Abstract: A routing protocol scatters a stream of packets along a number of parallel paths, the packets being treated independently. The next hop for each packet is chosen probabilistically by comparing the ‘resistance’ of available options. The resistance of a given hop depends upon the time the packet would spend in an output buffer from the current node, the time the packet would spend in the input buffer of the next hop node, the transfer time between the nodes and the number of hops that the packet would take from the current node to the ultimate destination of the packet using the shortest path. This routing protocol is more efficient that shortest path first routing under simulation.

Abstract: An emergent network is autonomous at the service level. Network nodes have policies that enable them to process different types of service requests, with the processing earning the nodes ‘rewards’. Successful nodes can pass some or all of their policies to other nodes using the evolutionary biology of bacteria as a model.

Abstract: An emergent network is autonomous at the service level. Network nodes have policies that enable them to process different types of service requests, with the processing earning the nodes ‘rewards’. Successful nodes can pass some or all of their policies to other nodes using the evolutionary biology of bacteria as a model.

Abstract: A method of obtaining positional information about individual wireless devices a1–a16, r1–r125 within a wireless ad-hoc network including a plurality of position determining devices r1–r125 which include means for estimating the distance between themselves and other similar devices which are within range.

Abstract: An emergent network that is autonomous at the service level. Network nodes have policies that enable them to process different types of service requests, with the processing earning the nodes ‘rewards’. Successful nodes can pass some or all of their policies to other nodes using the evolutionary biology of bacteria as a model.

Abstract: The present invention provides an emergent network that is autonomous at the service level. Network nodes have policies that enable them to process different types of service requests, with the processing earning the nodes ‘rewards’. Successful nodes can pass some or all of their policies to other nodes using the evolutionary biology of bacteria as a model. The network is arranged into clusters of nodes, with unprocessed service requests being passed from cluster to cluster.

Abstract: The present invention provides a routing protocol that scatters a stream of packets along a number of parallel paths, the packets being treated independently. The next hop for each packet is chosen probabilistically by comparing the ‘resistance’ of available options. The resistance of a given hop depends upon the time the packet would spend in an output buffer from the current node, the time the packet would spend in the input buffer of the next hop node, the transfer time between the nodes O and the number of hops that the packet would take from the current node to the ultimate destination of the packet using the shortest path.

Abstract: The present invention provides an emergent network that is autonomous at the service level. Network nodes have policies that enable them to process different types of service requests, with the processing earning the nodes ‘rewards’. Successful nodes can pass some or all of their policies to other nodes using the evolutionary biology of bacteria as a model.

Abstract: An optical code recognition unit (OCRU) for recognizing a predetermined n-bit optical code has an n-way splitter having an input and n parallel outputs. A plurality of combiners are associated with the splitter outputs, and a respective gate is controlled by the output of each of the combiners. Each of the splitter outputs is subject to a different delay of from 0 to (n-1) bit periods, and each combiner receives an input from at least one of the splitter outputs. The OCRU is such that all the gates are turned on if a predetermined optical code is applied to the splitter input.

Abstract: A laser amplifier operable such that at the commencement of each output pulse the carrier level has recovered from depletion by the previous pulse. Under these conditions output power commensurate with a much higher carrier density than is usually available is possible. The mode of operation is especially useful as a way of providing high power pulses, for example for use in optical time domain reflectometry. Using a travelling wave amplifier in conjunction with return to zero format data pulses is also disclosed.

Abstract: A laser amplifier package comprises two laser amplifiers coupled via two lenses and an optical isolator. The first and second laser amplifiers may both be run as amplifiers to give an overall improved gain and reduced residual facet reflectivity. The first amplifier may be run as a pulse source as part of an LEC or gain switched DFB laser assembly. Pulses generated to be, or compressed to, near transform limited enable the output from the package to be optical solitons. The second laser amplifier may be switched to provide modulation.

Abstract: A laser amplifier in which the effective refractive index of the active region for the TE and TM modes is sufficiently different to provide multiple mode ripple beat frequency overlap within a 3dB gain envelope peak. The active region is made highly asymmetric with an aspect ratio of at least 10:1 and preferably 20:1 in order to provide the effective refractive index difference. Steps, grading or uniform difference in the material refractive index may also be used. The confinement factor ratio is made as high as possible by providing different material refractive index in the orthogonal dimensions of the active region cross section.

Abstract: An optical amplifier having a saturable absorption region is operated below the lasing threshold for the device. Non-linear effects and bistability are observable at temperatures above room temperature. A selected input wavelength .lambda..sub.i within the gain spectrum of the device is amplified and an output at the same wavelength .lambda..sub.i is produced. This is in contrast to the normal operation at threshold, where there is a wavelength shift to the lasing wavelength and, depending on the laser used for the naturable absorption device, the output may be multimode for a monomode input. Best gain is achieved by tuning the input wavelength to a peak of a Fabry-Perot mode in the gain spectrum for the amplifier.The amplifier may be used as wavelength controlled optical switch, when operated bistably, or as a regenerative amplifier when operated in the non-linear region without hysteresis effects.

Abstract: A lens assembly for focussing the light output of a device (2) on to a target (4), when there is relative movement between the target and device. The assembly comprises a pair of lenses with the device at the focus of the first and the target in the focal range of the second lens.