Abstract:
A communication receiving apparatus, a signal receiving method thereof, a signal processing method, and a signal transmitting method based Code Division Multiple Access (CDMA) technology are provided. The signal processing method includes the following steps: the communication transmitting apparatus encodes an original data sequence based on a perfect Gaussian integer sequence (PGIS) to generate a spread signal and transmits a radio frequency (RF) signal including the spread signal. An autocorrelation function of the PGIS conforms to an impulse characteristic, and the PGIS has a spectrum with equal magnitude. The communication receiving apparatus obtains the RF signal from the communication transmitting apparatus and transforms the RF signal into a baseband signal. The baseband signal is de-modulated into a data stream by the communication receiving apparatus. The data stream is recovered into at least one data value of the original data sequence based on the PGIS by the communication receiving apparatus.
Abstract:
Methods, apparatus and computer programs are provided for multiplication-free identification of the impulse response of an oversampled data channel. An input comprising a pseudo-random binary sequence of L symbols is supplied to the channel at a symbol rate of 1/T. A channel output is produced by sampling a channel output signal corresponding to the input with a sampling interval TS=(q/p)T, where q and p are relative prime integers with q
Abstract:
A wireless communication unit comprises circuitry configured to receive a voice data associated with a first logical channel. The circuitry further configured to receive a non-voice data associated with a second logical channel. The voice data and non-voice data carried by a wireless channel set during a time period. The wireless channel set comprises a plurality of wireless channels. The wireless channel is associated with a subscriber unit. Circuitry is configured to insert information into the non-voice data, when the non-voice data is missing in the wireless channel set during the time period.
Abstract:
Carrier interferometry (CI) methods may be used to provide transmission protocols having various desirable properties. Such properties may include interference rejection, reduced multipath fading, and/or operation across discontinuous frequency bands. Codes used for such CI techniques, known as CI codes, may be orthogonal polyphase codes.
Abstract:
A method of increasing utilization of user link bandwidth for a code division multiple access communications system is disclosed that includes the steps of selecting a set of orthogonal complex codes each having a code length that is greater than a code length of an optimum real code and less than or equal to a spreading code length; and transferring symbols across at least one of a plurality of user links to or from at least one of a corresponding plurality of user terminals wherein the symbols are represented by a corresponding one of the set of orthogonal complex codes.
Abstract:
A code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The CDMA system has a base station (BS), and a plurality of subscriber units (SUs). The signals transmitted between the BS and SU use spread-spectrum modulation. The apparatus for maintaining control of power from an SU to a BS, comprises sending from the SU, using spread-spectrum modulation, a SU-spreading code, and detecting at the base station, the SU-spreading code from the SU. In response to detecting the SU-spreading code at the BS, a BS-spreading code is sent to the SU, using spread-spectrum modulation. At the SU, if the BS-spreading code is detected, then transmit power of the SU is reduced. If the BS-spreading code is not detected at the SU, then transmit power of the SU is increased.
Abstract:
A method and system for rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system. A first long code and a second long code, with each long code having a length of N chips, are generated. The first long code is different from the second long code. The first long code and the second long code are transmitted at a first phase angle and at a second phase angle, respectively, on a carrier signal, over a communications channel using radio waves. The first long code and the second long code may be transmitted at an in-phase (I) angle and at a quadrature-phase (Q) angle, respectively, on the carrier signal. From the communications channel, an I-phase acquisition circuit and a Q-phase acquisition circuit may acquire, in parallel, the first long code and the second long code from the I-phase angle and the Q-phase angle, respectively, of the carrier signal by searching, in parallel, N/2 chips, the first long code and the second long code.
Abstract:
A code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The CDMA system has a base station (BS), and a plurality of subscriber units. The signals transmitted between the base station and subscriber unit use spread-spectrum modulation. The improvement method for adaptive forward power control (APC) from a base station (BS) to a subscriber unit (SU), comprises the steps of sending from the base station, using spread-spectrum modulation, a BS-spreading code on a forward channel. The subscriber unit despreads the BS-spreading code on the forward channel as a despread signal, determines a first power level Pd which includes power of the despread signal plus noise and a second power level PN, which includes despread-noise power. The subscriber unit determines a first error signal e1, from the first power level Pd, the second power level PN, and a required signal-to-noise ratio SNRREQ for service type, and a second error signal e2, from a measure of total received power Pr and an automatic gain control (AGC) set point Po. The subscriber unit forms a combined error signal from the first error signal e1, the second error signal e2, a first weight a1 and a second weight a2, and hard limits the combined error signal to form a single APC bit. The APC bit is transmitted to the base station. In response to the APC bit, the base station adjusts transmitter power to the subscriber unit.
Abstract:
An improvement for a method and system for tracking a spreading code, used in a code division multiple access (CDMA) system. An input signal has spread-spectrum modulation. The spreading code embedded in the spread-spectrum modulation has a plurality of chips. The input signal is sampled, and half-chip offset samples are formed from the sampled input signal. An even set of the half-chip offset samples are grouped into an early set of samples, and an odd set of the half-chip offset samples are grouped into a late set of samples. Each early set of samples is multiplied by spreading codes c(n+1), c(n+2), . . . , c(n+L), to generate a first plurality of products. L is approximately equal to the number of chips of delay between the earliest and latest multipath signals. A first plurality of sums and magnitudes are computed from the first plurality of products. The first plurality of magnitudes are multiplied by a first plurality of weights, to generate a first plurality of weighted-signal values. The first plurality of weighted-signal values are summed to generate an early signal-energy value. Each late set of samples is multiplied by spreading codes c(n−1), c(n−2), . . . , c(n−L), to generate a second plurality of products. A second plurality of sums and magnitudes are computed from the second plurality of products. The second plurality of magnitudes are multiplied by a second plurality of weights, to generated a second plurality of weighted-signal values. The second plurality of weighted-signal values are summed to generate a late signal-energy value. A difference is calculated between the early signal-energy value and the late signal-energy value, thereby producing an error signal.
Abstract:
A method of increasing utilization of user link bandwidth for a code division multiple access communications system is disclosed that includes the steps of selecting a set of orthogonal complex codes each having a code length that is greater than a code length of an optimum real code and less than or equal to a spreading code length; and transferring symbols across at least one of a plurality of user links to or from at least one of a corresponding plurality of user terminals wherein the symbols are represented by a corresponding one of the set of orthogonal complex codes.