 efficient. To achieve a proper latency calculation, parameters like propagation time, transmission time, and queuing time have to be considered. Propagation time refers to the time it takes a bit of information to travel from the source to the target receiver. This time will correspond to the ratio of the distance to the speed of propagation in the transmission network. Transmission time relates to the time to transfer a message. The messages (packets) consist of a set of bits that establish a message size. The transmission time, therefore, is the ratio of the packet size to the bandwidth of the channel. Queuing time is a parameter in the transmission network that is required because of several factors. One is the need to keep the packet stored while its destination prepares to receive it. Another is the need to avoid internal collisions of packets that are sent to the same destination. Queuing in a transmission system is a topic by itself and is treated elsewhere. Bandwidth Delay Product The bandwidth delay product is a measurement of the transmission link, which represents the maximum amount of information that can be stored in a point-to-point connection. This parameter is the multiplication of the total bandwidth of the link multiplied by the time it takes the transmitted data to reach the destination. When a binary system is used, the band- width delay product is expressed in bits per second. Timing and Synchronization System timing and synchronization make up one of the essential foundations of all transmis- sion equipment. A synchronized clock signal with minimal jitter is a fundamental parameter for proper data transmission. Clock Requirements Transmission systems need an efficient decision process at the receiver. Regenerators use timing recovery to extract a synchronization signal from the transmitted data. This is known also as clock extraction, and the most advanced receivers must include this function to decrease the number of possible errors. If the extraction is successful, the system becomes self