Calibrating Fiber Propagation Delay Asymmetry and Switch Queue Noise in PTP Boundary Clock Topologies
Precision time accuracy demands fixed optical wavelength asymmetry offsets and sub-nanosecond egress timestamping at each boundary clock.
Wavelength Division Multiplexing
Meaning
Optical transmission technology combines multiple optical carrier signals onto a single optical fiber by using different wavelengths of laser light. This method, known as wavelength division multiplexing, enables bidirectional communications over a single fiber strand and increases the aggregate data rate of the link. It is the standard technology for expanding the bandwidth of long-haul and metro optical networks.
Channel Capacity
By dividing the optical spectrum into discrete channels, the technology allows operators to transmit different data streams simultaneously without mutual interference. This wavelength division multiplexing approach increases the total throughput of an existing fiber link without the need to lay new cables. The capacity can be expanded by reducing the channel spacing or utilizing a wider spectral band.
Transmission Technology
Implementing the system involves multiplexers that combine the wavelengths at the transmitter and demultiplexers that separate them at the receiver. In a pilot test with a single channel, the signal quality can be evaluated easily, but production deployment requires testing all channels simultaneously to monitor for multi-channel crosstalk and non-linear optical effects, which can degrade signal integrity across the entire fiber span.
Deployment Cost
Upgrading a network with multiplexing equipment requires a significant initial investment in high-precision lasers and filters. However, this approach is far less expensive than laying new physical fiber cables over long distances. The technology provides a scalable path for future network expansion.