Abstract:
Briefly, an apparatus that may include scrambler to scramble data bits and control bit and filters to filter the scrambled data bits and control bits. The apparatus may also include a processor to adjust the gains of the filters.

Description:
A transmitter architecture that may be used with Wideband Code Division Multiple Access (WCDMA) systems, also known in the art as ITU IMT-2000 Spread spectrum standard, may generate chips of data symbols by spreading data and control bits using an Orthogonal Variable Spreading Factor (OVSF) code, applying different gains to the data and control bits and scrambling the spread-gained data and control bits to generate the data chips. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanied drawings in which: 
         FIG. 1  is a schematic illustration of a wireless communication system according to an exemplary embodiment of the present invention; 
         FIG. 2  is a block diagram of a transmitter according to one exemplary embodiment of the present invention; and 
         FIG. 3  is a block diagram of a transmitter according to another exemplary embodiment of the present invention. 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention. 
     Some portions of the detailed description, which follow, are presented in terms of algorithms and symbolic representations of operations on data bits or binary digital signals within a computer memory. These algorithmic descriptions and representations may be the techniques used by those skilled in the data processing arts to convey the substance of their work to others skilled in the art. 
     It should be understood that the present invention may be used in a variety of applications. Although the present invention is not limited in this respect, the circuits and techniques disclosed herein may be used in many apparatuses such as transmitters of a radio system. Transmitters intended to be included within the scope of the present invention include, by a way of example only, cellular radiotelephone transmitters, two-way radio transmitters, digital system transmitters, wireless local area network transmitters, wideband transmitters, ultra wideband transmitters, and the like. 
     Types of cellular radiotelephone transmitters intended to be within the scope of the present invention may include, but are not limited to, Code Division Multiple Access (CDMA), CDMA-2000 and wide band CDMA (WCDMA) cellular radiotelephone transmitters for receiving spread spectrum signals, transmitters for global system for mobile communication (GSM), transmitters for third generation cellular systems (3G), orthogonal frequency division multiplexing (OFDM) transmitters, and the like. 
     Turning first to  FIG. 1 , a schematic illustration of a wireless communication system  100  according to an exemplary embodiment of the present invention is shown. Although the scope of the present invention is not limited to this example, wireless communication system  100  may include at least one base station  110  and at least one mobile station  140 . In some embodiments of the invention, base station  110  may include a transmitter  120  and mobile station  140  may include a transmitter  150 . Transmitters  120  and  150  may have an architecture suitable for WCDMA communication systems, although the scope of the present invention is not limited in this respect. 
     Although the scope of the present invention is not limited in this respect, base station  110  may transmit symbols that include chips at a desired chip rate over a channel  160 , if desired. Mobile station  140  may also transmit symbols that include chips at a desired chip rate to base station  110  over channel  160 , if desired. 
     Turning to  FIG. 2 , a block diagram of a transmitter  200  according to an exemplary embodiment of the present invention is shown. Although the scope of the present invention is not limited in this respect, in some embodiments of the present invention, transmitter  200  may include a processor  210 , a baseband unit  220 , digital to analog (D/A) converters  240 ,  245 , modulator (MOD)  250 , a power amplifier (PA)  260 , and at least one antenna  270 . 
     Although the scope of the present invention is not limited in this respect, baseband unit  220  may be a digital baseband unit and may include a data bit source  221 , a control bit source  222 , an adder  223 , an adder  224 , a spreading generator  225 , a pseudo-random code (PRC) generator  226 , shape filters  227 , shape filters  228 , an adder  229 , an adder  230 , and a scrambler  231 . Although the scope of the present invention is not limited in this respect, scrambler  231  may include adders  235 . 
     Although the scope of the present invention is not limited in this respect, processor  210  may be a digital signal processor (DSP), a controller, or any other suitable type of processor. Processor  210  may control the gains of shape filters  227 , shape filters  228  and PA  260 , if desired. 
     Although the scope of the present invention is not limited in this respect, baseband unit  220  may be a digital base band and may be implemented by software, by hardware or by any combination of software and/or hardware, if desired. In some embodiments of the invention, data bits source  221  may provide, for example, data bits generated by a packet switch source, data bits generated by a computer communication network (e.g., Internet) or circuit source such as, for example, audio vocoders, video vocoder or the like. Furthermore, data bits may also undergo various manipulations such as, for example, channel encoding, ciphering, interleaving, or any other bit manipulation known in the art. Control bits source  222  may provide pilot bits, synchronization patterns, control information for power control, data structure, or any other suitable control information known in the art. In embodiments of the invention, spreading code generator  225  may generate spreading sequences such as, for example, a Walsh sequence, Hadamard sequence, or the like. Spreading code generator  225  may provide in-phase (I) spreading bits to adder  223  and quadrature (Q) spreading bits to adder  224 . In some embodiments of the invention, PRC generator  226 , for example, a Gold generator, a pseudo-noise (PN) generator or any other type of generator of pseudo-random sequences may provide I and Q PRC bits to scrambler  231 . 
     Although the scope of the present invention is not limited in this respect, for example, scrambler  231  may include four adders  235 . In some embodiments of the invention, adders  235  may add I and/or jQ PRC bits to output bits of adder  223  and/or adder  224 , to provide a scrambled output of scrambled control bits and scrambled data bits, for example, a scrambled I+jQ signal, to shape filters  227  and to shape filters  228 , respectively, if desired. 
     Although the scope of the present invention is not limited in this respect, shape filters  227  may provide a digital I shaped signal to D/A  245  and shape filters  228  may provide a digital shaped signal to D/A  240 . In some embodiments of the invention, D/As  245  and  240  may convert the digital I and Q signals, respectively, into analog I and Q signals, respectively, that may be provided to modulator  250 . In some embodiments of the invention, modulator  250  may modulate and combine the I and Q analog signals, as is known in the art, and may generated a modulated RF signal. PA  260  may amplify and transmit the modulated RF signal via antenna  270 . 
     Although the scope of the present invention is not limited in this respect, modulator  250  may modulate the I, Q analog signals according to a desired modulation scheme such as, for example, binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), quadrature-amplitude modulation (QAM) with different order such as, for example, QAM16, QAM32, QAM64, QAM128, QAM256, etc., differential BPSK (DBPSK), differential QPSK (DQPSK), or the like. 
     Although the scope of the present invention is not limited in this respect, types of antennas that may be used for at least one antenna  270  may include an internal antenna, a dipole antenna, an omni-directional antenna, a monopole antenna, an end fed antenna, a circularly polarized antenna, a micro-strip antenna, a diversity antenna, and the like. In some embodiments of the invention, more multiple antennas may be used, if desired. 
     Although it should be understood that the scope of the present invention is not limited in this respect, processor  210  may provide beta values β(e.g. via control line  212 ) and β(e.g. via control line  214 ) to filters  227  and  228 , respectively. In some embodiments of the invention, due to a wide range of beta values, for example, the exemplary beta value ranges provided below, the coefficients of filters  227 ,  228  may have a wide dynamic range. In order to provide constant root-mean square (RMS) level of I and Q signals, and a desired error vector magnitude (EVM) ratio, the beta values may be multiplied by filters  227 ,  228  coefficients to provide the desired EVM ratio. In addition, processor  210  may use a control line  216  to vary the power of PA  260  to a desired power level. 
     Although the scope of the present invention is not limited in this respect, calculations based on exemplary beta values and a desired power levels are given below. For example, if βc= 1/15 and βd=1, at a nominal power level of 2, the corresponding control values provided to PA  260  may be calculated to be βC′= 1/15*3.98=0.26 and βd′=1*3.98, and the RF compensation in this example may be equal to −27.6 dB (e.g. 20log(3.98)). In some embodiments of the invention, the RMS value at the output of D/A  245 ,  240  may be substantially constant and may be, for example, a maximum over the range of the possible gain values, if desired. 
     Turning to  FIG. 3  a block diagram of a transmitter  300  according to another exemplary embodiment of the present invention is shown. Although the scope of the present invention is not limited in this respect, in some embodiments of the present invention, transmitter  300  may include a processor  310 , a baseband unit  320 , digital to analog (D/A) converters  345 ,  340 , modulator (MOD)  350 , a power amplifier (PA)  360 , and at least one antenna  370 . 
     Although the scope of the present invention is not limited in this respect, baseband unit  320  may be a digital baseband unit and may include a data bit source  321 , a control bit source  322 , a spreading generator  325 , a pseudo-random code (PRC) generator  326 , shape filters  327  and shape filters  328  and a logic unit  380 . It should be understood that transmitter  300  may perform functions substantially similar to the functions preformed by transmitter  200  of  FIG. 2 , as described above, and may include similar components. For example, logic unit  380  may include components similar or identical to adder  223 , adder  224 , adder  229 , adder  230  and scrambler  231  of  FIG. 2 , if desired. 
     Although the scope of the present invention is not limited in this respect, in some embodiments, the at least one data bit source  321  of baseband unit  320  may include a plurality of data bit sources  321 , which may provide data bits to a plurality of data channels, and control bit source  322  that may provide control bits to a control channel, if desired. Although the scope of the present invention is not limited in this respect, in some embodiments of the invention the gain of filters  327  and  328  may be adjusted by processor  310 , if desired. 
     While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications, substitutions, changes, and equivalents as may fail within the true spirit of the invention.