Abstract: A system and method for encoding and transmitting data with a spread-spectrum packet-switched system. Data to be transmitted by a packet transmitter are encoded for privacy and to restrict intelligent receipt of the data to the intended recipient. The encoded data is demultiplexed into sub-data-sequence signals which are spread-spectrum processed and then combined as a multichannel spread-spectrum signal. The multichannel spread-spectrum signal is concatenated with a header to output a packet-spread-spectrum signal which is transmitted over radio waves to a packet receiver. The packet receiver obtains timing for the multichannel spread-spectrum signal from the header. The multichannel spread-spectrum signal is then despread and multiplexed as received-encoded data. The received-encoded data is decoded by the intended recipient and stored in a receiver memory for output.

Abstract: A system and method for encoding and transmitting data with a spread-spectrum packet-switched system. Data to be transmitted by a packet transmitter are encoded for privacy and to restrict intelligent receipt of the data to the intended recipient. The encoded data is demultiplexed into sub-data-sequence signals which are spread-spectrum processed and then combined as a multichannel spread-spectrum signal. The multichannel spread-spectrum signal is concatenated with a header to output a packet-spread-spectrum signal which is transmitted over radio waves to a packet receiver. The packet receiver obtains timing for the multichannel spread-spectrum signal from the header. The multichannel spread-spectrum signal is then despread and multiplexed as received-encoded data. The received-encoded data is decoded by the intended recipient and stored in a receiver memory for output.

Abstract: In a burst-mode, high-speed spread-spectrum communications system, faster convergence of a receiver's automatic gain control (AGC) circuit reduces the time required to bring a received signal within the operating range of an operation amplifier and other radio-frequency and digital sections of the receiving system. A gain control circuit includes a coarse-gain feedback loop and a fine-gain feedback loop to improve convergence speed and at the same time maintain the stability of the AGC circuit. The coarse-gain feedback loop quickly brings the received signal, using a large gain signal, to the desired operating range. The fine-gain feedback loop uses a smaller gain signal to gradually smooth the received signal to avoid saturation on the A/D converters.

Abstract: A programmable matched filter bank comprises a sliding integrator and compensation calculation circuits. The integrator receives a chip stream of samples derived from a received spread-spectrum signal and integrates a number of the most recent samples, to form a common integration value. Each of the compensation calculation circuits receives the same most recent samples and receives a respective one of the possible reference spreading code sequences. In operation, each compensation calculation circuit derives a compensation value, and an associated circuit modifies the common integration value by the respective compensation value. The result is a value of correlation between the predetermined number of most recent samples, for each respective reference code sequence. The inventive approach reduces the number of bit adders and inverters in the implementation of a matched-filter, a programmable matched filter and a programmable matched filter bank for spread spectrum receivers.

Abstract: A spread-spectrum communication system utilizes spreading code sequences, which can be expressed as a matrix. The matrix of code sequences has or can be transformed to have a certain orthogonal relationship. In accord with the invention, a matched filter bank in a spread-spectrum receiver processes input signals that purport to contain the code matrix using two halves of an input stream matrix and only two of four possible quadrants of the code matrix as the reference inputs. Such processing produces two quadrants of a correlation signal matrix. It is then possible to determine the other two quadrants of the full correlation signal matrix from the known relationship with the two quadrants derived from the matching operations. The processing of only two of the quadrants of the signal matrix substantially reduces the number of computations and the amount of processor hardware needed to implement a matched filter bank to recognize the codes embedded in a received spread-spectrum signal.

Abstract: To increase capacity in a spread spectrum packet communication system, a closed loop power control (CLPC) is provided for a common/shared downlink transport channel, such as a Forward Access Channel (FACH) and Downlink Shared Channel (DSCH), by using an existing uplink Common Packet Channel (CPCH) mechanism. After an appropriate access phase and a collision detection phase, a mobile station sends its closed-loop power control information along with any packet data over the CPCH uplink channel. Concurrently, the base station (BS) begins its downlink transmission of data and control information to the mobile station (MS). The base station transmits the packet data through the common/shared downlink transport channel, and the power of that transmission is controlled in response to the control information sent by the MS. The power of the uplink transmission from the MS is controlled in response to the control information sent by the BS, for example via a dedicated downlink channel (DCH).

Abstract: A demodulator system for a receiver in a multiple user-code spread-spectrum system, such as in a CDMA base station, utilizes a Quasi-Newtonian optimization routine to identify received codes and recover user data based on detected correlations between the received spread-spectrum signal and a set of the possible codes available to users of the system. The preferred optimization routine is a Davis-Fletcher-Powell (DFP) routine.

Abstract: An improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, with the CDMA system having a base station (BS) and a plurality of remote stations. The base station has a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver. A remote station has an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver. The BS transmitter transmits a broadcast common-synchronization channel, which includes a frame-timing signal. The broadcast common-synchronization channel has a common chip-sequence signal, which is common to the plurality of remote stations. In response to the RS-spread-spectrum receiver receiving the broadcast common-synchronization channel, and determining frame timing from the frame-timing signal, an RS-spread-spectrum transmitter transmits an access-burst signal. The BS-spread-spectrum transmitter, responsive to the BS-spread-spectrum receiver receiving the access-burst signal, transmits an acknowledgment signal.

Abstract: Multi-path effects are common in mobile communications. When coupled with spread-spectrum signals utilizing spreading code sequences, detection of more than one multi-path signal becomes a necessity in order to output a clean signal with little loss. In accord with the invention, a spread-spectrum sliding matched-filter searcher system comprises a partial matched-filter that receives the input spread-spectrum signal. The searcher matches samples of the input signal with a tap length m of the reference code and produces a first correlation value. The first correlation value is compared to a first threshold. When it equals or exceeds the first threshold, the first correlation value is integrated to produce a second correlation value. This second value is compared with a second threshold, which if met signifies the detection of the multi-path signal. The process is repeated until all significant multi-path signals are detected.

Abstract: A hybrid DSMA-CR/CDMA methodology provides efficient access to one of a group of common packet channels in a cell of a spread spectrum wireless communication network. The base station broadcasts status information as to the availability and/or available data rates for each common packet channel (CPCH) or group of CPCH channels. Each mobile station uses the status information to select an available channel and/or a channel with sufficient data rate. The mobile station then starts transmission of a series of access preambles, each of which contains a signature corresponding to the selected channel. The mobile station transmits the preambles at increasing power levels. When the base station detects a preamble transmission, the base station responds with a corresponding acknowledgment. Upon receiving this acknowledgment, the mobile station preferably selects a collision detection (CD) signature and transmits a CD preamble containing that signature.

Abstract: A base station (BS) and a plurality of remote stations in a code-division-multiple access (CDMA) system employ spread-spectrum communication. The base station has a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver. A remote station has an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver. The BS transmitter transmits a broadcast common-synchronization channel, which includes a frame-timing signal. The broadcast common-synchronization channel uses a common chip-sequence signal. An RS-spread-spectrum receiver receives the broadcast common-synchronization channel, and the RS determines frame timing from the frame-timing signal. In response, the associated RS-spread-spectrum transmitter transmits an access burst signal, including RS-preamble signals, RS-power-control signals, and RS-pilot signals, respectively, transmitted in time, at increasing power levels.

Abstract: A multi-clock matched filter for receiving signals with multipath. The signals may be modulated with a spread-spectrum spreading sequence, or other analog or digital signal. A number of signal registers store digital samples of the received signal. The gating of digital samples into each of the signal registers is controlled by a separate clock timing. The timing sequence may be derived from a common clock. A multiplexer sequentially selects each of the signal registers, and passes the respective content of each signal register to a matched filter. A number of delay-locked-loop circuits track each of the multipath signals, and generate the timing sequence for gating signal registers.

Abstract: An improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, with the CDMA system having a base station (BS) and a plurality of remote stations. The base station has a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver. A remote station has an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver. The BS transmitter transmits a broadcast common-synchronization channel, which includes a frame-timing signal. The broadcast common-synchronization channel has a common chip-sequence signal, which is common to the plurality of remote stations. In response to the RS-spread-spectrum receiver receiving the broadcast common-synchronization channel, and determining frame timing from the frame-timing signal, an RS-spread-spectrum transmitter transmits an access-burst signal, which includes, RS-power-control signals, transmitted in time, at increasing power levels.

Abstract: A mapping memory, for use with a transmitter, for mapping a first signal segment and a second signal segment of a packet so that each signal segment has the same average power level. Each signal segment is characterized by a different modulation format. The first signal segment might use BPSK, while the second signal segment might use QAM, having multiple amplitude levels.

Abstract: An improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, with the CDMA system having a base station (BS) with a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver, and a plurality of remote stations. Each remote station (RS) has an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver. The improvement includes the steps of transmitting from the BS-spread-spectrum transmitter, a broadcast common-synchronization channel. The broadcast common-synchronization channel has a common chip-sequence signal common to the plurality of remote stations, and a frame-timing signal. The improvement includes receiving at a first RS-spread-spectrum receiver the broadcast common-synchronization channel, and determining frame timing from the frame-timing signal, and transmitting from a first RS-spread-spectrum transmitter an access-burst signal. The access-burst signal has a plurality of segments, which have a plurality of power levels.

Abstract: A system and method for encoding and transmitting data with a spread-spectrum packet-switched system. Data to be transmitted by a packet transmitter are encoded for privacy and to restrict intelligent receipt of the data to the intended recipient. The encoded data is demultiplexed into sub-data-sequence signals which are spread-spectrum processed and then combined as a multichannel spread-spectrum signal. The multichannel spread-spectrum signal is concatenated with a header to output a packet-spread-spectrum signal which is transmitted over radio waves to a packet receiver. The packet receiver obtains timing for the multichannel spread-spectrum signal from the header. The multichannel spread-spectrum signal is then despread and multiplexed as received-encoded data. The received-encoded data is decoded by the intended recipient and stored in a receiver memory for output.

Abstract: A code-division-multiple-access (CDMA) system provides a collision avoidance mechanism for packet communications. When mobile stations attempt to establish links with a base station, the base station selects one mobile station to transmit data over an intended uplink channel. The base station transmits a predetermined sequence, during the first frame of the data transmission over the downlink control channel that corresponds to the intended uplink channel. If several mobile stations detect or mis-perceive successful access attempts, those stations begin data transmissions via respective desired uplink channels. At the same time, the mobile stations listen for the known sequence over the various corresponding downlink channels. Upon successful detection of the known sequence, one mobile station continues transmission of its data over the intended channel. However, any contending mobile station that does not detect the known sequence on the appropriate downlink channel immediately stops its data transmission.

Abstract: In a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, mobile stations initially seek access to a selected one of two or more groups of common packet channels (CPCHs) serviced through a base station. A second order collision resolution phase, conducted between the base stations and contending mobile stations, serves to allocate one or more available channels from the selected group of channels among the contending mobile stations. In the collision resolution phase, each mobile station randomly selects a collision detection (CD) signature and sends that signature in a CD preamble. For each available channel in the group, the base station assigns one of the mobile stations. For each assigned mobile station, the base station transmits a CD acknowledgement that corresponds to the CD preamble of the assigned mobile station and identifies the available channel assigned to that mobile station.

Abstract: A superior and scaleable architecture for implementing a large bit matched filter. The implementation of the bit matched filter requires less silicon and consumes less power as compared to the existing design. An effective way to turn the bit matched filter on and off for power saving is also disclosed.

Abstract: A spread-spectrum-matched-filter apparatus including a code generator, an in-phase-symbol-matched filter, a quadrature-phase-symbol-matched filter, an in-phase-frame-matched filter, a quadrature-phase-frame-matched filter, and a controller. The code generator generates replicas of a chip-sequence signal, which are used to set the symbol-impulse responses of the in-phase-symbol-matched filter and the quadrature-phase-symbol-matched filter. The in-phase-frame-matched filter and the quadrature-phase-frame-matched filter detect a despread-header-symbol-sequence signal and generate a maximum output signal which may be used as a data-start signal or for synchronizing the timing of the controller as to when to trigger sampling of the A/D converter, the output of the symbol-matched filters, detection of the data-symbol-sequence signal and other time-dependent processes.