MXPA00002633A - A method of and apparatus for transmitting data in a multiple carrier system - Google Patents

Abstract

A method of an apparatus for transmitting data in a multiple carrier system comprises encoding data and dividing the resulting encoded symbols for transmission on different frequencies. The transmitter comprises a control processor (50) for determining the capacity of each of a plurality of channels and selecting a data rate for each channel depending on the determined capacity. A plurality of transmission subsystems (56 to 72) are responsive to the control processor (50). Each transmission subsystem is associated with a respective one of the plurality of channels for scrambling encoded data with codes unique to the channel for transmission in the channel. Avariable demultiplexer (56) under the control of the control processor (50) demultiplexes the encoded data into the plurality of transmission subsystems at a demultiplexing rate derived from the data rates selected for the channels by the controller. In one embodiment of the transmission subsystems, the encoded symbols are provided to a symbol repetition unit (58) which keeps the symbol rate of data to be transmitted fixed. In another embodiment, no symbol repetition is provided and variable length Walsh sequences are used to handle data rate variations.

Description

METHOD AND APPARATUS FOR TRANSMITTING DATA IN A MULTIPLE CARRIER SYSTEM I. FIELD OF THE INVENTION The present invention relates to a method and apparatus for transmitting data in a multiple carrier system. The present invention can be used to maximize the performance of the system and to increase the diversity of the signal to dynamically multiplex signals in multiple carriers, in an extended spectrum communication system.

II. Description of Related Art It is desirable to be able to transmit data at speeds that are greater than the maximum data rate of a single CDMA channel. A traditional CDMA channel (as it is standardized for cellular communication in the United States), is capable of carrying digital data at a maximum speed of 9.6 bits per second, using a 64-bit Walsh dispersion function, at 1.2288 MHz. Many solutions have been proposed for this problem. One solution is to assign multiple channels to the users and allow these users to transmit and receive data in parallel in the plurality of channels available to them. Two methods for providing multiple CDMA channels for use by a single user are described in co-pending US Patent Application Serial No. 08 / 431,180, entitled "METHOD AND APPARATUS FOR PROVIDING VARIABLE SPEED DATA IN A SYSTEM OF COMMUNICATIONS USING STATISTICAL MULTIPLEXING ", filed on April 28, 1997, and United States Patent Application, Serial No. 08 / 838,240, entitled" METHOD AND APPARATUS FOR PROVIDING VARIABLE SPEED DATA IN A COMMUNICATIONS SYSTEM USING CHANNELS OF NON-ORTOGONAL OVERFLUX ", presented on April 16, 1997, both of which are assigned to the assignee of the present invention, and are incorporated herein by reference. In addition, the frequency diversity can be obtained by transmitting data over multiple extended spectrum channels, which are separated from one another in frequency. A method and apparatus for redundantly transmitting data over multiple CDMA channels is described in U.S. Patent No. 5,166,951, entitled "EXTENDED HIGH-CAPACITY SPECTRUM CHANNEL", which is incorporated herein by reference. The use of modulation techniques with code division multiple access (CDMA) is one of several techniques to facilitate communications in which a large number of users of the system are present. Other techniques of the multiple access communication system, such as time division multiple access (TDMA), frequency division multiple access (FDMA), and AM modulation schemes, such as the single sideband with compressed-expanded amplitude (ACSSB), are known in the art. However, the extended spectrum modulation technique of the CDMA has significant advantages over these other modulation techniques for multiple access communication systems. The use of CDMA techniques in a multiple access communication system is described in U.S. Patent No. 4,901,307, entitled "COMMUNICATION SYSTEM WITH MULTIPLE ACCESS OF EXTENDED SPECTRUM USING SATELLITE OR TERRESTRIAL REPEATER", assigned to transferee of the present invention, and incorporated herein by reference. The use of CDMA techniques in a multiple access communication system is further described in U.S. Patent No. 5,103,459, entitled "SYSTEM AND METHOD FOR GENERATING SIGNAL WAVE FORMS IN A CDMA CELLULAR TELEPHONE SYSTEM" , assigned to the assignee of the present invention and incorporated herein by reference. Multiple division code access communications systems have been standardized in the United States in the Interim Standard of the Telecommunications Industry Association, IS-95, entitled "Compatibility Standard for a Mobile Station-Base Station for a Spectrum Cell System Extended with Dual Mode Bandwidth ", which is incorporated here as a reference. The CDMA waveform, by its inherent nature, being a bandwidth signal, offers a form of frequency diversity, extending the energy of the signal over a wide bandwidth. Therefore, the selective fading of the frequency affects only a small part of the CDMA signal bandwidth. The diversity of the space or trajectory in the sending / reversing link is obtained by providing multiple signal paths through simultaneous links to / from a mobile user, through two or more antennas, cell sectors or cell sites. In addition, path diversity can be obtained by exploiting the multi-trajectory medium through extended spectrum processing, allowing a signal up? with different propagation delays, it is received and processed separately. Examples of the use of path diversity are illustrated in copending U.S. Patent No. 5,101,501 entitled "FLEXIBLE TRANSFER IN A CDMA CELLULAR TELEPHONE SYSTEM" and U.S. Patent No. 5,109,390. entitled "RECEIVER OF DIVERSITY IN A CELLULAR TELEPHONE SYSTEM CDMA", both assigned to the assignee of the present invention and incorporated herein by reference. FIGURE 1 illustrates a transmission scheme for a code division multiple access system (CDMA) with multiple carriers, in which each carrier carries a fixed fraction of the transmitted data. The information bits of the block with variable speed are provided to the encoder 2, which encodes the bits according to a convolutional coding format. The coded symbols are provided to the repeating means of the symbols 4. The repeating means of the symbols 4 repeat the coded symbols to provide a fixed symbol rate at the output of the symbol repetition means 4, regardless of the speed of the information bits. The repeated symbols are provided to the block interleaver 6, which rearranges the sequence in which the symbols are to be transmitted. The interleaving process, coupled with the error correction sent, provides the diversity of time, which helps in the reception and recovery of errors of the transmitted signal, in view of the burst errors. The interleaved symbols are provided to the symbol mixer 12. The symbol mixer 12 multiplies each interleaved symbol by +1 or -1, according to a pseudonoise (PN) sequence. The pseudonoise sequence is provided by passing a long PN sequence, generated by a long code generator 8, at the rate of the portions, through the decimator 10, which selectively provides a subset of portions of the long code sequence , at the speed of the interspersed symbol flow. The data from the data mixer 12 is provided to the demultiplexer (DEMUX) 14. The demultiplexer 14 divides the data stream into three equal sub streams. The first subflow is provided to the transmission subsystem 15a, the second subflow to the transmission subsystem 15b, and the third subflow to the transmission subsystem 15c. The sub-blocks are provided to the series-to-parallel converters (BINARIO AT LEVEL 4), 16a-16c. The outputs of the series-to-parallel converters 16a-16c are quaternary symbols (2 bits / symbol) to be transmitted in the QPSK modulation format. The signals of the series to parallel converters 16a-16c are provided to the Walsh encoders 18a-18c. In the Walsh encoders 18a-18c, the signal of each of the converters 16a-16k is multiplied by a Walsh sequence consisting of ± 1 values. The encoded Walsh data is provided to the QPSK 20a-20c propagators, which propagate the data according to two short PN sequences. The signals propagated with the short PN sequence are provided to the amplifiers 22a-22b, which amplify the signals according to the gain factor. The system described above suffers from a plurality of disadvantages. First, because the data is provided in equal subflows in each of the carriers, the available numerology is limited to blocks with a number of code symbols that will be divided integer by a factor of three. Table 1 below illustrates the limited number of possible velocity sets, which are available using the transmission system illustrated in FIGURE 1.

Table 1 As illustrated in Table 1, because the symbols are distributed evenly across the three carriers, the total data rate is limited by the carrier, with the power less available or requiring the higher SNR. That is, the total data rate is equal to three times the data rate of the "worst" link (here, worse means the one that requires the higher SNR or that has the least available power). This reduces the performance of the system, because the worst link speed is always chosen as the common speed for all three carriers, which results in underutilization of the channel source in the two best links. Second, fading that depends on frequency can severely affect one of the frequencies, while having a limited effect on the remaining frequencies. This implementation is not flexible and does not allow the transmission of a block, that is provided in a way that reduces the effect of the poor channel. Third, due to fading that depends on the frequency, fading typically always affects the same groups of symbols in each block. Fourth, if the implementation is to be superimposed on a voice transmission system, there is no good way to balance the loads carried at the different frequencies on a block-by-block basis, in view of variable voice activities in each block. This results in a loss in the total system performance. And fifth, for a system with only three frequency channels, with the described implementation, there is no method to separate the voice and the data, to provide the data in a frequency or set of frequencies, and the voice in a frequency or sets of different frequencies. This results in a loss of system performance, as mentioned above. Therefore, there is a need for a CDMA communication system with multiple carriers improved, which offers greater flexibility in numerology and load balancing, better resolution at the data rates supported and which offers superior performance, in view of fading that depends on frequency and non-uniform charge.

BRIEF DESCRIPTION OF THE INVENTION In one aspect, the invention provides a transmitter for transmitting data at a data rate, in a plurality of channels, each having a capacity less than the data rate, the transmitter comprises: a controller for determining the capacity of each of the plurality of channels and selecting a data rate for each channel, depending on the determined capacity; a plurality of transmission subsystems, responsive to the controller and each associated with a respective one of the plurality of channels, for mixing the data with codes unique to the channel, for transmission in the channel; and a variable demultiplexer responsive to the controller, for demultiplexing the encoded data in the plurality of transmission subsystems, at a demultiplexing rate derived from the data rates selected for the channels by the controller. In another aspect, the invention provides a receiver comprising: a receiver circuit for simultaneously receiving signals in a plurality of channels, each of the signals defining mixed symbols, which together represent, data of a common origin, a controller for determining a symbol speed for the signals in each channel; a plurality of receiver subsystems, responsive to the controller and each associated with a respective one of the plurality of channels for ordering the codes encoded with codes unique to the channel, to allow the data to be extracted therefrom; and a variable multiplexer responsive to the controller, for multiplexing the data of the plurality of reception subsystems, at a demultiplexing rate that is derived from the symbol rates determined for the channels per in controller, in one output.

In a further aspect, the invention provides a wireless transmitter, comprising: an encoder for receiving a set of information bits and encoding the information bits to provide a set of code symbols; and a transmission subsystem for receiving the code symbols and for providing a subset of code symbols on a first carrier frequency and the rest of the symbols on at least one additional carrier frequency. The invention also provides a method for transmitting data at a data rate, in a plurality of channels, each having a capacity less than the data rate, the method comprising: determining the capacity of each of the plurality of channels and select a data rate for each channel, depending on the determined capacity; mixing the encoded data with codes unique to the channel, for transmission in the channel, and demultiplexing the encoded data in the plurality of channels at a demultiplexing rate derived from the data rates selected for the channels by the controller. The invention further provides a method for receiving data, the method comprising: receiving signals simultaneously in a plurality of channels, each of the signals defining mixed coded symbols, which together represent, data of a common origin, determining a speed of symbol for the signals in each channel; order symbols coded with codes in each channel, with codes unique to the channel, to allow data to be extracted from them; and multiplexing the ordered data of the plurality of channels at a multiplexing rate that is derived from the symbol rates determined for the channels. To better use the channel source, it is necessary to be able to transmit at a different data rate, on each carrier, according to the condition of the channel and the available power on each channel. One way to do this is by changing the proportion of the inverse multiplex in each of the carriers. Instead of distributing the symbols with a ratio of 1: 1: 1, a more arbitrary ratio can be used, together with different repetition schemes, provided that the resulting symbol speed in each carrier is a factor of the speed of the Walsh function. The speed of the Walsh function can be 1228800, 614400, 307200, ..., 75 for a length of the Walsh function from 1 to 16384. Give the length of the Walsh function, if the symbol rate is less than The speed of the Walsh function, the symbol repetition is used to "match" the speed. The repetition factor can be any number, integer or fractional. It will be understood by one skilled in the art that when repetition is present, the total transmit power can be proportionally reduced to maintain the energy of the constant code symbol. The length of the Walsh function may or may not be the same in all three carriers, depending on whether we need to save the code channels. For example, if the bearable code symbol speed in all three channels is 153600 sps, 30720 sps and 102400 sps (for speed coding, these correspond to data rates of 76.8 kbps, 15.36 kbps and 51.2 kbps). , respectively - the total data rate is 143.36 kbps), therefore, the inverse multiplexing ratio will be 15: 3: 10. If a Walsh function with a length of 8 is used for all three channels (assuming a QPSK modulation with a QPSK symbol rate of 153.6 Ksps), then each code symbol is transmitted twice, 10 times, and three times in the three channels, respectively. Additionally, time diversity may be obtained if the repeated symbols are interspersed further. In an alternative mode, different lengths of the Walsh function are used. For example, Walsh functions can be used for the three channels in the previous example, of a length of 16, 16 and 8, respectively, with each code symbol transmitted once in the first channel, five times in the second and three times In the third. The above method does not affect the encoder, since it has to be capable of the highest data rate in any way. All that changes is the number of data octets in the encoder input. However, this method has no impact on the implementation of the interleaver, because the interleaver will have many possible sizes (in terms of the number of symbols), if all combinations of data rates in all three channels are allowed. An alternative to the previous method, which mitigates this problem, is to multiplex inverse the code symbols at the output of the encoder, to the three carriers directly, and perform the interleaving of the repeated code symbols on each channel, separately . This simplifies the numerology and reduces the number of possible sizes of the interleaver in each channel.

BRIEF DESCRIPTION OF THE DRAWINGS The features, objects and advantages of the present invention will become more apparent from the detailed description set forth below, of the embodiments of the invention, when taken in conjunction with the drawings, in which the characters similar reference numbers identify accordingly and where: FIGURE 1 is a block diagram illustrating a multi-frequency CDMA communication system, with fixed speeds and carriers; FIGURE 2 is a block diagram illustrating a transmission system embodying the present invention; FIGURE 3 is a block diagram illustrating a receiver system embodying the present invention; and FIGURE 4 is a table of the Walsh symbols of the code channel, in a traditional CDMA IS-95 communication system.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Referring to FIGURE 2, which is a block diagram illustrating a transmission system embodying the present invention; The first operation to be performed is to determine the amount of data that can be supported in each of the carriers. Three such carriers are illustrated in FIGURE 2, although one skilled in the art will realize that the present invention can easily be extended to any number of carriers. The control processor 50, based on a set of factors, such as the load on each of the carriers, the amount of data put in a row for transmission to a mobile station and the priority of the information to be transmitted to the mobile station, determines the speed of data transmission in each of the carriers. After the speed of the data to be transmitted has been selected in each of the carriers, the control processor 50 selects a modulation format that is capable of transmitting data at the selected speed. In the exemplary mode, Walsh sequences of different lengths are used to modulate the data, depending on the speed of the data to be transmitted. The use of Walsh sequences of different length to modulate the data, depending on the speed of the data to be transmitted, is described in U.S. Patent Application, co-pending, Serial No. 08 / 654,443, filed in Mayor 28, 1996, entitled "WIRELESS COMMUNICATION SYSTEM WITH HIGH SPEED DATA", which was assigned to the assignee of the present invention and is incorporated herein by reference. In an alternative embodiment, the high-speed data can be supported by joining the CDMA channels as described in the aforementioned Patent Applications, Serial Nos. 08 / 431,180 and 08 / 838,240. Once the speeds that will be supported by each of the carriers has been selected, then the control processor 50 calculates a proportion of inverse multiplexing, which will determine the amount of each transmission that will be carried on each of the carriers. For example, if the bearable code symbol speed in all three channels is 153600 sps, 30720 sps, and 102400 sps (for speed coding, these correspond to data rates of 76.8 kbps, 15.36 kbps, and 51.2 kbps, respectively - the total data rate is 143.36 kbps), therefore, the inverse multiplexing ratio will be 15: 3: 10. In the exemplary embodiment, the blocks of the information bits are provided to the device to format block 52. In the exemplary mode, the formatting device 52 generates and appends to the block, a set of check bits of 1. cyclic redundancy (CRC). In addition, the device for formatting 52 appends a predetermined set of bits of the back or tail. The implementation and design of the devices for block formatting is well known in the art, an example of a typical block formatting device, is described in detail in U.S. Patent No. 5,600,754, entitled, "METHOD AND SYSTEM FOR THE ARRANGEMENT OF DATA OF A VOCODER FOR THE MASKING OF ERRORS INDUCED BY THE TRANSMISSION CHANNEL", which was assigned to the transferee of the present invention and was incorporated herein by reference. The formatted data is provided to the encoder 54. In an exemplary embodiment, the encoder 54 is a convolutional encoder, although the present invention may be extended to other forms of encoding. A signal from the control processor 50 indicates to the encoder 54 the number of bits to be encoded in this transmission cycle. In an exemplary embodiment, the encoder 54 is a convolutional encoder with a speed of H, with a restricted length of 9. It should be noted that due to the additional flexibility provided by the present invention, essentially any encoding format can be used.

The coded symbols of the encoder 54 are provided to a variable proportion demultiplexer 56. The variable proportion demultiplexer 56 provides the coded symbols to a set of outputs based on a symbol output signal provided by the control processor 50. In the embodiment exemplary, there are three carrier frequencies and the control processor 50 provides a signal indicative of the number of coded symbols to be provided at each of the three outputs. As one skilled in the art will appreciate, the present invention easily extends to an arbitrary number of frequencies. The coded symbols provided in each of the outputs of the variable ratio demultiplexer 56 are provided to the corresponding symbol repetition means 58a-58c. The symbol repetition means 58a-58c generates repeated versions of the coded symbols, so that the resulting symbol rate coincides with the speed of the particular Walsh function used in that carrier. The implementation of the repeat generators 58a-58c is known in the art and an example thereof is described in U.S. Patent No. 5,629,955, entitled "Variable Response Filter", which was assigned to the transferee of the present invention and is incorporated herein by reference. The control processor 50 provides a separate signal to each repetition generator 58a-58c, indicating the speed of the symbols on each carrier or alternately, the amount of repetition to be provided on each carrier. In response to the signal from the control processor 50, the repeating means 58a-58c generates the required numbers of the repeated symbols to provide the designated symbol rates. It should be noted that in the preferred embodiment, the repetition amount is not limited to an integer, where all the symbols are repeated the same number of times. A method for providing a non-entire repetition is described in detail in U.S. Patent Application Serial No. 08 / 886,815, filed on March 26, 1997, entitled "METHOD AND APPARATUS FOR TRANSMITTING HIGH SPEED DATA IN A EXTENDED SPECTRUM COMMUNICATIONS SYSTEM ", which was assigned to the assignee of the present invention and is incorporated herein by reference. The symbols of the repetition generators 58a-58c are provided to a corresponding one of the interleavers 60a-60c, which rearranges the repeated symbols according to a predetermined interleaver format. The control processor 50 provides 2 a signal of the interleaver format to each of the interleavers 60a-60c, which indicate one of a predetermined set of interleaving formats. In exemplary mode, the collation format is selected from a predetermined set of bit inversion interleaving formats. The reordered symbols of the interleavers 60a-60c are provided to the data mixers 62a-62c. Each of the data mixers 62a-62c changes the sign of the data, according to a pseudonoise (PN) sequence. Each PN sequence is provided by passing a long PN sequence, generated by a long code generator or PN 82 generator, at the rate of the portions, through the decimator 84a-84c, which selectively provides some of the scattered symbols for provide a PN sequence at a speed no greater than that provided by the PN 82 generator. Because the symbol rate at each carrier may be different from one another, the decimation rate of the decimators 84a-84c may be different. The decimators 84a-84c are sample and hold circuits, which take samples of the PN sequence at the output of the PN 82 generator, and continue to produce that value for a predetermined period. The implementation of the PN 82 generator and decimators 84a-84c, is well known in the art, and is described in detail in the aforementioned U.S. Patent No. 5,103,459. The data mixers 62a-62c, OR exclusively the binary symbols of the interleavers 60a-60c with the binary pseudo-noise sequences decimated, of the decimators 84a-84c. Mixed, binary symbol sequences are provided to series-to-parallel converters (BINARY AT LEVEL 4), 64a-64c. Two binary symbols provided to the 64a-64c converters are plotted in a quaternary constellation, with values (± 1, +1). The values of the constellation are provided in two outputs of the converters 62a-62c. The symbol flows of the converters 64a-64c are provided separately to the Walsh propagators 66a-66c. There are many methods to provide data at high speed in a communication system with multiple access by division of code. In the preferred embodiment, the length of the Walsh sequence is varied according to the speed of the data to be modulated. Short Walsh sequences are used to modulate the data with higher speed and long Walsh sequences are used to modulate the data with lower speed. For example, a 64-bit Walsh sequence can be used to transmit data at 19.2 Ksps. However, a 32-bit Walsh sequence can be used to modulate data at 38.4 Ksps. A system describing a modulation of the variable length Walsh sequence is described in detail in copending U.S. Patent Application No. 08 / 724,281, entitled "SUPPLEMENTARY CHANNEL FOR HIGH-SPEED DATA FOR A CDMA TELECOMMUNICATION SYSTEM. ", presented on January 15, 1997, and incorporated here as a reference. The length of the Walsh sequences used to modulate the data depends on the speed of the data to be transmitted. FIGURE 4 illustrates the Walsh functions in a traditional IS-95 CDMA system. In the preferred embodiment of the invention, the number of Walsh channels allocated for the high-speed data can be any 2N value, where N =. { 2. 3. 4, , 6.}. . The Walsh codes used by the Walsh codecs 66a-64c are 64 / 2N length symbols, instead of the 64 symbols used with the Walsh IS-95 codes. In order for the high-speed channel to be orthogonal with the other channels with the Walsh codes of 64 symbols, 2N of the 64 possible channels with quaternary phase with Walsh of 64 symbols, are removed from use. Table I provides a list of the possible Walsh codes for each value of N, and the corresponding sets of the Walsh codes of 64 symbols, assigned.

Walsh, Walsh Codes of 64 Assigned Symbols +, + +, + 0, 16.32,48 + + 1,17,33,49 2, 18,34,50 3,19,35,51 4,20, 36 , 52 -, -, + -. + 5,21,37,53 6,22,38,54 +, -, +, +, 7,23,39,55 rrrr 8,24,40,56 9,25 , 41.57 +, +, 10.26.42.58 11.27.43.59 12.28.44, 60 13.29.45.61 14.30.46.62 15.31.47.63 0.8,16.24, 32,40,48,56 1,9,17,25,33,41,49,57 2,10,18,26,34,42,50,58, 3.11.19.27.35.43.51.59, 4.12.20.28. 36.44.52.60, 5,13,21,29,37,45,53, 61, 6, 14,22, 30, 38, 46, 54, 62, +, - 7,15,23,31,39,47 , 55, 63 Table I Table I (continued) The + and - indicates a positive or negative integer value, where the preferred integer is 1. As is evident, the number of Walsh symbols in each Walsh code varies as N varies, and in all cases, is less than the number of symbols in the Walsh IS-95 channel codes. Regardless of the length of the Walsh code, in the embodiment described in the invention, the symbols are applied at a speed of 1.2288 Mega-per-second (Mcps). Thus, Walsh codes of shorter length are repeated more frequently. The control processor 50 provides a signal to the Walsh coding elements 66a-66c, which indicates the Walsh sequence to be used to propagate the data. Alternative methods for transmitting data at high speed in the CDMA communication system also include methods generally referred to as channel joining techniques. The present invention is equally applicable to methods for joining channels to provide high-speed data in a CDMA communication system. One method for providing linked channel data is to provide a plurality of Walsh channels to be used by a user of the signal. This method is described in detail in U.S. Patent Application Serial No. 08 / 739,482, mentioned above. An alternative channel joining technique is to provide the user with the use of a Walsh code channel but at different signals from one another by means of different mixing signals, as described in detail in the US Patent Application. United Series No. 08 / 838,240. The propagated Walsh data is provided to propagators PN 68a-68c, which apply a propagation of the short PN sequence, in the output signals. In the exemplary embodiment, the PN propagation is performed by means of a complex multiplication, as described in detail in copending United States Patent Application Serial No. 08 / 784,281, mentioned above. The data channels Dt and DQ are multiplied complex, like the first real and imaginary terms respectively, with the propagation codes PN! and PNQ, as the second real and imaginary terms, respectively, producing the term Xi in phase (or real) and the term XQ in the quadrature (or imaginary) phase. The PNi and PNQ propagation codes are generated by the propagation code generators 67 and 69. The PNT and PNQ propagation codes are applied to 1.2288 Mcps. Equation (1) illustrates the complex multiplication performed. (Xi + jXQ) = (DT + jDQ) (PNT + jPNQ) (1) The term Xt in phase is then filtered with a low pass filter at a bandwidth of 1.2288 MHz (not shown), and converts upwards by a multiplication with the COS phase carrier (coct). Similarly, the term XQ in quadrature phase is then filtered with a low pass filter at a bandwidth of 1.2288 MHz (not shown), and is converted upwardly by a multiplication with the carrier in phase of quadrature SIN (? Ct). The terms Xt and XQ converted in an ascending manner are summed, providing the signal of the sending link s (t). The complex multiplication allows the set of the channel in quadrature phase to remain orthogonal to the set of the channel in phase, and therefore, to be provided without adding additional interference to the other channels transmitted on the same path with a phase recovery of the receiver, perfect The PN propagated data is then provided to the filters 70a-70c, which spectrally form the signals for transmission. The filtered signals are provided to the gain multipliers 72a-72c, which multiply the signals for each carrier. The gain factor is supplied to the gain elements 72a-72c, by the control processor 50. In the exemplary embodiment, the control processor 50 selects the gain factor for each carrier, according to the condition of the channel and with the speed of the information data to be transmitted on that carrier. As known to one skilled in the art, data that is transmitted with repetition can be transmitted with a lower symbol energy than data without repetition. The amplified signals are provided to an optional switch 74. The switch 74 provides additional flexibility of the channel, by skipping the data signals on different carriers. Typically, switch 74 is used only when the number of carriers currently used to transmit the signal is less than the total number of possible carriers (3 in the present example).

The data is passed through the switch 74 to the modulators of the carrier 76a-76c. Each of the modulators of the carrier 76a-76c, up-converts the data to a different predetermined frequency. The upconverted signals are provided to the transmitter 78, where they are combined with other signals processed in a similar manner, filtered and amplified for transmission through the antenna 80. In the exemplary embodiment, the amplified frequency with which each of The signals are transmitted, vary with time. This provides an additional frequency diversity, for the transmitted signals. For example, a signal that is currently transmitted through the carrier modulator 76a will be switched to a predetermined time interval, so that it will be transmitted at a different frequency through the modulators of the carrier 76b or 76c. In accordance with a signal from the control processor 50, the switch 74 directs an amplified input signal from the gain multiplier 72a-72c, to an appropriate carrier modulator 76a-76c. Returning to FIGURE 3, a receiver system embodying the present invention is illustrated. The signal received in the antenna 100 is passed to a receiver (RCVR) 102, which amplifies and filters the signal before it is provided to the switch 104. The data is provided through the switch 104, to a demodulator of the carrier 106a-106c appropriate. It will be understood by one skilled in the art that although the structure of the receiver is described for the reception of a signal transmitted on three frequencies, the present invention can easily be extended to an arbitrary number of frequencies, consecutive to one another or not. When the carriers on which the data is transmitted, rotated or jumped to provide additional frequency diversity, the switch 104 provides the received signal to a demodulator of the selected carrier 106a-106c, in response to the processor control signal control 125. When the carrier frequencies are not skipped or rotated, switch 104 is not necessary. Each of the demodulators of carrier 106a-106c, Quaternary Phase Shift Keying (QPSK), demodulates the received signal to a baseband using a differently descending converted frequency, to provide separate baseband I and Q signals. The signals down-converted from each of the demodulators of the carrier 106a-106c are provided to a PN binder 108a-108c, which removes the propagation of the short code from the converted data in a downward manner. The I and Q signals are depropagated by a complex multiplication with a pair of short PN codes. PN non-propagated data is provided to the Walsh HOa-llOc demodulators, which do not cover the data according to the allocated code channel sequences. In exemplary mode, Walsh functions are used in the generation and reception of CDMA signals, but other forms of code channel generation are equally applicable. The control processor 125 provides a signal to the Walsh HOa-llOc demodulators, which indicate the Walsh sequences to be used to discover the data. The non-propagated Walsh symbols are provided to the parallel-to-series converters (LEVEL 4 A BINARY), 112a-112c, which plot the two-dimensional signal in a one-dimensional signal. The symbols are provided to computers 114a-114c. The computers 114a-114c order the data according to a long decimated code sequence, generated as described with respect to the decimated long code sequences used to mix the data in FIGURE 2.

The ordered data is provided to deinterleavers (DE-INT) 116a-116c. The deinterleavers 116a-116c, reorder the symbols according to the selected deinterleaving formats that are provided by the control processor 125. In the exemplary mode, the control processor 125 provides a signal indicative of the size of the deinterleaving and the scheme of deinterleaving for each of the deinterleavers 116a-116c. In the exemplary embodiment, the de-interleaving scheme is selected from a predetermined set of reverse bit de-interleaving schemes. The deinterleaved symbols are then provided to the symbol combiners 118a-118c, which coherently combine those symbols that are repeatedly transmitted. The combined symbols (flexible decisions), are then provided to a variable proportion multiplexer 120, which reassembles the data stream and provides the data stream mounted again to the decoder 122. In the exemplary embodiment, the decoder 122 is a probability decoder. maximum, the implementation of which is well known in the art. In the exemplary embodiment, the decoder 122 contains a buffer (not shown), which waits until the complete data block has been provided to it, before beginning the decoder process. The decoded block is provided to the CRC 124 verification means, which determine whether the verification of the CRC bits and if so, provides them to the user, otherwise a deln is declared. Having thus described the invention, with reference to the preferred embodiment, it will be understood that the modality in question is exemplary only and that modifications and variations as will occur to those who possess appropriate knowledge and skills, can be made without departing from the spirit and scope of the invention, as set forth in the appended claims and equivalents thereof. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (39)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property.

1. A transmitter for transmitting data at a data rate in a plurality of channels, each having a capacity less than the speed of the data, the transmitter is characterized in that it comprises: a controlled to determine the capacity of each of the plurality of channels and selecting a data rate for each channel, depending on the determined capacity; a plurality of transmission subsystems, responsive to the controller and each associated with a respective one of the plurality of channels for mixing the encoded data with unique codes to the channel for transmission in the channel; and a variable demultiplexer responsive to the controller, for demultiplexing the encoded data in the plurality of transmission subsystems, at a demultiplexing rate derived from the data rates, selected for the channels by the controller.

2. The transmitter according to claim 1, characterized in that it also comprises an encoder for generating coded data of the data input blocks thereof.

The transmitter according to claim 1 or 2, characterized in that each transmission subsystem comprises a symbol repetition unit for repeating the symbols to produce them at a speed corresponding to the speed selected for the channel by the controller.

The transmitter according to claim 3, characterized in that each transmission subsystem comprises an interleaving unit for reordering repeated symbols depending on an interleaved format determined by the controller.

The transmitter according to claim 4, characterized in that it further comprises a long code generator, for generating a respective long code for each channel, and in each transmission subsystem, a mixer for mixing the reordered symbols using the code respective for the channel.

6. The transmitter according to claim 5, characterized in that the long code generator comprises for each channel, a decimator unit for decimating a long code generated at a decimation speed determined by the controller, to produce the respective long codes for each channel.

The transmitter according to claim 6, characterized in that it also comprises variable coding units, in each transmission subsystem, for modulating the mixed symbols of the mixer.

The transmitter according to claim 7, characterized in that the coding units are arranged to modulate the symbols mixed with a walsh code.

The transmitter according to claim 7 or 8, characterized in that it also comprises a pseudonoise propagator in each channel, for propagating the modulated symbols.

The transmitter according to any of the preceding claims, characterized in that it further comprises: a switch; and a plurality of carrier modulators, where the switch responds to the controller for switching the mixed data of the plurality of transmission subsystems between the plurality of carrier modulators, for modulating signals on different carriers at different times.

11. A receiver, characterized in that it comprises: a receiver circuit pair receiving signals simultaneously in a plurality of channels, each of the signals defines mixed coded symbols, which, together, represent the data of a common origin; a controller to determine the symbol rate for the signals in each channel; a plurality of subsystems that respond to the controller and each one associated with a respective one of the plurality of channels for ordering the codes encoded with codes unique to the channel, to allow the data to be extracted from them; and a variable multiplexer, which responds to the controller to multiplex the data of the plurality of receiver subsystems, at a switching speed derived from the symbol rates determined for the channels by the controller, at an output.

The receiver according to claim 11, characterized in that it further comprises a decoder for decoding the encoded data produced by the multiplexer, in data blocks.

13. The receiver according to claim 11 or 12, characterized in that it also comprises a pseudo noise agglucer in each channel, to bind the mixed coded symbols.

The receiver according to claim 13, characterized in that it also comprises variable decoding units in each subsystem to demodulate the non-propagated symbols of the agglutinator.

The receiver according to claim 14, characterized in that the decoding units are arranged to demodulate the symbols not propagated or agglutinated with a respective Walsh code.

16. The receiver according to claim 15, characterized in that it also comprises, in each receiving subsystem, a computer for ordering the symbols not propagated or agglutinated using a respective long code for the channel.

The receiver according to claim 16, characterized in that the subsystem comprises a de-interleaving unit for reordering the repeated symbols depending on the de-interleaving format determined by the controller.

18. The receiver according to claim 17, characterized in that each subsystem comprises a symbol combiner for combining the symbols to produce the same to the demultiplexer, at a speed that corresponds to the speed determined for the channel by the controller.

19. The receiver according to any of claims 11 to 18, characterized in that it further comprises: a switch; and a plurality of modulators of the carriers, where the switch responds to the controller to switch the received signals between the plurality of demodulators of the carriers, for the modulation of signals in different receiving subsystems, at different times.

20. A wireless transmitter, characterized in that it comprises: an encoder for receiving a set of information bits and encoding the information bits to provide a set of code symbols; and a transmission subsystem, for receiving the code symbols and for providing a subset of code symbols on the first carrier frequency and the remaining symbols on at least one additional carrier frequency.

21. A method for transmitting data at a data rate in a plurality of channels, each having a smaller capacity than the data rate, the method is characterized in that it comprises: determining the capacity of each of the plurality of channels and selecting a data rate for each channel, depending on the determined capacity; mix the encoded data with codes unique to the channel, for transmission on the channel; and demultiplexing the encoded data in the plurality of channels at a demultiplexing rate derived from the data rates selected for the channels by the controller.

The method according to claim 21, characterized in that it also comprises an encoder for generating coded data of the data input blocks thereof.

23. The method according to claim 21 or 22, characterized in that it also comprises repeated symbols for each channel to produce them, at a speed corresponding to the speed selected for the channel.

24. The method according to claim 23, characterized in that it also comprises rearranging the repeated symbols depending on a given interleaving format.

25. The method according to claim 24, characterized in that it further comprises generating a respective long code for each channel, and mixing the reordered symbols in each transmission subsystem, using the respective code for the channel.

26. The method according to claim 25, characterized in that the long code generated for each one, decimating a long code generated at a determined decimation rate for each channel.

27. The method according to claim 26, characterized in that it also comprises modulating the symbols mixed with a code.

28. The method according to claim 27, characterized in that the mixed symbols are demodulated with a respective walsh code.

29. The method according to claim 27 or 28, characterized in that it also comprises propagating the modulated symbols with a pseudonoise.

The method according to any of claims 21 to 29, characterized in that it also comprises modulating the mixed data in different carriers at different times.

31. A method for receiving data, the method is characterized in that it comprises: receiving signals simultaneously in a plurality of channels, each of the signals defining mixed coded symbols, which, together, represent the data of a common origin; determine the symbol rate for the signals in each channel; order the coded symbols in each channel, with codes unique to the channel, to allow the data to be extracted from them; and multiplexing the ordered data of the plurality of channels, at a multiplexing rate derived from the symbol rates determined for the channels.

32. The method for receiving data according to claim 31, characterized in that it further comprises decoding the encoded multiplexed data into blocks of data.

The method for receiving data according to claim 31 or 32, characterized in that it further comprises agglutinate the mixed coded symbols using a pseudonoise code.

34. The method for receiving data according to claim 33, characterized in that it further comprises demodulating the non-propagated symbols, by means of a variable decoding.

35. The method for receiving data according to claim 34, characterized in that the non-propagated symbols are demodulated with a respective walsh code.

36. The method for receiving data according to claim 35, characterized in that it also comprises ordering the non-propagated symbols in each channel, using a respective long code for the channel.

37. The method for receiving data according to claim 36, characterized in that it also comprises reordering the repeated symbols' depending on a given interleaving format.

38. The method for receiving data according to claim 37, characterized in that it further comprises combining the symbols in a channel, before demultiplexing them at a speed corresponding to the speed determined for the channel.

39. The method for receiving data according to any of claims 31 to 38, characterized in that it also comprises: demodulating the signals in different channels, at different times.