Determining the data transfer rate for communication systems, multiple access, code-division multiplexing and variable speed transmission
It is proposed to perform data transmission with variable speed and in the same frame that contains the data information is transmitted on the data transmission speed in bits. When using extensions using Walsh codes, the compression process can be divided into two separate compression operations with buffering between the two operations. Buffering is performed with intermediate characters between stages of compression, and can be produced with a maximum transmission rate of user data instead of the much higher speed sequence of code elements. This way you can significantly reduce the size of the buffer in the receiver. The technical result consists in the creation of new methods and systems to transmit information about the speed explicitly in the same frame, which she describes, while minimizing the amount of data that must be buffered in the receiver. 3 S. and 17 C.p. f-crystals, 5 Il. Technical field the Invention relates to data transmission with variable speed, in particular, to methods for effective detection of data transmission with variable speed, when the information about the data transfer rate in bits is passed explicitly.Predseda ways modulation spread spectrum and multiple access code division multiplexing (mdcr). In the conventional system with mdcr the transmitted stream of data is superimposed on the data stream with a much higher bit rate, which is sometimes referred to as the expansion code. Each character expands code is usually called a code element. Information signal and a signal extender code are typically combined by multiplication in the process, sometimes called coding or extension of the information signal. Each information signal is allocated a unique code extends. Many of coded information signals are transmitted as modulations of the radio frequency carrier, which are taken together in the receiver in the form of a combined signal. Each of the coded signals overrides all other coded signals, and signals related to noise, both in frequency and in time. The corresponding information signal can be selected and decoded by correlating the combined signal with one of the unique extend codes.Since radio communication is becoming more and more wide application, to meet the needs of users, it is desirable to provide them with a variety of Radiocommunication services. For example, podremala, Internet access, etc. moreover, it is highly likely that users simultaneously may require multiple communication services of various kinds. For example, for a video conference between two users may require support voice communication and video data. For some of these diverse services will require a relatively high data rate in comparison with traditionally provided in the radio communication by voice, while other services may involve the transmission of data with variable speed. Thus, it is expected that future communication systems must support high speed data transfer and communication with the variable speed transmission of data.To implement communication with the variable speed transmission in wireless systems with mdcr we developed several ways. As for data transmission with variable speeds, these methods include, for example, the use of discontinuous transmission (PP), variables, coefficients of expansion, multitool transmission and coding with variable speed and direct error correction (PIO). In the case of systems that use PP, transmission occurs only in telenova size. The ratio between the part of the frame used for transmission, and the entire frame is usually called a work cycle. For example, when transmitting as fast as possible, i.e. within the whole frame=1, while when the transmission with zero speed, for example, during a pause in the conversation,=0. PP is used, for example, to provide data transmission with variable speed systems designed in accordance with the U.S. standard "Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System", TIA/EIA Interim Standard TIA/EIA/IS-95 (July 1993) and his edition of TIA/EIA Interim Standard TIA/EIA/IS-95 (may 1995). These standards, which define the characteristics of cellular communication systems USA, published by the Association of industry of telecommunications (TIA) and electronics industry Association (EIA), located in Arlington, Virginia.Another known method of providing communication at a variable data rate is the change in expansion coefficient. As mentioned above, in systems with spread spectrum signals extended data transmitted in the available frequency band by multiplying each of the data signals according to the output of characters or code elements of one data symbol, that is, the coefficient of expansion, and maintaining constant the speed of transmission of the code characters. Usually when you use variable expansion factor, its value is limited by the ratio SF=2kSFminwhere SFmin- the minimum value of the coefficient of expansion corresponding to the maximum allowable transmission rate of user data.Another known method of changing the speed of transmitted data is the so-called multinodular transfer. According to this method, data is transmitted using a variable quantity extends codes, where the exact number of codes used depends on the current transmission rate of user data in bits. Example multitool transmission described in patent application U.S. 08/636648 on "Systems and methods mdcr direct modulation sequence mode multitool compressed transfer" from April 23, 1996Another way to change the speed data communications systems involves changing the coding rate with PIO. In particular, the encoding speed direct error correction (PIO) is changed by using the "punch code" and repetition of the motor is changed, while the channel data rate in bits is maintained constant. Specialists in the art it is obvious similarity between encoding speed with PIO and the use of variable coefficient of expansion as the mechanisms that implement the data transmission with variable speed.Regardless of the specific method adopted in the communication system to enable data transmission with variable speed, the receiver must be provided with information about a specific data rate with which the signal is transmitted in order to accurately detect and decode the received signal. Ways of informing the receiver about the current data rate of the received signal generally can be divided into two categories: when in communication systems together with the transferred signal explicitly transmitted information data rate in bits (ISPB); when in communication systems, the receiver has the ability, "acting blindly, to determine the speed with which the transmitted data, for example, trying different speeds and searching using control cyclic redundancy code (CRC). An example of detecting the transfer speed, the barb data "blind") have some drawbacks. For example, determining the transmission speed blindly leads to the necessity of using relatively complex receivers, as they will be required to provide additional schema/logical blocks to correctly identify one of many possible data transmission speeds.Transfer ISPB explicitly also creates a number of problems for developers. For example, ISPS can be sent either in the data frame in front of the frame data that it describes, or send in the same frame, to which this information applies.If IPB is transmitted in the previous frame, the transmitter there is an additional delay of one frame. As soon as the transmitter see the data for a frame is calculated and transmitted ISPB for this frame, while data transmission of this frame is delayed until the next HR interval. This additional delay may be undesirable for communication services that require a small delay, for example, voice transmission, especially when the shots are of great length.On the other hand, if IPB is transmitted in the same frame, and the data in the receiver will need to buffer any received signal until, until you find what jemnice and consequently, will lead to additional cost and complexity to the system.Accordingly, it is desirable to develop new methods and systems that help to transfer information about the speed explicitly in the same frame, which she describes, while minimizing the amount of data that must be buffered in the receiver.Summary of the invention These and other problems of known communication systems are solved using the present invention, providing a data transmission with variable speed alternating expansion coefficient, and ISPB is transmitted in the same frame as the data itself. When using extensions using Walsh codes, the compression process can be divided into two separate stages of compression with buffering between these two stages. In this case, the buffering can be performed at the maximum data transfer rate of the user, instead of the much higher speed sequence of code elements. In this way, the buffer size can be significantly reduced.On the first stage of compression can be performed using the first code, which is common to all the physical channels based on the maximum data rate of the user and the properties of the code is C physical control channel, this information is fed to the second stage of compression, which identifies the individual code words associated with each decoded physical channel.A brief description of the drawings the features and objectives of the invention will be clear from the description, illustrated by the drawings, which show the following: Fig. 1 is a block diagram illustrating the structure of the receiver, which may be implemented with the present invention; Fig.2 - variable expansion on two physical channels with a common scrambling; Fig.3 is an example of the code tree;
Fig.4 - two-stage compression in accordance with an illustrative embodiment of the present invention; and
Fig.5 is a more detailed version of the block diagram in Fig.4.Detailed description of the invention
Although this description is made with reference to cellular communication systems, which include portable or mobile radiotelephones, specialists in the art it is obvious that the invention may find application in other communication systems.According to an illustrative variation of the present invention system with mdcr can support communication services with variable bit rate, such as speech, PR and character data for a given frame. In order to perform it at regular time intervals, the physical channels can be divided into frames of equal length. Each frame carries an integer number of code elements and integer data bits.When using this structure frames for each frame mdcr may be provided with control information about the transmission rate in bits by passing this information on a separate physical channel. Physical channels carrying data and control information can be described respectively as physical data channels (FCD) and physical control channels (PKU). Extend the code, the rate of repetition of symbols or equivalent coefficient of expansion PKU known to the receiver in advance.Transmission with variable speed has many potential benefits. For example, can be reduced interference for different users of the system, since the rate of repetition of code elements is maintained constant, while a lower bit rate provides a higher coefficient of expansion, which allows to reduce the transmit power. Specialists in this field of technology it is easy to appreciate how you can benefit from the ability of the receiver (used for example, either the base station or mobile station) shown in Fig.1. First, the received signal is processed by the processor 10 to obtain a comprehensive sample group range. Then the signal is distributed over separate channels of signal processing multi-tap receiver containing the demodulators 12 and 14 taps for the control channel and data channel, respectively. Although in Fig.1 shows only one channel signal processing FCD, specialists in the art it is obvious that according to the present invention multi-tap receiver can contain many such channels. The demodulators 12 and 14 also serves a corresponding widening codes for FCD and PKU from blocks 16 and 18. As described above, the frame PKU contains the necessary information about the structure of the parallel transmitted FCD, and, therefore, before demodulation FCD must be decoded information PKU. Thus the frame buffer 20 before demodulator FCD 14 tap delay filing for his signal baseband, so that the demodulator FCD 14 receives drainage coefficient of expansion FCD to decode. This information is related to the speed with which they were transferred data in VCD, frame by frame served decumulative the decoder FCD 24. The size of the frame buffer 20 can be minimized in accordance with the illustrative variants of the present invention, as described below.In order to finally evaluate how you can reduce the size of the buffer 20, first briefly discuss the prospects of using variable coefficients of expansion and orthogonal codes. As mentioned above, communication services variable speed transmission can be supported by enhancing data flow with variable coefficient of expansion. Consider, for example, the connection type for which you want the first (low) speed of data transmission over a first interval and a second (high) data transfer rate during the second interval, and such transfer is supported through the use of one FKD between the mobile station and the base station. During the first interval based on the first data transfer rate can be selected by first extending the code. During the second interval of the extension frames to be transmitted from the second data rate may be selected second extender code. Because the second data rate higher than the first, the second extends the code will be shorter than the first rasshirjajusheesja. For example, multiple data streams can be expanded up to speed following code elements by using Walsh codes of different lengths, then the summation and the scrambling. In Fig.2 shows the operation of the expansion and scrambling on the example of two physical channels. Here the first data stream is fed to the multiplier 30, having a data rate R1that is equal to the speed of the repetition code Rcdivided by the spreading factor SF1for a given data flow. This data stream is expanded with the code word C1whose length is chosen so that the output signal of the multiplier 30 corresponds to a physical channel with the speed of the repetition code Rwith. Similarly, the second data stream is fed to the multiplier 32 having the second data rate R2that is equal to the speed of the repetition code Rcdivided by the second spreading factor SF2. This data stream is expanded using a second code word With2whose length is chosen to receive the physical channel with the speed of the repetition code Rwith. These two physical Kuusela code Cscr. The resulting signal is displayed, for example, in the signal processing of transmission and, in the end, on the antenna. Speed data streams may be limited to specified interval, so that the used coefficients of expansion were greater than or equal to a predetermined SFmin.Walsh codes used for expansion in the multipliers 30 and 32, can be represented by the tree shown in Fig.3. Codes on the same level of the tree are orthogonal and have the same coefficient of expansion. If the physical channel is expanded using the first code in the tree, and the other physical channel extends through another code that (1) does not coincide with the first code, (2) is not located to the left of the first code on the branch from the root of the tree, and (3) is not in the subtree that has as root the first code, advanced physical channels are orthogonal. Each physical channel from tree stands extend the code, and the expansion coefficients correspond to the respective data rates. If the data rate for a particular PCD changes, the highlighted code from another level of the tree. For example, increasing the data rate selection process Yes is shifted in the right part of the tree. Thus, conventional PCD variable speed transmission will move up and down some branches in the code tree, if the data rate change.In Fig. 3 it can be seen that any given code tree is used for building codes to the right of it (that is farther from the root). Thus it is obvious that any given code consists of code at a lower level, which are on the way to the root of the code tree. Applicants have found that this property codes can be used to reduce requirements for buffering in the receiver.In the receiver described in connection with Fig.1, the received signal descrambled and compressed. However, before compression frame receiver must have information about the expansion coefficient, which was used in the transmission of this frame. Because IPB is transmitted in the same frame according to an illustrative variation of the present invention, the signal must be buffered. However, applicants have found that compression using the largest possible total of all Walsh codes that are available for the installation of specific compounds can be performed without buffering, that is, before decoding ISPB. Accordingly, the channel of the receiver shown in f is La partial compression of the received symbol signal is correlated with the first code in the root of Zubareva, in which all the possible codes are block 50. This process is performed for all paths of multipath signal, next is combining the signals of taps, and the resulting intermediate symbols buffered in the buffer 20. As soon as the decoder PKU 22 is decoded ISPB, the intermediate symbols from the buffer 20 are correlated in block 52 with a second code to obtain compressed raw bits. The code used for the second step of compression, it can be easily determined from the code tree. For example, the compression code(+1+1-1-1-1-1+1+1) can be executed by the first compression unit 50 using the code (+1+1), followed by the compression unit 52 using the code (+1-1-1+1). Another alternative is the compression unit 50 using the code (+1+1-1-1), followed by the compression unit 52 using the code (+1-1). The latter combination leads to buffering of intermediate symbols with a higher speed and, therefore, will require a buffer of 20 larger. But in any case, buffering according to the present invention is performed at a rate considerably less than the velocity of receipt of code elements. For example, in a system that uses variable expansion ratio with values ranging from 64 to 256, buffering is performed with compression according to the present invention for the two codes in duotones the receiver. First in blocks 60 and 62 received signal descrambled to complete the process in the opposite direction compared to the process performed in block 36 of Fig.2. Then in blocks 64 and 66 of the received signal is partially compressed by using a common code, i.e. code that is in the left side of the code tree, which is common to all possible values of a variable expansion ratio for this particular transmission. The resulting partially compressed signals are integrated in blocks 68 and 70, respectively, and are modified in blocks 72 and 74 on the basis of channel estimates. The last two operations are well known to experts in the field of signal processing in multi-tap receivers. Then the resulting partially compressed signals are summed in block 76 and introduced into the buffer 20 where they are stored until such time as the decoder PKU is not received information about the bit rate. However, because prior to storage in the buffer 20 signals were partially compressed, the speed of transmission of stored data will be significantly less than the rate of the repetition code elements that allows the developer to reduce the size of the buffer 18. As soon as the information ISPB for this scene can be selected snova integrated in blocks 82 and 84, and then executes the subsequent processing, the usual multi-tap receiver.It is obvious that the invention is not limited to the above specific variants of its implementation and that specialists in this field of technology can be offered to its various modifications. Scope of the present invention is defined by the subsequent claims and assumes that the scope of the invention includes any modification.
1. The receiver containing means for receiving the signal from the spread spectrum comprising at least two physical data flow channels, means for partial compression of one of the at least two data flows physical channel using a first code that is common to all of the expansion coefficients of the signal, to obtain a partially compressed signal, the means for buffering partially compressed signal and means for compressing the buffered signal using the second code.2. The receiver under item 1, characterized in that the signal spread spectrum taken with the speed of the sequence of code elements, and means for buffering remembers partially s fact, that at least two of the data flow of the physical channels include a data flow control channel and the data stream of the first channel data.4. The receiver under item 1, wherein one of the at least two data flows physical channels can be made with any of a variety of data rates, and the first code is selected based on a variety of data transfer speeds.5. The receiver under item 3, characterized in that it further comprises means for demodulating and decoding the stream data control channel for information transfer rate in bits related to the data stream of the first data channel, and means for presenting information about the transmission rate in bits per tool compression buffered signal using at least the second code.6. The receiver under item 5, wherein the second code is selected on the basis of the information transmission speed in bits.7. The receiver under item 3, characterized in that the data streams of at least two physical channels include a data stream of the second channel data in addition to data flow control channel and the data flow of the first control channel.8. The receiver under item 7, characterized in that sredstvo code.9. The receiver under item 8, characterized in that it further comprises means for demodulating and decoding the stream data control channel for information transfer rate in bits related to the data streams of both the first and second channel data, and the compression tool selects the second code and the third code to compress the data streams of the first and second data channels, respectively, based on the information about the transmission speed in bits.10. The receiver under item 9, wherein the information transfer rate in bits includes the expansion coefficients of the data streams of both the first and second data channels.11. The receiver under item 5, wherein the information transfer rate in bits represents the coefficient of expansion.12. The receiver under item 8, wherein the first code is selected based on the code bits that are common to the data streams of the first and second data channels.13. Method for compressing data frame, comprising the steps of (a) compression frame data using the first code, (b) buffering the output signal obtained at step (a), (C) determining the speed at which transmitted the data frame, and (d) compressing the buffered output signal and the persons under item 13, characterized in that step (b) further includes buffering the output signal with a speed less than the speed of the sequence of code elements of the data frame.15. The method according to p. 13, wherein step (C) further comprises the step of determining the speed by compressing and decoding the stream data control channel.16. The method according to p. 13, wherein step (a) further includes determining the first code on the basis of the speed with which you can transfer your data frame.17. The receiver containing the first compressor unit to compress the received signal with spread spectrum, the buffer connected to the first compressor unit, for storing the output signal of the first compressor and the second compressor unit connected to the buffer, to compress the stored output signal.18. The receiver under item 17, wherein the first compressor compresses the received signal spread spectrum using at least two channels, and each channel uses the same first code to compress the received signal with spread spectrum.19. The receiver under item 17, characterized in that the second compressor unit compresses the stored output signal using at least d is greater least two channels.20. The receiver under item 17, characterized in that the first block compression descrambled received signal spread spectrum using scramblase code.
FIELD: radio engineering; construction of radio communication, radio navigation, and control systems using broadband signals.
SUBSTANCE: proposed device depends for its operation on comparison of read-out signal with two thresholds, probability of exceeding these thresholds being enhanced during search interval with the result that search is continued. This broadband signal search device has linear part 1, matched filter 2, clock generator 19, channel selection control unit 13, inverter 12, fourth adder 15, two detectors 8, 17, two threshold comparison units 9, 18, NOT gates 16, as well as AND gate 14. Matched filter has pre-filter 3, delay line 4, n attenuators, n phase shifters, and three adders 7, 10, 11.
EFFECT: enhanced noise immunity under structural noise impact.
1 cl, 3 dwg