Communication system performance index

Effectiveness index

1 Data transfer rate (the higher the effectiveness, the better)

The amount of data transmitted per unit time

• Bit transfer rate

  Number of data bits transmitted per unit time

• Bit rate

  The number of bits of data transmitted by the communication system per second, in bit/s or b/s

• Bit time

  The time required to transmit one data, that is, one bit

• Baud rate

  Baud refers to a waveform of signal change, the number of signal waves transmitted per second is the baud rate unit: Baud or B

  Each signal can contain one or more data bits. When only one data bit is included, bit rate = baud rate

2 Throughout

The number of bits, bytes or frames received and sent by the communication system per unit time

3 Band utilization

The transmission speed in the unit frequency band, the unit is: bit/s · Hz, that is, the bit rate that can be achieved per hertz of broadband

4 Protocol efficiency

Refers to the ratio of valid data bits to the length of the entire data packet in the transmitted data packet. Generally expressed as a percentage, it can be used as a measure of the additional amount in the communication frame.

5 Transmission delay

The time required for data to be transmitted from the sending end of the link or network segment to the receiving end, also known as transmission time

• Send time
• Propagation time
• Queuing forwarding time

6 Communication efficiency

The ratio of the transmission time of the data frame to all the time used to send the message

• Communication efficiency = 1, which means that all the time is effectively used to transmit data frames
• Communication efficiency=0, the bus is flooded by message collisions and conflicts

Reliability index

1 Bit error rate $P_e$

The probability of transmission errors in binary symbols in digital communication.

• The average bit error rate is often used in practical applications
• In computer communication, the average bit error rate is generally required to be less than $10^{-9}$

Validity and reliability are interrelated and mutually restrictive