Abstract: A method and apparatus for modifying the level of a speech signal is provided in which the gain parameter in the encoded speech signal is changed in a variable and cyclical manner over time. More specifically, a speech signal is encoded as a bit stream and the speech signal is transported in frames with each frame potentially being further sub-divided into sub-frames. The gain parameter, e.g., fixed codebook gain, is modified in the speech signal in a variable and cyclical manner over a plurality of frames or sub-frames so that gain is temporally dispersed over a plurality of frames or sub-frames. In effect, the change in the amount of gain applied to the signal is effectively dispersed over time so that gradual and accurate changes in the output level of the signal can be achieved to better match actual signal conditions.

Abstract: A channel quality feedback method for wireless transmission is described in which the rate for reporting channel quality information from a mobile station to a base station is variable as a function of the presence or absence of a transmission from the base station to the mobile station. In particular, the feedback rate from the mobile station to the base station is increased when the mobile station detects a transmission from the base station. As such, the feedback rate is slower when there is no data transmission for the mobile station and faster when the mobile station is receiving data.

Abstract: A heterogeneous mix of traffic having one or more protocol formats and supplied by one or more users or sub-networks is transported in a communication network by using digital containers that are routed and processed in network nodes interconnecting the users or sub-networks. A digital container includes a frame structure comprising a header section and a payload section, the header section including information for routing the digital container and for identifying the type of payload being carried. The payload section is capable of carrying one or more different types of traffic formatted according to one or more protocols, e.g., IP, ATM, and so on. Processing of the individual payload remains a user or sub-network responsibility while the less processor-intensive routing and processing of digital containers occurs at the network node level.

Abstract: A method is described for transporting information in frames comprising header and payload information from a first network to a second network via a third network. The first and second networks are commonly managed but are independent of management of the third network. Network nodes generate respective headers for each outgoing frame from the node but completely copies payload from an incoming frame to the outgoing frames. Upon crossing a first boundary between the first and third networks, only a first part of the header is copied into the payload such that a reduced size header in the third network fits into space that would otherwise be occupied by a second part of the header that is not copied into the payload. Upon crossing a second boundary between the third and second networks, the headers are retrieved from the payload and used to generate header information in the second network.

Abstract: An add/drop arrangement using broadband optical couplers provides a low-loss, highly flexible add/drop capability for survivable wavelength division multiplexed (WDM) ring networks. At each node in the ring having the broadband optical coupler-based add/drop element, a portion of optical signal power of the entire WDM signal (i.e., all optical channels) is tapped off so that one or more optical channels of particular wavelengths can be dropped at the node. Information (e.g., data) to be added at the node is supplied in an optical channel that is added to the WDM signal via the broadband coupler. Because the add/drop element uses a broadband coupler, another portion of optical signal power of the WDM signal, including any added optical channels, passes through the node onto the ring. Depending on the specific ring topology being used with the broadband coupler-based add/drop arrangement, additional wavelength assignment and handling measures may be required.

Abstract: A power supply particularly suitable for high-speed optical data transmission employs readily available components to achieve desired voltage tolerances. More specifically, a voltage signal supplied to a load is converted into a digital signal and provided to a processor that derives a digital correction signal from the digital signal. The digital correction signal is then converted to an analog correction signal and is used by a feedback control circuit in the power supply to regulate the output voltage.

Abstract: Substantial reduction in crosstalk and improved scalability for supporting high channel counts in dense wavelength division multiplexed (DWDM) systems is achieved in an optical demultiplexer arrangement that partitions the total number of input optical channels into separate demultiplexer modules, demultiplexes smaller groups of optical channels in the separate demultiplexer modules, and filters the individual optical channels at the outputs of the separate demultiplexer modules. Partitioning the total number of channels into smaller demultiplexing groups and post-filtering a reduced number of demultipexed optical channels reduces the number of non-adjacent channels that can contribute to the total crosstalk level. The modularity of the optical demultiplexer arrangement results in smaller device footprints and smaller free spectral ranges associated with the demultiplexer modules. This modularity also allows for future system upgrades without redesign and without disruption to existing service.

Abstract: A method and apparatus are provided for displaying network information to a user connected to a network or sub-network manager of a hierarchical telecommunications network by providing a map on a visual display unit showing network elements and connections between network elements. A plurality of views may be selected which include not only a conventional physical view, in which all network elements and the optical fibre links between them are shown, but also one or more views showing connections at respective virtual container levels (e.g. VC-4, VC-12). In these views only the multiplexers are shown and virtual containers at the respective level are shown as lines joining the multiplexers which are their termination points.

Abstract: High speed transport in a dense wavelength division multiplexed system is achieved by transmitting information supplied by multiple sources in a parallel format using a subset of the total number of optical channels in a wavelength division multiplexed signal as a parallel bus transmission group. In one illustrative embodiment, a selected number of optical channels, i.e., wavelength channels, in the wavelength division multiplexed signal are allocated to form a parallel bus transmission group, i.e., a wavelength bus. Information from one or more sources is supplied in a parallel format and then transmitted at the same transmission rate in each of the optical channels in the wavelength bus. When information from more than one source is to be transported, the information from each source is multiplexed into a parallel format.

Abstract: A smart card is adapted to partially include and employ a triply-secure algorithm for data exchange. The algorithm verifies a user's identity and his simultaneous membership in any groups that he has joined. For this purpose, the algorithm requires only a single insertion of the smart card and only a single input of the user's personal identification number. The algorithm can be used in smart cards or in computer networks for identity verification and membership proof. A combination of three different hard problems is used. The first one is based on integer factorization, such as the RSA authenticating technique, and the second one is based on a discrete logarithm, and the third one is based on the coefficients of a polynomial function. In a typical application using smart cards, a certification authority (CA) establishes requirements for preparation and issuance of a multi-purpose card.

Abstract: Memory requirements and processing delays associated with the application of forward error correction in high speed optical transmissions are substantially reduced by mapping a forward error correction code on a row-by-row basis into unused overhead bytes in a high bit rate signal frame. By applying the forward error correction code to an entire row of the signal frame on a row by row basis, approximately one row needs to be stored at a time thereby reducing the total memory requirements for forward error correction processing. Using SONET as an exemplary application, approximately {fraction (1/9)}th of the entire SONET frame (e.g., one of nine rows) needs to be buffered for forward error correction processing. In an illustrative embodiment, four forward error correction (FEC) blocks are provided for each row for a total of 36 FEC blocks for a frame. Each FEC block comprises four bytes of correction bits for a total of 32 correction bits.

Abstract: Distortion and crosstalk that occurs when operating optical amplifiers in saturation is substantially reduced by passively compensating for gain variations caused by changes in input power to the optical amplifiers. More specifically, in an optical communication system having one or more optical amplifiers, a “reservoir” optical channel is supplied in addition to the other traffic-carrying optical channels. The wavelength of the reservoir channel is selected such that the power level of the reservoir channel varies in response to changes in power levels of the traffic-carrying channels. Because gain variations are typically highest around the gain peak region in an optical amplifier's gain bandwidth, the reservoir channel in one exemplary embodiment is assigned a wavelength around the gain peak region.

Abstract: Optical signal power levels for selected optical channels processed within an add/drop node in a wavelength division multiplexed (WDM) system are adjusted as a function of variations in signal power in an incoming WDM signal caused by gain ripple. In particular, a “ripple fitting” method is described whereby the optical signal power of individual optical channels being added at the add/drop node are adjusted to levels that correspond to the ripple profile of other optical channels being routed through the add/drop node. In this manner, the gain ripple in the WDM signal being output from the add/drop node approximately corresponds to the gain ripple in the incoming WDM signal at the node.

Abstract: An uncorrelated Michelson interferometer is formed with single mode optical fiber. In a first embodiment, light is transmitted into an optical 3 dB coupler, and split into a transmission down a first optical fiber and transmission down a second, significantly longer second optical fiber. In the disclosed embodiment, the second optical fiber path may be several meters, and even hundreds of meters longer than that of the first fiber optic path. The light at the ends of the respective first and second fiber optic paths is reflected back into the single mode optical fiber, and coupled in the optical coupler. In the first embodiment, since the second fiber optic is relatively long, an unknown amount of rotation of the polarization would otherwise occur. Thus, a polarization controller is used to control the polarization in the longer, second optical fiber such that a maximum signal is output from the optical coupler.

Abstract: An optical filter/combiner arrangement is used for filtering and combining optical signals in at least two wavelength bands supplied by at least two respective Wavelength Division Multiplexed (WDM) systems along the same optical fiber. More specifically, optical signals received by the optical filter/combiner arrangement from an optical fiber are appropriately filtered so that optical signals in one wavelength band are processed by components of one WDM system and optical signals in another wavelength band are processed by components in another WDM system. After processing by the respective WDM system components, the optical signals in each of the wavelength bands are then re-combined and supplied along the same optical fiber. By using the optical filter/combiner arrangement, existing WDM systems can be upgraded to higher capacity using the existing optical fiber and without replacing existing components or disrupting existing service.

Abstract: A method is provided for verifying that optical signals are properly routed between inputs and outputs of an optical cross-connect according to the prescribed routing paths defined in the cross-connect map. More specifically, optical signals are independently tagged at the cross-connect input ports with connection verification messages containing identification information. Connection verification messages can include, among other information, a message identification, incoming and outgoing wavelength information, incoming and outgoing port information, a time stamp, user verification data, and so on. At the cross-connect output ports, the messages are retrieved (and optionally removed) from the optical signals so that the identification information from the retrieved messages can be compared to the routing defined in the cross-connect map.

Abstract: Crosstalk and signal to noise degradation contributed by fiber nonlinearities in a WDM system are reduced by transporting data in a parallel format using a plurality of optical channels in a WDM signal as a parallel bus and by coding the parallel-formatted data so that bit patterns in the parallel-formatted information that would otherwise contribute to nonlinear impairments are changed. In one illustrative embodiment, an n-bit wide byte is transmitted using n optical channels (i.e., using n wavelengths) so that each of the n optical channels carries one of the n bits of the byte. In conjunction with the parallel transmission of information, a coding scheme is employed to reduce the occurrence of bit patterns, e.g., “all ones”, in the n-bit wide bytes that would give rise to four wave mixing or other nonlinear effects. The coding scheme may be used to transform bytes having “all ones” bit patterns to bytes having “non-all ones” bit patterns.

Abstract: Transmission-based data security is provided in dense wavelength division multiplexing systems using a transmission scheme that incorporates hierarchical scrambling techniques with a unique multiplexing arrangement. Information supplied by one or more sources is multiplexed according to a predetermined scrambling pattern and transmitted in a parallel format using one or more wavelength channels in a wavelength division multiplexed signal. By transmitting the multiplexed and scrambled information in parallel, the wavelength channels effectively function as a parallel bus (a “wavelength bus”). Multiple stages of scrambling can be applied to the multiplexed and scrambled information transported in the wavelength bus. For example, individual bit streams carried within each wavelength channel of the wavelength bus can be separately scrambled according to another predetermined scrambling pattern.

Abstract: An enhanced synchronization status messaging capability for synchronous networks is provided in a messaging format that is compatible with existing synchronization messaging standards. Additional messages, which are based on the same predefined code words used in existing synchronous status messages, are differentially coded and carried in available, but unused message positions, in the existing messaging scheme. In one illustrative embodiment, a two part message format is used for carrying information between network elements and between a network element and a co-located BITS clock in-a synchronous network. A first part of the message format carries the traditional quality level information of synchronization references using the set of code words predefined in the applicable standards. For example, the quality information of a synchronization reference is conveyed using 7 out of 10 “like” messages selected from the group of predefined code words set forth in the standards.

Abstract: Distributed switch fabrics can support multiple switching functions while meeting established performance requirements by using a control architecture based on multiple layers of signal status carried within signals transported through the distributed switch fabrics. More specifically, a method and apparatus is provided for controlling the selection of signals through distributed switch fabrics by deriving signal status information for the signals at any point along a transmission path and embedding the signal status information in each of the signals using multiple signal status layers. Each of the signals carries its respective signal status information as it propagates along the transmission path, so that the embedded signal status information can be selectively extracted from any of the multiple signal status layers to facilitate a selection decision at any of the distributed switch fabrics.