Abstract: A system and method are described for providing least-cost call routing for mobile wireless devices having access to voice-over-IP (VoIP) infrastructure, such as may be operated by an enterprise having global presence. Using a local wireless connection, such as a wireless local area network (WLAN), a software agent on the mobile wireless device registers with a common, enterprise-wide registrar, which, in turn, informs a VoIP gateway in the device's home region of the device's new location. The home region VoIP gateway will then re-route incoming calls for the device to a VoIP gateway serving the region in which the device is currently located. The local VoIP gateway will then route the call to the device via the WLAN. Seamless routing occurs even when the wireless device obtains a local phone number in a foreign network. Outgoing calls from the device can be routed via the VoIP infrastructure or the foreign network based on availability of service and/or cost.

Abstract: A method and system for communicating the identity of devices detected in a wireless communication system. The devices connect to a mobile wireless network comprising a wireless access network and a core Internet Protocol (IP) network. The identities of devices so detected are specified by a combination of device and network-level identities and is communicated to a management server. In an exemplary embodiment, network elements of the core IP network are used to detect and convey the identity of wireless devices to a management server.

Abstract: An optoelectronic receiver and associated method of operation.

Abstract: In an internet protocol television (IPTV) system, fast channel change (FCC) transactions that experience late multicast joins are handled specially, thereby allowing the system to be provisioned for the vast majority of multicast joins that are within an expected range. During an FCC transaction, the subscriber interface device, such as a set-top box (STB), can determine how long it can wait to join the multicast stream of the new channel before a gap can be predicted to occur in the handover from the FCC unicast to the multicast. If the STB has not joined the multicast stream by the determined time, a recovery procedure is invoked in which the STB sends a RESTART request to the FCC server which, in turn, increases the rate of the FCC unicast as if the FCC transaction were restarted, thus allowing the handover to occur seamlessly. This solution reduces the demands of each FCC transaction, allowing for greater scalability and reduced cost.

Abstract: For wavelength division multiplexing (WDM) communications, apparatus and methods are provided for performing tone-based optical channel monitoring that is less sensitive to stimulated Raman scattering (SRS). In tone-based optical channel monitoring, in which WDM channels are modulated with one or more tones, detecting and measuring the tone power is commonly used as a measure of signal power in each channel. In WDM systems with long fiber spans and high signal powers, however, SRS tends to transfer energy from shorter wavelengths to longer wavelengths, whereby the tones are no longer accurately indicative of the signal power of the individual wavelength channels. Apparatus and methods are provided which reduce the effect of SRS by filtering the monitored WDM signals into sub-bands and detecting each sub-band independently.

Abstract: An optical amplification method and apparatus implemented using RZ-DPSK modulation or variants thereof and a deeply saturated semiconductor optical amplifier.

Abstract: Systems and methods are described for establishing credentials at a device and at a device management server for the purpose of exchanging secure credentials in order to mutually authenticate the device and the server. A credential generation algorithm is described which uses a plurality of seeds, including the hardware identity of the device, the server identity, and a shared private key, to generate two sets of credentials, one to be used by the device and the other to be used by the device management server. The credentials are exchanged between the device and the server during any session, thereby assuring mutual authentication.

Abstract: A method is provided for distributing multicast channels from a multicast/predictive multicast cache located in at least one selected network device of a multicast network. The network device upon receiving a channel request from an end-user transmits the requested channel from the multicast cache if the requested channel is available in the multicast cache. Else, the network device requests the multicast source for the requested channel along with a group of one or more multicast channels centered at the requested channel. The network device transmits only the requested channel and other channels are cached in the multicast cache on the network device. Upon receiving a request for removing a channel the network device caches the channel for a prescribed duration before evicting the channel.

Abstract: A network design method for Ethernet-type networks exhibiting capacities sufficient for operation during normal periods as well those as periods when a single node or link has failed.

Abstract: A portable autonomous terminal guidance system can be located in an aircraft landing zone. The terminal guidance system generates a signal indicative of the position, the terrain, and the meteorological conditions where the guidance system is located. A receiving aircraft may process the signal produced by the terminal guidance system to generate a self-contained GPS obstacle-avoidance approach path for the aircraft to the landing zone.

Abstract: An apparatus and a method for accurately detecting Loss of Optical Power (LOS) by noise power cancellation effect and optical power is measured at two output ports of an athermal periodic filter, wherein one output port in the optical frequency domain, is aligned with the signal channels of an input WDM signal (on-grid port), whereas the second output port is aligned complementary to the first output port (off-grid port). In a preferred embodiment, the apparatus computes the ratio of the measured optical powers at the two output ports of the periodic filter, and comparing them to a threshold value that is determined from the overall common-mode rejection ratio (CMRR) of the detection apparatus. In an alternative embodiment, the apparatus additionally compares the optical power measured at the on-grid port to a threshold power that is determined from system design parameters.

Abstract: Electrical and visual test structures monitor the degree of removal of conductive sacrificial layers used in micromachining processes that fabricate micro-electromechanical systems (MEMS).

Abstract: A novel 100+ Gbit/s opto-electronic receiver uses hybrid integration of a photodiode and a demultiplexer. The photodiode converts a high speed optical data stream to an electrical data stream that is input to an electronic demultiplexer. The photodiode and the demultiplexer are connected together by a novel planar microwave transmission structure.

Abstract: A quantized multi-rank beamforming scheme for multiple-antenna systems such as a multiple-input-multiple-output (MIMO) wireless downlink. User equipment (UE) estimates downlink channel and transmit power and determines rank and power allocations. A quantized beamforming matrix is then determined by the UE using successive beamforming. The UE also determines channel quality indices (CQI) which it feeds-back to the wireless downlink base station along with the index of the quantized beamforming matrix. The base station uses the CQI information to select a UE for scheduling of downlink transmission and the quantized beamforming matrix index received from the selected UE to beamform the downlink transmission to the UE. Base station overhead and is minimized while providing near-optimal performance given the constraints of a limited feed-back channel and computational complexity of the UE.

Abstract: An optical apparatus including a 360-degree star coupler with derivative structure(s) and applications to optical imaging, optical communications and optical spectroscopy.

Abstract: A self-polarization diversity technique to combat PMD in a direct-detection optical OFDM system. This technique does not require any dynamic polarization control, and can simultaneous compensate PMD in a WDM system with one device. Simulation results show that this technique virtually completely eliminates the PMD impairments in direct-detection optical OFDM systems.

Abstract: An optical imaging system and method for producing panoramic images exhibiting a substantial field of view.

Abstract: Duobinary and NRZ modulation of an X-Gb/s optical signal is achieved with a lumped element InP Mach-Zehnder device configured to operate at X/k-Gb/s where k>1 and arranged in a push-pull configuration.

Abstract: A Centralized Resource Management (CRM) system that supports the sharing of all the transponders in a WXC node, i.e., any spare transponder can be reconfigured to accommodate any drop channel, regardless of wavelength or input port. Consequently, network restoration in case of network failures is supported as well as the ability to reconfigure as a result of dynamic traffic requirements in the network. CRM advantageously is applied to conventional WXC node as well as WSS-based WXC nodes in the WDM networks. Three CTM schemes which manage the transponders in the WSS-based WXC node are described along with reconfiguration algorithms for an optical switchless CRM solution.

Abstract: A method of optically equalizing a multi-level (amplitude or phase) optical signal through the effect of an optical equalizer wherein the optical equalizer (OEQ) is placed at either a transmission end or a receiver end of the optical communications link and a tap delay characteristic of the OEQ need not be determined by symbol spacing, rather it may advantageously be adjusted to desirably compensate non-linear mapping performed in the modulation process or simultaneous operation on a plurality of wavelength division multiplexed (WDM) channels.