Abstract:
A method and apparatus for combining space-frequency block coding (SFBC) and frequency shift transmit diversity (FSTD) in a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system.
Abstract:
A method and apparatus for combining space-frequency block coding (SFBC) and frequency shift transmit diversity (FSTD) in a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system.
Abstract:
An automatic gain control system prevents input overload by precisely controlling the input level of a received, digitally modulated signal without variable gain amplification. Limiting amplification in conjunction with a logarithmic detection splits an input signal path in two, providing separate phase and amplitude information for downstream digital signal processing, where the separate phase and amplitude information is processed without variable gain artifacts. The separated phase information may further be divided into I and Q signals.
Abstract:
A transmitter splits a user-data stream into a plurality of sub-streams. The transmitter then adaptively selects a modulation scheme and coding rate for each of the sub-streams based on current channel conditions. Next, a plurality of sub-carriers are modulated and encoded with the sub-stream data according to the selected modulation schemes and coding rates. The modulated sub-carriers are each allocated to one or more transmit antennas for transmission. Prior to transmission, a transmission power for each of the sub-carriers is adjusted based on the channel conditions. The adaptive modulation and coding function, the sub-carrier allocation function, and the power control function are jointly controlled to optimize throughput, signal quality, and system efficiency.
Abstract:
A base station for controlling transmission power during the establishment of a communication channel utilizes the reception of a short code during initial power ramp-up. The short code is a sequence for detection by the base station which has a much shorter period than a conventional access code. The ramp-up starts from a power level that is lower than the required power level for detection by the base station. The power of the short code is quickly increased until the signal is detected by the base station. Once the base station detects the short code, it transmits an indication that the short code has been detected.
Abstract:
In order to compensate for performance degradation caused by inferior low-cost analog radio component tolerances of an analog radio, a future system architecture (FSA) wireless communication transceiver employs numerous digital signal processing (DSP) techniques to compensate for deficiencies of such analog components so that modern specifications may be relaxed. Automatic gain control (AGC) functions are provided in the digital domain, so as to provide enhanced phase and amplitude compensation, as well as many other radio frequency (RF) parameters.
Abstract:
A User Equipment (UE) has a circuit that performs the acquisition for the low chip rate option of the Universal Mobile Telecommunication System (UMTS) Time Division Duplex (TDD) standard as formulated by the Third Generation Partnership Project (3GPP). The present invention implements the detection of the basic SYNC code; the determination of the midamble used and the detection of the superframe timing based on SYNC code modulation sequence. This enables reading of a full Broadcast Channel (BCH) message.
Abstract:
A method for removing selected signals from a received signal prior to decoding begins by receiving communication signals from a transmitter over a CDMA air interface. The received communication signals are input to a traffic signal cancellation system for canceling unwanted traffic signals, thereby producing an output (O). The received communication signals are input to a pilot signal cancellation system for removing a global pilot signal, thereby producing an output (Oadd). The output (Oadd) of the pilot signal cancellation system is subtracted from the output (O) of the traffic signal cancellation system to provide a cancellation system output.
Abstract:
A wireless communication system and method generates and shapes one or more three-dimensional control channel beams for transmitting and receiving signals. Each three-dimensional beam is directed to cover a particular coverage area and beam forming is utilized to adjust bore sight and beam width of the three-dimensional beam in both azimuth and elevation, and the three-dimensional control channel beam is identified. In another embodiment, changes in hot-zones or hot-spots, (i.e., designated high volume user coverage areas), are managed by a network cell base station having at least one antenna. Each of a plurality of wireless transmit/receive units (WTRUs) served by the base station use a formed beam based on one or more beam characteristics. When the coverage area is changed, the base station instructs at least one of the WTRUs to change its beam characteristics such that it forms a return beam concentrated on the antenna of the base station.
Abstract:
Signal processing techniques are applied to digital image data to remove the distortion caused by motion of the camera, or the movement of the subject being photographed, or defective optics, or optical distortion from other sources. When the image is captured, the effect of relative motion between the camera and the subject is that it transforms the true image into a blurred image according to a 2-dimensional transfer function. The 2-dimensional transfer function representing the motion is derived using blind estimation techniques or by using information from sensors that detect the motion. The transfer function is inverted and used to define a corrective filter. The filter is applied to the image and the blur due to the motion is removed, restoring the correct image. Another embodiment uses the transfer function to avoid blur by combining multiple consecutive images taken at a fast shutter speed.