Method and device for assessing the quality of the channel in the receiver
(57) Abstract:The present invention includes a method and apparatus for assessing the quality of the channel (OKK) in the receiver. Each channel is divided into intervals of observation and putinterval. The duration of putinterval is chosen as the largest interval on which the channel is static. The device JCC generates error information for each character on pointervalue and collects error information for character spacing, forming the magnitude of the error pointervalue. The device COC converts the magnitude of the error on pointervalue in the evaluation of error rate in bits (BER) on pointervalue. This transformation is a nonlinear function that depends on the specific radio system. The device then COC averages assessment BER on pointervalue throughout the observation interval, forming a BER assessment in the interval. Finally, the device COC compare assessment OKK on the interval with a given threshold, forming the estimate of the channel quality for each observation interval, which is the technical result. 2 S. and 6 C.p. f-crystals, 11 ill. The invention generally relates to receivers and in particular to a method of evaluating the quality of the channel in the receiver with digital modulation.Before Telefonnaya system usually contains numerous fixed transceivers, who are able to serve numerous phones. Quality of service each of the fixed transceivers and a separate phone differently. If the phone can evaluate the quality of the receiving channel, the radio system can choose the most appropriate fixed radio transmitter.There are several different conventional methods for assessing the quality of the receiving channel. Usually the assessment of the quality of the channel includes the evaluation of error rate in bits (bit error rate BER). Phone system multiple access with time division multiplexing (mdvr) divides time into frames, words and time intervals. System statement requires the evaluation of the quality of the channel (JCC) for each frame. Each frame is called the observation interval. The phone must identify one of four possible categories of characteristics, where each category corresponds to a specific range BER channel, as shown in table 200 of Fig. 2. Moreover, the statement requires that the phone identified the correct category characteristics at standard values R in the band Rayleigh fading 40 Hz with a flat top.The accuracy of the conventional technology is in the above-mentioned systems mdvr, requiring the OCC for each frame. You can refer to the article "Techniques for Estimating the Bit Error Rate in the Simulation of Digital Communications". IEEE Journal on Selected Areas in Communications, Vol SAC-2, No. 1, January 1984 to determine an appropriate number of bits observations to estimate the BER with the desired accuracy.The frame in this system contains 36 words. The word contains 140 characters allocated to each phone. Thus, the phone gets 5040 symbols of each frame. Each symbol contains 2 bits. Two conventional method, the COC include: (1) calculation of bit-error for the known parts of words (e.g., synchroscope, headers and so on), and (2) the encoding bits of the decoded data, and comparing the resulting sequence of bits with the accepted channel bits. This second method works only on bits FEC /FEC/. Both of these methods are unacceptable for this special system due to the fact that the number of errors in bits? observed in the frame, is not enough to ensure the desired accuracy.The accuracy of the OCC can be improved by using "soft" information errors, available at the output of the demodulator. Information about phase error is a special case of "soft" information errors. The accumulation value of the phase error (or square in which to improve the JCC. However, this method is too sensitive to the frequency of the fading channel and produces different results for environments without fading and fading. This is the result of the fact that the determination of the magnitude of the error (or squared error) is a nonlinear function of the error rate in bits of the channel.The exact JCC desirable for use in the receiver MDR. The COC must be accurate to a specified level of accuracy in environments without fading, and fading to the observation interval, with a limited number of bits observations.Brief description of drawings
The invention is further explained in the description of variants of its implementation with reference to the accompanying drawings, in which:
Fig. 1 - depicts a block diagram of a radiotelephone system in accordance with the present invention.Fig. 2 is a table describing the requirements of the special radiotelephone system.Fig. 3 is a detailed block diagram of the phase demodulator shown in Fig. 1, in accordance with the present invention.Fig. 4 is a detailed block diagram of a device for estimating the quality of the channel (JCC), shown in Fig. 1, in accordance with the present invention.Fig. 5 - is characteristic the characteristics of conventional JCC and JCC of the present invention.Fig. 7 is a table illustrating decision COC produced by the device JCC in Fig. 3.Fig. 8 is a table illustrating the non-linear display in the system described in the preferred implementation.Fig. 9 is a graph depicting the average COC and the average probability of error in bits for linear and nonlinear mappings COC.Fig. 10 is a graph corresponding to the average value of the COC and the average probability of error in bits for static channels and channels with Rayleigh fading when the conventional COC.Fig. 11 is a graph showing the probability that the magnitude of the phase error exceeds the limit of 5 /32 radians compared to the ratio of error bits to a static channel in accordance with the present invention.Description of the preferred options for performing
The preferred implementation includes a method and apparatus for evaluating the quality of the channel in the receiver. Device for evaluating the quality of the channel (JCC) divides the received data into equal-size intervals and potentially observations. The device JCC produces independent evaluation for each observation interval, reflecting the quality of the receiving channel.The PE the flax performing device quality assessment of channel uses information about the magnitude of the phase error, per interval of each symbol, to generate error information. The device COC can also be supplied by other generators of information about equivalent sufficient and common mistakes. Further, the device COC collects the generated error information for each potential, forming the error value of putinterval. The duration of putinterval is selected as the most long interval in which the channel is essentially no fading. Further, the device COC converts the value of the error potential in the assessment of the quality of the channel on pointervalue. In a preferred embodiment, the evaluation of the quality of the channel on pointervalue is an estimate of the error rate, in bits, and the transformation is a nonlinear function depending on type of radio system. Finally, the device COC averages assess the quality of the channel on pointervalue throughout the observation interval, forming the evaluation of the quality of the channel at the interval.In a preferred embodiment of the device COC compares the evaluation of the quality of the channel at the interval with a preset threshold, forming the decision to assess the quality of the channel for each observation interval. The phone may use the decision to assess the OCC or maybe the shows impact on the decisions of the radiotelephone system. These decisions include the choice of a suitable fixed transceiver to service the phone and regulation of the power output of the fixed transceiver and/or phone.In Fig. 1 shows a block diagram of the radiotelephone system in accordance with the present invention. In a radiotelephone system fixed transceiver 103 sends signals to radio frequency (RF) to portable radiotelephones located in a specific geographical area served by the fixed transceiver 103, and receives from them these signals. The radiotelephone 101 is one such radio telephones served by the fixed transceiver 103.While receiving signals from the fixed transceiver 103 apparatus 101 uses the antenna 105 for introducing RF signals and convert the RF signals into electrical RF signals. The radio receiver 111 receives the electrical RF signals for use in the radiotelephone 101. The receiver 111 produces a signal 115 intermediate frequency, denoted by r1(t) in Fig. 1. This signal 115 intermediate frequency (if) is introduced in the phase demodulator 119. The phase demodulator 119 outputs a signal 123 definitions of symbol for epoetinum structure of the phase demodulator 119. The circuit 131 COC uses the signal 127 of the magnitude of the phase error to generate a signal 129 decision COC. The CPU 121, in turn, uses the signal 129 decision COC. Fig. 4 illustrates the circuit elements 131 COC. The CPU 121 includes a microprocessor type MC68000 supplied by Motorola Inc and associated memory. The processor 121 converts the signal 123 the definition of a symbol in a voice signal and/or data for use by the interface 125 of the user. The user interface includes a microphone, speaker and keyboard.When transmitting RF signals from the portable radiotelephone 101 in a fixed transceiver 103, the CPU 121 converts a voice signal and/or data signals from the user interface 125. In a preferred embodiment, the converted signals include a signal 129 decision COC. The converted signals are input to the transmitter 109. The transmitter 109 converts the data into electrical RF signals. The antenna 105 receives the electrical RF signals and outputs them as RF signals. The transceiver 103 receives these RF signals.In Fig. 3 depicts a block diagram of the phase demodulator 119, shown in Fig. 1. The phase demodulator 119 contains the limiter 301, differential demodul 301 receives the if signal 115 and limits the voltage of the if signal 115 to levels the respective logical levels 0 and 1. The limiter 301 issues a limited signal 321. Differential demodulator 303 is digital and includes a phase detector 311, which produces a phase signal 323. The phase signal 323 is entered in element 313 delay in the adder 315, forming signal 333 phase difference for discretization 317 frequencies of the symbols. Discretization 317 frequencies of the symbols discretetime signal 333 phase difference once for each symbol to generate a discrete differential phase signal 327. The discretized differential phase signal 327 extends from the differential demodulator 303 and put the stopper 305 characters on the maximum and minimum. The limiter 305 characters on the maximum and minimum decides that the differential phase signal 327 is the closest, and outputs the value of the solution in the form of symbolic values 123 solutions. Generator 331 phase error produces a signal 127 of the magnitude of the phase error. First, the generator 331 phase error generates a signal 329 phase error equal to the difference between the discretized differential phase signal 327 and the closest to the character signal value 123 solutions. Block 309 generate absolute mn is I.Signal 127 of the magnitude of the phase error provides a measure of the instantaneous channel quality for each received symbol. Graph 1100 of Fig. 11 illustrates the probability of exceeding a signal 127 of the magnitude of the phase error 5 /32 radians as a function of the probability of error in bits per channel. This drawing relates to transmission using quadrature manipulation phase shift (QPSK) in the additive channel without fading white Gaussian noise.Line 1101 bench measurements and simulated line 1103 measurements illustrate the relationship between the characteristic of the ratio error in bits and measured values of the phase errors. However, the relationship between the error rate in bits and the measured value of the phase error for the phone in the preferred embodiment, is a nonlinear relationship. Characteristics in environments without fading and fading differ significantly due to the nonlinear relationship. This discrepancy is illustrated by the curves 1001 and 1003 graph 1000 of Fig. 10. Averaging the magnitude of the phase error on the interval, which changes the quality of the receiving channel, it is not enough to determine the error rate in bits per interval.Method of assessment the quality of the channel predpochtitelno the s. Length putinterval is determined by experimentation with a particular system. The optimal duration of putinterval is the longest interval in which the receiving channel is approximately static (no fading), i.e. the quality of the channel is estimated as a constant.Graph 500 in Fig.5 illustrates the intervals and potentially observations, certain to provide the best characteristics for the radio system of the preferred option. In the General case, the observation interval contains N symbols, as mentioned POS. 501. Each of the L potentialof contains M characters, so that N = LM. The preferred option is that the maximum frequency of fading for the system is approximately equal to 100 Hz. System check using the maximum frequency of the fading showed that the optimum length M equal to 10 characters, which provides the static quality of the receiving channel. Interval N observations in the preferred embodiment, is equal to 5040, as required by the radiotelephone system. Thus, the number L of peginterferon equal to 504 in a preferred variant.Fig. 4 is a detailed block diagram of the circuit 131 evaluation of the quality of the channel in Fig. 1. The circuit 131 evaluation of the quality ka the novena evaluation of the quality of the channel for the K-th symbol R th putinterval, using the signal 127 of the magnitude of the phase error. It is measured from 1 to M, and P denotes the number of potential, which varies from 1 to L. In the preferred embodiment, M is 10, and L is equal to 504. Instant assessment of the quality of the channel is usually known as the error information on the character interval. Unit 401 displays the error on the character interval, when the magnitude of the phase error exceeds a certain threshold. In a preferred embodiment, the predetermined threshold is equal to 5 /32 radians. This threshold may vary depending on the specific requirements of the receiving system.Signal 411 instant assessment of the quality of the channel is passed to the block 403. Unit 403 determines the number of characters in this pointervalue R, having a magnitude of a phase error exceeding the predetermined threshold. Unit 403 generates a signal 413 error on pointervalue for each of the L potentialof.Signal 413 error on pointervalue comes in block 405. Unit 405 displays the signal values of the error on pointervalue in the appropriate assessment of the quality of a channel using the static display quality of the channel. The preferred option uses the display of the evaluation of error rate in bits (BER). Characterization of the BER is a function of the modulation method, p is is an illustration of non-linear display, defined for the radio system of the preferred option. Column 801 represents the number of times when the magnitude of the phase error of this symbol on putinterval R exceeded the threshold of 5 /32 radians. The corresponding error rate in bits in the column 805 is determined from the static JCC in comparison with the curve of the error rate in bits previously discussed graph 1100 of Fig. 11. Column 803 - the probability that the instantaneous value of the phase error will exceed 5 /32 radians during the R-th putinterval. Converted COC column 807 approximately linearly proportional to the BER numbers in the column 805. In accordance with the ratio between columns 803 and 807 in the table 800 unit 405 displays the signal 413 error in pointervalue signal 415 evaluation of the BER. Signal 415 is supplied in block 407.Unit 407 calculates the average rating 417 quality of the channel in the current monitoring interval by averaging L converted potentially estimates R by the formula
< / BR>The average value 417 COC for the observation interval is served in the threshold block 409 comparison.Unit 409 performs determination the OCC, comparing the average COC with a given set of thresholds. The preferred option uses a table 700 of Fig. 7. The thresholds T1, the designated radiotelephone system in the preferred embodiment. The threshold block 409 comparison is not necessary in the invention, but is an additional characteristic required in the preferred embodiment. The output unit 409 preferred option is the signal 129 solutions evaluate the quality of the channel, which is the digit decision COC, as defined in the column 703. The circuit 131 evaluation of the quality of the channel may be embedded in the programmable matrix of logic elements, such as Xilinx 3090 supplied by the company Xilinx Inc.Graph 900 in Fig. 9 shows the average evaluation of the quality of the channel as a function of average probability of error bits in environments without fading and fading. Line 909 and 911 Express linear transformation on the observation interval, as described in the prototype and named the accepted way. Line 909 is modeled in a static environment, line 911 in an environment with a sinking. The difference between 909 and 911 illustrates the shortcomings of the conventional way. The conventional method, in particular, gives a different assessment of the quality of the channel depending on conditions, static or fading, in which is placed the receiver.Line 905 and 907 Express the OCC, as described in the preferred embodiment. Line 905 is a measurement in a static environment, and 907 in an environment with a sinking. Zametki average probability of error bits as in static environments, and in environments with fading. In addition, line 901 and 903 are VBEs, similar to the system shown by lines 905 and 907. The second system, represented by lines 901 and 903, averages by more potentialof L. As shown by lines 901, 903, 905, 907, a closer match between the characteristics of static and fading occurs when the length of the observation interval increases.Poster dimensions are summarized in table 600 of Fig. 6. Table 600 compares the characteristics of the conventional way of JCC and how the preferred option. The conventional method uses a linear mapping on the observation interval. With standard BER described in the table 200 of Fig. 2, both methods predict the appropriate category characteristics with accuracy exceeding 85% in a Rayleigh fading in the band of 40 Hz. The preferred method variant corresponds to this accuracy when in static environments. However, the conventional method is rarely predicts the appropriate category characteristics when in static environments. Thus, the OCC described here provides an accurate assessment of the probability of error bits in the received signal as in environments with fading and static environments for intervenience with digital modulation, receiving symbols with a symbol interval, namely, that divide the received data into intervals with a predetermined length, characterized in that share a pre-determined length of the first interval for a predetermined number of peginterferon, generate error information for each symbol interval, combine the specified error information for each pointervalue form the magnitude of the error on pointervalue, convert the specified value of the error on pointervalue in the assessment of the quality of the channel on pointervalue and average the specified evaluation of the quality of the channel on pointervalue by a predetermined interval with the formation of assessing the quality of the channel at the interval.2. The method according to p. 1, wherein generating the error information by measuring the magnitude of the phase error of each symbol, comparing the specified value of the phase error of each symbol with a prescribed threshold and specify the error symbol interval if the specified value of the phase error exceeds a certain specified threshold.3. The method according to p. 1 or 2, characterized in that share a pre-determined length of the first interval to the specified number of peginterferon by selecting the most pointercount the magnitude of the error on pointervalue in the assessment of the quality of the channel on pointervalue by defining conversion as a nonlinear transformation of the magnitude of the error on pointervalue in the assessment of the quality of the channel on pointervalue, which is proportional to the error rate in bits on pointervalue.5. The method according to any of paragraphs.1-4, characterized in that the above conversion operation depends on the characteristics of the receiver, the modulation type and length of putinterval.6. The method according to any of paragraphs.1-4, characterized in that it further compare the evaluation of the quality of the channel at the interval with at least the first threshold and produce an assessment of the quality of the channel in accordance with the specified comparison operation.7. The phone, made with connectivity between multiple fixed transceiver contains a transmitter and a receiver and receiving the radio frequency signal at least from the first fixed transceiver on the first channel, characterized in that it contains a tool for decision-making about the symbols of the received radio frequency signals and outputs the signal value of the phase errors of the means of evaluation to determine the quality of the first channel during the first time period on the length of the first predetermined interval using a predetermined number of peginterferon, compare means containing means for generating error information for each REShENIYa errors pointervalue, means for converting the magnitude of the error on pointervalue in the evaluation of error rate in bits (R) putinterval, means for averaging the evaluation R on pointervalue at a predetermined first interval and signal evaluation R on the interval and means for making decisions about the evaluation of the quality of the first channel using the specified signal evaluation R on the interval, and means for transmitting the evaluation of the quality of the first channel specified by the first fixed transceiver.8. The phone on p. 7, characterized in that it further comprises evaluating means for determining the quality of the second channel during the second period of time to the length of the second predetermined interval with the formation of assessing the quality of the second channel and means for transmitting the evaluation of the quality of the second channel specified by the first fixed transceiver, and said first fixed transceiver is configured to select the preferred fixed transceiver.
FIELD: radio communications.
SUBSTANCE: pulse noise is detected upon conversion of signal received into intermediate frequency, noise active time is determined, information signal is disconnected from amplifier incorporated in superheterodyne receiver, noise-affected part of information signal is recovered by eliminating simulator signals during extrapolation, and superheterodyne receiver is checked for serviceability at intermediate frequency.
EFFECT: enhanced precision of superheterodyne receiver serviceability check.
1 cl, 1 dwg