Abstract: A method of forward error control in which a transmitter receives data from an input device and creates one or more original codewords that are transmitted onto each of two physically distinct telecommunications channels. Two copies of the original codeword are transmitted to the receiver via physically distinct channels to increase the robustness of the telecommunications channel between the transmitter and the receiver and to minimize the elapsed time between when the transmitter transmits the original codeword and when receiver has a final estimate of the original codeword available for output.

Abstract: A method of forward error control is disclosed in which a transmitter receives data from an input device and from it creates one or more original codewords pursuant to an error-control coding scheme. The transmitter then transmits a copy of the original codeword onto each of two physically distinct telecommunications channels for delivery to the intended receiver. The receiver then checks the validity of the estimates of the original codewords that it receives. If at least one received estimate of the original codeword that is deemed to be valid, then the receiver uses it. Alternatively, when the both of the received estimates of the original codeword are deemed invalid (because they have been both corrupted), then the receiver begins the process of constructing a final estimate of the original codeword based on the both of the received estimates.

Abstract: A method of forward error control is disclosed in which a transmitter receives data from an input device and from it creates one or more original codewords that are transmitted onto each of two physically distinct telecommunications channels. The reason that two copies of the original codeword are transmitted to the receiver via physically distinct channels is to increase the robustness of the overall effective telecommunications channel between the transmitter and the receiver, and to minimize the elapsed time between when the transmitter transmits the original codeword and when receiver has a final estimate of the original codeword available for output.

Abstract: A technique for preventing the user of a wireless terminal from carrying a wireless terminal into the umbra of a fade is disclosed. In particular, some embodiments of the present invention notify the user that the user is in danger of entering the umbra and assist the user in navigating from the fade. An illustrative embodiment of the present invention comprises: creating a first measurement of signal quality, SQ(n), of a signal received from a wireless terminal; and, when the first measurement of signal quality, SQ(n), is unsatisfactory, transmitting a first message to the wireless terminal to direct a user of the wireless terminal to move the wireless terminal in one direction.

Abstract: A method and apparatus for transmitting messages from one processor to a plurality of other processors in a distributed processing system having no hardware message broadcast facilities. The transmitting processor includes a broadcast program process for controlling the transmission of any messages destined for a plurality of other processors. Different client processes in the transmitting processor request the broadcast process to transmit a broadcast message. The single broadcast process controls the number of individual messages which are sent out sequentially to each of the receiving processors in such a way as to ensure that the broadcast messages do not interfere with other message traffic that frequently has tighter delivery time requirements. The broadcast process transmits the broadcast messages to each of the plurality of recipient processors without waiting for acknowledgment response messages from any of these processors.

Abstract: A distributed control switching system where the system control units cooperatively perform the terminating port determination function. Multi-port hunt groups having members that span a number of switching modules each having an associated control entity, are controlled in an efficient manner by assigning, for each multi-port hunt group, one of the switching modules as the group controller for that multi-port group. All calls to a given group necessarily require a control communication with the group controller which maintains the dynamic busy/idle data for the group and performs the hunting function to assign idle group members to calls.

Abstract: A distributed control switching system having a plurality of switching modules interconnected by a time-multiplexed switch, where all call processing including the hunting of time-multiplexed switch paths between modules, is cooperatively performed by the switching modules without involving a system central control. To set up a given inter-module call, the terminating switching module sends a path hunt request message to the originating switching module defining the available time slots on the links from the originating switching module to the time-multiplexed switch. The originating switching module then selects a candidate set of time slots that are available on the links to the time-multiplexed switch from both the originating and terminating switching modules. Both the originating switching module and the terminating switching module are then available to process other path hunt requests while they contemporaneously negotiate to finally select the time slot to be used for the given call.

Abstract: A distributed control switching system where the system control units cooperatively perform the terminating port determination function. In particular, the directory number translation function is done in a manner allowing flexibility in assigning directory numbers to switching system ports but minimizing the magnitude of the storage facilities required in each control unit. Each control unit stores the complete directory number translation for certain directory numbers but stores an index referencing other control units for the other directory numbers. Advantageously, the control units referenced are not necessarily the same ones that are associated with the ports defined by those other directory numbers. Thus the call setup sequence frequently involves three control units-the units associated with the originating and terminating ports, and an intermediate unit which stores the directory number translation information for the received directory number.

Abstract: A duplicated switching system including a number of communication units wherein each digital word transmitted by an originating communication unit is conveyed via both of the duplicate time-multiplexed switches in the system and a destination communication unit autonomously selects the digital words to be used for further communication based upon whether the word error check portions can be derived from the word information portions. Advantageously, the system continues to operate in the presence of system faults not simultaneously affecting digital words from both time-multiplexed switches without any erroneous words being used for further communication and without involving a system central control.

Abstract: A number of communication units are connected to a time-multiplexed switch via communication links. Control messages are conveyed among the communication units and a central control whereby paths are established through the time-multiplexed switch from originating communication units to terminating communication units. One of the control messages conveyed to a terminating communication unit during call setup includes a link identifier defining the communication link between the originating communication unit and the time-multiplexed switch. In accordance with the present invention, when the originating communication unit begins transmitting data words, one bit position of each data word is used to transmit consecutive bits of the link identifier so that the link identifier is transmitted repetitively every fixed number of frames.

Abstract: A data processing system having a processor, main memory, and a cache memory system which implements the least recently used replacement algorithm in replacing cache memory words with main memory words. The cache memory system is comprised of a cache control circuit and a plurality of cache memories. Each cache memory stores cache memory words having a similar time usage history. The first cache memmory stores cache memory words which are more recently used than the cache memory words in the second cache memory, and the second cache memory stores cache memory words which are more recently used than the cache memory words in the third cache memory. When a main memory word must be transferred to the cache memory, the main memory word is stored in the first memory; and the first cache memory's least recently used cache memory word is stored in the second cache memory. The least recently used cache memory word from the second cache memory is stored in the third cache memory.

Abstract: A data processing system includes a memory arrangement comprising a main memory, and a cache memory including a validity bit per storage location to indicate the validity of data stored therein. Cache performance is improved by a special read operation to eliminate storage of data otherwise purged by a replacement scheme. A special read removes cache data after it is read and does not write data read from the main memory into the cache. Additional operations include: normal read, where data is read from the cache memory if available, or, from main memory and written into cache; normal write, where data is written into main memory and the cache is interrogated, in the event of a hit, the data is either updated or effectively removed from the cache by invalidating its associated validity bit; and special write, where data is written both into main memory and the cache.