Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for jointly positioning a 5G network and a UWB, wherein a small time slice is reserved in the range of a cyclic prefix (or a cyclic suffix) in a downlink CP-OFDM signal in a 5G-NR frequency band to transmit and position the UWB positioning signal, the 5G-NR and UWB technologies are simultaneously integrated into a frequency spectrum, mutual interference is avoided, and the advantages and the disadvantages of the two technologies are fully utilized to achieve higher positioning accuracy.
The purpose of the invention is realized by the following technical scheme:
a method of co-location with UWB in a 5G network, comprising the steps of:
the method comprises the following steps: planning UWB positioning signals, planning a positioning area on a core network side by the 5G-NR, selecting a certain number of positioning base stations as positioning cooperative base stations, planning UWB positioning signal sending conditions of each positioning cooperative base station, and then respectively informing the planned UWB positioning signal sending conditions to each positioning cooperative base station;
step two: signal preprocessing, namely dividing a positioning time slice with a preset length in a CP-OFDM signal of a 5G-NR frequency band after a positioning cooperative base station receives a UWB positioning signal sending condition, and simultaneously, in a 5G downlink signal, not adding a CP time slice in a reserved time slice, but sending a corresponding UWB positioning signal;
step three: the method comprises the following steps that (1) UWB positioning signal notification is carried out, and a 5G-NR base station side informs terminal UE of information that the terminal UE needs UWB positioning signal time delay detection through a high-level signaling;
step four: a positioning signal is issued, and UWB positioning signals are issued by the 5G-NR positioning cooperation base station sides by utilizing a positioning time slice;
step five: measuring a time delay value, namely, carrying out time delay measurement on a received UWB positioning signal by the terminal UE, and reporting a time delay measurement result to a network side;
step six: and (3) positioning and resolving the terminal, and accurately calculating the position of the terminal UE by the network side according to the time delay measurement result reported by the terminal UE and the absolute position corresponding to the 5G-NR base station by using a positioning technology.
Specifically, the second step specifically includes: according to the length of the UWB positioning signal, within the cyclic prefix range or cyclic suffix range of the CP-OFDM signal of the 5G-NR frequency band, a time slice with the same length as the UWB positioning signal is reserved and divided as a positioning time slice; meanwhile, in the 5G downlink signals, the CP is not added in the reserved time slice, namely the CP time slice is not reserved for the UWB positioning signals, but the corresponding UWB positioning signals are sent.
Specifically, the first step specifically includes: the 5G-NR plans a positioning area at the core network side, selects a certain number of positioning base stations as positioning cooperative base stations, and plans a UWB positioning signal sending condition of each positioning cooperative base station, wherein the UWB positioning signal sending condition comprises the sending time, the signal format and the signal sending power of a UWB positioning signal and the preset length of the UWB positioning signal in a reserved CP time slice; and then, the planned UWB positioning signal sending conditions are notified to each positioning cooperation base station or terminal UE needing to perform UWB positioning.
Specifically, the fifth step specifically includes: and the terminal UE measures the time delay parameter of each received UWB positioning signal to obtain a time delay measurement value corresponding to each UWB positioning signal, and reports the time delay measurement value of each UWB positioning signal to the network side respectively.
Specifically, the time delay parameter is the arrival time and the delay of the UWB positioning signal.
Specifically, the positioning technology comprises E-CID positioning, AOA positioning, TOA positioning and TDOA positioning.
The invention has the beneficial effects that:
1. the invention can realize simultaneous positioning of a large number of terminals by transmitting UWB positioning signals through the base station. There is theoretically no limit to the number of terminals.
2. The positioning method of the invention reserves a small time slice for transmitting and positioning UWB positioning signals, simultaneously integrates the 5G-NR and UWB technologies into a frequency spectrum, avoids mutual interference, fully utilizes the advantages and disadvantages of the two technologies to achieve higher positioning precision, can realize strict whole network synchronization, and reduces the probability of occurrence of positioning estimation deviation.
The CP length of the 3.5G-NR design is designed to overcome the worst multipath environment, and for the 5G-NR dense networking scenario, especially the room division scenario, the CP length is completely excessive, and a small portion of the time slice reservation is allocated to the UWB positioning signal, which has no influence on the performance in the multipath scenario. For a small number of SSB symbols, the CP is not reserved for UWB positioning signals, so as to ensure that the synchronization performance of the UE is not affected. Under the condition that synchronization is not influenced, under a large number of scenes, other downlink signals can still maintain good communication quality under the condition that the CP is reduced by a certain time slice.
4. Compared with the new positioning technology such as PRS, the invention does not use 5G-NR data bearing resources to transmit the positioning signals. Therefore, the capacity of the system is not affected, and the downlink capacity of the system is greatly reduced after the PRS positioning technology is added because the PRS technology uses the radio resources of the data bearer.
Detailed Description
The following detailed description will be selected to more clearly understand the technical features, objects and advantages of the present invention. It should be understood that the embodiments described are illustrative of some, but not all embodiments of the invention, and are not to be construed as limiting the scope of the invention. All other embodiments that can be obtained by a person skilled in the art based on the embodiments of the present invention without any inventive step are within the scope of the present invention.
The first embodiment is as follows:
in this embodiment, as shown in fig. 1, a method for co-location between a 5G network and a UWB includes the following steps:
the method comprises the following steps: and planning UWB positioning signals, planning a positioning area on the core network side by the 5G-NR, selecting a certain number of positioning base stations as positioning cooperative base stations, planning UWB positioning signal sending conditions of each positioning cooperative base station, and then respectively informing the planned UWB positioning signal sending conditions to each positioning cooperative base station.
The step is mainly to plan out when each positioning cooperation base station sends UWB positioning signals, and what format of positioning signals are transmitted with what power, and how many of CP time slices are reserved for the UWB positioning signals. Then notifying the planned data to each positioning cooperative base station;
step two: signal preprocessing, the positioning cooperative base station divides a positioning time slice with a preset length in a CP-OFDM signal of a 5G-NR frequency band, and in a 5G downlink signal, the CP is not added in the reserved time slice, but a corresponding UWB positioning signal is sent. For a small number of SSB symbols, the CP is not reserved for UWB positioning signals, thereby ensuring that the synchronization performance of the terminal UE is not affected.
Step three: and informing the terminal UE of the information that the terminal UE needs to carry out UWB positioning signal time delay detection by the UWB positioning signal notification and the 5G-NR base station side through a high-level signaling.
Step four: and (4) sending a positioning signal, wherein the 5G-NR base station side sends the UWB positioning signal by using a positioning time slice.
Step five: and measuring a time delay value, namely, carrying out time delay measurement on the received UWB positioning signal by the terminal UE, and reporting a time delay measurement result to the network side.
Step six: and (3) positioning and resolving the terminal, and accurately calculating the position of the terminal UE by the network side according to the time delay measurement result reported by the terminal UE and the absolute position corresponding to the 5G-NR base station by using a positioning technology.
In this embodiment, a typical 5G system with a bandwidth of 100Mhz, a subcarrier spacing of 30khz, and a normal CP length is taken as an example. A TTI is 500us in time length and comprises 14 OFDM symbols, each symbol consisting of 4096 time slices of the original signal and 2 parts of a cyclic prefix, which is 352 or 288 time slices. The time length of each time slice is 8.14ns. Taking the CP length of 288 time slices as an example, the design is to resist the propagation time difference between the shortest path and the longest path of the user reaching 288 × 8.14ns, which is about 2300ns. And the maximum path difference of most channel models does not exceed 1000ns. Therefore, in most scenarios, especially in dense networking scenarios, the length of the CP is more than sufficient. In particular, the redundancy is greater when the CP length of the first symbol of each TTI is 64 more time slices, which reaches 352 time slices.
Wherein TTI (Transport Time Interval) refers to a transmission Time Interval. The TTI is introduced by the WCDMA system and is the beat of the wireless device. Data is exchanged between the link layer and the physical layer of the device once per TTI.
The TTI for WCDMA is 10ms, the TTI for HSPA is 2ms, the TTI for LTE is compressed to 1ms, and the TTI for 5G NR is variable and is 0.5ms at most.
In the embodiment, the method is mainly characterized in that in a downstream CP-OFDM signal in a 5G-NR frequency band, a short time slice is reserved in the range of a cyclic prefix or a cyclic postfix, and a UWB positioning signal is reserved for transmission as positioning.
For example, in the first OFDM symbol of each TTI, the first 64 time slices of the 352 CP symbols are not used as the cyclic prefix portion of the OFDM signal (in response, the cyclic prefix of the first symbol is 288 time slices), and the 64 time slices are reserved and divided as positioning time slices for transmitting the UWB positioning signal.
The pulse length of the UWB positioning signal is nanosecond, so that 64 reserved time slices are enough to transmit a UWB positioning signal.
The advantages of this method are that 5G-NR and UWB technology are merged into a frequency spectrum at the same time, and mutual interference is avoided, and the advantages and disadvantages of the two technologies can be fully utilized to achieve higher positioning accuracy.
Moreover, the invention issues UWB positioning signals at the side of the 5G-NR base station, and the benefit of this is that the UWB positioning signals are strictly aligned in the whole network (the 5G system provides a strict time alignment function in the whole network). Therefore, when a plurality of cooperative stations send out UWB positioning signals in turn according to a certain rule, and the user UE measures the delay parameter of each UWB positioning signal, and reports and summarizes the delay parameter to the network side, the network side can accurately calculate the position of the UE through a conventional positioning scheme (such as TDOA) according to the delay measurement value of the UWB positioning signal of the base station reported by the current UE and the absolute positions corresponding to the base stations.
Compared with conventional UWB positioning, the present invention has 2 benefits:
1. the method of the invention is that the base station sends UWB positioning signals, but not in most UWB positioning models, the terminal side sends UWB positioning signals. The advantage of base station side transmission is that a large number of terminals can be located simultaneously. There is theoretically no limit to the number of terminals.
2. Even if a pure UWB positioning system which sends UWB positioning signals on the network side is used, because the industrial structure is not large, strict whole-network synchronization as good as a 5G base station is difficult to achieve. When the whole network is not well synchronized, positioning estimation deviation occurs. The method of the invention can realize strict whole network synchronization.
In this embodiment, as shown in fig. 2, a conventional 5G signal is added with a CP in front of each OFDM symbol (symbol) of a TTI to overcome the multipath problem.
In this embodiment, a part of time slices in the CP is not used as cyclic prefixes, but the part of time slices is reserved and divided to transmit UWB positioning signals, and the structure of the divided signals is shown in fig. 3.
The base station broadcasts the UWB positioning signal to all the terminals, and needs to search and analyze the time slice number reserved for the UWB positioning signal in the front section of each OFDM symbol and the time slice number remained and allocated to the CP part in each TTI. The UE needs to find the OFDM symbol boundary after synchronization by the SS, and the boundary needs to remove the part of the time slice reserved for UWB.
After finding a new boundary, IQ data in the time slice range of the UWB positioning signal can be removed, and IQ data in a normal OFDM symbol is used for OFDM waveform analysis (FFT conversion), so that OFDM characteristics and advantages of the 5G system can be continuously maintained, and as long as the maximum multipath delay is still in the reserved CP length protection, no performance loss exists.
Meanwhile, the user can also obtain the pulse edge of the UWB positioning signal through the UWB receiver, so that the correlation calculation of the UWB positioning signal is carried out.
Example two:
on the basis of the method provided by the first embodiment, this embodiment gives an example of how to implement high-precision positioning by using multiple base stations to transmit different UWB positioning signals:
as shown in fig. 4 and 5, different UWB positioning signals are transmitted through the UWB region of 14 OFDM symbols in one TTI and allocated to different base stations (cells).
For a TTI 5G signal, there are 14 OFDM symbols, each symbol reserving a small time slice for UWB positioning signals. The block diagrams in fig. 4 and 5 represent base stations, numbered a, b, c, d, e, f, g, h, respectively, with different numbered base stations corresponding to different points in time, each base station transmitting its own UWB positioning signal. E.g., base station h, transmits UWB positioning signals only in the UWB interval preceding the CP of symbol 7, and does not transmit UWB positioning signals the rest of the time. The base station g only transmits UWB positioning signals in the UWB interval preceding the CP of symbol 6, and does not transmit UWB positioning signals the rest of the time, and so on.
The UE will always measure the time of arrival and delay of the UWB positioning signal. If the UE is in the middle region as shown in fig. 5, then the UE will hear the UWB positioning signals from 8 base stations within one TTI and calculate the time delay of arrival of the 8 UWB positioning signals (since each UWB positioning signal is transmitted from a base station that is strictly time aligned).
Then, the UE reports the time delay information of all UWB positioning signals to the network side, and the network side knows the absolute positions of all base stations, and then calculates the position of the user accurately by using the conventional mature positioning technology (such as TDOA) according to the time delay from the UE to each base station.
From 2G to 4G, the positioning technologies of cellular networks mainly include E-CID, AOA, TOA, TDOA and the like. The E-CID can roughly lock the position of the mobile phone according to the Cell ID because the longitude and latitude of the base station are known. However, the coverage area of a Cell is large, usually several hundred meters to several kilometers, and the positioning error based on Cell ID only is very large, all of which have the E-CID positioning technology. A conventional base station is divided into three sectors, one sector corresponding to each Cell, each sector typically 120 degrees, each Cell having a different identification code (Cell ID).
Since the latitude and longitude of the base station is known, the location of the handset can be substantially locked based on the Cell ID. However, the coverage area of a Cell is large, usually several hundred meters to several kilometers, and the positioning error based on Cell ID only is very large, all of which have the E-CID positioning technology. E-CID, enhanced Cell-ID, refers to Enhanced location technology based on Cell ID, including Cell ID + RTT, cell + RTT + AoA, etc.
Angle-of-Arrival location AOA (Angle-of-Arrival) is based on the measurement of the Arrival direction of electromagnetic waves, and finally realizes the position confirmation of a transmitting target. And different positioning modes are realized according to different antenna array types and algorithms. The linear array can realize the measurement of plane incident angle, and the area array can realize the measurement of incident angle in three-dimensional space.
The AOA positioning method does not consider the strength, only measures the incoming wave direction of a signal, is not influenced by the strength, is not influenced by a battery and is not influenced by the direction of an antenna, determines the unique position through angles, obtains more accurate absolute positions through a plurality of angles, is a new positioning technical means under the Bluetooth standard specification, and can adjust the arrangement distance to be as far as nearly 20 meters according to the precision and the arrangement condition. The technology sets a directional antenna or an array antenna at more than two position points, obtains the angle information of radio wave signals transmitted by a terminal, and then estimates the position of the terminal by an intersection method. Compared with the positioning systems of technologies such as TDOA and the like, the system has a simple structure, but requires the antenna array to have high sensitivity and high spatial resolution. The positioning accuracy of the AOA is greatly influenced by the density, height and topography of the building, and the typical values of the AOA are 360 degrees, 20 degrees and 1 degree in indoor, urban and rural areas respectively. As the distance between the base station and the terminal increases, the positioning accuracy of the AOA gradually decreases. The AOA positioning error is mainly caused by urban multipath propagation and system error, the influence of the system error can be counteracted through pre-correction, the multipath effect in a dense building area is always a difficult problem troubling antenna communication, and an intelligent antenna can reduce the influence of multipath interference to a certain extent, but is not widely applied due to the problems of complexity in implementation and equipment cost. Therefore, the AOA technique, although simple in structure, has not been applied to the urban cellular positioning system.
The TOA mobile phone positioning technology is a technology for positioning a mobile phone by using a GPS positioning technology or a base station positioning technology. The positioning mode based on the GPS is to utilize a GPS positioning module on the mobile phone to send own position signals to a positioning background to realize the positioning of the mobile phone. The positioning of the base station determines the position of the mobile phone by using the measured distance of the base station to the distance of the mobile phone. The latter does not require the handset to have GPS location capability, but the accuracy depends heavily on the density of base stations, sometimes with errors in excess of a kilometer. The former has higher positioning precision. In addition, a mode of positioning in a small range by utilizing Wifi exists. The TOA positioning mode can be realized on any existing mobile phone, and the mobile phone does not need to be changed.
The method comprises the following specific implementation steps:
(1) The mobile phone to be positioned sends a known signal, three or more LMUs receive the signal at the same time, and the known signal is an access burst signal sent when the mobile phone performs asynchronous switching;
(2) After each LMU obtains the absolute GPS time when the signal arrives, the Relative Time Difference (RTD) can be obtained;
(3) Based on the information from the first two steps, the SMLC compares two by two, calculates the time difference of arrival (TDOA) of the burst signal, derives the precise location, and returns to the application. To obtain the precise location of the handset by triangulation, two other parameters must be known: the geographic location of the LMUs and the time offset between the LMUs. Such as absolute GPS time that each LMU must provide, or actual time difference (RTD) parameters that can be obtained by placing a reference LMU at a location with a known location.
The LMU determines the TOA using the access burst signal. When a location request is issued, the LMU is selected and the correct frequency is configured in order to receive the access burst signal. At this time, the handset transmits up to 70 access pulses (duration 320 ms) at a certain power on the traffic channel (possibly in frequency hopping mode). Each LMU achieves and improves TOA measurements in a variety of ways. The probability of successful measurement and the measurement accuracy can be improved by using the received burst signal. The diversity technology (such as antenna diversity and frequency hopping) is adopted, the influence of multipath effect can be reduced, and the measurement precision is improved. When an application needs to know the position of the mobile phone, the application sends a request to the SMLC and simultaneously informs the mobile phone number and the positioning accuracy requirement. The measured TOA parameters and the error values thereof are collected together and sent to the SMLC, and according to the data, the SMLC can calculate the required mobile phone position for the application and then send the position information and the error range back to the application.
The TOA positioning approach requires additional hardware (LMU) for the purpose of accurately calculating the time of arrival of the burst signal. The implementation mode has various modes: the LMUs may be integrated within the BTSs or may be stand alone devices. When the LMUs are used as separate devices, the LMUs can have separate antennas or share antennas with the BTSs, and communication between networks is realized through an air interface.
TDOA location is a method of location using time differences. By measuring the time of arrival of the signal at the monitoring station, the distance of the signal source can be determined. The location of the signal can be determined by the distance from the signal source to each monitoring station (taking the monitoring station as the center and the distance as the radius to make a circle). However, the absolute time is generally difficult to measure, and by comparing the absolute time difference of the arrival of the signal at each monitoring station, a hyperbola with the monitoring station as the focus and the distance difference as the major axis can be formed, and the intersection point of the hyperbola is the position of the signal.
Unlike TOA, TDOA (time difference of arrival) is the determination of the location of a mobile station by detecting the absolute time difference of arrival of signals at two base stations, rather than the time of flight of the arrival, reducing the time synchronization requirements of the signal source with each monitoring station, but increasing the time synchronization requirements of each monitoring station. Two TDOAs can be measured using three different base stations, and the mobile station is located at the intersection of two hyperbolas determined by the two TDOAs.
The positioning technology can be applied to various mobile communication systems, in particular to a CDMA system which spreads the signal spectrum to a wide range by a spread spectrum mode so that the system has stronger anti-multipath capability. CDMA belongs to a non-power sensitive system, and the influence of signal attenuation on the accuracy of time measurement is small. One of the advantages of the TDOA and TOA methods over other methods is that when computing TDOA values, the computed errors are the same for all base stations and the sum is zero, these errors including common multipath delays and synchronization errors. However, due to the small transmission power of the mobile station close to the serving base station caused by the power control, the received power of another base station neighboring the serving base station and participating in positioning is very small (i.e. the SNR of the neighboring base station is too small), resulting in a relatively large measurement error.
The TDOA algorithm is an improvement on the TOA algorithm, the position of the mobile station is determined by using the time difference of signals received by a plurality of base stations instead of directly using the arrival time of the signals, and compared with the TOA algorithm, the TDOA algorithm does not need to add special time stamps and the positioning accuracy is improved. There are generally 2 forms of TDOA value acquisition:
the 1 st form is obtained by taking the difference of the time TOAs of the mobile station arriving at 2 base stations, and this still requires strict synchronization of the base station time, but when the transmission characteristics of the mobile channel between two base stations are similar, the error caused by the multipath effect can be reduced.
The 2 nd form is to perform correlation operation on a signal received by one mobile station and a signal received by another mobile station to obtain a TDOA value, and this algorithm can estimate the TDOA value when the base station and the mobile station are not synchronized. TDOA is more practical for the location of mobile stations in cellular networks, and this approach has relatively low network requirements and high location accuracy. Therefore, TDOA location techniques are the preferred location method of the present invention.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are given by way of illustration of the principles of the present invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, and such changes and modifications are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.