Abstract:
A multiple access, spread-spectrum communication system processes a plurality of information signals received by a Radio Carrier Station (RCS) over telecommunication lines for simultaneous transmission over a radio frequency (RF) channel as a code-division-multiplexed (CDM) signal to a group of Subscriber Units (SUs). The RCS receives a call request signal that corresponds to a telecommunication line information signal, and a user identification signal that identifies a user to receive the call. The RCS includes a plurality of Code Division Multiple Access (CDMA) modems, one of which provides a global pilot code signal. The modems provide message code signals synchronized to the global pilot signal. Each modem combines an information signal with a message code signal to provide a CDM processed signal. The RCS includes a system channel controller coupled to receive a remote call. An RF transmitter is connected to all of the modems to combine the CDM processed signals with the global pilot code signal to generate a CDM signal. The RF transmitter also modulates a carrier signal with the CDM signal and transmits the modulated carrier signal through an RF communication channel to the SUs. Each SU includes a CDMA modem which is also synchronized to the global pilot signal. The CDMA modem despreads the CDM signal and provides a despread information signal to the user. The system includes a closed loop power control system for maintaining a minimum system transmit power level for the RCS and the SUs, and system capacity management for maintaining a maximum number of active SUs for improved system performance.
Abstract:
A multiple access, spread-spectrum communication system processes a plurality of information signals received by a Radio Carrier Station (RCS) over telecommunication lines for simultaneous transmission over a radio frequency (RF) channel as a code-division-multiplexed (CDM) signal to a group of Subscriber Units (SUs). The RCS receives a call request signal that corresponds to a telecommunication line information signal, and a user identification signal that identifies a user to receive the call. The RCS includes a plurality of Code Division Multiple Access (CDMA) modems, one of which provides a global pilot code signal. The modems provide message code signals synchronized to the global pilot signal. Each modem combines an information signal with a message code signal to provide a CDM processed signal. The RCS includes a system channel controller coupled to receive a remote call. An RF transmitter is connected to all of the modems to combine the CDM processed signals with the global pilot code signal to generate a CDM signal. The RF transmitter also modulates a carrier signal with the CDM signal and transmits the modulated carrier signal through an RF communication channel to the SUs. Each SU includes a CDMA modem which is also synchronized to the global pilot signal. The CDMA modem despreads the CDM signal and provides a despread information signal to the user. The system includes a closed loop power control system for maintaining a minimum system transmit power level for the RCS and the SUs, and system capacity management for maintaining a maximum number of active SUs for improved system performance.
Abstract:
A multiple access, spread-spectrum communication system processes a plurality of information signals received by a Radio Carrier Station (RCS) over telecommunication lines for simultaneous transmission over a radio frequency (RF) channel as a code-division-multiplexed (CDM) signal to a group of Subscriber Units (SUs). The RCS receives a call request signal that corresponds to a telecommunication line information signal, and a user identification signal that identifies a user to receive the call. The RCS includes a plurality of Code Division Multiple Access (CDMA) modems, one of which provides a global pilot code signal. The modems provide message code signals synchronized to the global pilot signal. Each modem combines an information signal with a message code signal to provide a CDM processed signal. The RCS includes a system channel controller coupled to receive a remote call. An RF transmitter is connected to all of the modems to combine the CDM processed signals with the global pilot code signal to generate a CDM signal. The RF transmitter also modulates a carrier signal with the CDM signal and transmits the modulated carrier signal through an RF communication channel to the SUs. Each SU includes a CDMA modem which is also synchronized to the global pilot signal. The CDMA modem despreads the CDM signal and provides a despread information signal to the user. The system includes a closed loop power control system for maintaining a minimum system transmit power level for the RCS and the SUs, and system capacity management for maintaining a maximum number of active SUs for improved system performance.
Abstract:
The present invention claims a multiple access spread-spectrum communication system for dynamically changing a transmission rate of an information signal received from a remote processing unit (RPU) over a telecommunication line and transmitted to a subscriber through a first spread-spectrum message channel of a plurality of spread spectrum message channels, the system comprising a) a base station, connected to the RPU, which identifies an information signal rate of the respective information signal and provides a modify signal responsive to the information signal rate; comprising: a system channel controller which assigns the information signal and the modify signal to respectively different ones of the plurality of spread-spectrum message channels; first information channel mode modification means connected to the system channel controller and responsive to the modify signal for switching the respective information signal from the first spread-spectrum message channel supporting a first information channel rate to one other pre-determined spread-spectrum message channel, the one other pre-determined spread-spectrum message channel having a different information channel rate supporting the identified information signal rate; and b) a subscriber unit comprising: a first despreading means for recovering the respective information signal and modify signal from the first spread spectrum message channel; second information channel mode modification means responsive to the modify signal for reassigning the first despreading means to a second despreading means which supports the different information channel rate, the second despreading means corresponding to the second spread spectrum message channel.
Abstract:
PROBLEM TO BE SOLVED: To provide a code sequence generating apparatus for generating a plurality of spread code sequences having inter cross correlation within a prescribed range and having a prescribed inter code phase relation. SOLUTION: The spread code sequence generating apparatus includes a plurality of stages including a first stage and a final stage, wherein each stage has: a linear feedback shift register (LFSR) for demarcating a tap for generating a tap signal, applying a prescribed tap signal group to a logic circuit where the signals are composed and a feedback spread signal for input to the first stage is produced; a memory means being a first memory means for storing a plurality of spread code seeds, connected to the LFSR, and for respectively transferring each of a prescribed set of the spread code sequences of the spread code seed to be selected in response to a load signal; and a code generating unit control means for selecting one of a plurality of the spread code seeds and producing the load signal corresponding to the spread code. The LFSR transfers the tap signal from one stage to the next, transfers the feedback spread code value to the first stage, and demarcates a master spread code sequence by each of consecutive tap signal values of the final stage. COPYRIGHT: (C)2003,JPO
Abstract:
PROBLEM TO BE SOLVED: To provide an adaptive matching filter (AMF) apparatus for collecting signal power of a spread spectrum data channel from a spread spectrum signal. SOLUTION: The adaptive matching filter apparatus includes; a pilot vector correlation means for producing a plurality of multi-path signal weighting values depending on a plurality of multi-path signal carrier components; a local code sequence generating means for generating a plurality of local code sequences being code phase shift outputs of a prescribed spread code sequence; a plurality of spread code correlating units for producing respective multi-path data signal components having already been subjected to despread processing having carrier phase values in a data AMF for receiving the spread spectrum signal; a plurality of weighting means for producing a plurality of scaling and matched data signal components applying scaling to the multi-path data in response to the multi-path weighting values; and the data AMF means provided with a combining means for combining the scaling and matched data signal components to produce data values. COPYRIGHT: (C)2003,JPO
Abstract:
PROBLEM TO BE SOLVED: To provide a subscriber station unit for a large capacity multiple access spread spectrum communication system, which forms a plurality of concurrent user bearer channels through a prescribed radio frequency, to enable dynamic allocation of a bearer channel speed, while preventing multipath interference. SOLUTION: The subscriber station unit for the multiple access spread spectrum communication system includes a receiving means, a subscriber station unit controller, and a modem-processing means provided with a global pilot code acquiring means, a plurality of message code generators, a global pilot code tracking means, a phase-adjusting means and a plurality of message- acquiring means. COPYRIGHT: (C)2003,JPO
Abstract:
PROBLEM TO BE SOLVED: To provide a high-speed capture device by which the spread code phase of a spread spectrum communication system is rapidly synchronized with a transmission code signal provided with a transmission I code signal including a first spread code sequence and a transmission Q code signal includ ing a second spread code sequence. SOLUTION: The high-speed capture device includes: a receiving means for receiving the transmission code signal, and separating the transmission I code signal from the transmission Q code signal; a correlation means provided with an I code signal correlator and a Q code signal correlator; a local code sequence generator; and a controller which is connected to the I code signal correlator, the Q code signal correlator, and the local code sequence generator, so as to decide, achieve and keep a code sequence lock. COPYRIGHT: (C)2003,JPO
Abstract:
PROBLEM TO BE SOLVED: To reduce power consumption of each of a plurality of transceiver stations constituting a spread spectrum communication system, especially a mobile subscriber station unit, as much as possible.SOLUTION: In a spectrum communication system which maintains an initial transmission power level of a second transceiver station in an inactive state, a first transceiver station despreads reception signals by using a selected chip code associated with a specific spread spectrum signal from the second transceiver station and measures a power level of the despread specific signal. The second transceiver station sometimes transmits the specific spread spectrum signal during the inactive state to a first transceiver, and the first transceiver station receives it, measures a noise power level in a communication channel, estimates a system transmission power level, compares the measured values with the estimated values, and transmits automatic power control (APC) signals to the second transceiver station on the basis of a comparison result. The second transceiver station adjusts the initial transmission power level in response to the APC signals.
Abstract:
PROBLEM TO BE SOLVED: To provide a code division multiple access modem for a spread spectrum communication system. SOLUTION: The system provides a modem transmitter, which includes a code generator, a spread spectrum measure composing code signals respectively, a global pilot code generator generating global pilot code signals, and a modem receiver which includes a pilot code generator, and a pilot code correlation device correlating between the code phase delay output of a pilot signal and a received CDMA signal and generating a relating pilot signal, after being inverse spread. The system responses a captured signal value and changes a code phase of the pilot signal, until the pilot signal is received. A related pilot code tracking logical circuit responses to the captured signal and adjusts phase of the relating pilot code signal, and the system provides a signal seizure circuit which makes the signal power level of the related pilot code signal after the inverse spread to be a maximum value. COPYRIGHT: (C)2003,JPO