuming this is a blocking system?

b. [2] What is the utilization for a single cell, assuming it is a blocking system?

c. [2] If calls were queued in the cell, what would be the average delay (in seconds) for all callers in a single cell?

3. [6] Determine where the cell boundary is between two cell towers using the information in the diagram below. Answer by solving for X in the diagram, which is the distance to the boundary from tower B. Antenna As transmit power is 16 times greater than antenna Bs transmit power. Also, antenna As gain is 16 times greater than antenna Bs gain. The height of towers A and B are identical. There are no miscellaneous losses to account for in this scenario. You must show your work.

A(> | <)B

| Boundary |

| | |

+-------------------------------+-------------------------+

| | |

| |<---------[ X ]--------->|

| |

|<---------[ Distance between towers = 8000 m ]---------->|

4. Accurately define the following terms using your own definitions written in complete sentences [2 pts. each].

Refraction

Scattering

Power control

Reuse group

Interference

Noise

Queue jumping

A_b

5. Cellular Planning

You may find it easier to print out the hexagon diagram and complete with pencil (on real paper). Then take a photo (a clear one) and paste back into this word document.

Complete the below parts (a) (d) for a cellular system with 21 channels, where i = 1 and j = 2. For parts (b) through (d), use the hexagonal graph paper on the next page.

(a) [2] How many cells are in a reuse group for this system (show your calculation below)?

(b) [2] Beginning with cell A in the hexagonal diagram on the following page, label all the other cells on the sheet that are also cell A (use i and j to determine the other locations).

(c) [2] Draw boundary lines around two reuse groups (around the edges).

(d) [2] In one of the reuse groups, assign channels 1 to 21 in the cells in an appropriate manner.

A