Lucent Technologies Inc.

Nvidia Corporation

At+t Corp.

Icera, Inc.

Nvidia Technology UK Limited

Nallepilli S Ramesh

Quinn Li

Tarik Tabet

Stephen Alan Allpress

Godfrey Costa

Carlo Luschi

Robert Atmaram Soni

R Michael Buehrer

Abdelkader Medles

Krishnamurthy Sreenath

Provided is a recursive method and apparatus for processing a signal for determining a plurality of frequency components of the signal, the signal being a chirp-like polyphase sequence. In one embodiment, the method includes: (1) determining a first frequency component of the plurality of frequency components, (2) determining a component factor by accessing a factor table, (3) determining the second frequency component using the determined first frequency component and the determined component factor. If there is at least one further frequency component of the signal, the method further comprising for each of the further frequency components: (4) determining a respective further component factor by accessing the factor table, and (5) determining the further frequency component using a previously determined frequency component and the determined further component factor, wherein the previously determined frequency component is the frequency component determined most recently prior to determining each respective further frequency component.

Fourier transform for a signal to be transmitted on a random access channel

Method and apparatus for processing a signal using a recursive method for determining a plurality of frequency components of the signal, the signal being a chirp-like polyphase sequence, wherein a first frequency component of the plurality of frequency components is determined; a component factor is determined by accessing a factor table for use in determining a second frequency component of the plurality of frequency components; and the second frequency component is determined using the determined first frequency component and the determined component factor.

The present disclosure relates to a method of transmitting channel quality data for channels in a wireless communication system, and to a corresponding receiver and transmitter. In one embodiment, the method includes determining a plurality of channel quality indicators for a corresponding plurality of frequency intervals and transmitting information about channel quality indicators in the form of differentially encoded slope data.

Reporting channel quality information

A transmitter for wireless communications provides multiple types of orthogonality to improve transmit diversity. Transmit diversity is improved by using both coding and carrier frequency orthogonality. Data to be transmitted is broken into four parallel channels. Two of the channels are transmitted on a first carrier signal and the other two channels are transmitted on a second carrier signal. Channels transmitted on the same carrier signal are provided with orthogonal codes so that they may be separated by a receiver. Channels transmitted on different carrier signals may be encoded with identical orthogonal codes. The modulated carrier signals are then transmitted using at least two antennas, where one antenna is used for each carrier.

Method of providing downlink transmit diversity

A long code generator is disclosed that maintains a common long code state between a system with multiple spreading rates, such as a spreading rate equal to the chip rate (1&times;) and a spreading rate at a multiple of the chip rate (n&times;), such as three-times the chip rate (3&times;). An n&times; long code generator generates n bits for every clock pulse, where the clock operates at the system chip rate. n bits are generated for every clock period by having the long code mask value assume n values for each clock period. Thus, the long code mask value is changed at n times the chip rate, while the shift register is operated at the chip rate. Each of the long codes corresponding to the n long code mask values are multiplexed, for example, using an interlacing technique. The long code generator includes a conventional shift register, AND gate array, modulo-2 adder and clock. In addition, the disclosed long code generator includes a novel long code mask generator that generates n long code masks for each clock period. The long code mask generator operates with a chip rate of n-times the system clock (n&times;1.2288 MHz). The three long code masks generated for each user must be different from one another, and different from the three long code masks generated for all other users. All the randomness properties necessary for proper CDMA operation are preserved. The present invention applies to both the forward and reverse links for long code generation. Long code state synchronization is maintained between two systems employing different spreading rates, thereby facilitating handoffs without explicit messaging of state information.

Method and apparatus for generation of CDMA long codes

Disclosed is a common transmitter architecture having incorporated both open loop transmit diversity schemes using a plurality of binary switches. Employment of binary switches allows for the sharing of certain components whether the transmitter is utilizing a orthogonal transmit diversity (OTD) scheme or a space time spreading (STS) scheme. Accordingly, the number of components in the transmitter is minimized and the complexity of the transmitter is simple enough to be implemented into a single application specific integrated chip.

Transmitter architecture employing space time spreading and orthogonal transmit diversity techniques

A complex spreading and/or scrambling code sequence generation system uses a first complex code sequence having at least two components and a second complex code sequence having at least two components. The components of the first complex code sequence are respectively mixed with the corresponding components of the second complex code sequence to generate the complex scrambling code sequence. In doing so, an offset between the components of the complex scrambling code sequence is achieved for the same and/or different users. The complex scrambling code sequence can be used for spreading, scrambling, de-spreading or descrambling an information signal.

Method and apparatus for generating a complex scrambling code sequence

Multi-carrier CDMA transmission system with frequency and transmit diversity

A wireless telecommunications system is disclosed that mitigates multipath fading through an improvement in transmit diversity. Furthermore, embodiments of the present invention are well-suited for use with all forward channel multiplexing schemes (e.g., frequency-division multiplexing, time-division multiplexing, code-division multiplexing, etc.) and all modulation techniques (e.g., amplitude modulation, frequency modulation, phase modulation, etc.). An illustrative embodiment of the present invention comprises: a signal inverter for inverting and alternately not-inverting a first signal in accordance with a schedule to create a second signal; a first antenna for transmitting the first signal; and a second antenna for transmitting the second signal.

Wireless telecommunications system that mitigates the effect of multipath fading

A plurality of modulated signals are generated for a data stream. Each modulated signal, which contains all of the information in the data stream, is generated at a different carrier frequency. The modulated signals are combined for transmission as a multi-band signal. In one embodiment, the modulated signals are compatible with signals generated in accordance with the IS-95 telecommunications standard. According to this embodiment, wideband data streams are combined with code sequences that are based on the same Walsh code sequences used to generate IS-95 signals. Each wideband data stream is encoded using either a particular Walsh code sequence or its logical negation to generate one coded stream for each carrier frequency used to generate the IS-95 signals. Each coded stream is then modulated at one of the carrier frequencies using spread-spectrum modulation to generate one of a plurality of modulated signals for that wideband data stream, where each modulated signals contains all of the information in the original wideband data stream. Through systematic assignment of Walsh code sequences and their logical negations, and through appropriate spread-spectrum modulation of the wideband data, the resulting multi-band modulated signal for each wideband data stream is assured of being orthogonal to all other such multi-band modulated signals, as well as orthogonal to every IS-95 signal. As such, the invention increases both the user and data-rate capacities of an IS-95 network without requiring any additional carrier frequencies or code sequences beyond those already supported by the IS-95 network.

IS-95 compatible wideband communication scheme

The modulation scheme has two versions that can transform two data streams into two mutually orthogonal modulated signals within the same carrier-frequency band. In one embodiment, the modulation scheme is a quadrature-phase shift-keying (QPSK) modulation scheme having an in-phase part and a quadri-phase part. In this embodiment, one version of the QPSK modulation scheme conforms to the IS-95 telecommunications standard. In this version, the in-phase part is applied to a first data stream to generate an in-phase signal that is multiplied by a cosine function of the carrier frequency. In a parallel path, the quadri-phase part is applied to the first data stream to generate a quadri-phase signal that is multiplied by a sine function of the carrier frequency. The resulting signals are combined to generate a conventional IS-95 signal. In this embodiment, the other version of the QPSK modulation scheme is designed to transform a second data stream into a second modulated signal that is orthogonal to the IS-95 signal, even though the second modulated signal is within the same carrier-frequency band and even if the second data stream is encoded using the same Walsh code sequence as the first data stream. In one implementation of the second version, the logical negation of the quadri-phase part of the QPSK modulation scheme is applied to the second data stream to generate an quadri-phase signal that is multiplied by the cosine function of the carrier frequency. In a parallel path, the in-phase part of the QPSK modulation scheme is applied to the second data stream to generate an in-phase signal that is multiplied by the sine function of the carrier frequency. The resulting signals are combined to generate a modulated signal that is orthogonal to the IS-95 signal and which therefore will not interfere with the IS-95 signal, even though the two modulated signals exist within the same carrier-frequency band and may in fact be based on two data streams that were encoded using the same Walsh code sequence. Those skilled in the art will understand that the modulation scheme of the present invention can be implemented in contexts other than the IS-95 standard.

Orthogonal modulation scheme

Disclosed is a circuit for automatic gain control (AGC) of random access channels (RACH) and traffic channels in a radio system. The amplitude of the input signal is detected at an intermediate frequency (IF) stage, digitized, and coupled to a digital signal processor (DSP) which produces an AGC signal for reducing the gain of the input when the input crosses a threshold value. For RACH bursts, the AGC signal tracks the input signal when it crosses the threshold and the AGC signal remains at a constant value for the the remainder of the time slot unless and until the input increases a threshold amount over its previous highest value. For traffic channels, the DSP will use the AGC signal from the RACH burst as an initial value and change the AGC signal only if the detected input is outside a predetermined range.

Growing community of inventors

New Providence, NJ, United States of America

Nallepilli S Ramesh