Abstract: A base station system (203, 303) in a wireless communication system (208, 308) establishes a link between a mobile station (200, 300) and a speech recognition system (209, 312). When the base station system (203, 303) determines that such a connection is required, the base station system (203, 303) instructs the mobile station (200, 300) to switch from a first codec (201) specific to human speech to a second codec (202) specific to speech recognition. Only after the switch between codecs in the mobile station (200, 300) does the base station system (203, 303) establish the link between the mobile station (200, 300) and the speech recognition system (209, 312).

Abstract: A communication system mitigates signal distortion of output signals transmitted by a transmitter element (406). The communication system obtains parameters related to, inter alia, the number of traffic channels utilized by the system, the number of RF channels utilized by the system, the voltage levels of certain signal waveforms (321) within the system and information related to power levels being transmitted by the transmitter element (406). The communication system utilizes the obtained parameters to, in a first embodiment, clip the signal waveform at certain portions that exceed a determined threshold, and, in a second embodiment, automatic gain control the signal waveform during a symbol time period. By clipping or automatically gain controlling the input signal into the transmitting element (406), the distortion of a signal output from the transmitting element (406) is mitigated.

Abstract: A method for wireless communication system planning includes, in a first embodiment, determining an image tree (500), based on a transmitter location (401) and the reflective (415) and diffractive (425) surfaces within a coverage region, and limiting the image tree to exclude branching for higher order images requiring more than a predetermined number of reflections and/or diffractions, or potential child images corresponding to surfaces not within the scope of the parent image (530, 560). Based on the image tree and propagation path back-tracing (620) a received signal quality measure (e.g., power) is determined for each receive location. By comparing the different received signal powers an optimal receiver unit location is determined. Further, by building further image trees for further transmitter locations, an overall coverage quality can be determined for each transmitter and compared to yield an optimal transmitter location.

Abstract: A transmitter (300) is utilized to provide wireless communication in a sectorized coverage area. The transmitter (300) incorporates a hybrid matrix (303) and an inverse hybrid matrix (306) to combine input control signals (315) and traffic signals (316). The hybrid matrix (303) transforms the control signals (315) and traffic signals (316) into output signals which each contain a portion of the control signals (315) and traffic signals (316). The outputs from the hybrid matrix (303) are amplified by amplifiers (319), and the outputs from the amplifiers (319) are then inverse transformed by the inverse hybrid matrix (306). The inverse transform matrix (306) recombines the portions of the control signals (315) and traffic signals (316) originally input to the hybrid matrix (303), and the resulting signals are transmitted to mobile stations (203-205 and 208) in sectorized coverage areas (S1.sub.A and S1.sub.B) using sector antennas (320).

Abstract: A method and apparatus is provided to facilitate coherent communication in a random access channel. In encoding, reference symbols are inserted into a stream of access channel message data symbols and appended to a synchronization message to form a reference coded access channel transmission. Subsequently, the access channel transmission is prepared for transmission over a communication channel by being spread with a spreading code. In decoding, a known synchronization sequence is correlated with a received communication signal to generate a correlation peak when a synchronization message is present. The received communication signal is despread with a spreading code to derive a stream of reference samples and data samples. A channel response is determined from the correlation peak and revised based on estimates derived from the stream of reference samples. Finally, an estimated data symbol is detected from the stream of data samples by utilizing the revised channel response.

Abstract: A wireless communication system (200, 300, 400, 500) mitigates the effects of excess timing delay caused by varying lengths of communication paths. In one general implementation, a transition communication path (206, 323, 329) is used to transfer a time-advanced version of a timing reference signal so that the cumulative time delay at a transition cell (209, 325, 331) is reduced. In another general implementation, the timing reference signal is time-advanced in all communication paths (403-411), and selected communication paths (403-407) include a time delay means (423-427, 503-507) such that the cumulative time delay at an area (421) near a target coverage area (130) is reduced. By reducing the cumulative time delay at the area (421) near the target coverage area (130), a handoff of a communication of a mobile station (128) into the target coverage area (130) can be performed.

Abstract: A beacon signal (313) is provided in a wireless communication system using a hybrid matrix (303) and an inverse hybrid matrix (306). Using an unused port of the hybrid matrix (303), the beacon signal (313) is combined with traffic signals (316) intended for users of the wireless communication system. The hybrid matrix (303) transforms beacon signal (313) and the traffic signals (316) into output signals that each contain a portion of the beacon signal (313) and the traffic signals (316). The outputs from the hybrid matrix (303) are amplified by amplifiers (315). The outputs from the amplifiers (315) are then inverse transformed by an inverse hybrid matrix (306). The inverse transform matrix (306) recombines the portions of the beacon signal (313) and the traffic signals (316) originally input to the hybrid matrix (303), and the resulting signals are transmitted using sector antennas (320) and a beacon antenna (323).

Abstract: A frequency translation device in a first embodiment includes a plurality of multiplying digital-to-analog converters (MDACs) that multiply an input signal by phase shifted digital sinewave approximation signals to perform frequency translation. In the preferred embodiment the input includes inphase and quadrature phase components, one of which is multiplied by a digital sinewave approximation and the other is multiplied by a digital cosinewave approximation. The use of the multiple MDACs with differing sinewave approximation signals provides a signal that multiplies the input signal such that the effects of odd harmonics at an output are mitigated while the advantages of a traditional switching mixer are retained.

Abstract: To mitigate the adverse affects of the load imbalance phenomenon prevalent in spread spectrum, multi-carrier wireless communication systems, the system beneficially employs the use of handoff as a means for balancing the call traffic (commonly referred to as "load") among a plurality of carriers within the communication system. The multi-carrier wireless communication system monitors a plurality of metrics corresponding to the loading of each of the plurality of carriers in the communication system and, based upon the metrics, will handoff call traffic to and between the plurality of carriers, thereby mitigating the adverse effects associated with the load imbalance, in accordance with the invention.

Abstract: A communication system receiver sorts through potential Walsh indexes and determines survivors for use in subsequent processing. The sort process is implemented in parallel with the subsequent processing so that large amounts of memory to implement a store/sort are eliminated. The communication system receiver implements the sorting operation in a small number of cycles, thereby conserving cycles which could be beneficially utilized for other tasks as required. The sorting operation also lends itself well to a practical implementation from a communication system receiver design perspective.

Abstract: A receiver (156) includes both a coherent and noncoherent demodulator. When the confidence that estimates of the channel is high, the coherent demodulator is implemented. When the confidence that estimates of the channel is low, the noncoherent demodulator is implemented. A controlling microprocessor (162) controls the selection process and also provides a signal (158) to enable the noncoherent demodulator in instances when noncoherent demodulation would most likely be better than coherent demodulation. As an example, such an instance would be immediately after handoff of a mobile station (505) from a source base-station (503) to a target base-station (502).

Abstract: A method and apparatus for determining the location of a communication unit in a CDMA system includes in a first embodiment, sending a location request via a spread spectrum signal to the subscriber (140), and receiving in return a subscriber signal including a response message showing a receive time of a particular symbol of the base's spreading sequence and a transmit time of a particular symbol of the subscriber's spreading sequence. The base (130), along with other receiving base(s) (140), also receives a predetermined symbol of the subscriber spreading sequence, and each determines a respective receive time of the predetermined symbol. The received information is then processed, along with known base location and delay information, to determine the subscriber location. If insufficient number of bases are capable of communicating with the subscriber, for example due to high loading/interference, auxiliary bases (121) are also provided for receiving from or transmitting to the subscriber.

Abstract: A code division multiple access (CDMA) communication system reduces system self-interference and enhances system capacity by making rate selection decisions for individual speech encoders in concert with other speech encoders. The system utilizes perpetually weighted error metrics (401) as input into a rate controller (404) which determines and provides selected rates (402) back to the encoders (105). The system provides optimum voice quality and system capacity in that it allows specific encoders to decrease their rate, which improves capacity, as necessary while allowing other encoders to maintain their rates. This prevents needless degradation in voice quality at those times when system capacity needs to be temporarily increased.

Abstract: Generally stated, a receiver in a communication system implements coherent channel estimation by first receiving an encoded signal and then generating a complex channel estimate from the encoded signal. The receiver then combines the complex channel estimate with the encoded signal to produce a coherent demodulated signal. After combining, the receiver decodes a version of the coherent demodulated signal to produce an estimate of the encoded signal prior to encoding.

Abstract: Reverse channel power control in a CDMA system is accomplished by measuring a power-control group transmitted from a remote unit (403) and determining a transmission time of a next power-control bit. The measurement of the power-control group is discontinued (405) based on the transmission time of the power-control bit and a round trip delay between the base station and the remote unit in order to transmit the power-control bit (419) to the remote unit in the next time slot.

Abstract: A sectorized cellular radio base station antenna is provided comprising: a plurality (e.g. six) of angularly separated directional transmit antennas (11), each transmit antenna having a central access of transmission, for serving mobile units located in sectors centered on the axis of transmission of the transmit antennas; a plurality (e.g. six) of angularly separated directional receive antennas (30), each having a central axis of reception; and diversity combining means for combining signals from adjacent receive antennas. The central axis of the receiving antennas are at an angular offset to the central axis of the transmit antennas and, for a mobile in a given sector served by a given transmit antenna, the diversity combining means are arranged to combine the signals from the two receive antennas the axes of which lie on either side of that transmit antenna axis.

Abstract: There is provided a method of rapid Received Signal Strength Indication (RSSI) of a time-dispersed signal having echoes (where the time dispersal represents a significant fraction or more of the transmitted symbol interval). It comprises a sliding correlation of a received signal against a known sequence or via channel sounding to obtain the time-dispersal function of the communications channel upon which the signal is transmitted and a summation of the squares of the quadrature components of the energies at relative maxima of the correlations (correlation peaks determined with reference to a threshold level) to integrate the energy defined by the correlation function to determine the energy present among the time-dispersed echoes utilizing the time-dispersal function.

Abstract: A method and apparatus for determining the location of a communication unit in a CDMA system includes in a first embodiment, sending a location request via a spread spectrum signal to the subscriber (140), and receiving in return a subscriber signal including a response message showing a receive time of a particular symbol of the base's spreading sequence and a transmit time of a particular symbol of the subscriber's spreading sequence. The base (130), along with other receiving base(s) (140), also receives a predetermined symbol of the subscriber spreading sequence, and each determines a respective receive time of the predetermined symbol. The received information is then processed, along with known base location and delay information, to determine the subscriber location. If insufficient number of bases are capable of communicating with the subscriber, for example due to high loading/interference, auxiliary bases (121) are also provided for receiving from or transmitting to the subscriber.

Abstract: A code division multiple access (CDMA) communication system reduces interference by reducing the encoding rate for selected mobiles. The system primarily uses link related characteristics such as, inter alia, distance measurements, physical resource power and mobile determined noise, to determine which mobiles require a encoding rate reduction. Once determined, the encoding rate of the determined mobiles is reduced, which in turn reduces self-interference and enhances system capacity.

Abstract: A new data circuit equipment (DCE) coupled to an IWF and a terminal adapter (TA) coupled to a mobile station provide interconnection within a RF communication system such that Class 2 service common to wireline network equipment can be beneficially employed in the wireless RF communication system. The new DCE and TA are transparent to external wireline systems while maintaining compatibility with, inter alia, the predetermined data service protocol layers of the RF communication system, the RF air-interface and/or radio link protocol (RLP) of the RF communication system.