Wideband digital intermediate frequency software radio Digital Clustering base station transceiver
Technical field
The utility model relates to a kind of wideband digital intermediate frequency software radio Digital Clustering base station transceiver, specifically, a kind of wideband digital medium-frequency receiving and sending letter machine that adopts software and radio technique is applied in the digital clustering communication system, as the transceiver of group system base station.
Background technology
From domestic and international existing Digital Clustering product, its base station and handset products transceiver all adopt traditional baseband digitized solution shown in Figure 1, adopt the major defect of this scheme to be: 1) for the channel of different carrier frequency, all need take independent radio-frequency (RF) transceiver of a cover and baseband processing equipment receives, the hardware configuration complexity of base station is unfavorable for safeguarding and reducing cost; 2) adopt the baseband digitized transceiver designs, because analog quadrature demodulator or intrinsic homophase and quadrature branch amplitude and the unbalance in phase of demodulator can cause corresponding performance loss; 3) digitlization of system and software implementation degree are lower, and flexibility is relatively poor, are not easy to systemic-function expansion and upgrading; 4) design of customizations, hardwareization is unfavorable for interconnecting between different communication systems.
The utility model content
The purpose of this utility model is to overcoming the deficiencies in the prior art, and a kind of wideband digital intermediate frequency software radio Digital Clustering base station transceiver is provided.
Technical solution of the present utility model is: a kind of wideband digital intermediate frequency software radio Digital Clustering base station transceiver, its feature comprises broadband rf front end parts and carrier processing plate, described broadband rf front end parts comprise receive path and transmission channel, described receive path comprises radio frequency receiving filter (RF BPF), low noise amplifier (LNA), low-converter, reception intermediate-frequency filter (IF BPF) and the intermediate frequency automatic gain control amplifier (AGC) that connects successively, and described radio frequency receiving filter (RF BPF) connects with antenna diplexer; Described transmission channel comprises emission intermediate-frequency filter (IF BPF), intermediate frequency amplifier (Amp), upconverter, radio-frequency transmissions filter (RF BPF) and the radio-frequency power amplifier (PA) that connects successively, and described radio-frequency power amplifier (PA) connects with antenna diplexer; Described carrier processing plate comprises analog-to-digital conversion module (high-speed ADC), D/A converter module (high-speed DAC), Field Programmable Gate Array (FPGA) and digital signal processor (DSP) and clock unit, described analog-to-digital conversion module (high-speed ADC) connects with the intermediate frequency automatic gain control amplifier (AGC) of aforementioned receive path, and described D/A converter module (high-speed DAC) connects with intermediate-frequency filter (IF BPF) with the emission of aforementioned transmission channel; Field Programmable Gate Array (FPGA) is connected between analog-to-digital conversion module (high-speed ADC), D/A converter module (high-speed DAC) and the digital signal processor (DSP); The other end of digital signal processor (DSP) connects with logical link control layer (LLC); Described clock unit is provided with and connects with broadband rf front end parts, analog-to-digital conversion module (high-speed ADC), D/A converter module (high-speed DAC), Field Programmable Gate Array (FPGA), digital signal processor (DSP) respectively and provide each port of homology clock for it.
Broadband rf front end parts (wide band radio-frequency transceiver) are finished the processing capacities such as amplification, frequency conversion and filtering to wireless signal: in receive path (wideband radio receiver), reception is from all carrier signals of the whole uplink band of antenna diplexer, the carrier signal of whole frequency is moved on the fixing intermediate frequency, and the composite signal of whole frequency carried out automatic gain control and amplify, export to the carrier processing plate at last; At transmission channel (wide band radio-frequency transmitter), receive carrier signal from the whole band downlink of carrier processing plate, it is carried out frequency spectrum shift to radio frequency band, the line linearity power of going forward side by side control is amplified, and launches by antenna diplexer at last.
The carrier processing plate is finished the A/D of Wideband Intermediate Frequency signal, D/A, functions such as Digital Signal Processing: at receiving terminal, the carrier processing plate receives the signal from receive path (wideband radio receiver), carrier signal to whole uplink band is sampled, and flow to the digital signal processor spare of rear end, finish the signal processing of whole physical layer; At transmitting terminal, the carrier processing plate receives the packet from last layer protocol processes equipment, finish the signal processing of whole physical layer, generate the synthetic modulated intermediate frequency signal of numeral at last, produce the analog intermediate frequency modulation signal by D/A and flow to transmission channel (wide band radio-frequency transmitter).
Further technical solution of the present utility model is: the Field Programmable Gate Array of described carrier processing plate (FPGA) comprises receive channel and the send channel that is provided with a plurality of carrier channels; The carrier channel of described receive channel comprise digital quadrature low-converter, CIC decimation filter, multistage HB filter with and wave digital lowpass filter, described digital quadrature low-converter comprises that two digital multipliers that are used to finish signal mixing and one are used to produce the mutually orthogonal carrier wave numeral carrier generator NCO of two-way; The carrier channel of described send channel comprises RRC filter, low pass filter, multistage HB interpolation filter, CIC interpolation filter and digital quadrature upconverter, and described digital quadrature upconverter comprises that two digital multipliers that are used to finish signal mixing and one are used to produce the mutually orthogonal carrier wave numeral carrier generator NCO of two-way.For receive channel, finish digitlization quadrature frequency conversion, the channelizing filtering, down-sampled of broadband signal, export the low sampling rate narrow-band digital signal of corresponding different carrier channel.For send channel, interpolation, digitlization quadrature up-conversion and the numeral of finishing low sampling rate narrow-band digital signal are synthetic, output Wideband Intermediate Frequency digital signal.
Further technical solution of the present utility model is: the Field Programmable Gate Array of described carrier processing plate (FPGA) is provided with and receives with baseband digital signal processing unit and emission baseband digital signal processing unit, and described reception comprises residual frequency departure correction module, SRRC matched filtering module, symbol synchronization module, differential ference spiral and judging module and the slot synchronization Frame output module that connects successively with the baseband digital signal processing unit; Described emission comprises that with the baseband digital signal processing unit time slot that connects successively becomes frame module, base band differential modulation module, interpose module and SRRC matched filtering module.For the reception aspect, the baseband digital signal processing unit carries out processing such as residual carrier frequency, phase place adjustment, digitlization gain adjustment, moulding matched filtering, symbol synchronization, π/4DQPSK differential ference spiral and judgement, the primary data information (pdi) after the output demodulation to the narrow-band digital signal from the digitlization front end; For the emission aspect, the baseband digital signal processing unit carries out π/4DQPSK modulation, processing such as moulding matched filtering, the modulated baseband digital signal of output I/Q two-way to primary data information (pdi).
Compared with prior art, the beneficial effects of the utility model are:
1) performance is higher: compare with baseband digitized, owing to adopt if digitization to eliminate the performance loss that intrinsic homophase of analog quadrature demodulator or demodulator and quadrature branch amplitude and unbalance in phase bring;
2) have higher flexibility, it is stronger that signal is changed (as modulation system, speed etc.) adaptation, and the adaptability that the air interface protocol of wireless communication system is changed is strong;
3) system hardware structure is easy to modularization, Structured Design, and hardware platform is simple in structure, and has very high versatility, is easy to the expansion and the upgrading of systemic-function;
4) because most of function all realizes that in FPGA/DSP inside the interface of chip chamber is simplified greatly, this is easy to systemic-function adjustment and maintenance;
5) conform to existing components and parts production technology level, can rationally fully adopt existing hardware resource.
Below in conjunction with the drawings and specific embodiments the utility model is further described.
Description of drawings
Fig. 1 is a baseband digitized Digital Clustering base station transceiver implementation structure block diagram commonly used;
Fig. 2 is the utility model wideband digital intermediate frequency software radio Digital Clustering base station transceiver specific embodiment structured flowchart;
Fig. 3 is the utility model specific embodiment broadband rf front end modular construction block diagram;
Fig. 4 a is the carrier channel structured flowchart of the utility model specific embodiment FPGA receive channel;
Fig. 4 b is the carrier channel structured flowchart of the utility model specific embodiment FPGA send channel;
Fig. 5 is that the utility model specific embodiment receives with baseband digital signal processing unit structured flowchart;
Fig. 6 is the utility model specific embodiment emission baseband digital signal processing unit structured flowchart.
Embodiment
In order to more fully understand technology contents of the present utility model, the technical solution of the utility model is further introduced and explanation below in conjunction with the drawings and specific embodiments.
Extremely shown in Figure 6 as Fig. 2, the utility model wideband digital intermediate frequency software radio Digital Clustering base station transceiver, comprise broadband rf front end parts 1 and carrier processing plate 2, broadband rf front end parts 1 comprise receive path 11 and transmission channel 12, receive path 11 comprises radio frequency receiving filter (RF BPF) 111, low noise amplifier (LNA) 112, low-converter 113, reception intermediate-frequency filter (IF BPF) 114 and the intermediate frequency automatic gain control amplifier (AGC) 115 that connects successively, and radio frequency receiving filter (RF BPF) 111 connects with antenna diplexer 4; Transmission channel 12 comprises emission intermediate-frequency filter (IF BPF) 125, intermediate frequency amplifier (Amp) 124, upconverter 123, radio-frequency transmissions filter (RF BPF) 122 and the radio-frequency power amplifier (PA) 121 that connects successively, and radio-frequency power amplifier (PA) 121 connects with antenna diplexer 4; Carrier processing plate 2 comprises analog-to-digital conversion module (high-speed ADC) 21, D/A converter module (high-speed DAC) 22, Field Programmable Gate Array (FPGA) 23 and digital signal processor (DSP) 24 and clock unit 25, analog-to-digital conversion module (high-speed ADC) 21 connects with the intermediate frequency automatic gain control amplifier (AGC) 115 of aforementioned receive path 11, and D/A converter module (high-speed DAC) 22 connects with intermediate-frequency filter (IF BPF) 125 with the emission of aforementioned transmission channel 12; Field Programmable Gate Array (FPGA) 23 is connected between analog-to-digital conversion module (high-speed ADC) 21, D/A converter module (high-speed DAC) 22 and the digital signal processor (DSP) 24; The other end of digital signal processor (DSP) connects with logical link control layer (LLC) 3.Described clock unit 25 is provided with and connects with broadband rf front end parts 1, analog-to-digital conversion module (high-speed ADC) 21, D/A converter module (high-speed DAC) 22, Field Programmable Gate Array (FPGA) 23, digital signal processor (DSP) 24 respectively and provide each port of homology clock for it.Received signal in 806~821MHz frequency range is input to radio frequency band filter by antenna and duplexer, the radio frequency band filter passband central frequency is 813.5MHz, pass band width is 15MHz, filtered signal is passed through the broadband low-converter by low noise amplifier thereafter, signal in the whole 15MHz spectral range is shifted to the 70MHz intermediate frequency, the passband width of intermediate-frequency filter is similarly 15MHz, and signal is through exporting the broadband analog if signal that mates with rear end ADC input range after AGC amplifies behind the intermediate frequency filtering.Here intermediate frequency is selected 70MHz, on the one hand follow-up digital signal processor spare is required lowlyer, also can have preferable performance (going out as mirror image and combination interference are more for a short time) simultaneously.Transmission channel is made up of Wideband Intermediate Frequency filter, intermediate frequency amplifier, upconverter, radio-frequency transmissions filter and the high power amplifier of RF linearization etc.At the wideband digital signal of carrier processing intralamellar part different carrier channel through the synthetic formation of numeral 70MHz intermediate frequency 15MHz bandwidth, this signal forms the broadband analog if signal of 70MHz intermediate frequency 15MHz bandwidth behind DAC, this signal is through intermediate frequency filtering with after amplifying, move radiofrequency signal in 851~866MHz scope by upconverter, this signal is launched by antenna for base station by duplexer after by rf filtering and linearisation power amplification.High-speed ADC realizes that to the Wideband Intermediate Frequency signal sampling in order to reduce the burden that sample rate reduces follow-up digital signal processor spare simultaneously, sampling is owed in employing to the Wideband Intermediate Frequency signal.High-speed DAC is realized the simulation reconstruct to digital Wideband Intermediate Frequency signal, output simulation Wideband Intermediate Frequency signal.FPGA finishes the signal processing work of all computation-intensive such as the processing of digitlization front end signal, base band signal process, TDMA data framing reconciliation frame, it is strong that it has disposal ability, can characteristics such as heavy duty configuration etc., can revise algorithm software wherein at any time as required, the raising of performances such as the flexibility of whole base station, extensibility is had very big meaning.DSP finishes work such as channel coding/decoding, is responsible for the work such as data interaction of same last layer (LLC layer) simultaneously.
The Field Programmable Gate Array of carrier processing plate (FPGA) comprises receive channel and the send channel that is provided with a plurality of carrier channels; The carrier channel of receive channel comprise digital quadrature low-converter 520, CIC decimation filter 521, multistage HB filter 522 with wave digital lowpass filter 523, digital quadrature low-converter 520 comprises that two digital multipliers that are used to finish signal mixing and one are used to produce the mutually orthogonal carrier wave numeral carrier generator NCO of two-way.Though the later signal of quadrature frequency conversion still comprises very wide spectrum signal, for the real useful just close very narrow part of direct current component of this carrier channel, this part signal can be represented with lower sample rate.CIC filtering extraction rate on the one hand removes high-frequency signal, plays a part the anti-mixed repeatedly filtering of low pass, simultaneously filtered signal is extracted, and reduces signals sampling speed.Cic filter simple in structure, operand is less, being particularly suitable for the high power sample rate changes, but because the passband end of its filtering characteristic has higher roll-offing, for the radio-frequency head branch that prevents passband signal is decayed, sample rate after general CIC extracts is still higher with respect to baseband signal bandwidth, so the multistage HB filter of following adopted is realized the further extraction to signal.The HB filter has amount of calculation features of smaller simple in structure equally, but a HB filter once can only carry out 2 times extraction meeting interpolation to signal, so adopts multistage (2~3 grades) HB filter here.Signal sampling rate behind the HB filtering extraction is generally the chip rate about 8~16 times, the Base-Band Processing that relatively is suitable for the rear end, thereafter low pass filter plays a part signal and filtering, its objective is that filtering has the outer noise of small-signal frequency range and other residue signals, reduces the performance requirement to baseband portion RRC filter.
The carrier channel of send channel comprises RRC filter 514, low pass filter 513, multistage HB interpolation filter 512, CIC interpolation filter 511 and digital quadrature upconverter 510, and the digital quadrature upconverter comprises that two digital multipliers that are used to finish signal mixing and one are used to produce the mutually orthogonal carrier wave numeral carrier generator NCO of two-way.Its input is the symbol after the differential coded modulation, for symbol is carried out the symbol moulding, earlier symbol is carried out the zero padding interpolation, carries out molding filtration then.Out of band components in the further filtered signal of low pass filter behind the formed filter reduces the monkey chatter of signal.Thereafter HB, cic filter and quad upconverter just in time play and the receive channel opposite effect.
Field Programmable Gate Array (FPGA) 23 is provided with and receives with baseband digital signal processing unit and emission baseband digital signal processing unit, receives with the baseband digital signal processing unit to comprise residual frequency
departure correction module 610, SRRC matched
filtering module 611, symbol synchronization module 612, differential ference spiral and
judging module 613 and the slot synchronization
Frame output module 614 that connects successively; Emission comprises that with the baseband digital signal processing unit time slot that connects successively becomes
frame module 620, base band
differential modulation module 621,
interpose module 622 and SRRC matched filtering module 623.Aspect reception, the broadband signal of whole uplink band is through the arrowband I/Q baseband signal of digital front-end channelizing filtering and the corresponding different carrier frequency channels of down-sampled back formation, because the influence of Doppler frequency shift and travelling carriage local frequency error can cause received signal carrier frequency and local carrier frequency to have bigger frequency deviation.This transceiver adopts
![Figure Y20072012246400111](https://patentimages.storage.***apis.com/2d/81/96/c8f6e5659ca464/Y20072012246400111.png)
Modulation system, in the general method that adopts incoherent differential ference spiral of receiving terminal, do not need receiving terminal to recover coherent carrier, allow receiving terminal local frequency and transmitting terminal carrier frequency to have the interior frequency difference of certain limit, but when frequency difference is big, can cause the error rate to increase, when frequency difference exceeds allowed band, can't demodulate initial data further.Therefore, receive path baseband digital signal processing section is at first estimated carrying out residual carrier frequency from the baseband signal of each carrier frequency of correspondence of digital front-end, utilize the method for complex signal mixing that residual frequency deviation is revised according to estimated result, square root raised cosine filter thereafter carries out matched filtering to the adjusted baseband signal of carrier frequency.For correct restituted signal, must carry out symbol synchronization, this digital cluster adopts TDMA burst access way, to symbol synchronization time requirement relatively strict (requiring start element to be synchronized to enter time of symbol synchronization state can not surpass the protection sequence length of tdma slot regulation), adopt the sign indicating number synchronization scenario of feedback adjusting to be difficult to satisfy its requirement lock in time fully; And adopt the symbol synchronizaton error extraction algorithm of feedforward fully, then when there are frequency deviation in sign indicating number clock and the local code clock of received signal, slip phenomenon (have more in time slot or minus a code element) can appear in the accumulative effect of phase error if call duration time is long, causes packet loss easily.In native system, we have adopted the sign indicating number synchronized algorithm of forward estimation and feedback adjusting, utilize feedforward symbol synchronizaton error algorithm for estimating in the synchronous initial moment, fast detecting is to correct symbol phases, shortened sign indicating number expense lock in time, and in follow-up time, according to the symbol synchronizaton error estimated result, adopt the digital code element phase adjusting method that increases and decreases clock pulse to adjust the symbol phases of input signal in real time, can effectively prevent the slip that phase error accumulative total causes like this.After having finished symbol synchronization, the differential ference spiral module utilizes difference method right
![Figure Y20072012246400121](https://patentimages.storage.***apis.com/54/e2/42/dc17efe15dcbc7/Y20072012246400121.png)
Carry out demodulation, output serial bit stream and corresponding bit are all the time, last slot synchronization and Frame output module are finished the frame synchronization of different training sequences, and the time slot data are synchronously outputed to the channel decoding module (not shown) according to certain form.Aspect emission, base band signal process partly receives the data from the channel coding module (not shown), carries out framing as requested, and the data after the base band differential modulation module stack framing are carried out
Modulation, the I/Q data of the symbol correspondence after the generation modulation are carried out interpolation and square root raised cosine filtering to the I/Q data at last, form the baseband I/Q signal waveform of corresponding code element.
The above angle from specific embodiment discloses further to technology contents of the present utility model; its purpose is to allow everybody be easier to understand technology contents of the present utility model; but do not represent execution mode of the present utility model and rights protection to be confined to this, rights protection scope of the present utility model should be as the criterion in claims of the present utility model.