Motorola Corporation

Richard J Vilmur

Eugene J Bruckert

Ira A Gerson

David E Borth

Brett L Lindsley

Randall Wayne Rich

Robert Faust D'Avello

Larry C Puhl

Michael L Needham

Michael P Metroka

Leigh M Chinitz

Kenneth R Haddad

Philip J Smanski

Joseph J Barlo

To address the need for a base site and method for quickly establishing a CDMA dispatch call, the present invention provides for signaling mobile stations (e.g., ) to inform them of the call and then starting the dispatch call without waiting for the call participants to request their inbound links. The dispatch call is first transmitted by base sites (e.g., ) of all the service coverage areas (e.g., ) that may have call participants, and then discontinued at those base sites where no inbound link requests are received within a period of time. Thus, the dispatch call is established while &ldquo;call setup&rdquo; effectively continues.

Base site and method for quickly establishing a CDMA dispatch call

In a wireless CDMA system, responsive to receiving a request for a group call for a given talk group, a controller ( ) allocates an outbound group call channel to the group ( ), and uniquely assigned inbound and outbound channels to each subscriber unit in the group ( ). Each subscriber unit in the group receives an identification of its uniquely assigned inbound and outbound channels ( ). Via its uniquely assigned outbound channel, a given subscriber unit receives inbound control information ( ) from the controller. By providing each subscriber unit in the group with a uniquely assigned outbound channel, in addition to the outbound group call channel, control information is readily provided to multiple subscriber units, thereby facilitating the establishment of group calls in CDMA systems.

Method and apparatus for group calls in a wireless CDMA communication system using outbound traffic channels for individual group members

A radio subscriber unit (102) has a diversity receiver apparatus (106) including a first antenna (114) and a second antenna (116). A first representation (158) and a second representation (160) of a composite radio frequency (RF) signal are received from the first antenna (114) and the second antenna (116), respectively. The composite radio frequency (RF) signal includes a desired RF signal (156) and interfering signals (166). The desired RF signal (156) includes at least one coded pilot signal (Ec). A ratio (Ec/Io) (142) of the at least one coded pilot signal (Ec) to an estimate of the composite RF signal (Io) is determined responsive to receiving at least one of the first representation of the composite RF signal (158) and the second representation of the composite RF signal (160). A selected state of the first antenna(114) and the second antenna (116) is controlled responsive to at least one of the ratio (Ec/Io) (142) and an integrated received signal strength indication (.intg.RSSI) of the composite RF signal.

Method for controlling a diversity receiver apparatus in a radio

A radio subscriber unit (102) comprises a controller (108) and a switched antenna diversity receiver apparatus (106) including a first antenna (114), a second antenna (116) and a receiver (126). The first antenna (114) is adapted to receive a first representation (158) of a radio frequency (RF) signal (156). The second antenna (116) is adapted to receive a second representation (160) of the RF signal (156). The receiver (126), selectively coupled to the first antenna (114) and the second antenna (116), generates a received signal (153) responsive to receiving at least one of the first representation (158) of the RF signal (156) from the first antenna (114) and the second representation (160) of the RF signal (156) from the second antenna (116). The controller (108), coupled to the receiver (126), selectively couples to the receiver (126), responsive to the received signal (153), one of: only the first antenna (114), only the second antenna (116) and both the first antenna (114) and the second antenna (116).

Radio subscriber unit having a switched antenna diversity apparatus and

A wireless communication device (100) can be handed off while operating in the slotted mode of a CDMA system. The wireless communication device (100) stores, prior to entering slotted mode, an Active Set including at least one active pilot and a Neighbor Set including a plurality of neighbor pilots. At least one receiver searcher (109) scans the at least one active pilot and at least one of the plurality of neighbor pilots prior to an assigned slot. A logic and control circuit (113) includes in the Active Set, prior to the assigned slot, at least two pilots of the at least one active pilot and the at least one of the plurality of neighbor pilots scanned prior the assigned slot. At least two of a plurality of receiver fingers (107) simultaneously monitor the Paging Channels of the at least two pilots during the assigned slot.

Method of handing off and a wireless communication device

Performance of a radiotelephone (104) in a CDMA communication system (100) is enhanced using a receiver searcher (114) that includes a matched filter (128) to capture the pilot energies of all receivable transmissions from a base station (102) and other nearby base stations. A detected PN sequence is compared with a predetermined PN sequence stored at the radiotelephone (104). The predetermined PN sequence includes, for example, the last 512 chips in the short PN sequence used for spreading the in-phase channel and the quadrature-phase channel.

Method and apparatus for fast pilot channel acquisition using a matched

A wireless communication device (100) can be handed off while operating in the slotted mode of a CDMA system. The wireless communication device comprises a receiver searcher (109) that measures the signal strength of an active pilot prior to the assigned slot and at least one of a plurality of neighbor pilots during an assigned slot. Receiver fingers (107) demodulate a Paging Channel of the active pilot during an assigned slot and can also determine signal strength of pilots simultaneously with the receiver searcher. A Hot Neighbor List is used to prioritize the order in which neighbor pilots are scanned. A logic and control circuit (113) determines if neighbor pilots should be scanned beyond the assigned slot, if the Hot Neighbor List should be modified, and if the wireless communication device should be handed off to another pilot.

A code division multiple access (CDMA) radio receiver (104) having gain receives a radio frequency (RF) signal (122) to produce a received signal (124). The quality (130) of the received signal (124) is determined (111). The quality (130) is preferably a ratio of an energy per chip of a desired signal (Ec) to a total power spectral density of the received signal (Io) (124). For alternative radio receivers (104) the quality (130) may be an error rate estimate of a demodulated signal (126). The gain of the radio receiver (104) is adjusted responsive to the quality (130) of the received signal (124) to optimize the quality (130) of the received signal (124). Further, since the adjusted gain also changes a received signal strength indication (RSSI) (242) of the received signal (124), the RSSI (242) of the received signal (124) is estimated (217) and compensated (218) responsive to the gain of the radio receiver (104) to produce a compensated RSSI (134) of the received signal (124) indicative of the RSSI of a desired RF signal (122).

Apparatus and method for optimizing the quality of a received signal in

A method, performed by a mobile station (119), prevents an active call from being dropped when the mobile station (119) suddenly transitions from a first coverage area (121) to a second coverage area (122) in a code division multiple access (CDMA) cellular radiotelephone system (100). The active call is determined (601) to be in danger of being dropped responsive to the mobile station (119) suddenly transitioning from the first coverage area (121) to the second coverage area (122). The first base station (115) is notified (602) that the active call is in danger of being dropped responsive to the step of determining (601). The active call with the first base station (115) is determined (603) to be in the process of being dropped responsive to the step of notifying (602). The active call is established (604) with the second base station (116) in the second coverage area (122) before the active call with the first base station (115) is dropped responsive to the step of determining (603).

Method for preventing a dropped call during a handoff in a

The power of a first signal is measured and is compared with a threshold. If the first signal power meets a handoff threshold, the system enters the handoff procedure. Once in the handoff procedure, estimates of a first signal quality a signal would have, if transmitted from the first site to the subscriber, and a second signal quality a signal would have, if transmitted from the second site to the subscriber, are determined. If the estimated first signal quality meets a transmit threshold, the first will activate a traffic signal to the subscriber. If the estimated first or second signal quality fails to meet the transmit threshold, the first or second, respectively, will terminate its traffic signal to the subscriber, but the transmission resources will remain dedicated to the subscriber. If the estimated first or second signal quality fails to meet the handoff threshold, the first or second, respectively, will discontinue serving the subscriber.

Method for performing a handoff in a communication system

A channel bank speech synthesizer for reconstructing speech from externally-generated acoustic feature information without using externally-generated voicing or pitch information is disclosed. An N-channel pitch-excited channel bank synthesizer (340) is provided having a first low-frequency group of channel gain values (1 to M) and a second high-frequency group of channel gain values (+1 to N). The first group controls a first group of amplitude modulators (950) excited by a periodic pitch pulse source (920), and the second group controls amplitude modulators excited by a noise source (930). Both groups of modulated excitation signals are applied to the bandpass filters (960) to reconstruct the speech channels, and then combined at the summation network (970) to form a reconstructed synthesized speech signal. Additionally, the pitch pulse source (920) varies the pitch pulse period such that the pitch pulse rate decreases over the length of the word.

Method and apparatus for synthesizing speech without voicing or pitch

The power control apparatus of the present invention is comprised of a local oscillator signal path coupled to a mixer (106) through a variable attenuator (107) and an IF signal path coupled to the mixer (106) through two variable attenuators (108 and 109) coupled in series. The IF signal path attenuators (108 and 109) are controlled by digital control circuitry (111) while the local oscillator path attenuator (107) is controlled by the control circuitry through a level shifter (110). The power level of the signal generated by the mixing of these two signals is less than the conducted output of the radiotelephone's power amplifier.

Power control of a direct sequence CDMA radio

An improved noise suppression system (800) is disclosed which performs speech quality enhancement upon the speech-plus-noise signal available at the input (205) to generate a clean speech signal at the output (265) by spectral gain modification. The improvements of the present invention include the addition of a signal-to-noise ratio (SNR) threshold mechanism (830) to reduce background noise flutter by offsetting the gain rise of the gain tables until a certain SNR threshold is reached, the use of a voice metric calculator (810) to produce more accurate background noise estimates via performing the update decision based on the overall voice-like characteristics in the channels and the time interval since the last update, and the use of a channel SNR modifier (820) to provide immunity to narrowband noise bursts through modification of the SNR estimates based on the voice metric calculation and the channel energies.

Noise suppression system

Hands-free control system for a radiotelephone

Improved speakerphones (120 and 130 in FIG. 1) for both radio (112) and landline (138) telephones are described. The improved speakerphones (120 and 130) each include a microphone (102 and 132), a speaker (104 and 134) and unique control circuitry (106 and 136). The control circuitry of the improved speakerphone (200 in FIG. 2) interfaces a microphone (250) to a transmit signal (220) and speaker (260) to a receive signal (222) of a duplex communication path, such as a radio channel or telephone line. Variable gain stages (212 and 202) amplify and attenuate the speaker and microphone audio paths, respectively, in response to a gain control signal (223) from control logic (230). Transmit and receive signal detectors (206 and 207), each include gain adjust circuitry (208) a logarithmic amplifier (240), an envelope detector (241), a smoothing filter (245), a valley detector (242), a summer (243) and a comparator (244) for detecting the presence of audio signals in environments that may be subject to high background noise. Binary output signals from the transmit and receive signal detectors (206 and 207) are applied to control logic (230) which generates the gain control signal (223) and detector control signal (224). The control logic (230) includes delay circuitry (316 and 318) and gain control circuitry (392) for generating the gain control signal (223), the magnitude of which varies the amount of gain stages (202 and 212). Delay circuitry (316 and 318) and logic circuitry (304, 306, 308, 310, 312 and 314) in control logic (230) set and reset a flip-flop (302) for generating the detector control signals (224 and 225). Detector control signals (224 and 225) are coupled to gain adjust circuitry (208) and smoothing filter (245) for adjusting gain and response time of transmit and receive signal detectors (206 and 207).

Growing community of inventors

Palatine, IL, United States of America

Richard J Vilmur