CN102223596A

CN102223596A - Mobile positioning service method

Info

Publication number: CN102223596A
Application number: CN2010101477753A
Authority: CN
Inventors: 胡乐乐
Original assignee: SHANGHAI QIDIAN INFORMATION TECHNOLOGY Co Ltd
Current assignee: SHANGHAI QIDIAN INFORMATION TECHNOLOGY Co Ltd
Priority date: 2010-04-15
Filing date: 2010-04-15
Publication date: 2011-10-19

Abstract

The invention provides a positioning service method; firstly, a positioning management platform is connected with a plurality of LEs (logic elements) and LIUs (line internet units) through a communication network, wherein the LEs have the functions of positioning measurement, wireless sensing and communication, the LIUs have the functions of the wireless sensing and the communication; the LEs report positioning measurement data to the positioning management platform in a timing manner, and the positioning management platform obtains an optimal estimation of LE positions through an information fusion technology; when approaching a detection range of a wireless sensing unit of the LIUs, the LEs can be automatically identified, wherein an identification number ID-1 can be automatically read by the LIUs and is reported to the positioning management platform, and the positioning management platform corrects position data corresponding to the LEs. In the method of the invention, the data processing of the LEs can be greatly simplified, the power consumption is reduced, various positioning value-added services can be favorably developed, and particularly, the positioning services with requirements of low power consumption and hidden nature to the LEs can be favorably developed.

Description

Mobile positioning service method

Technical Field

The invention relates to a mobile positioning service method, in particular to a method for providing positioning service by comprehensively utilizing a GPS technology, an inertial navigation technology and a wireless communication technology.

Background

As one of the distinctive services of the wireless communication system, the positioning service has received general attention as a bright spot of mobile value-added service. Currently, mobile location services have been opened by major mobile operations in north america, europe, and asia-pacific. Mobile location services are broadly classified into the following types.

Public safety service: the emergency call positioning system is mainly used for positioning a user who makes an emergency call so as to provide quick and accurate rescue service for the user by a public safety department. The primary representative of such services is the mobile 911 emergency call service in the united states.

Tracking service: a tracking service for movable objects such as persons and vehicles is provided, allowing a user to periodically or as needed query the location of the object. The specific applications include child and old people monitoring, pet tracking, vehicle theft prevention, logistics, taxi fleet scheduling and management and the like.

Location-based personalized information service: the user is provided with comprehensive information services related to the current position of the user, such as providing classified information of local traffic conditions, weather forecast, tourist guides and the like for tourists, and helping the tourists to find nearby hotels, parking lots, entertainment places and the like.

Navigation service: the user is provided with guidance services from the current location to the destination, such as a route planning service for travelers and guidance services in the journey (providing turn-around prompts, arrival notifications, etc.).

All the mobile positioning services are implemented based on positioning technologies, and currently, the positioning technologies applied in the mobile positioning services mainly include the following:

a network-based source Cell (COO) positioning technology, namely a Cell ID-based positioning technology, which is used for acquiring Cell information of a base station where a user is currently located by a network side to acquire the current position of the user, wherein the accuracy of the positioning technology depends on the distribution of mobile base stations and the size of a coverage area;

triangulation techniques based on time of arrival (TOA) or time difference of arrival (TDOA) principles, such as aflt (advanced Forward Link correlation) positioning techniques used in CDMA networks, where, during positioning operations, a mobile phone/terminal monitors pilot information of multiple base stations simultaneously, determines distances to nearby base stations by using chip delay, and finally calculates specific positions by using triangulation;

assisted GPS (A-GPS) technology based on a satellite-based wireless navigation system. The traditional GPS technology integrates satellite scanning, acquisition, pseudo-range signal reception, positioning operation, and other operations into a whole, which is too dependent on the terminal performance, and thus has disadvantages of low positioning sensitivity, high power consumption of the terminal, and the like. The A-GPS simplifies the position calculation work of the terminal, the positioning work is completed by the cooperation of the positioning server at the network side and the terminal, and the heaviest work of satellite scanning, positioning operation and the like is transferred from the terminal side to the positioning server at the network side. The positioning accuracy, the sensitivity and the cold start speed of the terminal are improved, and the power consumption of the terminal is reduced. Specifically, the a-GPS technology utilizes a wide area GPS satellite reference network composed of a plurality of high sensitivity GPS receivers to monitor positioning information such as ephemeris data and doppler shift of all GPS satellites over a coverage area in all weather, and dynamically refreshes a GPS satellite database (a correspondence between satellite data and geographic position) stored in a positioning platform. The terminal notifies the positioning platform of the approximate position (which base station the terminal belongs to) through the wireless network only when positioning is needed, and then obtains GPS satellite information through the positioning platform, so that the satellite capturing time is greatly shortened, and the power consumption is greatly reduced. By means of strong computing power of the positioning server, a complex positioning algorithm can be adopted to reduce the influence of adverse factors such as weak received signals and the like, so that the positioning accuracy and the sensitivity are improved;

the GPSONE technology is a location technology developed by the american college of high traffic for location-based mobile services. The GPS-assisted GPS and AFLT triangulation positioning method organically combines two positioning technologies, under the condition that GPS satellite signals and wireless network signals can not be independently positioned, a GPSONE system can combine the two information sources, positioning can be completed only by one satellite and one cell site, the problem which can not be solved by the traditional GPS is solved, high precision, high availability and rapid positioning are realized, and the indoor positioning effect is improved. In an environment where both positioning technologies cannot be used, the gpson automatically switches to a Cell ID sector positioning mode, thereby ensuring a positioning success rate.

In addition, positioning schemes RTLS implemented by using short-range wireless technology and triangulation technology, such as WiFi positioning systems and ZigBee positioning systems, have appeared in recent years, and their working mechanisms are that multiple positioning base stations are deployed, and then a terminal to be positioned calculates position coordinates by measuring signal strength of a nearby base station and using a positioning algorithm model.

For services such as public safety, positioning tracking, navigation and the like, although the positioning technology based on CELL ID and base station wireless measurement has high success rate, the accuracy is far from meeting the service requirement, so that the services mostly adopt the positioning technology based on GPS, such as A-GPS or GPSONE. However, in practical applications, the availability of GPS technology has significant problems, such as that in urban environments, GPS signals are blocked by many high buildings, reflection of GPS signals by buildings around the positioning terminal causes measurement errors, and GPS signals cannot be received by many locations requiring positioning services (e.g., roads under urban highways, underground parking lots, indoor environments such as station terminals, etc.). In order to solve the above problems, new technologies have been introduced in the field of positioning services in recent years, such as a conventional vehicle navigation system that performs a navigation function by using a GPS receiver in combination with Dead-Reckoning (Dead-Reckoning) devices, such as a gyroscope, an accelerometer, an electronic compass, wheel rotation signals, and the like, which can measure a position change of a vehicle in a relatively short time, and the GPS receiver can measure an absolute position of the vehicle within a certain error range. Both have natural complementarity: the dead reckoning device can average out errors of the GPS receiver in a short time, and the GPS receiver can calibrate the dead reckoning device in a long time. The traditional dead reckoning equipment used in the aerospace field has high precision, but is huge in size and high in price, and is not suitable for general civil vehicle navigation. With the progress of micro-electro-mechanical systems (MEMS) technology in recent decades, the performance of micro-gyroscopes and micro-accelerometers adopting the MEMS technology is rapidly improved, and the MEMS devices provide new choices for the design of navigation positioning systems by virtue of the advantages of small volume, low cost, simple peripheral circuits and the like. In addition to the GPS receiver and the dead reckoning device, the car navigator is loaded with a digital map, which is a digitized traffic road database. The position of the vehicle to be navigated can be determined well by map matching using the information and measurement data of the digital map. The well-designed navigator can well integrate the measurement data from the GPS receiver and the dead reckoning device, thereby further making good map matching. In order to integrate these measurement data well to achieve satisfactory navigation effect, the industry often uses Kalman filter (Kalman filter) to balance the current measurement data and the historical measurement data, and uses the principles of linearity, unbiased, and minimum variance as the optimal estimation to reduce the system noise as much as possible so as to improve the positioning accuracy and usability.

US20080091351 proposes a method and system for adjusting the GPS navigation accuracy of a car by using an inertial system formed by MEMS devices. The system is integrated with an inertial measurement unit IMU, a GPS receiver unit and a Kalman filtering unit which are formed by MEMS devices, and when the positioning accuracy of the GPS receiver is reduced due to the influence of multipath signals, the method provided by the patent can improve the navigation accuracy of the system by using IMU measurement data. However, the method and the system provided by the patent are suitable for vehicle navigation application and do not meet the requirements of miniaturization, concealment and low power consumption when applied in the public safety field.

US20080143596 proposes a method for testing the three-dimensional movement speed of a mobile phone by using an MEMS device to provide auxiliary information for GPS positioning calculation, so that the mobile phone positioning can be still achieved when the GPS signal is not ideal enough and cannot capture enough GPS satellite signals. The patent is not concerned with specific location information based location services and technical solutions involved in meeting the needs of location services.

In summary, the mobile positioning technology has advanced significantly through the continuous development in recent years, but the market currently provides the following technologies and products to meet the requirements of high-quality mobile positioning services, especially for applications in public safety fields such as personnel positioning and tracking, and positioning and tracking of sensitive or dangerous goods:

the existing positioning product has larger size and does not consider hidden design, so that the requirements of miniaturization, miniaturization and concealment of the application are difficult to meet;

the existing positioning product is not specially designed on the aspect of low power consumption design, and the low power consumption requirement when a battery is adopted for power supply in the application is difficult to meet;

the existing positioning products and services are limited to obtaining positioning information, reporting the positioning information or providing a simple historical track recording function by combining a Geographic Information System (GIS) and an electronic map, and are lack of value-added service functions of tracking and early warning, unified management of a large number of positioning terminals by using a background system, positioning accuracy and success rate improvement by using historical redundant information of the background system and the like.

Therefore, there is a need in the market for a mobile location service method capable of providing reliable location information and providing value-added services based on the location information, and a location terminal therein satisfies low power consumption, miniaturization, and concealment.

Disclosure of Invention

The invention provides a method for providing positioning service, which comprises the following steps:

a) the positioning management platform is connected with at least one positioning terminal LE and at least one positioning beacon LIU through a communication network;

b) the positioning management platform receives positioning measurement information reported by a positioning terminal LE, and determines the current position and the related track of the LE by combining LE historical track information in a database after information fusion processing;

c) and the positioning management platform receives LE detection information reported by the positioning beacon LIU and corrects the track of the related LE by using the information.

The method further comprises: the location management platform is connected with an authorized third party location service provider LBS and a location service user LUE through a communication network, and issues location service information to the LBS and the LUE, wherein the location service information comprises LE instant location information, location triggered alarm and track.

The communication network refers to a mobile communication network capable of providing wide area coverage, a wired broadband network, a wireless broadband network or a combination thereof, and the mobile communication network includes a GSM network, a GPRS network, an EDGE network, a CDMA20001x network, a CDMA2000 EVDO network, a WCDMA network, a TD-SCDMA network, and an evolved network based on the above mobile networks.

The LE comprises a GPS unit, a wireless sensing unit, an Inertial Measurement Unit (IMU), a wireless communication unit and a main control unit. The LIU comprises a wireless sensing unit, a communication unit and a main control unit. The positioning management platform comprises an information acquisition and release unit, a database unit, a data processing unit and a management unit.

And the LE regularly triggers positioning measurement and result reporting according to the positioning strategy, wherein the positioning measurement comprises GPS measurement, inertial navigation measurement and wireless network parameter measurement. The positioning strategy comprises positioning parameters which need to be measured and reported by the LE at regular time and time intervals of the measurement and the reporting at regular time; the time interval is a dynamic variation quantity related to the LE instant movement speed, and the variation rule is that the time interval is smaller when the speed is higher; the positioning strategy is predetermined by the positioning management platform according to the positioning service type applied by the LE, the conventional motion mode of the LE and the operational capability of the LE and is configured in the LE by issuing parameters. And the LE enters a dormant state and turns off a power supply of a peripheral circuit during two positioning measurements and result reporting periods.

The positioning management platform processes the positioning measurement information reported by the LE through the following steps:

1) the positioning information acquisition unit receives the timing report message from the LE and extracts the positioning information therein, wherein the positioning information comprises GPS positioning measurement information, IMU measurement information and wireless network parameters;

2) the data processing unit firstly preprocesses positioning information, including calculating a confidence coefficient C _ L of GPS positioning data, calculating an LE instant speed vector and a course of each sampling moment contained in the reported data according to IMU measurement data, and determining a current service base station and an adjacent base station of the LE according to wireless network parameters contained in the reported information;

3) and (3) performing positioning information fusion processing according to the data obtained by preprocessing in the step 2) to obtain reliable LE position coordinates.

The wireless network parameters comprise: pseudo-random code phase offset coefficient, pilot frequency active set, pilot frequency candidate set and pilot frequency adjacent set data; determining the current service base station and the adjacent base stations of the LE by retrieving wireless network planning information prestored in a database according to the wireless network parameters; the approximate location of the LE is then estimated in conjunction with the digital map as an aid to LE positioning.

The confidence C _ L of the GPS positioning data is calculated by:

wherein N _ S is the number of satellites in the GPS positioning measurement information, SN_iN is the satellite signal-to-noise ratio, SN₀The unit is dB, and the value is stored in a positioning management platform database unit as an attribute parameter of LE in advance.

The positioning information fusion process further comprises:

(a) performing optimal estimation on GPS positioning measurement data by a Kalman (Kalman) filtering unit;

(b) a Dead Reckoning (Dead-Reckoning) unit performs Dead Reckoning using the IMU measurement data;

(c) the information fusion unit performs information fusion processing on the results of (a) and (b): when the confidence coefficient C _ L of the GPS positioning information is less than C _ L₀When the current position is larger than the preset value, the GPS positioning information is abandoned, the dead reckoning result is directly adopted as the positioning result of the LE, and meanwhile, a dead reckoning navigation timer T is started, and when T is larger than T, the T is larger than T₀When the system is in use, sending out a system alarm; otherwise, Kalman filtering processing is carried out on the output information of a) and b) to obtain the optimal estimation of the LE position information; the C _ L₀And T₀A threshold value is preset for the positioning management platform, and the threshold value can be modified at any time according to the requirement of corresponding positioning service on precision and the actual using effect;

(d) correcting the position coordinates and track of the LE by using a digital map of the area around the LE;

(e) sending the positioning result of the LE to a dead reckoning unit for feedback correction, and clamping system errors accumulated along with time of dead reckoning; and updating LE historical movement speed, track and attitude data recorded by a positioning management platform database unit.

The positioning management platform processes the LE detection information reported by the LIU through the following steps:

A) triggering to enter a positioning updating flow of a related LE according to an LE identification number ID-1 reported by the LIU after receiving an LE detection message from the LIU;

B) retrieving a database according to the identification number ID-2 of the LIU to call out attribute data of the LIU, wherein the attribute data comprise a deployment position, a distance capable of effectively detecting LE and directional parameters of a wireless sensing unit antenna;

C) calculating the relative position of the LE to the LIU according to the signal intensity of the LE wireless sensing unit reported by the LIU and the directional parameters of the antenna of the LIU wireless sensing unit, and then obtaining the time t when the LE is detected by the LIU according to the LIU deployment position information_sThe position of the time;

D) retrieving the database to call out the nearest motion trail data of the LE, and reporting the detection time t to the LIU_sLE position at time of day is corrected and t is updated by dead reckoning based on IMU historical data_sAnd updating the correction and calculation results to the database after the moment until the current LE track.

The invention greatly simplifies the data processing of LE, reduces the power consumption, is beneficial to developing various positioning value-added services, and is particularly beneficial to developing the positioning services which have low power consumption and concealment requirements on LE.

Other features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the present invention when taken in conjunction with the accompanying drawings.

Drawings

FIG. 1 is a system architecture diagram of one embodiment of the method of the present invention;

FIG. 2 is a functional block diagram of one embodiment of the LE of FIG. 1;

FIG. 3 is a functional block diagram of one embodiment of the LIU of the embodiment of FIG. 1;

FIG. 4 is a hardware implementation of one embodiment of the LE of FIG. 1;

FIG. 5 is a hardware implementation of one embodiment of the LIU of the embodiment of FIG. 1;

FIG. 6 is a schematic diagram illustrating a registration process of an LE in the location management platform in the embodiment of FIG. 1;

fig. 7 is a schematic diagram of an interface protocol between the LE and the location management platform in the embodiment of fig. 1;

fig. 8 is a schematic flowchart of the positioning management platform in the embodiment of fig. 1 for processing LE report information;

FIG. 9 is a schematic diagram of the principle of estimating LE approximate location by wireless parameters;

fig. 10 is a schematic flow chart of the positioning management platform processing LIU report information in the embodiment of fig. 1.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

Fig. 1 shows a system architecture diagram of an embodiment of the present invention, in which a positioning management platform S102 establishes a communication connection with a plurality of positioning terminals LE through a communication network S101, collects positioning measurement information reported by each LE, and determines and records a current position of each LE by combining terminal history track information and a positioning algorithm in a database. Meanwhile, the positioning management platform S102 also establishes a communication connection with the positioning beacon LIU through the communication network S101, receives LE identification information reported by the LIU in real time, and corrects the current position of the LE by using the information. In addition, the location management platform S102 also establishes a communication connection with an authorized third party location service provider LBS and a location service user LUE through the communication network S101, and issues value-added service information such as the instant location information and location alarm of the LE, and the historical track to the LBS and LUE. The communication network refers to a mobile communication network, a wired broadband network, a wireless broadband network or a combination thereof capable of providing wide area coverage, and for clarity and conciseness of the description, the idea of the present invention is described by taking a CDMA mobile communication network as an example. As shown in fig. 1, the location management platform S102 establishes communication connections with a plurality of LEs, LIUs, LUEs and LBS through the short message gateway, the packet data serving node pdsn (packet data serving node) and the router in S101.

The positioning management platform S102 adopts a distributed and modular architecture in specific implementation, and may flexibly adopt one server or a plurality of server groups to form a visual application scale. The system comprises an information acquisition and release unit, a data processing unit, a database unit and a management unit, wherein the functions and the connection relation of each unit are as follows:

the information acquisition and release unit is responsible for finishing the communication between the positioning management platform S102 and the LE, LIU, LUE and LBS based on a TCP/IP protocol or a short message SMS, and finishing the encapsulation and the decapsulation of the interactive messages between the positioning management platform S102 and the LE, LIU, LUE and LBS; meanwhile, the system is also responsible for extracting an LE identification number and positioning measurement information from the reported message of the LE and transferring the identification number and the positioning measurement information to the data processing unit, and extracting the identification number of the LE, the identification time of the LE information and the information of the LIL identification number from the reported message of the LIU and transferring the identification number and the information of the LE information to the data processing unit; in addition, the information acquisition and distribution unit is also responsible for distributing LE position information to the authorized LBS and LUE according to the instruction of the management unit.

The database unit is the integration of various logic databases, including a terminal management database TM _ DB, a user management database CM _ DB and a service database TF _ DB. The TM _ DB stores terminal management data including identification numbers of all LEs, conventional motion modes and current motion modes of the LEs, current postures of the LEs, location service types of the LEs, location measurement capability configured by the LEs, identification numbers of the LIUs, coordinate information of deployment positions of the LIUs, distances of the LIUs for identifying the LEs and the like. The CM _ DB stores user management data including identification numbers of LUEs and LBS, authentication information, authorized service class and level, etc. The service data stored in the TF _ DB comprises a digital map of a service-developing area, surface feature and landform information, mobile base station planning information, positioning measurement information reported by LE in the past, LE historical position information, LE identification information reported by LIU in the past and the like.

The data processing unit is responsible for processing LE positioning measurement data forwarded by the information acquisition unit according to a positioning algorithm, and determining the current position coordinates, the current movement mode and the movement posture of the LE and recording results by combining the LE historical movement track, the movement mode and the movement posture at the previous moment recorded by the database unit and the geographic information system of the area where the LE is located. And meanwhile, the LIU reporting information forwarded by the information acquisition unit is processed, the LIU correlation information in the database is inquired, and the current position coordinate of the LE is corrected in time by combining the information.

The management unit is responsible for managing registration, access authentication, working state monitoring statistics, upgrading maintenance and updating of associated attribute data of all the LEs and LIUs, and is also responsible for managing service opening, service change and service use records of LBS and LUE.

Figure 2 shows a functional block diagram of one embodiment of the LE. Wherein,

the GPS unit is responsible for receiving GPS signals and decoding and outputting positioning results to the main control unit. The output signal of the GPS complies with the NMEA-0183 protocol standard formulated by the national marine electronics association NMEA (national marine electronics association), which includes information such as GPS positioning data time, longitude, latitude, number of satellites used, altitude, number of GNSS satellites observed and their numbers, position, signal-to-noise ratio, ground rate, ground heading, date, etc.

The wireless sensing unit adopts a short-distance wireless communication technology, utilizes an RFID label or a ZigBee module configured into a simplified function device RFD to store the ID number ID-1 of the LE, and when the LE approaches the positioning beacon LIU, the LE can be automatically identified by the LIU and read the ID-1.

The inertial Measurement unit IMU (inertial Measurement unit) comprises acceleration sensors and angular velocity sensors in three directions of a rectangular coordinate system X/Y/Z, and is responsible for measuring the acceleration and the angular velocity of the LE in three coordinate axial directions in real time, so that the motion attitude, the heading and the navigational speed of the LE can be calculated and reported to the main control unit.

The wireless communication unit is responsible for establishing communication connection with the management platform S102 by accessing the communication network S101, and simultaneously can report some wireless network parameters according to the control instruction of the main control unit, and for the CDMA network, the wireless network parameters comprise a pseudo-random code phase offset coefficient, a pilot frequency active set, a pilot frequency candidate set and a pilot frequency adjacent set, and the parameters are acquired from the network side when the wireless communication module accesses the CDMA network.

The main control unit is connected with other functional units through control and data interfaces, completes initialization, parameter configuration and working state monitoring control of each unit, processes measurement results reported by the GPS unit and the IMU unit, reports the measurement results to the management platform S102 through the wireless communication unit, and receives and responds to a management instruction of the management platform S102 through the wireless communication unit.

Fig. 3 shows a functional block diagram of an embodiment of the LIU, wherein the wireless sensing unit adopts short-distance wireless communication technology such as RFID or ZigBee, and when the RFID technology is adopted, the wireless sensing unit is configured as an RFID reader, and when the ZigBee technology is adopted, the wireless sensing unit is configured as a ZigBee full-function device FFD. The detection range of the wireless sensing unit can be controlled in a proper sight distance range by adjusting the wireless transmitting power and the matched antenna of the LIU wireless sensing unit. Therefore, when an LE configured with an RFID label or ZigBee reduced function device enters the detection range of the LE, the LIU can automatically detect the identification number ID-1 of the LE and report the identification number ID-1 to the main control unit. The communication unit is responsible for accessing the communication network S101 in a wired or wireless manner, and further establishing a communication connection with the positioning management platform S102. The main control unit is connected with the wireless sensing unit and the communication unit through the control and data interface, completes initialization, parameter configuration and work state monitoring control of each unit, receives LE detection results reported by the wireless sensing unit and reports the results to the management platform S102 through the communication unit, and meanwhile receives and responds to management instructions of the management platform S102 through the communication unit. The LIU itself is also preconfigured with and stores a unique identification number ID-2 for identifying its identity when interacting with the location management platform S102.

In practical application, the positioning terminal LE is mounted on a vehicle or an article to be positioned and tracked, or worn on a person to be positioned and tracked, so that a battery is needed to supply power in most cases, and a miniaturized and low-power-consumption design is particularly important. The positioning beacon LIU is deployed at some key positions in the positioning service area, and for cargo positioning and tracking application, the LIU can be deployed at important road intersections, cargo yard entrances and exits, parking lot entrances and exits and the like; for the application of safe nursing of children, the system can be deployed in places such as community entrances and exits, kindergarten/school doorways, station terminals, important intersections and the like. The accurate position information of each LIU installation site, the identification number thereof and the wireless detection range information of the LIU are stored in the database unit of the positioning management platform S102, and are used for the data processing unit to correct the current position of the corresponding LE in real time after receiving the report message of the LIU.

Fig. 4 further shows a hardware implementation scheme of LE, which adopts a CDMA terminal chip solution of the american college to implement functions of a main control unit and a wireless communication unit, and simultaneously, an asynchronous serial interface UART of the main chip is connected with a ZigBee module to implement a function of a wireless sensing unit, and is connected with an acceleration sensor to implement a function of an IMU unit. As shown in fig. 4, the CDMA signal received by the antenna S401 is sent to the RFL6000 through the duplexer for low noise amplification, then sent to the RF receiving module RFR6000 after being filtered by the surface acoustic wave filter RxSAW, and the RFR6000 demodulates the received signal to an analog baseband and then sends the demodulated signal to the Rx ADC port of the CDMA main chip MSM6050 for AD conversion, and then the analog baseband signal is converted to a digital baseband signal and then CDMA signal processing is performed. The GPS satellite signal received by the antenna S402 is also sent to the RF receiving module RFR6000 after band-pass filtering, and the RFR6000 demodulates the received signal to an analog baseband and then sends the demodulated signal to the Rx ADC port of the MSM6050 for AD conversion, and the analog baseband signal is converted to a digital baseband signal and then further subjected to GPS signal decoding processing. The MSM6050 sends the CDMA baseband signal to be sent to the RF sending module RFT6100 through the Tx DAC, performs filtering TxSAW and power amplification PA after frequency conversion modulation, and finally feeds the radio frequency sending signal into the antenna S401 through the duplexer to be sent out. The power management chip PM6050 is responsible for power and clock management inside the LE, including battery management, such as power supply, charging, power display, etc.; the voltage of the power supply is boosted and reduced; backlight illumination management; providing a working power supply for each chip; RF receive, transmit clock management, system sleep clock management, and the like. The MSM6050 is connected with the PM6050, the RFR6000 and the RFT6100 through a serial bus interface SBI, so that the control and management of the chip are realized. The MSM6050 is embedded with an ARM7 microprocessor and can be used as a main control unit of the positioning terminal LE. SDRAM and FLASH are connected through the parallel data bus, address bus and memory management port as the storage unit of LE. The input button or keyboard of LE is connected to GPIO interface of MSM6050, and the audio codec interface is connected to the peripheral audio circuit, and can provide audio input and output function. The uim (user Identity model) card circuit may be directly connected to the UART interface of the MSM 6050. The output signal of the acceleration sensor for realizing the IMU function is input into a GPIO interface of the MSM6050 after analog-to-digital conversion, and the ZigBee module for realizing the wireless sensing function is connected to a UART interface of the MSM6050 through a serial port. The MEMS sensor can be selected from an acceleration sensor ADXL335 and a gyroscope ADXRS150 of ANALOG DEVICES of American ANALOG device company, and can realize acceleration measurement and angular velocity measurement in three axial directions of X/Y/Z. The ZigBee module can be realized by a CC2431 chip of American TI company, a C8051 microprocessor, a 2.4GHz radio frequency transceiver conforming to IEEE802.15.4 standard, a 128KB FLASH and an 8KB RAM are embedded in the CC2431, and the ZigBee RFD device function is realized by loading a ZigBee protocol stack in the C8051.

The LE hardware implementation shown in fig. 4 can be cut down to implement LIU, that is, circuits and devices related to GPS, an acceleration sensor, an input keyboard, and an audio interface are omitted, and of course, C8051 in CC2431 needs to be changed to be loaded with a ZigBee protocol stack for implementing the function of the FFD device. However, the LIU implemented according to this hardware scheme is connected to the background positioning management platform S102 through a CDMA wireless network, and if the LIU needs to be connected to the background positioning management platform through a wired broadband network, a hardware scheme as shown in fig. 5 may be adopted, where S3C4510B is an ARM7 microprocessor from Samsung corporation, and it is connected to the ZigBee module CC2431 through a UART interface, connected to the 100 ethernet interface circuit through an ethernet control interface, connected to SDRAM and FLASH through a storage control interface, and configured with peripheral circuits such as a power supply and a clock, to form the LIU supporting the 100M ethernet port.

After installing the new UIM card, the location terminal LE needs to obtain the legal authorization through the authentication of the location management platform S102 through the registration process before being used for the first time, and the specific steps are as shown in fig. 6:

s601: LE power up start;

s602: the LE detects whether the registration state is unregistered, if the registration state is unregistered, the process is switched to S603, and if the registration state is not unregistered, the process is ended, and the process is switched to a login process;

s603: the LE accesses a communication network S101 through a wireless communication unit, and then establishes communication connection with a positioning management platform S102;

s603: the LE sends a registration request to a positioning management platform S102, wherein the registration request comprises a terminal number and UIM card information;

s604: the positioning management platform S102 checks the LE information, including whether the positioning terminal number accords with the rule, whether the positioning terminal is registered on the platform or not and whether the positioning terminal is cancelled or not, and if the checking is wrong, the registration process is ended;

s605: the positioning management platform S102 checks the UIM card information, including whether the UIM card is opened or not and whether the state is available or not, and if the checking is wrong, the registration process is ended;

s606: the positioning management platform S102 performs logic check on the UIM card and the terminal number, respectively, checks whether the UIM card has been bound with other terminal numbers or whether the terminal number has been bound with other UIM cards, and releases the original binding if the binding relationship exists.

S607: the positioning management platform S102 returns a registration result to the LE according to the verification result, issues an access password and creates a binding relationship between the terminal number and the UIM card;

s608: the terminal changes its registration state to registered.

After the location terminal LE which has been successfully registered is powered on and started each time, the validity of the terminal and the UIM card also needs to be verified through a login process, so that the terminal can be ensured to be correctly accessed to a location management platform and smoothly perform location services.

The positioning management platform S102 controls the positioning policy of the LE by issuing the configuration parameters to the logged-in positioning terminal LE. The positioning strategy is determined according to the positioning service type applied by the LE, the conventional movement mode of the LE, the operational capability of the LE and other factors, and comprises the positioning parameters which need to be measured and reported by the terminal at regular time, the time interval of the measurement and the reporting at regular time, how to correspondingly change the positioning strategy when the movement state changes suddenly and the like. For example, for the vehicle positioning application, the positioning management platform S102 records information such as a normal driving speed range and a daily activity range of a vehicle to which the vehicle positioning terminal belongs in advance, and according to the information, in combination with the requirement of positioning and tracking accuracy and the energy saving requirement of the LE, may define a positioning policy of the LE as follows: when the LE movement rate measured by the IUM is less than 1m/s, the LE carries out GPS measurement once every 10 seconds and reports the result, samples and records the IUM measurement result every 100 milliseconds, reports the result after accumulating 100 times (namely reports the result every 10 seconds), and reports the wireless network parameters every 10 minutes; when the LE movement rate measured by the IUM is more than or equal to 15m/s, the LE carries out GPS measurement once per second and reports the result, samples and records the IUM measurement result once every 10 milliseconds, reports the result after accumulating 100 times (namely reports the result once per second), and reports the wireless network parameters once every 1 minute; and when the LE movement speed measured by the IUM is between 1m/s and 15m/s, gradually reducing the time interval between LE positioning measurement and reporting according to the movement speed from low to high. By adopting the positioning strategy, the LE can adopt power-saving measures such as dormancy, turning off a peripheral circuit power supply and the like during two measurement reporting periods, the average power consumption of the LE is obviously reduced, meanwhile, a positioning management platform is ensured to obtain enough positioning information in time, the positioning and track tracking precision of the LE is ensured, and the positioning service quality is ensured.

When a specific button on the location terminal LE is pressed, the LE enters an alarm state, at this time, the LE immediately sends an alarm message to the location management platform S102, after receiving the alarm message, the location management platform S102 may initiate a voice call to the LE while tracking the movement trajectory of the LE, the LE automatically responds to the call from the location management platform S102, establishes and maintains the voice call, and then the location management platform S102 monitors and records any sound information returned from the LE. Obviously, these sound information from the location of the LE help to identify and emergency handle the emergency situation in which the LE is located.

The above-mentioned interaction messages used in the traffic flow between the location terminal LE and the location management platform are encapsulated by a predefined application layer interface protocol carried on top of SMS, TCP or UDP, as shown in fig. 7. The TCP and UDP port numbers can be used as configurable parameters and can be configured in advance or modified online. The positioning terminal LE and the positioning management platform S102 complete functions such as registration, login authentication, parameter configuration, positioning information reporting, and alarm management by analyzing and responding to a message from the other party. It should be noted that, the above describes in detail the interaction process between the location terminal LE and the location management platform S102 only by the registration process of LE, and similar mechanisms can be adopted for other processes such as login, parameter configuration, location information reporting, and alarm, and are not described in detail here.

After the positioning beacon LIU is powered on and started, the validity authorization of the positioning management platform also needs to be obtained through a login process. If the LIU uses a wireless access mode (e.g. through a CDMA network) to connect with the location management platform, the UIM card needs to be used for the first time or replaced, and then authentication and authentication on the location management platform are completed through a registration process, and the UIM card and the identification number are bound. And the positioning management platform issues parameter information required by the LIU for automatically identifying the LE, such as frequency points, network identification numbers, encryption modes and the like configured by the LE wireless sensing unit to the LIU through a parameter configuration process. And the LIU automatically searches the LE in the coverage area according to the configuration information, and immediately reports LE detection information including detection time, the detected LE identification number ID-1, the signal intensity of the target LE and the like to the positioning management platform once the activity of the LE is detected. The positioning beacon LIU and the positioning management platform can adopt an interactive message encapsulation protocol and a service flow similar to those between the LE and the positioning management platform to complete registration, login, parameter configuration, LE detection information reporting and other functions of the LIU.

For the positioning information reported by LE m, the processing flow of the positioning management platform is shown in fig. 8:

1) the positioning information acquisition unit receives the timing report message from the LE and extracts the positioning information therein, including GPS positioning output information, IMU measurement information and wireless network parameters;

2) the data processing unit firstly preprocesses the positioning information and prepares for the next positioning operation:

A) for the GPS positioning output information (positioning time, longitude, latitude, number of satellites used, altitude, number of observed GNSS satellites and their numbers, position, signal-to-noise ratio, ground speed, ground heading, date, etc.), it needs to perform confidence evaluation, which is specifically done as follows: defining a confidence C _ L of GPS positioning information, which is formed by the number N _ S of satellites in GPS positioning output information and the signal-to-noise ratio SN of satellite signals_iN is calculated as follows,

in the formula SN₀The unit of the signal-to-noise ratio threshold value of the satellite signal required by the GPS receiver configured for the LE to correctly demodulate the signal is dB, and the value is stored in a positioning management platform database unit as an attribute parameter of the LE in advance.

B) And calculating the LE instant speed vector and the course of each sampling moment contained in the reported data according to the IMU measurement data.

C) If the reported information contains wireless network parameters, determining the current service base station and the adjacent base stations of the LE by retrieving wireless network planning information prestored in a database according to the pseudo-random code phase offset coefficient, the pilot frequency active set, the pilot frequency candidate set and the pilot frequency adjacent set data.

3) And further performing positioning operation according to the data obtained by the second step of preprocessing to obtain reliable LE position coordinates.

A) Performing optimal estimation on GPS positioning data by adopting a Kalman (Kalman) filtering structure commonly used in the industry;

B) carrying out Dead Reckoning (Dead-Reckoning) by using IMU (inertial measurement unit) measurement data, namely obtaining the track of the LE in the reporting period by integral operation according to the instant speed and the course of each sampling time point;

C) estimating the approximate position of the LE by combining the information of the LE current service base station and the adjacent base stations with a digital map; for example, in an ideal case as shown in fig. 9, it can be determined that the LE is located in the common coverage area S904 of the three base stations by searching the positions and coverage areas of the LE neighboring base stations S901, S902, and S903 stored in the database; although the actual wireless coverage situation is much more complicated, the coverage of the base station close to the actual situation can still be obtained by the common wireless network planning method, and then the approximate position of the LE is estimated. The wireless network planning method comprises the steps of establishing a radio wave propagation model according to topographic features of a peripheral area of a base station, and calculating the wireless coverage condition of the peripheral area of the base station by using radio parameters (such as antenna hanging height, transmitting power, receiving sensitivity and the like) of the base station and a digital map of the peripheral area and adopting the radio wave propagation model;

D) querying a database to determine the type and the current motion mode of the LE, and calling the motion attitude and trajectory data before the LE for standby;

E) inquiring a database to call a digital map of an area around the LE for later use;

F) comprehensively processing the positioning information obtained from a) to e) by using an information fusion technology so as to obtain a global optimal positioning estimation, wherein the method comprises the following steps:

i. when the confidence coefficient C _ L of the GPS positioning information is less than C _ L₀In time, the GPS positioning information is abandoned,directly adopting a dead reckoning result, and simultaneously starting a dead reckoning navigation timer T, when T is more than T₀Sending out system alarm; otherwise, performing information fusion processing on the output information of a) and b) by adopting a Kalman filtering technology to obtain the optimal estimation of the LE position information; the C _ L₀And T₀A threshold value is preset for the positioning management platform, and the threshold value can be modified at any time according to the requirement of corresponding positioning service on precision and the actual using effect;

ii, for the LE position information obtained by the i, performing matching operation by using a digital map, namely, performing correlation comparison between the current motion mode, the previous motion attitude, the track data, the course change and the expected position of the LE and the nearby map features, when the track change of the LE is correlated with the change of a vector road in the digital map, further correcting the current position and the track of the LE by using the road coordinate information in the digital map, and particularly when the LE moves along the road to turn at the intersection, well correcting the position coordinate of the LE by using a map matching algorithm;

confirming the consistency of the position information of the LE and the approximate position of the LE obtained by c);

G) the process is ended after a positioning result is output, the result is sent to an IMU dead reckoning unit for feedback correction, so that the system error accumulated along with the time is clamped in a tolerable range; and updating the LE historical movement speed, track and posture recorded by the database.

For the message reported by the LIU, the positioning management platform adopts the processing flow shown in fig. 10:

1) triggering to enter a positioning updating flow of a related LE according to an LE identification number ID-1 reported by the LIU after receiving an LE detection message from the LIU;

2) retrieving a database according to the identification number ID-2 of the LIU to call out attribute data of the LIU, wherein the attribute data comprise a deployment position, a distance capable of effectively detecting LE and directional parameters of a wireless sensing unit antenna;

3) according to the signal intensity of the LE wireless sensing unit reported by the LIU and the LIU is not availableCalculating the relative orientation of the LE to the LIU according to the directional parameters of the line sensing unit antenna, wherein the calculation can be carried out according to a propagation model of radio waves in free space, and then obtaining the time t when the LE is detected by the LIU according to LIU deployment position information_sThe position of the time;

4) retrieving the database to call out the nearest motion trail data of the LE, and reporting the detection time t to the LIU_sLE position at time of day is corrected and t is updated by dead reckoning based on IMU historical data_sAnd updating the correction and calculation results to the database after the moment until the current LE track.

As can be seen from the description of the above embodiments, the present invention is characterized in that: the positioning management platform is connected with a plurality of positioning terminals LE and a plurality of positioning beacons LIU through a communication network; the LE has the functions of GPS positioning measurement and IMU measurement, and has the functions of wireless sensing and communication; the LIU has a wireless sensing function and a communication function; preferably, the communication function is based on a mobile communication network and technology, and the communication network refers to a mobile communication network, such as a GSM, GPRS, EDGE, WCDMA, TD-SGDMA, CDMA20001x, CDMA2000 EVDO network, and an evolved network based on the mobile network. And the LE regularly reports the positioning measurement data to a positioning management platform according to a predefined positioning strategy, and the management platform comprehensively processes GPS, IMU and wireless network data and combines a digital map matching technology to obtain the optimal estimation of the LE position. When the LE approaches to the detection range of the LIU wireless sensing unit, the LE can be automatically identified, the identification number ID-1 is automatically read by the LIU and reported to a positioning management platform, and the management platform corrects the position data corresponding to the LE according to the LIU position information pre-recorded when the LIU is deployed and the detection range of the wireless sensing unit. Therefore, the positioning calculation work of the LE is mainly performed on the management platform, and the LE is only responsible for the measurement of the GPS and the IMU and reports the measurement data, so that the data processing requirement of the LE is greatly simplified, and the reduction of the power consumption of the LE is facilitated. Furthermore, different positioning strategies can be dynamically defined according to the movement state of the LE, the time intervals of positioning measurement and reporting of the LE are associated with the movement speed of the LE, when the movement speed is increased, the time intervals of positioning measurement and reporting are reduced, otherwise, the time intervals of positioning measurement and reporting are increased, and the LE can save power consumption through measures of sleeping, turning off a peripheral circuit power supply and the like during the two times of positioning measurement and reporting, so that the positioning tracking service quality of the positioning management platform on the LE is ensured, and the working time of the LE is reduced as much as possible, thereby reducing the average power consumption of the LE.

The method can provide various positioning value-added services for users, the positioning management platform can customize special service strategies for corresponding LE groups according to service requirements, for example, the legal activity range and the normal motion state of the LE are defined, once the management platform monitors that the position of the LE exceeds the preset normal range or the motion state of the LE exceeds the normal range, the management platform can send alarm information to the users, and the management platform can also predict whether the LE has the trend of triggering the alarm according to the flight path and the current state of the LE so as to determine whether to send the alarm information in advance.

Many changes and modifications may be made to the above-described location services method without departing from the scope and spirit of the present invention, and many modifications and variations will be apparent to those of ordinary skill in the art. The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. The scope of the invention is determined by the appended claims.

Claims

1. A method of providing location services, the method comprising:

2. The method of claim 1, further comprising: the location management platform is connected with an authorized third party location service provider LBS and a location service user LUE through a communication network, and issues location service information to the LBS and the LUE, wherein the location service information comprises LE instant location information, location triggered alarm and track.

3. The method of claim 1 or 2, wherein the communication network refers to a mobile communication network capable of providing wide area coverage, a wired broadband network, a wireless broadband network, or a combination thereof, and the mobile communication network includes a GSM network, a GPRS network, an EDGE network, a CDMA20001x network, a CDMA2000 EVDO network, a WCDMA network, a TD-SCDMA network, and an evolved network based on the above mobile network.

4. The method of any of claims 1-3, wherein the LE comprises:

the GPS unit is responsible for receiving GPS signals, decoding and outputting positioning results to the main control unit;

the wireless sensing unit is used for storing the identity identification number ID-1 of the LE by using an RFID label or a ZigBee module configured into a simplified functional device RFD by adopting a short-distance wireless communication technology;

the inertial measurement unit IMU is responsible for measuring the acceleration and the angular speed of the LE in three coordinate axial directions in real time, calculating the motion attitude, the course and the navigational speed of the LE according to the acceleration and the angular speed, and reporting the motion attitude, the course and the navigational speed to the main control unit;

the wireless communication unit is responsible for accessing a communication network and establishing communication connection with the positioning management platform, and reporting wireless network parameters according to a control instruction of the main control unit, wherein the wireless network parameters comprise a pseudo-random code phase offset coefficient, a pilot frequency activation set, a pilot frequency candidate set and a pilot frequency adjacent set for the CDMA network;

the main control unit is connected with other functional units through control and data interfaces to complete initialization, parameter configuration and working state monitoring control of each unit, process measurement results reported by the GPS unit and the IMU unit, report a positioning management platform through the wireless communication unit, and receive and respond to a management instruction of the positioning management platform through the wireless communication unit.

5. The method as claimed in any of claims 1-4, wherein the LIU is pre-configured and stores a unique identification number ID-2 for identifying its own identity when interacting with the location management platform, and the LIU further comprises:

the wireless sensing unit is configured into an RFID reader or a ZigBee full-function device FFD by adopting an RFID or ZigBee short-distance wireless communication technology, and the detection range of the wireless sensing unit can be adjusted by adjusting the wireless transmission power and a matched antenna; the system is responsible for automatically detecting the LE entering the detection range of the LE, automatically reading the identification number of the LE and reporting the identification number to the main control unit;

the communication unit is responsible for accessing a communication network in a wired or wireless mode and further establishing communication connection with the positioning management platform;

the main control unit is connected with the wireless sensing unit and the communication unit through the control and data interface, completes initialization, parameter configuration and working state monitoring control of each unit, receives an LE detection result reported by the wireless sensing unit, reports the LE detection result to the positioning management platform through the communication unit, and receives and responds to an instruction of the positioning management platform through the communication unit.

6. The method according to any one of claims 1 to 5, wherein the positioning management platform adopts a distributed and modular architecture and is composed of one server or a plurality of server groups; which comprises the following steps:

the information acquisition and release unit is responsible for finishing the communication between the positioning management platform and the LE, LIU, LUE and LBS based on a TCP/IP protocol or a short message SMS, and finishing the encapsulation and the decapsulation of the interactive messages between the positioning management platform and the LE, LIU, LUE and LBS; the data processing unit is responsible for extracting an LE identification number and positioning measurement information from the reported message of the LE and transferring the LE identification number and the positioning measurement information to the data processing unit, and extracting the identification number of the LE, the identification time of the LE information and the identification number information of the LIU from the reported message of the LIU and transferring the identification number information of the LE, the identification time of the LE information and the identification number information of the LI; the management unit is responsible for issuing LE positioning service information to the authorized LBS and the LUE according to the instruction of the management unit;

the database unit is the synthesis of various logic databases and comprises a terminal management database TM _ DB, a user management database CM _ DB and a service database TF _ DB; the TM _ DB stored terminal management data comprises identification numbers of all LEs, conventional motion modes and current motion modes of the LEs, current postures of the LEs, location service types of the LEs, location measurement capability configured by the LEs, identification numbers of the LIUs, coordinate information of LIU deployment positions and distances of the LIUs for identifying the LEs; the CM _ DB stores user management data including LUE and LBS identification numbers, authentication information, authorization service types and grades; the service data stored in the TF _ DB comprises a digital map of a service-developing area, surface feature and landform information, mobile base station planning information, positioning measurement information reported by LE in the past, LE historical position information and LE identification information reported by LIU in the past;

the data processing unit is responsible for processing LE positioning measurement data transferred by the information acquisition unit, determining the current position coordinates, the current motion mode and the motion attitude of the LE and recording the result by combining the LE historical motion track, the previous motion mode and the motion attitude recorded by the database unit and the geographic information system of the area where the LE is located; meanwhile, the LIU reporting information forwarded by the information acquisition unit is processed, the relevant information of the LIU in the database is inquired, and the current position coordinate of the LE is corrected in time by combining the information;

and the management unit is responsible for managing registration, access authentication, working state monitoring statistics, upgrading maintenance and updating of associated attribute data of all the LEs and LIUs, and is also responsible for managing service opening, service change and service use records of LBS and LUE.

7. The method according to any of claims 1-6, wherein the positioning measurements made by the LE include GPS measurements, inertial navigation measurements, and wireless network parameter measurements; the positioning measurement and result report are triggered regularly according to a positioning strategy, the positioning strategy is predetermined by a positioning management platform according to the positioning service type applied by the LE, the conventional motion mode of the LE and the operational capability of the LE and is configured in the LE through issued parameters, and the positioning strategy comprises positioning parameters which the LE needs to measure and report regularly and time intervals for measuring and reporting regularly; the time interval is a dynamic variation quantity related to the LE instant movement speed, and the variation rule is that the time interval is smaller when the speed is higher; and the LE enters a dormant state and turns off a power supply of a peripheral circuit during two positioning measurements and result reporting periods.

8. The method according to any of claims 1 to 7, wherein the location management platform processes the location measurement information reported by the LE by:

9. The method as claimed in claim 8, wherein the GPS positioning data confidence level C _ L in the step of processing the positioning measurement information reported by LE by the positioning management platform in step 2) is calculated by the following formula:

10. The method according to claim 8 or 9, wherein the positioning information fusion processing in the step 3) of processing the positioning measurement information reported by the LE by the positioning management platform comprises:

(c) the information fusion unit performs information fusion processing on the results of (a) and (b): when the confidence coefficient C _ L of the GPS positioning information is less than C _ L₀When the GPS positioning information is abandoned, the dead reckoning result is directly adopted as the positioning result of the LE, meanwhile, a dead reckoning navigation timer T is started, and when T is larger than T0, a system alarm is sent out; otherwise, Kalman filtering processing is carried out on the output information of a) and b) to obtain the optimal estimation of the LE position information; the C _ L₀T0 is a preset threshold value of the positioning management platform and can be modified at any time according to the requirement of the corresponding positioning service on the precision and the actual using effect;

11. The method as claimed in claim 8, wherein the step of the location management platform processing the wireless network parameters in the step 1) of the location measurement information reported by the LE comprises: pseudo-random code phase offset coefficient, pilot frequency active set, pilot frequency candidate set and pilot frequency adjacent set data; determining the current service base station and the adjacent base stations of the LE by retrieving wireless network planning information prestored in a database according to the wireless network parameters; the approximate location of the LE is then estimated in conjunction with the digital map as an aid to LE positioning.

12. The method according to any of claims 1-11, wherein the location management platform processes the LE probe information reported by the LIU by:

B) retrieving a database according to the identification number ID-2 of the LIU to call out attribute data of the LIU, wherein the attribute data comprise deployment positions and can effectively detect the distance of an LE and directional parameters of an antenna of a wireless sensing unit;