Abstract: Distributed precomputation techniques for determining primary and/or restoration paths in an optical or electrical network. The invention provides a number of partially and fully asynchronous distributed precomputation algorithms which may be implemented, for example, by the nodes of an all-optical network, in which network links are constrained in terms of optical signal wavelength and failure isolation. A given distributed precomputation algorithm may include a first phase in which paths are allocated for capacity demands to the extent possible without resolving contentions, and a second phase in which contentions between demands for the same capacity are resolved.

Abstract: A digital cellular/personal communications service (PCS) application incorporates a logical link connection (LLC) server. In this approach, there are two ATM connections in the path of an AAL-2 connection: one between a base station and the LLC Server and the other between the LLC Server and a vocoder group. All LLCs from, or to, a given base station use a common ATM connection irrespective of the vocoder used at the other end. Similarly, all LLCs from, or to, a given vocoder group use a common ATM connection irrespective of the destination base station at the other end. At the LLC Server, LLC packets from many base stations destined for the same vocoder group are extracted and bundled into the ATM connection between the LLC Server and the destination vocoder group. Similar treatment is given to the packets originating at vocoders and destined for base stations.

Abstract: A method and apparatus for transmitting and/or receiving variable-length packets (e.g., CDMA packets, CDPD packets) that are associated with different channels and which are multiplexed via a single virtual circuit (e.g., an ATM virtual circuit).

Abstract: The specification relates to a system supporting the transmission of multiple protocols over a single bytestream. The multiple protocol types supported include asynchronous transfer mode (ATM) protocol data units (PDUs), synchronous transfer mode (STM) PDUs, and variable length (VL) PDUs, as well as subtypes included within the aforementioned multiple protocol types. PDUs from higher layers are processed at three intermediate protocol layers where application layer PDUs are prepared, segmented, and repacked as asynchronous block multiplexing (ABM) PDUs. ABM PDUs include a type identification field. Cyclical redundancy checks and other error detection/correction techniques are optionally supported. ABM PDUs are multiplexed within a multiple protocol bytestream. Multiple protocol bytestream support is provided between a transmitter and receiver over a plurality of mediums, including but not limited to coaxial cable, wireless, optical fiber, hybrid fiber/coax, satellite, and twisted pair.

Abstract: Four stages of digital cellular architecture are presented which reuse much of the existing voice infrastructure while allowing graceful introduction of data and integrated voice/data services over industry standard, low cost platforms. First, a separate ATM-based infrastructure is introduced that supports data services. A new data call control is introduced on industry standard hardware platforms using object oriented and modular programming. Second, ATM is introduced at radio ports and call control functions are migrated to the new ATM-based call control platforms. Third, vocoders are introduced at the DCS. Fourth, the cellular functions of the legacy cellular switch are phased out and replaced by the ATM-based target architecture.

Abstract: A method and apparatus for managing a virtual circuit network is disclosed that enables hand-off management. An illustrative embodiment establishes a virtual ciruit by receiving, at a radio port, a virtual circuit identifier from a wireless terminal and attaching the virtual circuit identifier to an OA&M cell. The radio port then transmits, over a pre-established unidirectional virtual ciruit, the OA&M cell to a radio port manager.

Abstract: A method and apparatus for enabling one or more packets (e.g., CDMA packets, CDPD packets etc.) to be encapsulated into a cell (e.g., an ATM cell, a B-ISDN cell) for transmission and/or reception over a broadband network (e.g., an ATM Channel). An illustrative method includes building a basic control octet for a packet of N bytes, the basic control octet including (1) an additional control bit that indicates if a supplemental control octet accompanies the basic control octet, and (2) a length indicator based on N.

Abstract: A telecommunications architecture using ATM based technology is disclosed that supports wireless communications. Some embodiments of the present invention may provide a mechanism for hand-off, which has fewer costs and restrictions than other hand-off schemes the in the prior art. In one embodiment a plurality of virtual circuit identifiers is created such that each is unambiquously associated with the others. The virtual circuit identifiers are then transmitted to a wireless terminal, via a first radio port. Subsequently, the wireless terminal transmits one of the virtual circuit identifiers to second radio port.

Abstract: A method and apparatus for transmitting and/or receiving packets (e.g., CDMA packets, CDPD packets, etc.) that are associated with different channels and which are multiplexed via a single channel (e.g., an ATM Channel).

Abstract: Congestion in a high speed connection oriented packet network carrying bursty data and real time service is avoided by a novel in-call negotiation scheme for reserving bandwidth for real time calls and reserving buffer capacity for bursty calls.For a real time call, a centralized call controller in each switch in the network determines which of its outgoing trunks has available to it the peak bandwidth needed to accommodate the call. Once one of these trunks is found, the call routing is set up so that the call is directed through that trunk and the peak bandwidth requirement of the call is allocated on that output trunk for the duration of the call.The network contains one or more switches, each of which has a centralized call controller and a plurality of trunk controllers. The call controller routes calls from a plurality of input trunks to a plurality of output trunks, identifies kinds of calls, and allocates bandwidth on the output trunks.

Abstract: A method and apparatus are disclosed for the efficient generation of cyclic redundancy check (CRC) codes employing CRC generator polynomials of the form (1+x).multidot.f(x). The efficiency is achieved by independently and concurrently generating in parallel a preliminary CRC code word corresponding to f(x) and a term corresponding to (1+x) over a message M(x). The term corresponding to (1+x) is generated in a manner to have either a zero (0) state or a one (1) state. Then, the term corresponding to (1+x) is used to modify the preliminary CRC code word to obtain an overall CRC code word being generated over message M(x). If the term corresponding to (1+x) is a 0 state, then the overall CRC code word is obtained by shifting the bits of the preliminary CRC code word once to the left. If the term corresponding to (1+x) is a 1 state, then the overall CRC code word is obtained by shifting the bits of the preliminary CRC code word once to the left and adding f(x) to the shifted preliminary CRC code word.

Abstract: A congestion control scheme for connectionless networks relieves congestion by routing a portion of traffic on a congested primary path onto a predefined alternate path constructed such that loop-freedom is guaranteed. Explicit care is taken to avoid spreading congestion onto alternate paths. The control actions are taken in a completely distributed manner, based on local measurements only and therefore no signaling messages need to be exchanged between nodes.If desired, lower loss priority may be assigned to alternate routed traffic. Congestion is monitored locally and thresholds defined to declare the onset and abatement of congestion. The present invention affords at least an order of magnitude improvement in end-to-end cell blocking under sustained focussed overload.

Abstract: Disclosed is a method and circuit for modifying the check code of a data packet based on a first seed to accommodate the addition or substraction of a header. A number of bits, which include a second seed, an exclusive OR function of the first seed and a portion of a header, and a string of zeros dependent upon the length of an incoming data packet, is sent through a CRC generator. The resulting CRC calculation and the incoming packet check code are exclusive ORed to produce a modified check code taking into account the addition or substraction of the header.

Abstract: A facility is provided for use in a packet switch to control unnecessary multiple retransmissions of a data packet. In an exemplary embodiment of the invention, such control is achieved by tracking in a list the sequence numbers of transmitted data packets and retransmitting a data packet only if its sequence number appears in the list prior to the sequence number of the last data packet that is received correctly by a receiver. The sequence number associated with a retransmitted data packet is deleted from the list and then appended to the list to place the number in proper relationship with the sequence numbers of data packets transmitted after the initial transmission of the retransmitted data packet.

Abstract: A received digital signal is synchronized with a receiver in a communications network by employing a code word which is updated in accordance with a unique update technique. The synchronization arrangement receives the digital signal at a receiver, generates an error check code word over a prescribed portion of the received digital signal and compares the generated error check code word with an expected error check code word in the received digital signal. In response to the comparison result, the generation of the code word and the comparison is iteratged until synchronization is obtained. A new code word is generated as a function of a modified version of the last previously generated code word (previous code word), a function term based on a set of bits dropped from the prescribed portion of the received digital signal, and a set of bits added to the prescribed portion of the received digital signal. In one embodiment, a cyclic redundancy check (CRC) code word is employed.

Abstract: A decoder is arranged to operate as a single-bit error correction circuit (ECC) and as a multiple-bit error detection circuit (EDC). The decoder starts and remains in the ECC state as long as no errors are detected in a received data message. When an error is detected or corrected in a received data message, the decoder switches to the EDC state where it remains as long as errors are detected in the received data message. When no errors are detected in the received data message, the decoder switches back to the ECC state. In a generalized multistate decoder, switching occurs from one state to another state, each state having a different error correcting capability, in response to a predetermined number of errors corrected or detected in the received data.