Motorola Corporation

Other

Reuven Meidan

Michael D Kotzin

Mordechai Ritz

Giora Silbershatz

Noam Livneh

Meir Ariel

Duane C Rabe

Ofer Amrani

James H Stilwell

Hanan Achsaf

Nathan Ariav

James Howard Stilwell

A method for optimizing a service supplied to a mobile subscriber unit in a mobile telephone system offering a multitude of voice and data services from system base stations to mobile subscriber units. According to the invention, an improved service center receives a request for service to be provided to a mobile subscriber unit. A processor within the service center determines whether prevailing conditions allow for efficient execution of the requested service and if so carries it out, and otherwise prompts the mobile subscriber unit to take remedial action whereby the requested service can be carried out more efficiently.

Method for improving reception of messages in a communication network

A syndrome assisted iterative decoder ( ) uses iterative processing to decode an input sequence. A syndrome-assisted decoder ( ), which may operate independently of a soft-output decoder, provides a stopping algorithm for the soft output decoder ( ). When the syndromes s and s generated for sequence v and v , respectively, both equal 0, the soft output decoder is finished decoding the sequence of data. Additionally, the syndrome-assisted decoder can generate a modified error trellis used by the soft output decoder whereby the soft-output decoder operates on a simplified trellis providing improved decoder performance.

Syndrome assisted iterative decoder for turbo codes

Soft output decoding of signals represented by a trellis of block length N divided into windows includes a step of decoding a forward recursion to a location that is I sections from the beginning of the window. An optimum state is detected at the end of the forward recursion. A backward recursion is performed from the determined state at the end of the window back to the beginning of the window to define a set of known backward recursion state metrics. Soft outputs are calculated during the backward recursion using the stored forward recursion state metrics, the backward recursion state metrics, and branch metrics at each state.

Soft output decoder for convolutional codes

Subscriber power levels are adjusted to enhance interference cancellation in a DS-CDMA communication system. A base-station of the communication system receives signals from a plurality of subscribers and evaluates each signal. Based on the evaluation, particular subscribers are commanded to control their power levels such that different predetermined targets for the particular subscribers are maintained. The predetermined targets include, but are not limited to, received power, frame erasure rate, bit error rate and signal quality. The resulting power levels received at the base-station are substantially different, which is beneficially employed to enhance interference cancellation in the DS-CDMA communication system.

Method and apparatus for subscriber power level adjustment in a

A soft-decision decoder computes a maximum likelihood estimated transmitted code from a demodulated received signal with less complexity compared to a conventional Viterbi soft-decision decoder. A symbol-by-symbol detector determines a hard-decision vector from a demodulated received signal vector. A syndrome calculator multiplies the hard-decision vector by a scalar parity check matrix to calculate a syndrome vector. A syndrome modifier examines the syndrome vector for predetermined syndrome patterns corresponding to isolated errors in the hard-decision vector. Syndrome patterns are removed from the syndrome vector to create a modified syndrome vector, and the corresponding error in the hard-decision vector is recorded in an estimated error vector. A syndrome-based decoder uses the modified syndrome vector to create a simplified error trellis to produce a remaining error vector. Subtracting the estimated error vector and the remaining error vector from the hard-decision vector creates a maximum likelihood estimated transmitted code vector.

Soft-decision syndrome-based decoder for convolutional codes

A syndrome-based channel quality or message structure determiner (160) uses syndrome vectors to estimate the quality of a received signal in a variable message structure communication system. A digital signal from analog-to-digital converter (150) is separated into multiple branching paths, one for each potential message structure type. In a single path, a digital demodulator (221) demodulates the digital signal to produce a demodulated received signal. A deinterleaver (222) deinterleaves the demodulated received signal, and a symbol-by-symbol detector (2231) hard-decision detects the deinterleaved signal. For each hard-decision vector, at least one syndrome calculator (2241) calculates a syndrome vector. The syndrome vector is analyzed by a syndrome error estimator (2251) having an associated syndrome pattern memory (2271). A comparator (260) analyzes error counter totals from each syndrome error estimator.

Syndrome-based channel quality or message structure determiner

A method and apparatus is provided for reducing interference in a radio communication link from a central site (230) to a mobile unit (228) in a cellular communication system. The central site (230) includes a first (202) and a second (216) antenna which serve the geographic region (214) in which the mobile unit (228) is located. The radio communication link may be provided by communicating a signal in a first radio communication channel between the first central site antenna (202) and the mobile unit (228). Similarly, the radio communication link may be provided by communicating a signal in a second radio communication channel between the second central site antenna (216) and the mobile unit (228). A measure of interference in the first radio communication channel providing the radio communication link is determined. The radio communication link is switched, in response to the measure of interference being above a predetermined threshold, from the first to the second radio communication channel.

Method and apparatus for reducing interference in a radio communication

A technique for decoding and removing a single subscriber's signal from a composite signal in a DS-CDMA system is provided. A particular subscriber's signal is removed from the composite signal by despreading the composite signal (120) to form a multiplicity of despread QPSK signals representative of multiple subscribers. Next, multipath characteristics are determined (303) for each of the multiple subscribers. Utilizing multipath characteristics (204), the multiple subscribers' signals are determined by combining multipath components of each signal (305). Next, data related to a particular subscriber is determined (307) and the subscriber's signal is 'reconstructed' to contain multipath characteristics (204) as originally received (309). Finally, the reconstructed signal is output to a summing node (128) where it is combined with the delayed composite signal (120).

Method and apparatus for canceling interference in a spread-spectrum

A mobile radiotelephone, and associated method, which facilitates usage thereof by a user while also operating an automotive vehicle. The radiotelephone includes a handset having actuation keys of unique geometries permitting the user to identify the keys by tactile rather than visual inspection. A visual-signal display assembly comprised of a heads-up display, including a screen element positionable at a front windshield assembly portion of an automotive vehicle, forms an output display of the radiotelephone, also to facilitate usage of the radiotelephone by a user while also operating the automotive vehicle.

Radio transceiver with interface apparatus which visually displays

A communication unit for use in a communication system is provided which includes a hopping mechanism which hops communication frames over a plurality of carrier frequencies according to a predetermined hopping pattern. At least one of the communication frames preferably includes a synchronization channel time slot having data bits from which the predetermined hopping pattern may be derived. In addition, a communication unit is provided which includes a signal acquisition mechanism for initially acquiring a predetermined hopping pattern that specifies the sequence over which hop frames are hopped over a plurality of carrier frequencies. Also, this communication unit includes a hopping mechanism for hopping receiving frequency according to the predetermined hopping pattern such that a control channel may be detected. In an alternative embodiment, either communication unit may derive the predetermined hopping pattern from detected global position satellite information.

Method and apparatus for operating with a hopping control channel in a

A method and apparatus is provided for dynamic distribution of a communication channel load in a sectorized cellular radio communication system. The channel load is distributed by narrowing a first sector antenna beamwidth of an overloaded sector of a cell site and widening a second sector antenna beamwidth of an adjacent sector of the cell site and subsequently handing off subscriber units previously in the first sector antenna beamwidth. Alternatively, channel load is distributed by reducing power of a sector or omni-directional antenna which is adjacent to an overloaded antenna, if the channel from an overloaded antenna to an antenna of a subscriber unit is overloaded due to interference. Subsequent to the occurrence of the channel interference condition, subscriber units are handed off to the particular antenna which is best able to service the subscriber units.

Method and apparatus for dynamic distribution of a communication channel

A spread-spectrum noise canceller (390) is provided for cancelling user code noise from a spread-spectrum communication channel. The spread-spectrum noise canceller (390) includes a receiver for receiving a spread-spectrum signal (302) including a first and at least a second signal as well as a noise canceller (390) operatively coupled to the receiver for reducing spread-spectrum noise in the first received signal by substantially processing the at least second received signal out of the received spread-spectrum signal (302). In addition, a method is provided which cancels user code noise from a spread-spectrum communication channel. The method includes receiving a spread-spectrum signal (302) including a first and at least a second signal and subsequently reducing spread-spectrum noise in the first received signal by substantially processing the at least second received signal out of the received spread-spectrum signal (302).

Method and apparatus for cancelling spread-spectrum noise

A method and apparatus is provided for improving detection of data bits in data samples (120) of a hop of a slow frequency hopping spread spectrum signal (112). In the detecting process, the carrier to interference (C/l) power ratio of the hop is estimated (124) by using the data samples (120) of the hop. Subsequently, a data bit (130) is detected by using the estimated C/l power ratio (126). The detection process (128) may include utilizing maximum likelihood decoding techniques to derive a data bit (130) from decision metrics and the estimated C/l power ratio (126). The decision metrics correspond to a measurement of the distance of data samples (120) from constellation points within a constellation space representing data samples (120) previously used to generate decision metrics. The detection process (128) also may include utilizing the estimated C/l power ratio (126) in combining data samples (120) of the hop as received from two or more diversity receiver branches.

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Ramat Hasharon, Israel

Reuven Meidan