Kevin

A = Y * s

A = traffic in erlangs

Y = mean call arrival rate in (time)

s = mean holding time in (time)

Occupancy for state 0 would decrease (probability of being in a higher state increases)
Occupancy for state N would increase (greater Y results in more traffic), higher chance that all lines are occupied

When S >> N, the call arrivale rate is independent to the number of lines occupied, and therefore the average call arrival rates will be the same

Random (pure chance) traffic - calls are indepenedent, random mean arrival rate and holding times

Full availability - Any call can connect to any line (if the system is completely occupied, then the arrived call is blocked and lost - lost calls cleared system)

Number of subscibers >> Number of lines

Statistical equilibirum - the probability of a call leaving the system is equal to the probability of a call entering the system (probabilities remain constant over time)

When S = N, and N lines are occupied, then all of the subscribers are using a line and none remain to make a new call into the system

Therefore, there will never be a blocked call and so the call congestion is 0%

2^N = Alphabet size (2^N = 8 → N = 3)

N is the bit rate (bits per second)

F1 = Fa1 + (Fc - 1)/Ga1

F2 = Fa2 + (F1 - 1)/Ga2

F3 = Fa3 + (F2 - 1)/Ga3

If A → B
Ft = Fa + (Fb - 1)/Ga

Choose amp A to be the amp with the lowe noise figure

code rate = k/n

a (7,4) hamming block code would be 4/7

Pe = 0.15
P_no_error = (1-Pe) = 0.85 = P0

P_1_error = n(P0)^(n-1) * Pe = P1
P_2_error = 1 - Po - P1

Convolutional coding operates on the incoming message sequence continually in a serial manner

It does not require the entire message block to be present before coding commences

Information of single pixel = log_2(n)

n is the number of possible states or messages the informaiton can be in (i.e., a die has 6 states) (black or white)

H = P1*log_2(1/P1) + P2*log_2(1/P2)

Information = H * Number of pixels

C = B * log_2(1 + S/N)

C is the capacity of the channel

B is the bandwidth

S/N is the signal to noise ratio (S/N = input - NF)

Time required = (Number of elements ot pixels) / (capacity)

1) Application - Provision of access to the OSI environment for end users

2) Presentation - Transformation of the input data to provide services selected by the application, an example being encryption

3) Session - maintains the conncetions and is responsible for controlling ports and sessions

4) Transport - end to end (source destination) control of the messages exchanged between users

5) Network - Routing of packets through the network

6) Data link control - Error control for the reliable transfer of information across the channel

7) Physical - Transmission of raw bits of data over a physicla channel

Allows multiple-vendor development through the standardisation of network components

Prevents changes in one layer from affecting the other layers to accelerate development

Divides the network transferring process into smaller and simple components, fascilitating component development, design and trouble shooting

Allows for various types of hardware and software to be able to communicate