KR100514298B1 - Synchronizing apparatus of adaptive modem and method thereof - Google Patents

Abstract

The present invention relates to a synchronization processing apparatus and a synchronization method of a modem receiving end capable of adaptive time division duplex (TDD) and adaptive modulation support. This synchronization processing apparatus includes a burst frame detector, a frequency offset estimator, and a timing and phase estimator. The burst frame detection unit detects a burst frame using a preamble for fast synchronization parameter extraction in real time. The frequency offset estimator correlates the preamble pattern with the signal received by the burst frame detector, extracts the exact start point of the frame according to the correlation value, and estimates the frequency offset through cross correlation between the preamble patterns received from the start point. The timing and phase estimator extracts the symbol timing parameter and the carrier phase error parameter value from the maximum value of the correlated result value in the burst frame detector to compensate for the initial frame synchronization and the symbol timing and compensate for the carrier phase. According to the present invention, the efficiency of channel distribution and channel transmission efficiency can be increased in up and down receivers.

Description

Synchronous processing apparatus and method for synchronizing the adaptive modem receiver {SYNCHRONIZING APPARATUS OF ADAPTIVE MODEM AND METHOD THEREOF}

The present invention relates to a synchronization processing apparatus and a synchronization method of a modem receiving end, and more particularly, to a synchronization processing apparatus and a synchronization method of a modem receiving end capable of supporting an adaptive time division duplex (TDD) and an adaptive modulation scheme. It is about.

The WMAN (Wireless Metropolitan Area Network) has been proposed as a method to meet the inefficiency of the initial construction cost of the existing wired network system and the network demand due to the rapid growth of the city. IEEE 802.16 based on WMAN has been proposed to expand wireless data networks in a line of sight (LOS) environment. In the transmission scheme, 1) a TDD transmission scheme for increasing efficiency of a frequency band, and 2) such a scheme. An adaptive TDD scheme for changing the length of the uplink / downlink frame according to the amount of data in the TDD transmission scheme, and 3) an adaptive modulation scheme for maximizing the data rate in the LOS environment has been proposed.

Modem in such a TDD environment is controlled through a feedback loop as a single frame in order to achieve frame synchronization and frequency offset synchronization.

However, this feedback loop scheme has a problem in that the subframe length of the uplink and downlink varies in each TDD frame, and is not suitable for an adaptive TDD or a system supporting adaptive modulation.

On the other hand, the current wireless communication has been continued to propose an efficient frequency distribution and reuse, and an efficient data transmission scheme to derive the maximum transmission rate in a limited channel band and a limited frequency band. Among these transmission schemes, the FDD scheme allocates frequencies of the uplink and downlink differently, whereas the TDD scheme shares the same frequency with the uplink and downlink, so the efficiency of frequency distribution is excellent.

However, when the uplink and downlink frequency is shared, the FDD scheme processes data continuously. In the TDD scheme, when the uplink is converted to a data transmission mode during downlink data processing, the downlink transmitter transmits the data. It will shut down. Due to these characteristics, there is a problem that fast synchronization parameter processing is required in the initial synchronization processing of the downlink modem.

In addition, the adaptive modulation scheme is a method for increasing transmission efficiency within a limited frequency band. In such an adaptive modulation scheme, the complexity of the modulation scheme causes a problem in that the synchronization processing of the receiver is complicated. For example, a frequency offset, an extra symbol timing error, and a carrier wave are used during downlink processing transmitted in a TDM scheme. The processing of the modulation data according to the phase error becomes more complicated.

In order to solve this problem, a method of transmitting the preamble by setting the length of the uplink and the downlink sufficiently long may be applied, or a method of interpreting several frames as one continuous frame at the downlink receiving end may be applied. have. However, the first method has a problem in that data transmission efficiency is degraded due to the preamble transmitted in each frame, and the second method requires analog control or requires many control circuits for accurate tracking of the frame.

On the other hand, as a prior art, Korean Patent Application No. 1995-7003790 (filed September 9, 1995) discloses a "data signal comparator with a self-adjusting limit", which is a time division duplex (TDD) telecommunication environment A radio frequency transceiver is disclosed that includes a direct modulation transmitter and a single downlink frequency conversion receiver for operation.

Specifically, the invention of Korean Patent Application No. 1995-7003790 described above, in a radio frequency (RF) transceiver having a direct transmitter modulation and a single receiver downlink frequency conversion to an intermediate frequency (IF), a) the transmission carrier frequency Transmitter means for generating a transmit RF carrier signal having a transmit modulated signal and modulating the RF carrier signal with the transmit modulated signal to provide a modulated transmit RF signal; b) receiver means coupled to said transmitter means for receiving a modulated received RF signal having a received carrier frequency and down frequency converting it at one time to provide a modulated IF signal; And c) demodulator means coupled to the receiving end to receive and demodulate the modulated IF signal.

The invention of Korean Patent Application No. 1995-7003790 described above includes a direct modulation transmitter and a single downlink frequency conversion receiver for operation in a time division duplex (TDD) telecommunication environment, whereby a single RF signal source is based on time division. Used in the form of a phase-locked loop to provide both the transmit carrier signal and the receive local oscillator signal, time-divided by a single RF signal source as an interface between the transceiver and the main controller, and for different transmitter carrier and receiver frequencies. It is controllable and provides the signals needed to cut control of the transmitter and receiver to minimize transceiver power. As a result, the above-described invention implements the transceiver in the same analog manner as the frequency division duplex (FDD), uses the received RF synchronization parameters for transmission, and uses the same RF element in the transmitter through time division.

On the other hand, the Republic of Korea Patent Application No. 2002-7011104 (2002.8.24 application) discloses a "modulation scheme for FDD / TDD transceiver", the time division duplex (FDD) by applying a minimum change to the frequency division duplex (FDD) scheme Disclosed is a modulation method of a transceiver of an FDD / TDD scheme that can realize a TDD) system.

Specifically, the above-described invention of Korean Patent Application No. 2002-7011104 can be used in both the FDD mode or the TDD mode without changing the RF front end, and also stores a codec and a digitizing circuit and a buffer for digitized data. It eliminates the need for devices and burst-mode transmission circuitry, resulting in cost savings and also minimizing hardware complexity by eliminating the need for burst-based controllers for FDD and TDD as well as bandpass filters and dielectric lowpass filters. . However, the received signal is processed in analog and the TDD frame is processed in a continuous mode signal rather than in a burst form.

Meanwhile, in a paper published by Dengwei Fu et al. Under the name "A Fast Synchronizer for Burst Modems with Simultaneous symbol Timing and Carrier Phase Estimations" in the ISCAS 2000 IEEE international Symposium (May 28-31, p379, 2000), Since the application of open loop timing control is required for fast acquisition of timing and carrier phase error values, a synchronization circuit capable of estimating carrier phase and timing error values using a preamble is disclosed.

According to the above-mentioned paper, in order to process burst signals transmitted at high speed, timing and carrier phase error components are extracted using a preamble located at the beginning of a transmission frame, and a synchronization error value is extracted. By estimating the symbol timing and the carrier phase error value using the correlation result of, the preamble can be used to quickly acquire synchronization for a short burst frame.

Specifically, in the above-mentioned paper, a signal input to a receiver is sampled at a fixed frequency and a preamble having a predetermined rule exists before data of a received signal. The timing and phase error values are extracted using the preamble of the received signal. . In addition, the signal sampled at the fixed frequency is correlated with the inverse function of the preamble value known to the receiver after passing through the matched filter, and the beginning of the reception frame can be inferred by the change of the power value of the correlation result value. The starting point of the preamble can be found. Therefore, by finding the start of the frame and the start point of the preamble, it can be used for timing error value and carrier phase error estimation using the preamble pattern.

However, the above-mentioned paper is synchronized with a burst signal using only a preamble, and is simply a method of processing a burst-type frame, which is suitable for data frames transmitted on the uplink, and can be synchronized using only a preamble in a short time. The only problem is that accuracy is not taken into account.

An object of the present invention for solving the above problems, the adaptive TDD and the adaptive modulated data processing in the digital domain, and can be applied equally in the up and down receiver, it is possible to support the adaptive TDD and adaptive modulation scheme The present invention provides a synchronization processing device and a synchronization method of a modem receiver.

In accordance with one aspect of the present invention for achieving the above object, a synchronization processing apparatus of an adaptive modem receiver,

At the receiving end of a modem that supports adaptive time division duplex (TDD) and adaptive modulation,

a) a burst frame detector for detecting a burst frame using a preamble for fast synchronization parameter extraction in real time; b) Correlate the signal received by the burst frame detector with the preamble pattern, extract the exact starting point of the frame according to the correlation value, and estimate the frequency offset through autocorrelation between the preamble patterns received from the starting point. government; And c) a timing and phase estimator for extracting a symbol timing parameter and a carrier phase error parameter value from the maximum value of the correlated result in the burst frame detector, compensating initial frame synchronization and symbol timing, and compensating carrier phase. do.

Here, the synchronization processing apparatus of the adaptive modem receiver further includes a tracking unit for controlling an extra synchronization parameter error value required in a complex modulation scheme.

The tracking unit may further include: a symbol timing tracking unit coupled with a symbol timing estimation circuit to support a complex modulation scheme; And a carrier phase tracking unit for controlling the extra carrier phase error and combining with the carrier phase estimation circuit to compensate for the extra frequency offset.

In addition, the preamble is preferably composed of 32 symbols formed at the beginning of the burst frame.

In addition, the preamble preferably includes the transmission and reception information in the frame in the header of the frame to support the adaptive TDD and the adaptive modulation scheme.

The timing and phase estimator may include: a timing estimator configured to extract a symbol timing parameter value from a maximum value of the correlated result value to compensate for initial frame synchronization and symbol timing; And a carrier phase estimator for extracting a carrier phase error parameter value from the maximum value of the correlated result and compensating initial frame synchronization and carrier phase.

The timing estimator may include: a correlator first in first out (FIFO) for storing a correlation result value for a predetermined time until the burst detection unit detects a frame start point; A timing estimator for estimating timing using the symbol timing parameter value extracted according to the correlation result value; A loop filter for setting the output of the timing estimator to an initial value; A finite impulse response filter selector for selecting a filter according to an output of the loop filter; And an interpolator composed of an FIR filter selected from the FIR filter selector and compensating symbol timing error values according to timing error values.

In addition, the interpolator preferably requests information about a start point of a received frame extracted by the burst detector to determine symbol data to be transmitted to a carrier phase estimator.

The apparatus further includes a timing error tracker for compensating symbol timing in a complex modulation scheme after initial timing synchronization according to the timing estimator using the preamble.

The carrier phase estimator may include a carrier phase FIFO (storage phase FIFO) which stores a real number and an imaginary part of a correlation result value in a burst detector for a predetermined period until the burst detector detects a start point of a frame; A FIFO that stores the estimated carrier phase error value until the timing estimator compensates for a timing error when the burst detector informs the start of a frame; A ROM storing sine / cosine values for phase error values extracted from values stored in the FIFO; A loop filter using the carrier phase error estimation value as an initial value; A carrier phase reconstructor for transmitting the data compensated for the carrier phase to an equalizer; And a phase ambiguity block for determining the sign of a sine / cosine value of the carrier phase reconstructor to compensate for the exact position of the received signal.

In addition, a carrier phase error tracker is further included to compensate for the extra carrier phase error and to minimize the influence of the frequency offset in the downlink transmitted by the TDM scheme in the frame.

In addition, it is preferable that the carrier phase estimation calculation block estimates the sign of a real part and an imaginary part value of the carrier phase FIFO by estimating only a value within 0 ° to 90 °.

According to another aspect of the present invention, there is provided a synchronization method of an adaptive modem receiver.

As a synchronization method of a modem receiver that supports adaptive time division duplex (TDD) and adaptive modulation,

a) detecting a burst frame and correlating the received signal with the preamble pattern; b) extracting an exact starting point of the burst frame according to the correlated value and extracting a synchronization estimate value for initial synchronization of the burst frame; c) estimating a frequency offset through cross correlation between preamble patterns received later from the extracted frame start point; d) extracting a symbol timing parameter and a carrier phase error parameter value from the maximum value of the cross-correlated result; And e) performing initial frame synchronization, symbol timing compensation, and carrier phase compensation according to the extracted parameter values.

Here, the method of synchronizing the adaptive modem receiver further includes controlling, after step v), an extra synchronization parameter error value required in a complex modulation scheme.

In addition, it is preferable that fast data synchronization acquisition in up and down frames is performed according to the estimated synchronization parameter value.

Hereinafter, a synchronization processing apparatus and a synchronization method of a modem supporting an adaptive TDD and an adaptive modulation scheme according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The synchronization processing apparatus of the modem receiving end supporting the adaptive TDD and the adaptive modulation according to the present invention should be able to detect a frame using the preamble, and be able to estimate the symbol timing and the carrier phase error value from the preamble. There is a need for a fast compensation of the frequency offset, and also a tracking circuit is needed to control the extra error value and to continuously compensate for the frequency offset.

1 is a schematic configuration diagram of a synchronization processing apparatus of a time division duplex (TDD) adaptive modem receiver according to the present invention, and a detailed operation and structure of components of the synchronization processing apparatus of the adaptive modem receiver according to the present invention will be described. do.

The synchronization unit 100 of the adaptive modem receiver according to the present invention is roughly a burst (or burst frame) detector 200, a frequency offset estimation circuit 300, and a symbol timing and carrier phase estimation and recovery circuit 400 The symbol timing and carrier phase estimation and recovery circuit 400 is divided into a symbol timing estimation and recovery circuit 410 and a carrier phase estimation and recovery circuit 420, respectively. The circuit 410 is referred to as a timing estimation circuit, and the carrier phase estimation and recovery circuit 420 is referred to as a carrier phase estimation circuit.

In the synchronizer 100 of the adaptive modem receiver according to the present invention, the burst frame detector 200 detects a burst frame using a preamble for fast synchronization parameter extraction in real time.

The frequency offset estimation circuit 300 correlates the preamble pattern with the signal received by the burst frame detector 200, extracts the exact starting point of the frame according to the correlation value, and then performs cross correlation between the preamble patterns received later. Estimate the frequency offset.

In addition, the timing and phase estimation circuit 400 extracts a symbol timing parameter and a carrier phase error parameter value from the maximum value of the correlated result, thereby compensating for initial frame synchronization and symbol timing, and compensates for carrier phase. . Here, the timing and phase estimation circuit 400 may further include a tracking circuit for controlling an extra sync parameter error value required in a complex modulation scheme.

The tracking circuit includes a symbol timing tracking circuit coupled with a symbol timing estimation circuit to support a complex modulation scheme, and a carrier coupled with a carrier phase estimation circuit to control the extra carrier phase error and compensate for the extra frequency offset. Phase tracking circuitry.

Referring to FIG. 1, a signal converted into a digital signal through an analog / digital converter is input to a synchronizer 100 of an adaptive modem receiver. The synchronizer 100 of the adaptive modem receiver is a circuit for synchronizing the received signal. The output signal output after being synchronized by the synchronization unit 100 of the adaptive modem receiver according to the present invention is transmitted to the equalizer and the channel decoder block to increase data transmission efficiency.

FIG. 2A is a detailed configuration diagram of a burst frame detector in a synchronous processing device of an adaptive modem receiver according to the present invention, and FIG. 2B is a diagram illustrating a preamble and a preamble in a synchronous processing device of an adaptive modem receiver according to the present invention. A diagram illustrating a correlation result of a received frame.

The signal received by the synchronization unit 100 of the adaptive modem receiver is correlated with the conjugate preamble as shown in FIG. 2A. At this time, the result of the correlation is summed after squared the real part and the imaginary part, respectively, and has a result value as shown in FIG. 2B. Since the configuration and operation of detailed components of the burst frame detector 200 shown in FIG. 2A will be apparent to those skilled in the art, a detailed description thereof will be omitted.

The correlation between the received signal and the preamble is used to detect the presence or absence of a frame and the start point of the frame, and to detect the maximum peak point in the resultant value, which is used for symbol timing estimation and carrier phase estimation.

The burst detector 200 detecting the maximum peak point of FIG. 2B transmits parameter values extracted from the symbol timing and carrier phase recovery circuit 400 and the frequency offset estimation circuit 300.

The synchronization processing scheme of the adaptive modem according to the present invention controls frame detection, frame synchronization, symbol timing estimation, carrier phase estimation, frequency offset estimation circuits, and redundant frequency offset using a 32 symbol preamble pattern, and adaptive modulation. It consists of a tracking circuit to support it. Here, the preamble consists of 32 symbols formed at the beginning of the burst frame, and includes the transmit / receive information in the frame in the header of the frame to support the adaptive TDD and the adaptive modulation scheme.

Specifically, the synchronization processing apparatus of the adaptive modem receiver according to the present invention is a system in which uplink and downlink share the same channel band over time according to the channel state of each subscriber and the adaptive modulation and uplink to improve the transmission rate. ㆍ Adaptive TDD is supported according to the amount of downlink data.

When uplink and downlink share the same channel with the TDD, the downlink data characteristic is preceded by a fixed length preamble and includes information on the TDD frame characteristic after the preamble. This information includes information on the data time point, modulation type, and data length corresponding to each subscriber station, and after the TDD frame information is transmitted, data for each subscriber station is time-division multiplexed (TDM). Is sent.

Here, the data type of the transmitted subscriber station is transmitted in the order of complex modulation to simple modulation type, and the data transmitted in the downlink processes received power and frequency, timing synchronization, and carrier phase synchronization during initial synchronization acquisition. A process to do this is required.

Thereafter, the uplink data frame is transmitted in time division multiplexing (TDMA) without a specific order if the uplink transmission scheme of each subscriber is determined through the downlink. In this case, the data characteristic of the uplink has a frame length shorter than that of the downlink.

The present invention discloses a modem structure for achieving frame synchronization, timing synchronization, carrier phase synchronization, and frequency offset synchronization in a synchronization processing apparatus of a modem receiving end for processing such an adaptive TDD frame. The same may be used in the downstream receiver, and it may support adaptive modulation.

Meanwhile, the frequency offset estimation circuit 300 may be specifically configured as shown in FIG. 3. 3 is a detailed block diagram of a frequency offset estimation circuit in the synchronization processing apparatus of the adaptive modem receiver according to the present invention.

The frequency offset estimation circuit 300 receives the 16 symbol units when the burst detector 200 detects the start point of the frame using the preambles 310a and 310b that are repeatedly transmitted twice in 16 symbol units. Among the preambles 310a, autocorrelation between the conjugate values 320a, 320b, 320c, and 320d of the preceding received data and the 16 symbols preamble 310b received later is calculated. The autocorrelation value thus calculated is a frequency offset estimate ( , Which is transmitted to the loop filter 426 in the carrier phase recovery circuit 420 shown in FIG. 4 and compensated with the carrier phase error estimate. Operation of detailed components of the frequency offset estimation circuit 300 of FIG. 3 will be apparent to those skilled in the art, and thus detailed descriptions thereof will be omitted.

In addition, the synchronization parameter extracted after the burst detection circuit 200 detects a start point of a frame is transmitted to the timing estimation circuit 410 and the carrier phase estimation circuit 420 of FIG. ) And the carrier phase estimation circuit 420 will be described in detail with reference to FIG. 4.

4 is a detailed configuration diagram of a timing and phase synchronizer in a synchronization processing apparatus of an adaptive modem receiver according to the present invention, wherein the timing estimation circuit 410 is a correlator correlator first in first out (411), timing estimation block. 412, a loop filter 413, a finite impulse response filter selector 414, an interpolator 415, and a timing error tracking circuit TED 416. The carrier phase estimation circuit 420 includes a carrier phase FIFO (421), a carrier phase estimation calculation block (422), a ROM (423), a phase ambiguity block (424), a loop filter 425, A carrier phase compensator 426, a Pre-Decm 427, and a carrier phase error tracking circuit 428 are described in detail below.

The data input from the burst detector 200 of FIG. 4 to the interpolator 415 is the same as the input data of the burst detector 200 of FIG. 1, and data loss until the burst detector 200 extracts the starting point of the frame. In order to prevent this, data of a certain length is stored in memory before being inputted.

The signal input from the burst detector 200 to the correlator FIFO 411 in the timing estimation circuit 410 represents the correlation result of FIG. 2A.

The correlator FIFO 411 stores the correlation result for a period of time in order to provide the correlation value required in the timing estimation block 412 until the burst detector 100 detects the frame start point. The symbol timing parameter values thus extracted are used by the timing estimation circuit 412 to calculate timing estimation.

The output of the timing estimation circuit 412 is set to an initial value of the loop filter 413. The output of the loop filter 413 is sent to the FIR filter selector 414 for filter selection of the interpolator 415 for timing compensation.

The interpolator 415 is composed of an FIR filter selected from the FIR filter selector 414 and compensates for a symbol timing error value according to the timing error value. The interpolator 415 needs information on the start point of the received frame extracted by the burst detector 200 to determine the symbol data to be transmitted to the carrier phase estimation 420.

At the receiving end of a modem using such adaptive modulation, the precise timing and carrier phase recovery are achieved as the modulation type becomes more complicated. According to the present invention, after timing synchronization circuit 412 is used to perform initial timing synchronization using a preamble, a timing error tracking circuit 416 may be added to increase safety of symbol timing compensation in a complex modulation scheme.

In addition, a carrier phase FIFO (421) in the carrier phase estimation circuit 420, such as the correlator FIFO 411, is a burst detector 200 for a period of time until the burst detector 200 detects a start point of a frame. Stores the real and imaginary parts of the correlation result. The data stored in the carrier phase FIFO 421 is used to estimate the carrier phase error value of the signal received at the carrier phase estimation calculation block 422 when the burst detector 200 announces the beginning of the frame.

The estimated carrier phase error value is stored in the ROM 423 until the timing estimation circuit compensates for the timing error and then applied as an initial value of the loop filter 425. The sign of the real and imaginary values of the carrier phase FIFO 421 causes the carrier phase estimation calculation block 422 to estimate only values within 0 ° to 90 °, and then receives A phase ambiguity block 424 is sent for correct position compensation of the signal. The phase ambiguity block 424 determines the sign of the sine / cosine value in the carrier phase compensator 426. Thereafter, the carrier phase compensated data in the carrier phase recovery circuit 426 is transmitted to the equalizer. At this time, a carrier phase error tracking circuit 428 is added to compensate for the extra carrier phase error and to minimize the influence of the frequency offset in the downlink transmitted by the TDM scheme in the frame.

The signal whose carrier phase and frequency offset are compensated for is input to a carrier error tracking circuit 428. Here, the Pre-Decm 427 determines the value of the received signal to configure a carrier phase tracking circuit of the TDD scheme.

FIG. 5 is a flowchart illustrating a synchronization method of an adaptive modem according to the present invention. Referring to FIG. 5, the synchronization method of the adaptive modem according to the present invention will be described.

In the method of synchronizing an adaptive modem according to the present invention, first, a signal received by a burst frame detector operating in real time is correlated with a preamble pattern (S510).

Next, an exact starting point of the burst frame is extracted according to the correlated value, thereby extracting a synchronization estimation value for initial synchronization of the burst frame (S520). In this case, the estimated synchronization parameter value enables fast data synchronization acquisition in up / down frames.

Next, the frequency offset is estimated through cross-correlation between the preamble patterns received later from the extracted frame start point (S530).

Next, a symbol timing parameter and a carrier phase error parameter value are extracted from the maximum value of the cross-correlated result value (S540).

Next, initial frame synchronization, symbol timing compensation, and carrier phase compensation are performed according to the extracted parameter values (S550).

In addition, a symbol timing tracking circuit is coupled to the symbol timing estimation circuit to support complex modulation schemes, an extra carrier phase error is controlled, and a carrier phase tracking circuit is coupled to the carrier phase estimation circuit to compensate for the extra frequency offset. (S560).

As a result, the synchronization processing method of the adaptive modem receiver according to the present invention extracts a timing error component and a carrier phase error component using a preamble positioned at the beginning of a frame to support adaptive modulation and adaptive TDD. A tracking circuit can be added to extract each sync error value to correct for more precise sync errors.

The synchronization processing apparatus and its synchronization method of an adaptive modem receiver according to the present invention perform frame synchronization, symbol timing estimation, and carrier phase error correction through correlation between a received signal and a preamble, and from a detected frame synchronization start point. The frequency offset can be estimated. The estimated frequency offset value is compensated in the carrier phase recovery circuit. In addition, carrier phase tracking circuitry and symbol timing tracking circuitry will be added to support extra frequency offset and complex modulation.

While the invention has been described above, these examples are intended to illustrate rather than limit this invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments are possible without departing from the technical details of the present invention. Therefore, the scope of protection of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

According to the present invention, by acquiring a synchronization parameter value using a preamble, data synchronization acquisition in up / down frames can be made quickly and accurately.

In addition, according to the present invention, since the tracking circuit is used simultaneously with the estimation circuit, it is possible to support complex modulation schemes such as an adaptive TDD and an adaptive modulation scheme.

In addition, according to the present invention, by minimizing the memory usage in processing the burst signal, it is efficient for real-time data processing.

1 is a schematic configuration diagram of a synchronization processing apparatus of a time division duplex (TDD) adaptive modem receiver according to the present invention.

2A is a detailed block diagram of a burst frame detector in a synchronous processing device of an adaptive modem receiver according to the present invention.

2B is a diagram illustrating a correlation result between a preamble and a received frame in the synchronization processing apparatus of the adaptive modem receiver according to the present invention.

3 is a detailed block diagram of a frequency offset estimation circuit in the synchronization processing apparatus of the adaptive modem receiver according to the present invention.

4 is a detailed configuration diagram of a timing and phase synchronization unit in a synchronization processing apparatus of an adaptive modem receiver according to the present invention.

5 is a flowchart illustrating a synchronization method of an adaptive modem receiver according to the present invention.

Claims (15)

In the receiving end of a modem that supports adaptive time division duplex (TDD) and adaptive modulation, a) a burst frame detector for detecting a burst frame using a preamble for fast synchronization parameter extraction in real time; b) a frequency offset estimator for correlating a signal received by the burst frame detector with a preamble pattern, extracting an exact starting point of the frame according to the correlation value, and estimating a frequency offset through cross correlation between the received preamble patterns; And c) a timing and phase estimator for extracting a symbol timing parameter and a carrier phase error parameter value from the maximum value of the correlated result value in the burst frame detector to compensate for initial frame synchronization and symbol timing and to compensate for a carrier phase; Synchronous processing apparatus of the adaptive modem receiving end comprising a. The method of claim 1, And a tracking unit for controlling an extra synchronization parameter error value required in a complex modulation scheme. The method of claim 2, The tracking unit, A symbol timing tracker coupled with a symbol timing estimation circuit to support a complex modulation scheme; And Carrier phase tracking unit combined with carrier phase estimation circuit to control extra carrier phase error and compensate for extra frequency offset Synchronous processing apparatus of the adaptive modem receiving end comprising a. The method of claim 1, And said preamble comprises 32 symbols formed at the beginning of said burst frame. The method of claim 1, The preamble includes a transmission / reception information in a frame in the header of the frame to support an adaptive TDD and an adaptive modulation scheme. The method of claim 1, The timing and phase estimator, A timing estimator for extracting a symbol timing parameter value from the maximum value of the correlated result and compensating initial frame synchronization and symbol timing; And A carrier phase estimator extracts a carrier phase error parameter value from the maximum value of the correlated result and compensates for initial frame synchronization and carrier phase. Synchronous processing apparatus of the adaptive modem receiving end comprising a. The method of claim 6, The timing estimator, A correlator first in first out (FIFO) for storing a correlation result value for a predetermined time until the burst detection unit detects a frame start point; A timing estimator for estimating timing using the symbol timing parameter value extracted according to the correlation result value; A loop filter for setting the output of the timing estimator to an initial value; A finite impulse response filter selector for selecting a filter according to an output of the loop filter; And An interpolator composed of an FIR filter selected from the FIR filter selector and compensating symbol timing error values according to timing error values Synchronous processing apparatus of the adaptive modem receiving end comprising a. The method of claim 7, wherein And the interpolator requests information on a start point of a received frame extracted by the burst detector to determine symbol data to be transmitted to a carrier phase estimator. The method of claim 7, wherein And a timing error tracker for compensating symbol timing in a complex modulation scheme after initial timing synchronization according to the timing estimator using the preamble. The method of claim 6, The carrier phase estimator, A carrier phase FIFO for storing a real number and an imaginary part of a correlation result value in a burst detector for a predetermined period until the burst detector detects a start point of a frame; A FIFO that stores the estimated carrier phase error value until the timing estimator compensates for a timing error when the burst detector informs the start of a frame; A ROM storing sine / cosine values for phase error values extracted from values stored in the FIFO; A loop filter using the carrier phase error estimation value as an initial value; A carrier phase reconstructor for transmitting the data compensated for the carrier phase to an equalizer; And A phase ambiguity block that determines the sign of a sine / cosine value of the carrier phase reconstructor to compensate for the exact position of the received signal. Synchronous processing apparatus of the adaptive modem receiving end comprising a. The method of claim 10, And a carrier phase error tracker further comprising a carrier phase error tracker for compensating for extra carrier phase errors and minimizing the effects of frequency offsets in the downlink transmitted in a TDM scheme within a frame. The method of claim 10, The carrier phase estimation calculation block estimates the sign of a real part and an imaginary part value of the carrier phase FIFO by estimating only a value within 0 ° to 90 °. Processing unit. In a synchronization method of a modem receiver that supports adaptive time division duplex (TDD) and adaptive modulation, a) detecting a burst frame and correlating the received signal with the preamble pattern; b) extracting an exact starting point of the burst frame according to the correlated value and extracting a synchronization estimate value for initial synchronization of the burst frame; c) estimating a frequency offset through cross correlation between preamble patterns received later from the extracted frame start point; d) extracting a symbol timing parameter and a carrier phase error parameter value from the maximum value of the cross-correlated result; And e) performing initial frame synchronization, symbol timing compensation, and carrier phase compensation according to the extracted parameter values The synchronization method of the adaptive modem receiving end comprising a. The method of claim 13, And after step v), controlling an extra synchronization parameter error value required in a complex modulation scheme. The method of claim 13, And a method of acquiring fast data synchronization in uplink and downlink frames according to the estimated sync parameter value.