CN112929108B - Time delay estimation method for radio frequency module in millimeter wave integrated communication system - Google Patents
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Abstract
The invention discloses a time delay estimation method of a radio frequency module, which has the scheme that: 1) the base station and the user generate 1PPS signals through GPS for synchronization; 2) the base station as the sending end generates a time delay estimation signal r and generates a time delay estimation signal r at TiSending at any moment; 3) the user is used as a receiving end to detect the time delay estimation signal r and detects the time delay estimation signal r at Ti+1Switching a receiving beam at a moment; 4) the user detects the time t when the signal amplitude changes after the wave beam switching1And use T in combinationi+1Time t and1the time difference estimates the time delay from the baseband data of the local terminal to the radio frequency module and feeds back the time delay to the base station; 5) and (5) taking the user side as a sending end and the base station side as a receiving end, and repeating the steps 2) to 5) to estimate the time delay from the data of the base station side to the radio frequency module. The invention can effectively estimate the time delay of the radio frequency module under the condition of not using external equipment for measurement, saves a large amount of cost and can be used for a millimeter wave integrated communication system.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a time delay estimation method for a radio frequency module, which can be used for a millimeter wave integrated communication system and improves the time domain synchronization accuracy of system beam scanning.
Background
The millimeter wave has the advantages of wide frequency spectrum, high stability and good directivity, so the millimeter wave communication becomes one of the key technologies of the fifth generation mobile communication; the short wavelength of the millimeter wave and the small space occupied by the antenna array are favorable for building miniaturized and low-power millimeter wave integrated base station equipment, and further the network coverage in a hot spot area and the signal intensity of a weak coverage area are improved. In the application of millimeter wave technology, the transmission quality is improved by using the beam forming technology between the 5G base station and the user, and the method is characterized in that the main lobe of a radiation directional diagram is self-adaptively pointed to the incoming wave direction of the user, so that the signal-to-noise ratio is improved, and obvious array gain is obtained. In order to make better use of beamforming technology, the base station and the user need to use a beam scanning manner to determine the best beam pair between the base station and the user that meets the transmission quality requirement. When both the base station and the user support multiple beams, how to realize the baseband processing unit is a crucial research direction for the effective control of the radio frequency processing unit.
The millimeter wave integrated base station comprises three parts, namely a baseband processing unit (BBU), a radio frequency processing unit (RRU) and an antenna feedback system. The radio frequency processing unit is further divided into an intermediate frequency processing unit and a millimeter wave processing unit, and a control signal of the millimeter wave processing unit is generated in the baseband processing unit. The baseband data signal needs to be subjected to up-conversion twice, so that the path of the baseband data signal is longer than that of the control signal, the control signal and the baseband data signal are asynchronous, and when the radio-frequency signal is transmitted by using a corresponding beam number within the duration time of a specific Orthogonal Frequency Division Multiplexing (OFDM) symbol, the synchronism of signal and beam switching is influenced due to the time delay from the baseband data to the millimeter wave radio-frequency module, so that the beam scanning result is inaccurate.
The CN106226760A patent discloses a "measuring apparatus and method with wireless device delay calibration", which can calibrate the device delay of the transmitting link and the receiving link of the measuring system. The method comprises the following steps: firstly, a measurement signal generating device generates a wireless time delay calibration signal by taking a local measurement reference as a reference, and a calibration antenna receives the wireless time delay calibration signal and then sends the wireless time delay calibration signal to a device time delay processing device; the equipment time delay processing equipment measures the time difference between the local measurement reference and the wireless time delay calibration signal by taking the local measurement reference as a reference. Then, the measuring signal generating equipment generates a wireless time delay calibration signal by taking a local measuring reference as a reference; an antenna receives a wireless time delay calibration signal and sends the wireless time delay calibration signal to measurement signal receiving equipment; the measurement signal receiving equipment takes the local measurement reference as a reference, measures the time difference between the local measurement reference and the wireless time delay calibration signal, and takes the time difference as a receiving time delay calibration measurement result. Although the method can provide a device and a method for calibrating the time delay of the wireless equipment, the method needs external equipment to measure the time delay of the wireless equipment, and a large amount of cost and time cost are consumed.
Disclosure of Invention
The invention aims to provide a method for estimating the time delay of a radio frequency module in a millimeter wave integrated communication system aiming at the defects of the prior art, so that the time delay of the radio frequency module can be effectively estimated under the condition of not using external equipment for measurement, and a large amount of cost is saved.
In order to achieve the purpose, the technical scheme of the invention comprises the following steps:
1) the base station and the user are synchronized once through a Pulse Per Second (PPS) signal 1PPS generated by a Global Positioning System (GPS) tame clock at an interval of 1s, namely the base station and the user start to work simultaneously when the Pulse Per Second (PPS) signal 1PPS is generated, and 100 frame indication pulse signals s (n) of 10ms are generated through the Pulse Per Second (PPS) signal 1PPS in the period, wherein the generation time corresponding to each frame indication pulse signal s (n) is Tn，0<n≤100；
2) The base station end is used as a sending end, and the user end is used as a receiving end;
3) the base station end uses the pseudo-random sequence to generate a training sequence a (l), repeatedly splices the training sequence a (l) to obtain a time delay estimation signal r, and obtains a time delay estimation signal r at TiThe time delay estimation signal r is sent at a moment, i belongs to n;
4) the user end uses the periodicity of the training sequence a (l) to detect the received time delay estimation signal r by using a time delay correlation algorithm, and detects the time delay estimation signal r at Ti+1Switching a receiving beam at a moment;
5) the user end detects the time t when the signal amplitude changes after the wave beam switching by using a double-window sliding detection method1And according to the time t1Time T for switching receiving beam with user terminali+1Obtaining the delay from the baseband signal of the user side to the radio frequency module: mu.sa＝t1-Ti+1；
6) At Ti+2Time, user end feeds back delay information muaTo the base station end;
7) the user terminal is used as the sending terminal, and the base station terminal is used as the receiving terminalEnd, and at Ti+3Sending a time delay estimation signal r at a moment;
8) the base station end detects the received time delay estimation signal r by using the periodicity of the training sequence a (l) and a time delay correlation algorithm, and detects the time delay estimation signal r at Ti+4Switching a receiving beam at a moment;
9) the base station end detects the time t when the signal amplitude changes after the wave beam switching by using a double-window sliding detection method2And according to the time t2Receiving beam time T switched with base station endi+4Obtaining the delay from the base station baseband signal to the radio frequency module: mu.sb＝t2-Ti+4。
Compared with the prior art, the invention has the following advantages:
1. the invention uses a double-window sliding detection method, namely a sending end generates and sends a delay estimation signal, a receiving end switches wave beams after detecting the delay estimation signal, the moment when the amplitude of a baseband signal changes is detected by using the double-window sliding detection method, and the delay of the baseband signal transmitted to a radio frequency module in a millimeter wave integrated communication system can be effectively estimated without using external equipment according to the difference value between the change moment and the wave beam switching moment, so that a large amount of cost and time cost are saved.
2. The invention adopts the time delay correlation algorithm to carry out cross-correlation calculation on the received time delay estimation signal and the signal after time delay, can accurately detect the time delay estimation signal r, and the base station can initiate time delay estimation on the millimeter wave radio frequency module at any time, thereby improving the accuracy of beam control and increasing the accuracy of selecting the optimal beam pair.
Drawings
FIG. 1 is a block diagram of a millimeter wave integrated communication system according to the present invention;
fig. 2 is a schematic view of beam coverage of the millimeter wave integrated communication system according to the present invention;
FIG. 3 is a general flowchart of an implementation of the delay estimation method of the present invention;
FIG. 4 is a schematic diagram of the delay correlation detection in the present invention;
fig. 5 is a schematic diagram of the dual window sliding detection according to the present invention.
Detailed Description
The following describes in further detail specific embodiments of the present invention with reference to the accompanying drawings.
Referring to fig. 1, the millimeter wave integrated communication system in this example includes a base station and a user, where the base station and the user both include a baseband module, an intermediate frequency module, and a radio frequency module, where:
the baseband module is suitable for a millimeter wave frequency band and comprises an AD/DA digital-to-analog/analog conversion sub-module, an encoding/decoding sub-module, a modulation/demodulation sub-module, a digital pre-coding sub-module, a channel estimation sub-module and a beam selection sub-module:
the digital-analog/analog-digital converter module comprises N digital-analog/analog-digital converters for converting digital/analog signals into analog/digital signals;
the coding submodule comprises an information source coding and a channel coding, wherein the information source coding compresses signals, the channel coding adopts Turbo coding to resist channel interference and attenuation by adding redundant information, and the coding submodule simultaneously encrypts the signals;
the decoding submodule comprises channel decoding and decryption and is used for receiving signals, decrypting and decoding to obtain information;
the modulation submodule adopts 64QAM modulation to improve the information quantity which can be carried by a single symbol;
the digital pre-coding submodule is used for calculating a forming matrix to generate a digital pre-coding codebook of the base station;
the channel estimation submodule is used for estimating a wireless channel;
the beam selection submodule is used for calculating the power of the received signal and selecting the optimal beam pair corresponding to the maximum received signal power.
The baseband module also outputs a control signal to control the intermediate frequency module and the radio frequency module while processing data.
The intermediate frequency module is used for up-converting or down-converting signals.
The radio frequency module comprises a high-frequency modulation/demodulation sub-module, a power amplifier, a filter, a low-noise amplifier, a phase shifter and a millimeter wave antenna sub-module:
the power amplifier amplifies the signal to obtain enough radio frequency power;
the filter filters the signal to eliminate interference clutter;
the low noise amplifier amplifies the received signal, which is convenient for post-processing;
the phase shifter is used for changing the phase of the analog signal and generating a beam in a specified direction by combining a large-scale antenna array.
Referring to fig. 3, the present embodiment is directed to the method for estimating the delay of the radio frequency module of the millimeter wave integrated communication system, and is to estimate the delay generated when the system is transmitted from the baseband module to the radio frequency module, and the method includes the following steps:
step 1, synchronization is carried out between a base station end and a user end.
The base station end and the user end are synchronized once through the pulse per second signal 1PPS generated by the GPS discipline clock at intervals of 1s, namely the base station end and the user end start working simultaneously when the pulse per second signal 1PPS is generated. In this example, since the length of the radio frame in the 5GNR is 10ms, the baseband modules at the base station and the user side generate 100 frame indication pulse signals s (n) of 10ms through the pulse per second signal 1PPS during this period, and the generation time corresponding to each frame indication pulse signal s (n) is Tn，0<n≤100。
And 2, taking the base station end as a sending end and taking the user end as a receiving end.
And 3, generating and transmitting a time delay estimation signal r by the base station end.
3.1) generating training sequence a (l):
generating a training sequence a (l) by a pseudo-random sequence, wherein the expression mode is as follows:
a(l)＝1-2x(m)，m＝[l+43NUE]mod127，
wherein, x (m) is a pseudo random sequence, l is the length of a training sequence, l is more than or equal to 0 and less than 127, NUEIs the number of users, NUE∈{0，1，2，3...}；
3.2) generating a time delay estimation signal r:
the design of the time delay estimation signal r needs to meet the requirements of downlink channel detection and channel state information acquisition, and most importantly, the mutual interference between the time delay estimation signal r and other signals on the same time-frequency resource is reduced, so the time delay estimation signal r is formed by repeatedly splicing training sequences a (l), and the expression mode is as follows:
r＝[a(l) … a(l)]；
3.2) transmitting the time delay estimation signal r
Referring to fig. 2, in order to ensure coverage, the base station side is at TiAnd sending the time delay estimation signal r by using a wide beam mode of the millimeter wave antenna sub-module at any moment, wherein the setting of the base station end is kept unchanged before the feedback signal is received.
And 4, detecting the delay estimation signal r and switching beams by using a delay correlation algorithm at the user side.
4.1) the user terminal detects the delay estimation signal r by using a delay correlation algorithm:
referring to fig. 4, the specific implementation of this step is as follows:
4.1.1) calculating the delay correlation CqOf the received delay estimate signal rqDelay estimation signal r received by delaying it by D momentsq-DThe formula is as follows:
wherein r isq-kEstimating a signal r for a time delayqThe signal is delayed by k lengths, rq-k-DEstimating a signal r for delaying D momentsq-DDelaying signals with the length of k, wherein q is the current data receiving time, L is the data length, and D is the delay length, and for the example, L is 127, and D is 127;
4.1.2) calculating the received Signal energy PqI.e. delay estimation signal r received by delaying D momentsq-DFor normalization processing of decision statistics such that the decision variable mqIndependent of each otherAt the received power, the calculation formula is:
4.1.3) calculating the decision variable mqThe calculation method is as follows:
4.1.4) setting the threshold value of the decision variable to be 0.8, and calculating the obtained decision variable mqComparison with a threshold:
if the decision variable mq>0.8, keeping q for 64 moments, and judging that a time delay estimation signal r is detected; otherwise, continuing to detect;
4.2) user terminal at Ti+1The receive beams are switched in time.
Step 5, calculating the time delay mu from the user terminal baseband signal to the radio frequency modulea。
5.1) the user terminal detects T by using a double-window sliding method detection methodi+1Time t of signal amplitude change after time1：
Referring to fig. 5, the specific implementation of this step is as follows:
5.1.1) the two windows A and B in FIG. 5 remain relatively stationary during the rightward sliding, and when the packet edge reaches window A, the calculation of the accumulated values in windows A and B begins, as follows:
wherein, anRepresenting the energy within the sliding window A, bnRepresenting the energy in the sliding window B, rn-mEstimating a signal r for a time delaynDelaying the signal by m lengths, rn+hEstimating a signal r for a time delaynThe signal before H, n is the length of the currently received data, M is the length of the window a, H is the length of the window B, and the window length is set to M-H-64 in this example;
5.1.2) calculating the ratio of the received energies of two consecutive sliding windows as decision variable knThe formula is as follows:
5.1.3) setting the threshold values of the decision variables to 1.2 and 0.8, and calculating the obtained decision variable knComparison with a threshold:
if the decision variable kn>1.2 or knIf < 0.8, recording the time at this moment as the time t when the amplitude changes1(ii) a Otherwise, the detection is continued.
5.2) time t when the user end changes according to the signal amplitude1Time T for switching receiving beam with user terminali+1To obtain the delay mu from the baseband signal of the user terminal to the radio frequency moduleaThe calculation method is as follows:
μa＝t1-Ti+1。
step 6, the user side feeds back the delay information mua。
User end completes estimation of time delay muaThen, at Ti+2Time of day, feedback delay information muaProviding a base station end;
and 7, the user side sends a time delay estimation signal r.
The base station receives the feedback time delay information muaThen, the user terminal is used as the sending terminal, the base station terminal is used as the receiving terminal, and the T isi+3And at the moment, the user side transmits the delay estimation signal r by using the wide beam mode of the millimeter wave antenna module.
And 8, detecting a delay estimation signal r by using a delay correlation algorithm and switching beams by the base station end.
8.1) the base station end detects a delay estimation signal r by using a delay correlation algorithm, and the specific implementation is the same as that of the steps 4.1.1) -4.1.4);
8.2) at Ti+4At that time, the base station switches reception beams.
9.1) the base station uses the double-window sliding detection method to detect the time t of the signal amplitude change after the wave beam switching2The detection steps are the same as the steps 5.1.1) to 5.1.3);
9.2) the base station end according to the time t2Receiving beam time T switched with base station endi+4Obtaining the delay from the base station baseband signal to the radio frequency module: mu.sb＝t2-Ti+4。
The foregoing description is only an example of the present invention and is not intended to limit the invention, so that it will be apparent to those skilled in the art that various changes and modifications in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (1)
1. A method for estimating time delay of a radio frequency module in a millimeter wave integrated communication system is characterized by comprising the following steps:
1) the base station and the user are synchronized once through a Pulse Per Second (PPS) signal 1PPS generated by a Global Positioning System (GPS) tame clock at an interval of 1s, namely the base station and the user start to work simultaneously when the Pulse Per Second (PPS) signal 1PPS is generated, and 100 frame indication pulse signals s (n) of 10ms are generated through the Pulse Per Second (PPS) signal 1PPS in the period, wherein the generation time corresponding to each frame indication pulse signal s (n) is Tn，0<n≤100；
2) The base station end is used as a sending end, and the user end is used as a receiving end;
3) the base station uses the pseudo-random sequence to generate a training sequence a (l), repeatedly splices the training sequence a (l) to obtain a time delay estimation signal r,and at TiThe time delay estimation signal r is sent at a moment, i belongs to n; wherein the training sequence a (l) is represented as follows:
a(l)＝1-2x(m)，m＝[l+43NUE]mod127, where x (m) is a pseudorandom sequence, l is the sequence length, l is 0 ≦ l < 127, NUEIs the number of users, NUE∈{0，1，2，3...}；
4) The user end uses the periodicity of the training sequence a (l) to detect the received time delay estimation signal r by using a time delay correlation algorithm, and detects the time delay estimation signal r at Ti+1Switching a receiving beam at a moment; the user side detects the received time delay estimation signal r by using a time delay correlation algorithm, and the following steps are realized:
4.1) calculating the received delay estimate signal rqDelay estimation signal r received by delaying it by D momentsq-DTime delay correlation value C ofq：
Wherein r isq-kEstimating a signal r for a time delayqThe signal is delayed by k lengths, rq-k-DEstimating a signal r for delaying D momentsq-DDelaying signals with the length of k again, wherein q is the current data receiving time, k is accumulated data count, and k belongs to [0, L-1 ]]L is the data length, D is the delay length;
4.2) calculating the time delay estimated signal r received at D time momentsq-DSignal energy value P ofq：
4.3) according to the delay correlation value CqSum signal energy value PqCalculating a decision variable mq：
4.4) setting the threshold value of the decision variable to be 0.8, and calculating the obtained decision variable mqComparison with a threshold:
if the decision variable mqIf q is more than 0.8 and q lasts for 64 moments, judging that a time delay estimation signal r is detected;
otherwise, continuing to detect;
5) the user end detects the time t when the signal amplitude changes after the wave beam switching by using a double-window sliding detection method1And according to the time t1Time T for switching receiving beam with user terminali+1Obtaining the delay from the baseband signal of the user side to the radio frequency module: mu.sa＝t1-Ti+1(ii) a The user terminal uses a double-window sliding detection method to detect the time when the signal amplitude changes after the wave beam switching is recorded as t1The implementation is as follows:
5.1) calculating the cumulative value a in the A window and the B windownAnd bn：
Wherein, anRepresenting the energy within the sliding window A, bnRepresenting the energy in the sliding window B, rn-mEstimating a signal r for a time delaynDelaying the signal by m lengths, rn+hEstimating a signal r for a time delaynIn the signals before H lengths, n is the length of the current received data, M is the length of a window A, and H is the length of a window B;
5.2) according to the accumulated value a in the A windownAnd the accumulated value B in the window BnAnd calculating a decision variable:
5.3) setting the threshold values of the decision variables to be 1.2 and 0.8, and calculating the obtained decision variable knComparison with a threshold:
if the decision variable kn> 1.2 or knIf < 0.8, recording the time at this moment as the time t when the amplitude changes1；
Otherwise, continuing to detect;
6) at Ti+2Time, user end feeds back delay information muaTo the base station end;
7) using user end as transmitting end, using base station end as receiving end, and at Ti+3Sending a time delay estimation signal r at a moment;
8) the base station end detects the received time delay estimation signal r by using the periodicity of the training sequence a (l) and a time delay correlation algorithm, and detects the time delay estimation signal r at Ti+4Switching a receiving beam at a moment;
9) the base station end detects the time t when the signal amplitude changes after the wave beam switching by using a double-window sliding detection method2And according to the time t2Receiving beam time T switched with base station endi+4Obtaining the delay from the base station baseband signal to the radio frequency module: mu.sb＝t2-Ti+4。
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