Abstract: A power management system for a mobile unit wherein the frequency of scanning a neighboring cell may be controlled. A mobile unit consumes power in standby mode by periodically scanning the base station in each neighboring cell to determine which base stations are providing a usable signal. When the signal provided by the mobile unit's servicing base station diminishes, the mobile unit informs the cellular network of the base stations providing usable signals to assist in the handover. By detecting the rate of change of the signal strength received from a base station, the mobile unit may change the scanning rate of each neighboring cell. Alternatively, the mobile unit can estimate the relative speed it is traveling through a cell. If traveling slowly through the cell or if the signal strength is not changing over time, the need for a rapid handover diminishes. The mobile unit may also increase the scanning rate if traveling rapidly through the cell.

Abstract: An improved encoding technique improves the error detection provided in conventional communication systems. Traditional encoding systems for communication systems often utilize channel-coding in the form of block-coding and convolutional encoding. Block-coding typically utilizes parity bits for error detection. These parity bits are typically placed as a block at the end of the data frame. The present invention provides an improved encoder and decoder which utilize parity bits placed within the data and spread within the data bits for higher reliability.

Abstract: A power management system for a mobile unit wherein the frequency of detecting a paging message may be controlled. The quality of the signal transmitted by a base station and the acceptable delay are determined by the mobile unit. The mobile unit compares these factors to the current paging message monitoring rate. If a further delay is acceptable, the present invention inhibits monitoring of at least one cycle of the paging message. Each cycle of the paging message inhibited conserves battery power in the mobile unit. The mobile unit also includes a technique for the user to disable the power savings feature.

Abstract: A digital subscriber line (DSL) communication system that utilizes the high frequency band of a standard telephone line does not require the use of a plain old telephone service (POTS) splitter in the resident's home, which provided isolation between the POTS frequency band (0 to 4 kHz) and the DSL frequency band. Digital signal processing techniques are utilized to adapt to varying subscriber line conditions due to POTS telephone equipment. The digital signal processing techniques eliminate the need for a splitter by reducing susceptibility to distortion due to varying subscriber line characteristics. The digital subscriber line modem utilizes constant envelope modulated signals and frequency division multiplexing, where the constant envelope modulations lessens the intermodulation distortion products due to DSL signals that are transmitted by the modem and which may result in audible noise at the POTS telephone equipment due to non-linearities of the POTS telephone equipment.

Abstract: An improved encoding technique improves the error detection provided in conventional communication systems. Traditional encoding systems for communication systems often utilize channel-coding in the form of block-coding and convolutional encoding. Block-coding typically utilizes parity bits for error detection. These parity bits are typically placed as a block at the end of the data frame. The present invention provides an improved encoder and decoder which utilize parity bits placed within the data and spread within the data bits for higher reliability.

Abstract: The invention comprises a method and apparatus for decoding an incoming symbol stream comprised of a plurality of known missing symbols. Within the incoming symbol stream, those symbols corresponding the known missing symbols are replaced with a first set of values to create a modified symbol stream. The modified symbol stream is convolutionally decoded to produce a first decoded information bit stream. An error detection mechanism is performed on the first decoded information bit stream to determine a “pass” or “fail” indication. If the error detection mechanism produces a “fail” indication, a second set of values replaces the known missing symbols to produce a second modified symbol stream. The second modified symbol stream is convolutionally decoded to produce a second decoded information bit stream. The error detection mechanism is performed on the second decoded information bit stream.

Abstract: A digital subscriber line (DSL) communication system that utilizes the high frequency band of a standard telephone line does not require the use of a plain old telephone service (POTS) splitter in the resident's home, which provided isolation between the POTS frequency band (0 to 4 kHz) and the DSL frequency band. A digital subscriber line modem utilizes either constant envelope modulation or quadrature amplitude modulation for outputting DSL signals upstream to a central office. When a telephone in the resident's home is detected as being off-hook, then the constant envelope modulation is used by the DSL modem in order to lessen the intermodulation product distortion that results in audible noise heard by a user of the telephone. When the telephone is on-hook, then another type of modulation, such as QAM, is used to maximize the upstream data rate capability in the DSL frequency band, since any noise generated by the QAM is not a problem due to the non-use of the POTS frequency band.

Abstract: A telecommunications system and method for improving the detection of speech and control signals within a telecommunications transmission, particularly, reducing the probability that the control signals and other non-speech transmission segments are interpreted as speech and played. Also, the system and method of the present invention is directed to techniques for reducing the probability that random noise during discontinuous transmission periods are interpreted as speech and played.

Abstract: A power management system for a mobile station reduces standby mode processing by receiving and processing single time slots of a short paging channel. Each single time slot of a short paging channel includes a mobile station identifier which alerts a receiving mobile station that a pending telephone call or paging message may be directed to the mobile station. Once so alerted, the mobile station receives and processes full paging channels comprising four time slots to determine whether the mobile station is the intended recipient of the telephone call or paging message. If the mobile station determines that it is not the intended recipient, then the mobile station resumes receiving and processing single time slots of the short page channel. Processing fewer time slots of data for purposes of call detection conserves mobile station battery power.

Abstract: Desired audio information intermittently present in a first audio signal is communicated over a communications medium by generating a first communications signal in the communications medium when the desired audio information is present in the first audio signal, the first communications signal representing the first audio signal encoded as blocks of communications data according to a predetermined code. A second communications signal is received from the communications medium. The received second communications signal is processed to produce processed blocks of communications data. A metric representing the validity of a plurality of the processed blocks of communications data is then determined, and a second audio signal is generated from the plurality of processed blocks of communications data when the metric is within a predetermined range.

Abstract: An improved coding and decoding process is disclosed to determine the ending state of a convolutional decoding using Viterbi algorithm without the use of tail bits. The most important information bits are first coded with a block code. The block code word and the rest of the information bits are then split into several bursts. Each burst is coded with a convolutional code. The most important information bit part of the block code word is then placed in the beginning of the code burst for the convolutional encoder. The parity bit part can be placed between the end of the most important information bit part and the end of the code burst. In the convolutional decoding process for each burst, the ending state is determined by detected valid block code word after combining the convolutional decoding processes for all the bursts. The performances of average BER and missed detection rate can be optimized by moving the placement of the parity bit in each message code burst.

Abstract: A portable radio having a transmitter power controller connected to the portable radio's receiver and transmitter for controlling the power transmission level of the portable radio, resulting in reduced power consumption by the portable radio and extended battery life. The transmitter power controller estimates the signal strength and quality of the down-link signal by determining a threshold adjustment parameter for the received signal. Thus, this invention eliminates false power adjustment caused by the interfering signals when RSSI (Received Signal Strength Level) is used as a means to estimate transmitter power level. The threshold adjustment parameter is an adjustment parameter used in adjusting the received signal to produce a degraded signal having a predetermined signal quality, and is determined by incrementally adjusting the received signal until the degraded signal is determined to have the predetermined signal quality.

Abstract: A diversity receiver employing maximum-likelihood-sequence estimation employs a separate channel estimator (44-1, . . . , 44-L) for each of a plurality of diversity channels. Each channel estimator (44-1, . . . , 44-L) produces channel-model parameters ([f.sub.1 ], . . . , [f.sub.L ]) that characterize their respective channels. A weighting-and-accumulation circuit (56) computes the responses of the thus-represented models to candidate symbol sequences, and metrics indicating the likelihoods that respective candidate sequences were the sequences actually sent are determined by comparing the model output with the received signal in a comparison circuit (58) and squaring the magnitudes of the results in a squaring circuit (60). The receiver then employs a Viterbi algorithm (62) to determine which sequence is the one most likely to have been sent.

Abstract: An improved decision feedback equalizer for use with digital communications. The equalizer includes an error detector, a process controller, a parameter selector and a data buffer for temporarily storing a digital data signal received from a communication channel. The error detector determines whether the equalizer is accurately tracking changes in the communication channel's characteristics or is lost. When the error detector determines that the equalizer is lost, the process controller responsively generates control signals for initiating an optimal retraining/recovery method for the prevailing conditions. In some retraining/recovery methods, data is temporarily stored in the buffer. The stored data is later retrieved and processed once the equalizer is retrained. Retraining is performed using a retraining signal received via the communication channel or, if available, a portion of the data signal which is suitable for retraining, thereby permitting more rapid resumption of data reception.

Abstract: The channel-impulse-response estimator (44') in a maximum-likelihood-sequence-estimation receiver produces channel-model parameters for a model that produces outputs not only for symbol times but also for intermediate times between the symbol times. A symbol-sequence-derivation circuit (42') determines the most-likely sequence on the basis of metrics computed from the differences between the received signal and the responses of the model to candidate sequences not only at the symbol times but also at the intermediate times. An interpolator (100) receives the symbol decisions from the symbol-sequence-derivation circuit (42') and generates intermediate values from them by simulating the Nyquist filter formed by the concatenation of pulse-shaping filters (22 and 24) in the transmitter and matched filters (36 and 37) in the receiver. The channel-impulse-response estimator (44') uses these values together with the derived-symbol values as inputs to its updating process to maintain the model.