Abstract:
A wireless telecommunications system (1) includes a central terminal (10) for transmitting and receiving radio frequency signals to and from a subscriber terminal (20). A downlink communication path is established from a transmitter (200) of the central terminal (10) to a receiver (202) of the subscriber terminal (20). A downlink signal (212) is transmitted from the transmitter (200) to the receiver (202) during setup and operation of the wireless telecommunications system (1). The wireless telecommunications system (1) operates in one of three operating modes. In an acquisition mode during establishment of the downlink communication path, the downlink signal (212) is transmitted at a high power level and a low transmit rate with the receiver (202) operating at the low transmit rate. In a standby mode after establishment of the downlink communication path, the downlink signal (212) is transmitted at a low power level and a low transmit rate with the receiver (202) operating at the low transmit rate. In a traffic mode upon a request for wireless communication transmission, the downlink signal (212) is transmitted at a high power level and a high transmit rate with the receiver (202) adjusting to operate at the high transmit rate. Upon completion of the wireless communication transmission, the wireless telecommunications system (1) returns to the standby mode and the receiver (202) adjusts to operate at the low transmit rate.
Abstract:
A wireless telecommunications system (1) includes a central terminal (10) for transmitting and receiving radio frequency signals to and from a subscriber terminal (20). A downlink communication path is established from a transmitter (200) of the central terminal (10) to a receiver (202) of the subscriber terminal (20). A downlink signal (212) is transmitted from the transmitter (200) to the receiver (202) during setup and operation of the wireless telecommunications system (1). The downlink signal (212) includes an overhead channel (224) having a code synchronization signal (234). The code synchronization signal (234) is capable of adjusting a phase of a transmitter (204) in the subscriber terminal (20). A receiver (206) in the central terminal (10) monitors an uplink signal (214) transmitted by the transmitter (204) in the subscriber terminal and provides changes to the code synchronization signal (234) such that the transmitter (204) is synchronized to the receiver (206). Synchronization of the transmitter (204) in the subscriber terminal (20) to the receiver (206) in the central terminal (10) facilitates establishment of an uplink communication path from the subscriber terminal (20) to the central terminal (10).
Abstract:
A receiver for a multi-mode wireless device is provided. The receiver has multiple analog RF front end modules, with each module supporting a different mode of operation. The receiver has a single digital backend module for generating a digital baseband signal. A controller selects one of the available RF modules to use, and the selected RF module provides an analog communication signal to the digital backend. Each available mode has an associated set of factors. When a particular mode is selected, the set of factors associated with the selected mode is provided to the digital backend. The digital backend uses these factors to adjust the processing characteristics of its components, such as its analog to digital converter, filters, and gain controller. In this way, the single digital backend is adaptable to the requirements of each of the available radio modes.
Abstract:
The present invention relates to re-configurable signal processing modules in particular, although not exclusively, for wireless communications terminals. In general terms in one aspect the present invention provides a system for reconfiguring a signal processing module having a number of re-configurable resources such as re-configurable hardware blocks including ASIC's and field programmable logic gate arrays (FPGA's), as well as software modules for implementing different functions and which can be run on a DSP or other processing platform within the signal processing module. The module may be a mobile terminal or a base station in a wireless communications system for example. The system comprises means for generating a commands data structure comprising configuration commands for the resources, and may further comprise means for communicating this data structure to the signal processing module. The module has means for reconfiguring itself using this data structure. Typically the data structure will be a process timetable having time stamped configuration and run-time commands suitable for being dispatched to the appropriate resource.
Abstract:
The invention provides methods and apparatus for multiple user detection (MUD) processing that have application, for example, in improving the capacity CDMA and other wireless base stations. One aspect of the invention provides a multiprocessor, multiuser detection system for detecting user transmitted symbols in CDMA short-code spectrum waveforms. A first processing element generates a matrix (hereinafter, "gamma matrix") that represents a correlation between a short-code associated with one user and those associated with one or more other users. A set of second processing elements generates, e.g., from the gamma matrix, a matrix (hereinafter, "R-matrix") that represents cross-correlations among user waveforms based on their amplitudes and time lags. A third processing element produces estimates of the user transmitted symbols as a function of the R-matrix.
Abstract:
The receiver for code division radio interface (CDMA - Code Division Multiple Access) works on the signal received from a mobile network terminal and converted into baseband, where the group of digital signals obtained represents the sum of all the signals and the codes relating to the users that are transmitting at that moment on the frequency band assigned to the service. The information destined for each user is extracted by correlating the group of digital signals received with the user's code. The receiver can be designed as an integrated circuit library cell and, as such, gives a high degree of flexibility that permits it to be integrated in various terminals.
Abstract:
A configurable all-digital coherent demodulator system for spread spectrum digital communications is disclosed herein. The demodulator system includes an extended and long code demodulator (ELCD) (112) coupled to a traffic channel demodulator (TCD) (114) and a parameter estimator (PE) (116). The demodulator also includes a pilot assisted correction device (PACD) (118) that is coupled to the PE (116) and the TCD (114). The ELCD (112) provides a code-demodulated signal to the TCD (114) and the PE (116). The PACD (118) corrects the phase error of the demodulated output data based on an error estimate that is fed forward from the PE (116). Accumulation operations in the ELCD (112), TCD (114), and PE (116) are all programmable. Similarly, a phase delay in the PACD (118) is also programmable to provide synchronization with the error estimate from the PE (116).
Abstract:
A CDMA signal processing circuit (300) includes a summer circuit (302) that receives a plurality of CDMA signals from a plurality of channels (304). The summer circuit (302) combines the plurality of CDMA signals according to a power magnitude value and power direction value associated with each CDMA signal. The summer circuit (302) generates a summed signal (306) that is applied to a clipping circuit (308). The clipping circuit (308) removes a portion of the summed signal (306) outside a desired threshold range and generates a clipped signal (310) therefrom. Digital to analog processing circuits (312 and 314) convert the clipped signal (310) into a half width encoded format. Digital to analog processing circuits (312 and 314) transform the half width encoded clipped signal into analog I and Q signals, respectively. The analog I and Q signals are applied to corresponding filters (316 and 318) prior to transmission.
Abstract:
A downlink communication path is established from a transmitter (200) of the central terminal (10) to a receiver (202) of the subscriber terminal (20). A downlink signal (212) is transmitted from the transmitter (200) to the receiver (202) during setup and operation of the wireless telecommunications system (1). The downlink signal (212) includes an overhead channel (224) having a code synchronization signal (234). The code synchronization signal (234) is capable of adjusting a phase of a transmitter (204) in the subscriber terminal (20). A receiver (206) in the central terminal (10) monitors an uplink signal (214) transmitted by the transmitter (204) in the subscriber terminal and provides changes to the code synchronization signal (234) such that the transmitter (204) is synchronized to the receiver (206). Synchronization of the transmitter (204) in the subscriber terminal (20) to the receiver (206) in the central terminal (10) facilitates establishment of an uplink communication path from the subscriber terminal (20) to the central terminal (10).