CN101286755A

CN101286755A - Integrated receiver suitable for TDS-OFDM signal and TDS single carrier signal

Info

Publication number: CN101286755A
Application number: CNA2007101300164A
Authority: CN
Inventors: 杨林
Original assignee: LEGEND SILICON
Current assignee: Tsinghua University
Priority date: 2006-10-17
Filing date: 2007-07-23
Publication date: 2008-10-15
Anticipated expiration: 2027-07-23
Also published as: CN101286755B

Abstract

The present invention relates to a unified receiver structure for TDS-OFDM signals and TDS single carrier signals, belonging to communication technique field. The receiver adapted to receive both OFDM signals and single carrier signals is provided. The receiver possesses substantially commonly shared circuitry or function blocks, except an IFT (inverse Fourier transform) block adapted a receive frequency domain signals from a channel equalizer for converting the received frequency domain signal to a time domain signal, and a bypass for bypassing the IFT.

Description

Be applicable to the unified receiver of TDS-OFDM signal and TDS single-carrier signal

Related application is quoted

The disclosure of the Invention that the application advocates is on July 25th, 2006, and provisional application number is 60/820,319, and name is called " the LDPC receiver in the TDS-OFDM communication system ".Therefore, the present invention advocates the right under 35USC § 119 (e) clause of U.S. Provisional Application, and the above-mentioned application that relates to merges into a single whole at this.

Technical field

The invention belongs to communication technical field, more particularly, the present invention relates to be applicable to time-domain synchronization OFDM (TDS-OFDM, Time Domain Synchronous-Orthogonal FrequencyDivision Multiplexing) the unified receiver of signal and Domain Synchronous (TDS, Time Domain Synchronous) single-carrier signal.

Background technology

OFDM (OFDM, Orthogonal Frequency Division Multiplexing) is known disclosed technology.Authorize people such as Chang, U.S. Patent number is 3,488,445 patent has been described the equipment and the method for an OFDM, it realizes the frequency division multiplexing of mass data signal on mutually orthogonal in a large number carrier wave, therefore, exist overlapping between the subcarrier, but frequency band is limited, the frequency spectrum that produces does not exist interchannel interference (ICI, Interchannel Interference) and intersymbol interference (ISI, Intersymbol Interference).The narrow band filter amplitude-frequency characteristic of each channel and phase-frequency characteristic are by they symmetry defineds separately.For each signal provides the protective capability of identical opposing interchannel noise, the signal in each channel is by incoherent media transmission seemingly, and removes intersymbol interference by reducing data transfer rate.Along with the increase of channel number, total data transfer rate is near maximum theoretical.

The OFDM transceiver is known disclosed technology.Authorize people such as Fattouche, U.S. Patent number is that 5,282,222 patent has been described the mutual exchange message of a plurality of radio receiving-transmitting units of a kind of permission (data, voice or video) method.In first transceiver, first frame of information is multiplexed on the broadband, sends second transceiver to.Second transceiver receives and process information.Information adopts the differential coding of phase shift keying.In addition, after the time interval of selecting in advance, first transceiver can transmit information once more.During the time interval of selecting in advance, second transceiver can be used time division duplex and other transceiver exchange message.The signal processing of second transceiver comprises to be estimated to send the phase difference of signal and carries out pre-distortion to sending signal.Transceiver comprises an encoder that is used for information coding, be used for information multiplexing to the broadband voice channel broadband frequency division multiplexing device and be used for the local oscillator of multiplexed information up conversion.Equipment comprises a processor, and it carries out Fourier transform to multiplexed information, and information conversion is transmitted to time-domain.

(PN is known disclosed technology as protection interval (GI, Guard Interval) Pseudo-Noise) to adopt pseudo noise in OFDM.Authorize people such as Yang Lin, U.S. Patent number is that 7,072,289 patent has been described under the situation that has time delay in signal channel, a kind ofly estimates that transmission signal frame begins and/or the method for stop timing.Each signal frame all has a pseudorandom (PN) m sequence, wherein the satisfied orthogonality of selecting of PN sequence and irrelevant.Signal that receives and PN sequence are carried out convolution, and deduct the PN sequence from received signal, thereby determine the beginning and/or the end of PN sequence in the received signal.The PN sequence is used for regularly recovering, carrier wave recovers, channel transfer characteristic is estimated, received signal frame synchronization, and the protection of replacement OFDM at interval.

Known receiver can only receive ofdm signal usually, perhaps can only receive single-carrier signal.In other words, two types reception usually can not in conjunction with.Yet even two types receiver combines, two kinds of signals have own independent signal path respectively.Therefore, what enjoy popular confidence is that a kind of receiver (being used for ofdm signal and single-carrier signal) that integrates two kinds of receiver functions is arranged, and realizes with improved or simple method.

Summary of the invention

The invention provides the unified receiver that is applicable to TDS-OFDM signal and TDS single-carrier signal.

Be applicable to the unified receiver of TDS-OFDM signal and TDS single-carrier signal, the TDS single-carrier signal is by the transmission of inverse Fourier transform (IFT) module, and this IFT module is crossed in the bypass of TDS-OFDM signal.

Be fit to receive the receiver of above-mentioned two kinds of signals.Receiver has circuit or the functional module of fully sharing, and except inverse Fourier transform (IFT) module is used to receive the frequency-region signal that comes from the channel balancing device, the frequency-region signal that receives of conversion becomes time-domain signal then, and with the bypass apparatus of IFT bypass.

First type of signal and second type of signal are fully shared circuit or functional module; Except: inverse Fourier transform module, this module frequency-region signal after the channel frequency domain equalization is converted to time-domain signal; With

Bypass the bypass apparatus of IFT.

Description of drawings

Reference number in the accompanying drawing refers to identical or intimate elementary cell, and accompanying drawing and following detailed have constituted an integral body together, become the key element of specification, and is used for further setting forth various specific embodiments and explains various principles of the present invention and advantage.

Fig. 1 is the concrete a kind of receiver schematic diagram implemented of the present invention;

Fig. 2 is the modified model schematic diagram of receiver among Fig. 1;

Fig. 3 is a flow chart of the present invention.

What the professional person needed is that the elementary cell among the figure is showed simply, and whether describe in proportion is not necessary.For example, understand specific embodiments of the invention, can exaggerate the size of some elementary cell among the figure with respect to other unit in order to help better.

Embodiment

Before describing the concrete implementation detail of the present invention in detail, what should be noted that is that specific embodiment is present among the combination of method step and device feature, and it relates to the receiver of being made up of by mode after improving or that oversimplify two parts function (being used for ofdm signal and single-carrier signal).Therefore, provided device feature and method step with conventional sign in the drawings, and described the details that those help to understand the specific embodiment of the invention in detail, in order to avoid these details are misunderstood, those of ordinary skill in the art is understood easily, and income therefrom.

In this manual, relevant term for example first and second, top and bottom, and similar term, may use separately, to distinguish different entities or processing, do not represent must needs hint these entities or processing between relation or in proper order.Term " comprises ", " by ... .. forms ", or any other associated distortion mean and comprise non-exclusive result.So, the processing of being made up of a series of elementary cells, method, article or device not only comprise those elementary cells that has indicated, the elementary cell that also may comprise other is not though these unit clearly are listed in or belong to above-mentioned processing, method, article or device." comprised " elementary cell of being quoted from, do not had under the situation of more restrictions, be not precluded within the other identical elementary cell of existence in processing, method, literal or the device that constitutes by elementary cell.

Specific embodiments of the invention as described herein are made of one or more common processors and unique stored program instruction, program command is controlled one or more processors, cooperate certain non-processor circuit, go to realize some, the receiver (being used for ofdm signal and single-carrier signal) of two kinds of functions making up of the improved or simple mode of most or all of usefulness.Non-processor circuit may include but not limited to wireless receiver, transmitting set, signal driver, clock circuit, power circuit and user input device.Same, these functions can be interpreted as finishing the method step of above-mentioned receiver.Select as an alternative, some or all functions can realize with the state machine that does not have stored program instructions, perhaps use one or more application-specific integrated circuit (ASIC) (ASIC, Application SpecificIntegrated Circuit), certain combination of a function or some functions realizes as customized logic in these ASIC.Certainly, these two kinds of methods also can be used in combination.Therefore, the ways and means of realizing these functions has been described here.Further, the expectation those skilled in the art through great efforts with many design alternatives after, for example effectively development time, current technology and the consideration of economic aspect, under the notion and guidance of principle that is here disclosed, can obtain described software instruction, program and integrated circuit (IC, Integrated Circuit) by minimum experiment easily.

As shown in Figure 1, realize LDPC system receiver 10 exactly based on TDS-OFDM.In other words, Fig. 1 be with block diagram Benq in the functional block diagram of low-density checksum (LDPC, the Low Density Parity Check) receiver 10 of TDS-OFDM.The TDS-OFDM modulation principle is followed in the demodulation here.Error code correction mechanism is based on LDPC.The primary and foremost purpose of receiver 10 is the input in noise factor is arranged, and transmitter sends the finite aggregate of waveform, and the finite aggregate of the discrete signal that receiver sends with signal processing technology regeneration transmitter.

Block diagram among Fig. 1 has been set forth the signal and the crucial treatment step of receiver 10.Here the input signal 12 of supposing receiver 10 is digital signals of down conversion.The output signal 14 of receiver 10 is the transmission stream of Motion Picture Experts Group's standard-2 (MPEG-2) form.In particular, radio frequency (RF, Radio Frequency) input signal 16 is received by RF tuner 18, then the RF signal is downconverted to Low Medium Frequency or zero intermediate frequency signals 12.Low Medium Frequency signal or zero intermediate frequency signals 12 offer receiver 10 as analog signal or digital signal (by optional analog to digital converter 20).

In receiver 10, intermediate-freuqncy signal is transformed into baseband signal 22.Then, finish the TDS-OFDM demodulation according to the parameter of LDPC in the TDS-OFDM modulation scheme.Time solution interleaver 28 is delivered in the output of channel estimating 24 and correlation module 26, delivers to forward error correction block then.The output signal 14 of receiver 10 is that the parallel or serial MPEG-2 that has comprised valid data, synchronizing signal, clock signal transmits stream.The configuration parameter of receiver 10 can be surveyed or automated programming control or manually setting automatically.Receiver 10 main configuration parameters comprise: (1) subcarrier modulation modes: quadriphase PSK (QPSK, Quad Phase Shift Keying), 16 quadrature amplitude modulation (QAM, QuadratureAmplitude Modulation) and 64QAM; (2) forward error correction code check: 0.4,0.6 and 0.8; (3) protection at interval: 420 or 945 symbols; (4) time solution interlace mode: 0,240 or 720 symbols; (5) control frame is surveyed; (6) channel width: 6,7 or 8MHz.

Each functional module of receiver 10 is described below.

Digitized signal strength signal intensity and reference data that automatic gain control (AGC, Automatic Gain Control) module 30 will be imported compare, and the difference that obtains is carried out filtering, and filter value 32 is used to control the gain amplifier of tuner 18.The analog signal 12 that tuner provides is by analog to digital converter 20 samplings, and signal finally is the lower medium-frequency IF signal of centre frequency.For example, with 36MHz medium-frequency IF signal of 30.4MHz sampling, the result is that centre frequency of generation is the 5.6MHz signal.Intermediate frequency is converted to complex base band signal to baseband module 22 intermediate-freuqncy signal that this is lower.Analog to digital converter ADC20 uses fixed sample rate.Interpolater in the use module 22 is finished the transformation from fixed sample rate to the OFDM sample rate.Clock recovery module 33 evaluation time errors reach error filtering, drive digital controlled oscillator (NCO then, Numerically Controlled Oscillator) (not shown) is calibrated with this employed sampling timing of interpolater of controlling in the sample conversion device.

Input signal 12 has frequency shift (FS).The skew of automatic frequency control module 34 calculated rates, and adjust the reference IF-FRE of intermediate frequency to base band.In order to improve capture range and tracking performance, FREQUENCY CONTROL is finished by two steps: coarse adjustment and fine tuning.Because transmit is to be shaped by square root raised cosine filter, so received signal will be carried out identical processing.In the TDS-OFDM system, comprise a PN sequence as everyone knows before inverse discrete Fourier transformer inverse-discrete (IDFT, the Inverse Discrete Fourier Transform) symbol.Carry out related calculation by PN sequence and the input signal that this locality is produced, be easy to find information synchronously such as relevant peaks (just can determine frame head thus) and frequency offset and time error etc.The channel time domain response is based on the signal correction that has obtained.Conversion obtains through fast fourier transform (FFT, Fast Fourier Transform) by time-domain response in frequency response.

In the TDS-OFDM system, the PN sequence has replaced traditional Cyclic Prefix and has filled.So just need deletion PN sequence, and recover by the OFDM symbol of channel expansion.Module 36 has been recovered traditional OFDM symbol, and it has used the equalizer of a tap.FFT module 38 has realized 3780 FFT.FFT 38 transform datas based on channel frequency response are carried out channel equalization 40.Go postrotational data and channel condition information to give forward error correction (FEC, Forward ErrorCorrection) and do further processing.

In TDS-OFDM receiver 10, time solution interleaver 28 is used to improve the repellence of paired pulses noise.Time solution interleaver 28 is convolution de-interleaver, and it needs the memory of B* (B-1) * M/2 size, and B is a weaving width here, and M is an interleave depth.For the specific embodiment of TDS-OFDM receiver 10, two kinds of time solution interlace modes are arranged, pattern 1, B=52, M=240; Pattern 2, B=52, M=720.

For decoding, LDPC decoder 42 is soft-decision iterative decoders, for example, and the quasi-cyclic low-density parity check codes (QC-LDPC, Quasi-CyclicLow Density Parity Check) that provides by the transmitter (not shown).LDPC decoder 42 is configured to 3 kinds of different QC-LDPC code checks (being code check 0.4, code check 0.6 and code check 0.8), and three kinds of code checks are shared identical hardware circuit.When iterative process has reached the maximum iteration time (all iteration) of regulation, or when not had error code (part iteration) in error detection and error correcting processing, iterative process will finish.

TDS-OFDM modulating/demodulating system system is based on the multi code Rate of Chinese character system of multiple modulation scheme (QPSK, 16QAM, 64QAM) and multiple encoder bit rate (0.4,0.6 and 0.8), and interim QPSK represents quadriphase PSK, and QAM represents quadrature amplitude modulation.BCH Bose-Chadhuri-Hocquengham's sign indicating number (BCH, Bose, Chaudhuri ﹠amp; Hocquenghem Type of Code) decoder 46 is to export by bit.According to different modulation schemes and encoder bit rate, rate conversion module is combined as byte (byte) to the output of the bit of BCH decoder 46, adjust the speed of byte output clock simultaneously, make the MPEG bag output of receiver 10 in whole rectification/decode procedure, keep distributing uniformly.

BCH decoder 46 is that the decoding for the shortening binary system Bose-Chaudhuri-Hocquenghem Code BCH (762,752) of BCH (1023,1013) designs, and its generator polynomial is x ¹⁰+ x ³+ 1.

(PN, Pseudo-Random) sequence has been carried out randomization, so the error correction data that is produced by LDPC/BCH decoder 46 must go randomization because the data in the transmitter had been used pseudorandom before Bose-Chaudhuri-Hocquenghem Code device (not shown).The generator polynomial of PN sequence is 1+x ¹⁴+ x ¹⁵, its initial condition is 100101010000000.Descrambler 48 can reset to initial condition at each signal frame.In addition, descrambler 48 meeting free-running operations always are up to reset next time.To make XOR with the input word throttling for minimum 8.

The situation of data flow by the demodulator disparate modules is described below.The RF information 16 that receives is handled by digital ground tuner 18, and tuner need to select the bandwidth and the frequency of restituted signal, and signal 16 is downconverted to base band or Low Medium Frequency signal.The information 12 that obtains of down conversion transforms to numeric field by A/D converter 20 then.

Baseband signal is converted to symbol through after the processing of sampling rate converter 50.PN information in the protection is at interval made related operation with the local PN sequence that produces, and obtains the time domain impulse response.The FFT conversion of time domain impulse response provides the estimation of channel response.Correlator 26 also is used for the correction of clock recovery 33, Frequency Estimation and received signal.Extract the OFDM symbol that receives in the data, and pass through 3780 FFT conversion 38, obtained the symbolic information in the frequency domain.Use the resulting channel estimating information in front, the OFDM symbol is carried out equilibrium treatment, deliver to the fec decoder device then.

In fec decoder device part, time solution interleaving block 28 has realized that deconvoluting of transmission symbol sequence interweaves, and then the piece of these 3780 points is delivered to ISN LDPC decoder 42.LDPC decoder 42 and BCH decoder 46 receive accurate 3780 symbols in the tandem working mode, remove 36 parameter signals (TPS, Transmission Parameter Signal) behind the symbol, handles 3744 remaining symbols, and recover the transport stream of emission.Rate converter 44 is adjusted output data rate, and descrambler 48 is rebuild the code stream information of emission.The external memory storage 52 that is connected to receiver 10 provides memory space for this part predefined function or demand.

What Fig. 2 described is the special example 60 of Fig. 1.The type that controller 62 is followed the tracks of transmission signals by the signal path of receiver 10, and the type of definite transmission signals.Such as, controller 62 is determined at whether distinctive signal passes through channel equalizer 40 in special time or time cycle, thereby determines that signal type is ofdm signal or single-carrier signal.If signal is the single carrier form, signal will be by inverse Fourier transformer 64 passages so.Change to time domain by inverse Fourier transformer 64, the signal after the inverse transformation is given time solution interleaver 28 and is finished time solution and interweave.Otherwise controller 62 is directly delivered to time solution interleaver 28 to signal, thus bypass inverse Fourier transformer 64.It should be noted that time solution interleaver 28 should be counted as the interframe deinterleaver.Controller 62 both can pass through channel equalizer 40, also can determine signal type by the miscellaneous part 66 of receiver 10 among Fig. 1.Just as seen, the signal that receives sometimes has identical bandwidth, but signal is dissimilar, and for example first signal is the OFDM form, and second signal is the single carrier form.The present invention wishes to pass through to share many parts in receiver 10, maximal efficiency ground receives two kinds of signal types as far as possible.

Flow process Figure 70 of the present invention as shown in Figure 3.A channel equalizer 40 (step 72) is arranged among Fig. 3, and it may be the existing parts of receiver 10.A judgement is done in equalizer output currently or later, to determine that what type (step 74) signal is.This judgement can be by controller 62 by channel equalizer 40 or similarly other parts 66 realizations of scheme therewith.If determining signal is first type signal, i.e. single carrier type, then signal becomes time-domain signal (step 76) through inverse Fourier transform, and the signal of inverse transformation is sent to time solution interweave (step 78) then.Yet, if signal is second type a signal, i.e. ofdm signal, skips steps 76, and signal directly arrives time domain deinterleaving (step 78).

The invention provides a method and a specific embodiment that is applicable to the receiver that receives ofdm signal and single-carrier signal.Receiver is fully shared circuit or functional module, and except inverse Fourier transform (IFT) module and IFT bypass, the frequency-region signal of IFT module after the channel frequency domain equalization is converted to time-domain signal.

In conjunction with the accompanying drawings specific embodiments of the invention are had been described in detail above, but the present invention is not restricted to the foregoing description, do not breaking away under the spirit and scope situation of claim of the present invention, those of ordinary skill in the art can make various modifications or change.Therefore, this specification and block diagram be illustrative and nonrestrictive, simultaneously, all modifications is included in the scope of the present invention.The solution of benefit, advantage, problem and may produce benefit, advantage or any elementary cell of the solution that produces solution or become clearer and more definite can not explained as characteristic or principle important, essential or essence in any or all of claim.Following claim, comprise the application during uncertain any correction and with all rights that are equal to of those claims of promulgation, defined the present invention individually.

Claims

1. a receiver that is suitable for receiving first type of signal and second type of signal is characterized in that, comprising:

First kind of signal and second kind of signal are fully shared circuit or functional module; Except:

IFT module, this module frequency-region signal after the channel frequency domain equalization is converted to time-domain signal;

With the bypass apparatus that bypasses IFT.

2. the receiver that is suitable for receiving first type of signal and second type of signal as claimed in claim 1 is characterized in that, further comprises to judge that received signal is the ofdm signal or the decision method of single-carrier signal.

3. the receiver that is suitable for receiving first type of signal and second type of signal as claimed in claim 1 is characterized in that, described first type of signal is made up of the TDS-OFDM signal.

4. the receiver that is suitable for receiving first type of signal and second type of signal as claimed in claim 1 is characterized in that, described second type of signal is made up of the TDS single-carrier signal.

5. the receiver that is suitable for receiving first type of signal and second type of signal as claimed in claim 1 is characterized in that described IFT module comprises the IFFT module.

6. the receiver that is suitable for receiving first type of signal and second type of signal as claimed in claim 1 is characterized in that, single-carrier signal is carried out inverse Fourier transform through the IFT module.

7. the receiver that is suitable for receiving first type of signal and second type of signal as claimed in claim 1 is characterized in that, ofdm signal bypass IFT module.

8. a processing method that is suitable for receiving the receiver of first kind of signal and second kind of signal is characterized in that, may further comprise the steps:

With the bypass apparatus that bypasses IFT.

9. the processing method that is suitable for receiving the receiver of first type of signal and second type of signal as claimed in claim 8 is characterized in that, further comprises to judge that received signal is the ofdm signal or the decision method of single-carrier signal.

10. the processing method that is suitable for receiving the receiver of first type of signal and second type of signal as claimed in claim 8 is characterized in that described first type of signal is made up of the TDS-OFDM signal.

11. the processing method that is suitable for receiving the receiver of first type of signal and second type of signal as claimed in claim 8 is characterized in that described second type of signal is made up of the TDS single-carrier signal.

12. the processing method that is suitable for receiving the receiver of first type of signal and second type of signal as claimed in claim 8 is characterized in that described IFT module comprises the IFFT module.

13. the processing method that is suitable for receiving the receiver of first type of signal and second type of signal as claimed in claim 8 is characterized in that single-carrier signal is carried out inverse Fourier transform through the IFT module.

14. the processing method that is suitable for receiving the receiver of first type of signal and second type of signal as claimed in claim 8 is characterized in that ofdm signal bypass IFT module.