Abstract: 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.

Abstract: An apparatus and method for implementing an equalizer which combines the benefits of a decision feedback equalizer (DFE) with a maximum-a-posterori (MAP) equalizer (or a maximum likelihood sequence estimator, MLSE) to provide an equalization device with significantly lower complexity than a full-state MAP device, but which still provides improved performance over a conventional DFE. The equalizer architecture includes two DFE-like structures, followed by a MAP equalizer. The first DFE forms tentative symbol decisions. The second DFE is used thereafter to truncate the channel response to a desired memory of L1 symbols, which is less than the total delay spread of L symbols of the channel. The MAP equalizer operates over a channel with memory of L1 symbols (where L1<=L), and therefore the overall complexity of the equalizer is significantly reduced.

Abstract: This invention describes an apparatus and method to improve the performance of a decision feedback equalizer (DFE) for time-varying multi-path channels. For minimum-phase channels, the equalization is performed in a time-forward manner. For maximum-phase channels, the equalization is performed in a time-reversed manner. More specifically, for maximum-phase channels, the filter coefficients are computed based on the channel estimates reversed in time, and the filtering and equalization operations are performed with the received block of symbols in a time-reversed order. In the context of this invention, the term “minimum-phase channel” implies that the energy of the leading part of the channel profile is greater than the energy of the trailing part. The term “maximum-phase channel” implies that the energy of the leading part of the channel profile is less than the energy of the trailing part.

Abstract: An apparatus and method for implementing an equalizer which (1) combines the benefits of a decision feedback equalizer (DFE) with a maximum-a-posterori (MAP) equalizer (or a maximum likelihood sequence estimator, MLSE) (2) performs equalization in a time-forward or time-reversed manner based on the channel being minimum-phase or maximum-phase to provide an equalization device with significantly lower complexity than a full-state MAP device, but which still provides improved performance over a conventional DFE. The equalizer architecture includes two DFE-like structures, followed by a MAP equalizer. The first DFE forms tentative symbol decisions. The second DFE is used thereafter to truncate the channel response to a desired memory of L1 symbols, which is less than the total delay spread of L symbols of the channel. The MAP equalizer operates over a channel with memory of L1 symbols (where L1<=L), and therefore the overall complexity of the equalizer is significantly reduced.

Abstract: In a wireless communications system, a base station transmits power control signals (e.g., the power control bits of a power control sub-channel) to a mobile using a forward-link channel that is decoupled from all other signals transmitted from that base station to that mobile. For example, the decoupled forward-link channel may be a common power control channel. The mobile then uses the power control signals received in the decoupled forward-link channel to control its power level for transmitting one or more reverse-link channels to the base station. The ability of base stations to use decoupled forward-link channels in order to transmit their power control signals to a mobile enables a mobile to operate with different active sets for the forward and reverse links. This enables forward-link data traffic to be implemented using a simplex mode, even when the mobile is operating in soft handoff in the reverse link.

Abstract: 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.

Abstract: 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.