KR20070114286A - Synchronization of transmit and receive base stations - Google Patents

Abstract

In network overlay wireless positioning solutions for GSM or UMTS communication networks, spectrum utilization can be made much more efficient by synchronizing BTSs. At this time, synchronization may require spraying one timing signal to all BTSs or installing a satellite-based timing unit at each site. The present invention provides an architecture where location measuring units (LMUs) are installed at all or only some of the BTS sites for positioning of wireless devices. LMUs are used to measure the timing of various uplink or downlink signals occurring in the cellular network using various positioning techniques. These LMUs can include a GPS-based timing reference module that can be used to synchronize the time references of all LMUs. To reduce the overall cost of BTS synchronization, the LMU distributes timing signals over serial or other interfaces, including periodic electrical pulses and time description information, which are available to other nodes for synchronization purposes. have. The format of the electrical pulse and time description signals is modified through hardware or software to suit the various formats required by the various BTS formats. For example, BTSs with LMUs can receive synchronization signals at little cost. An external interface unit (EIU) can be used to fit various BTS hardware formats. For BTS sites that do not have an LMU, a timing measurement unit (TMU) may be used. The TMU has a unique function of providing BTS time signals in the same format as that provided in the LMU. The time signals provided by the TMUs are synchronized with the signals provided by the LMUs. These timing-only TMUs are less expensive than LMUs because they do not support uplink or downlink signal measurement functions. This approach allows cellular operators to synchronize BTSs at a relatively low cost.

Description

Synchronization of base transceiver stations {BASE TRANSCEIVER STATION (BTS) SYNCHRONIZATION}

The present invention relates generally to the field of wireless positioning and related wireless communication systems. More specifically, the present invention relates to a system for synchronization of a base transceiver station (BTS) of GSM or UMTS coupled with an overlay wireless location system (WLS), but is not limited thereto. It doesn't happen.

The present invention is particularly suited to the field of use of GSM and UMTS and other similar technologies, but is not necessarily limited thereto. GSM stands for Global System for Mobile Communication, and is a digital mobile phone system widely used in Europe and other parts of the world. UMTS stands for Universal Mobile Telecommunications System, and is a third generation based on the GSM standard. , 3G) broadband system. The present disclosure describes a system and method for providing global positioning system (GPS) based timing information to base stations of a wireless communication system for the purpose of network synchronization. For example, GSM network synchronization can be beneficial to wireless carriers in many ways. In a GSM network in an unsynchronized state, co-channel interference due to frequency reuse can be reduced by synchronizing. Reducing the noise / interchannel interference level allows for enhanced frequency reuse patterns, allowing wireless operators to increase system capacity (eg, Erlang capacity) or improve voice / data quality.

The following description summarizes some important aspects of the present invention and is described in more detail in the detailed description.

1. A network overlay wireless positioning solution for a wireless communication system comprising a network of transmit and receive base stations (BTS), such as, for example, a GSM or UMTS communication network, comprising: a method for enhancing spectrum by synchronizing the transmit and receive base stations; and system.

2. The method and system, wherein the timing signal is provided to each transmit / receive base stations (BTS) by either a location measurement unit (LMU) or a timing measurement unit (TMU). It is done.

3. The method and system, wherein each LMU and TMU is a GPS-based timing reference module and timing signals generated by each other LMU and TMU within a predetermined level of accuracy. Means for generating a periodic timing signal that is synchronized with.

4. The method and system, wherein the LMUs are used to measure the timing of various uplink or downlink signals made within the cellular network using various positioning techniques.

5. The method and system, wherein the LMUs and TMUs distribute timing signals including time description information along with a periodic electrical pulse.

6. The method and system, wherein the format of the electrical pulse and time description information is modified through hardware and software in accordance with the various formats required by the various BTS formats.

7. In the above method and system, a BTS co-located with an LMU receives synchronization signals with very little or no hardware cost, and BTS sites that are not equipped with an LMU are provided by the LMU. A TMU having a unique function of providing BTS time signals of the same format is installed, and the time signals provided by the TMUs are synchronized with the signals provided by the LMUs, and the timing function The full TMU can be deployed at a lower cost than the LMU because it does not support uplink or downlink signal measurement functions.

It should be noted that the concept of time signals being "synchronized" is not limited to signals having essentially the same shape or occurring simultaneously. For example, some two signals, at least in view of the object of the present invention, may be considered sufficiently synchronized if these signals have a well known relationship between them even if there are errors in time.

1 schematically illustrates an example embodiment of an emergency-only overlay location solution.

2 illustrates a method of deploying base station synchronization devices (LMUs and TMUs) in accordance with the present invention.

3 illustrates an example embodiment of an internal architecture and an external interface of a TMU.

4 shows an exemplary relationship between one PPS timing signal and synchronization data.

FIG. 5 shows an exemplary GSM / UMTS network in which BTSs with synchronization / location functionality support and BTSs without synchronization / location resolution support are mixed.

6 shows an exemplary architecture of an external interface unit (EIU).

1. Overview

The invention is particularly suitable for use in connection with network overlay solutions for GSM communication networks. The GSM network is defined by the European Telecommunications Standards Institute (ETSI) and has been extended by the 3rd Generation Partnership Project (3GPP). Within a fully integrated GSM standard compliant location services solution, the Serving Mobile Location Center (SMLC) relies on an existing Base Station Controller (BSC) or Packet Control Unit (PCU) to determine the mobile station (MS), or location. RF assignment information is provided to a mobile unit). By adapting the LMU to monitor uplink or downlink control channels, such emergency dedicated systems meet the Federal Communications Commission's E911 mandate but require no changes to conventional GSM terminals or networks. only) It is possible to implement an overlay positioning solution. An exemplary architecture for such a solution is illustrated in FIG. 1. (For more information on this architecture, see US Patent Application No. 20040203429, “E911 Overlay Solution for GSM, for Use in a Wireless Location System,” filed September 3, 2002 and issued October 14, 2004). )

As shown in FIG. 1, the E911 overlay solution includes the following elements.

1. GSM communication network 100. The GSM communication network 100 includes receive / transmit antennas 102A coupled to a base transceiver station (BTS) 104, a base station controller (BSC) 106, a mobile switching center (MSC). 108, Gateway Mobile Location Center (GMLC) 110. All of these components and subsystems are well known in the art. See, for example, Technical Specification (TS) 0.37 V8.6.0 (June 2002 edition) of 3GPP.

2. Location Measuring Unit (LMU) 200A. The LMU 200A may share a location with the BTS 104, as indicated by the broken line in the figure, thereby sharing the antenna 102A that also receives RF signals from the mobile stations MS. have. The LMU 200A may include an internal GPS receiver and may also be provided with a GPS antenna 202A. The LMU may also provide the ability to monitor and demodulate forward channel signals transmitted from the BTS to the MS. This forward link monitor port may be connected to a separate antenna or may be directly connected to the BTS forward link path. The system also has a primary LMU, in this case an LMU 200A, for one given call, and one or more Cooperative LMUs, eg, LMUs indicated as 200B. It may be configured to. The cooperative LMUs will generally be configured identically to the primary LMU and will therefore be associated with the GPS antenna 202B and will typically share location with any BTS.

3. The LMUs are coupled to a Serving Mobile Location Center (SMLC) 300, which in turn is connected to a Gateway Mobile Location Center (GMLC) or a Mobile Posistioning Center (MPC) 400. Such concepts of LMU, SMLC, GMLC and MPC are well known and can be found in the GSM specification document mentioned above.

4. Also shown in FIG. 1 is a mobile station (MS) 500. Of course, there will typically be numerous such units operating within a certain geographic area, and at any given time one or more units may be making emergency calls.

In some cellular / wireless systems, such as GSM systems or UMTS systems, spectrum utilization can be made very efficient by synchronizing BTSs. For example, BTS synchronization allows 10-20% more voice calls per unit bandwidth. It is difficult to synchronize a large number of BTSs with an appropriate level of accuracy in the network, and either all the BTSs must have a timing signal or a satellite-based timing unit must be installed at each site. Satellite-based timing units are very expensive and can take up valuable power and space at the BTS site.

The present invention provides an architecture in which location measuring units (LMUs) can be installed in all or some BTS sites for the location of wireless devices. The LMUs are used to measure the timing of various uplink and downlink signals made within the cellular network, assisted by various positioning techniques. These LMUs may include a GPS-based timing reference module that is used to synchronize the time bases of all LMUs. This enables relative time difference measurements in the process of supporting location verification.

In order to reduce the overall cost of BTS synchronization, the LMU distributes not only periodic electrical pulses, but also timing signals, including time description information, through a serial interface or other interface, which is used by other nodes ( It can also be used to synchronize at nodes. The format of the electrical pulse and time description signal can be modified through hardware and software to suit the various formats required in the form of various BTSs. For example, BTSs with LMUs can receive synchronization signals with little or no hardware cost. The EIU, which will be described later, is used to adapt to various BTS hardware formats.

Of course, not all BTS sites will be able to mount LMUs together. For sites that do not have such an LMU, a timing measurement unit (TMU) can be used. The TMU has a unique function of providing BTS time signals in the same format as provided by the LMU. The time signals provided by the TMUs are in synchronization with the signals provided by the LMUs. These timing function-specific TMUs are less expensive than LMUs because they do not support uplink or downlink signal measurement functions. A system of such devices allows a cellular system operator (wireless operator) to synchronize BTSs at a relatively low cost.

2. BTS Synchronization

According to the present invention, the LMUs may have a high performance GPS receiver to provide a high accuracy timing reference common to all LMUs in the positioning system. The GPS receiver may provide a timing reference reference to a co-located base station for the purpose of synchronizing the base station network, i.e., to synchronize the BTSs within a certain level of precision. In one exemplary implementation of the invention, the LMU may comprise a network synchronization interface, which may be suitably implemented to be compatible with the corresponding interface in the associated BTS. That is, through additional software modifications, existing LMUs can be upgraded to a configuration compatible with the BTS interface. This software upgrade is called BTS Timing Option (BTO), which can be installed within an existing LMU / BTS or loaded with new LMUs.

For BTS sites that do not have an LMU installed, a timing measurement unit (TMU) may be employed. The TMU includes a GPS receiver and the necessary software suitable for the BTS timing interface. There may be a mix of LMUs with BTO and TMU timing modules in the market, and wireless operators may choose to use only the TMUs to synchronize in a market where no LMUs are installed.

The timing measuring unit is a standalone product and can be deployed independently of the wireless positioning system. The TMU has a built-in GPS receiver that includes a GPS antenna to construct an accurate timestamp. The clocked output includes one pulse per second, that is, one pulse per second (PPS) signal and timing information. The TMU provides data in the form of a pre-specified ASCII format developed for use with a particular BTS device already deployed.

TruePosition base station synchronization products may be used in a variety of ways, as described in FIG. 2 and described below.

1. Place on unexplored land with neither location nor synchronization

2. Upgrade already synced BTS to include location check

3. Upgrade to integrate synchronization with BTS with location support

3. Timing measurement unit (example embodiment)

In order to enable the wireless operator to operate a synchronized GSM system, the TMU may be arranged to provide periodic signals and related timing data information to the BTSs. The TMU preferably comprises a GPS receiver designed to provide this periodic signal and associated timing data information to the BTS, for example via an RS-422 communication interface.

In one exemplary embodiment, the TMU is a magnetically operated device, comprising: a GPS receiver / engine (collectively GPS), an 80C51 microcontroller (C51), a serial interface for supplying timing information to the BTS, and a console interface. It includes. The purpose of the TMU is to obtain accurate time information from the GPS and supply it to the BTS. Timing is provided to the BTS in the form of a PPS signal, which precedes the serial message indicating the exact time of the rising edge of the pulse.

The TMU tries to maximize the time for supplying accurate timing information to the BTS. For this purpose, the TMU takes the means to bring the GPS function online as soon as possible after power outage and also to keep it online as soon as possible.

In order to support maintenance and inspection, the TMU has three modes of operation: boot mode, test mode and operational mode. The boot mode may update the TMU firmware after manufacture. Test mode supports testing and diagnosing TMU hardware platforms. Normal operating mode provides the most important TMU function to provide timing to the BTS.

The TMU provides synchronization information as described above for two main reasons.

1) When the LMU is not present in the BTS. If LMU exists, synchronization

Information is provided by the LMU via an external interface unit (EIU).

The external interface unit is the one PPS signal and the timing associated with it

Acquire an information signal and RS-422 two signals for interface to the BTS.

Convert to communication format.

2) Although the LMU is deployed with a device that utilizes the signal output function,

When there is no ability to provide timing signals.

3 illustrates an example embodiment of an internal architecture and an external interface of a TMU. The received GPS satellite signal is input to the internal GPS receiver of the TMU. The internal microcontroller offers the following features:

1) GPS timing data in serial format, if required, as required

   Formatted

2) Upgrade TMU firmware via external RS-232 console port

3) Provides tricolor LEDs to indicate the health and synchronization status of the TMU

4) Reset function via reset switch on the front panel

The 1 PPS signal output from the GPS receiver and the formatted serial timing data signal output from the microcontroller are both converted to the RS-422 signal level and output to the BTS. The 1 PPS and serial data signals are fanned out to four four ports, including a quad output connector. Each output port provides both 1 PPS and serial data outputs set to the RS-422 signal level.

The microcontroller firmware of the TMU may be upgraded via the RS-232 console port.

The TMU will send a synchronization timing data message and a 1 PPS signal to the BTS in accordance with the RS-422 signal level as shown in FIG. The interface of the synchronization timing data to the BTS may be a serial communication link.

The 1 PPS signals distributed at the four output ports by the TMU may have a frequency of 1 Hz and an accuracy of 100 ns on average over UTC time.

The physical layer of the serial communication link is based on RS-422 UART. Specific features are as follows.

RS-422 Interface with 100 Ohm Termination on BTS Side

600 9600 bits / s

­ no parity

시작 Start bit of 1 bit

8-bit data length

종료 1 bit end bit

The RS-422 transmitter in the TMU drives one PPS signal. The 10-90% rise time will be less than 10 ns at each TMU output port. The BTS may include an embedded 100 ohm termination.

Synchronization data follows the 1 PPS pulse. See FIG. 4 for detailed timing. The arrows in FIG. 4 indicate the rising edge of the PPS pulse. The data signal containing the timing information follows the corresponding PPS pulse.

5 is a block diagram illustrating an exemplary GSM network or UMTS network where BTSs are synchronized using timing information obtained from an LMU or TMU. The LMUs may or may not require an EIU, as discussed herein, depending on the BTS interface requirements.

[Operational Description of TMU (Example Embodiment)]

As described, the TMU provides timing for one BTS to allow that BTS to synchronize its operation with other BTSs in the network. The TMU derives timing information from its internal GPS receiver and provides the BTS with a PPS signal, Periodic PPS Report and Position Data messages. The TMU is located where no LMU exists or where no timing signals are available from an already deployed LMU. Where the LMU is deployed, the LMU can provide the same timing function as the TMU by using an EIU. Synchronized BTSs can precisely manage radio resources, thereby increasing network capacity.

In a preferred embodiment, the TMU software supports three modes of operation: boot mode, test mode and normal operation mode. Although each mode provides a mechanism to switch to the remaining modes, each mode is independent and mutually exclusive. That is, the boot mode does not support the test mode function, the test mode does not support the boot mode function, and neither the boot mode nor the test mode provides any type of normal operation mode function. In addition, the normal operation mode does not support any of the other two modes.

In order to use a function of a mode, the TMU must first be switched to that mode via an appropriate mechanism (usually via a console command). Once switched to a particular mode, it will be understood that the functionality of the other modes is not available. For example, when switching to test mode, the time synchronization function for the BTS is disabled because this function is only supported in the normal operating mode. BTS timing synchronization cannot be restarted until the TMU returns to normal operation mode.

In some cases it may not be possible to switch from one mode to another. For example, it is impossible to switch from boot mode to another mode if a valid program image is not provided. In addition, some conditions may automatically cause the mode to switch. For example, the TMU automatically enters boot mode on reset if no valid program image exists.

The current mode of the TMU can be identified by the console's prompt. The console prompt displays the current mode as follows:

T "TMU>" in normal operation mode

­ "Boot>" in boot mode

때 In "Test>" test mode

[Boot mode]

Boot mode may allow the TMU software to be updated in the field. In boot mode, the software image can be downloaded through the console port. The downloaded image can replace the image stored in flash memory. In this way, only parts of the image related to the test mode and the normal operation mode can be replaced. The part related to the boot mode of the image can only be replaced during the manufacturing process or through the JTAG port.

Boot mode may be entered via console mode, or may automatically occur following a reset if no valid program image is found. Some fault conditions, such as, for example, a watchdog timeout, cause a reset, which can soon lead to boot mode. Boot mode can be exited by a reset if a valid program image is provided. Reset can be implemented by pressing a reset button, switching power, or console command. Boot mode cannot exit if no valid program image is provided. Upon successful exit from boot mode, the TMU returns to normal operation mode.

[Test mode]

Test mode supports console commands that directly run the TMU hardware. Such commands may generally be either low level commands or high level commands. Low level instructions directly manipulate the TMU hardware and provide little or no machine translation for the operator. Low level commands are useful for board level test and error detection. The high level command provides signal interpretation and can manipulate the combination of signals to support the interaction with the hardware by the operator. These instructions are useful for diagnosing operational problems.

The test mode is intended for use during testing, installation, and for on-site failure diagnosis and repair during the manufacturing process. The test mode is intended for use by trained technicians. The test mode can be entered in normal operation mode using console commands. The test mode can be exited by various resets and the TMU returns to normal operation mode (as long as a valid program image is provided).

[Normal operation mode]

Normal operation mode is the most important mode of the TMU. When operating in the normal mode of operation, the TMU operates autonomously to supply accurate time synchronization information for its BTSs, its most important purpose. When operating in the normal mode of operation, the TMU may communicate alarms or status information to the console port. In addition, the normal mode of operation can query the operating conditions and manipulate the operating parameters.

Normal operating mode is automatically entered following a reset if a valid program image exists. Normal operating mode can be exited by initiating a test or boot mode via a console command. The normal mode of operation can automatically exit if certain fault conditions are detected.

[Operational states]

The status LEDs on the front panel of the TMU reflect the current state of the TMU. The state of the TMU is determined according to its operating mode and the present conditions. Of the ten possible LED states, the following states are defined as valid. The LED state always indicates what is present.

Red Solid Red (Fault)-This means a failure and the TMU

By a qualified or replacement technician who cannot function normally

It must be repaired.

Green Flash Green (initializing)-This indicates that the TMU is operating normally

In the meantime, this means that no other unforeseen circumstances were detected.

This state will only last for a short time following a reset,

The circumstances necessary to provide timing have not yet been established

it means. If the required situations are not established within 2 minutes after the reset,

The operating state will proceed to the "Flash Amber" state.

Once out of this operating state, the TMU will remain until it is reset again.

Does not return to the operating state.

Green Solid Green (fully functional)-which means that the TMU

Is operating normally, there are no outstanding alarms,

This means that the BTS is getting the correct timing.

Green Flash Green (Fault)-This indicates that the TMU will

Situations that can cause the TMU to provide timing to the BTS.

I mean that an alarm exists. This operating state is always

Impact, so replacing the TMU itself will eliminate this issue.

Once all the unresolved situations have been resolved, the TMU is "persistent green".

Return to the state.

Alarms and Status Messages

In normal operation mode, the TMU monitors for situations that may adversely affect the ability to provide accurate timing information to the BTS. In addition, the TMU also records unusual situations or various situations encountered during the execution of a program. Messages relating to these situations are sent to the console. These messages are either alert or current. The "Status" message is purely informational and may indicate anything of interest. The occurrence of a Status message does not affect the operation of the TMU. An alarm message refers to situations that may affect the performance of the TMU. The presence of such an alert may cause a change in the TMU state. If multiple alerts have occurred, this may be considered the most serious condition.

Alarm indication on the TMU number Warning condition Explanation One CPU clock failure Continuous red CPU's external oscillator is not running Occurrence: Resolving during software initialization: Only by reset Notifying BTS: No message 2 TMU initialization error Continuous red TMU's CPU experiences an error during initialization Occurrence: During software initialization Resolution: Only by reset Notify BTS: No message or GPSS Status = (3) PPS not Synchronized GPSS Faulty = (1) GPS Receiver Faulty

number Warning condition Explanation 3 GPS not detected Continuous red The CPU cannot detect the presence of GPS. It is believed that GPS is completely malfunctioning. Occurrence: During software initialization, the GPS does not respond to the initialization procedures. Resolution: Resetting only Notified BTS: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (1) GPS Receiver Faulty 4 GPS communication failed Continuous red The CPU is struggling to communicate with the GPS so that the CPU cannot control the GPS or obtain the necessary information for mandatory BTS reporting. Occurrence: First time the mandatory BTS report could not be completed due to GPS communication. Remedy: The first time the BTS was not successfully completed by the mandatory BTS report: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (1) GPS Receiver Faulty 5 GPS internal error Continuous red GPS self tests reported errors in the GPS ROM or GPS RAM. The GPS self test is performed following a CPU reset. Occurrence: According to self test result Resolution: Only by reset Notify BTS: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (1) GPS Receiver Faulty 6 No GPS satellites Flashing tan (flashing green) There is no satellite available to the GPS receiver. Occurrence: When "Number of satellites used for positioning" is displayed as 0 in the GPGGA sentence: Notify BTS when one or more satellites are displayed: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (0 ) GPS Receiver Running 7 GPS PPS not available Flashing tan (flashing green) GPS indicates that no PPS signal will be output. Occurrence: When the "PPS Available Status" item in the GPTps sentence shows "No PPS Output" Remedy: Notify BTS when PPS output is displayed: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (0) GPS Receiver running 8 No UTC parameter in GPS Flashing tan (flashing green) The accuracy of the PPS cannot be guaranteed because no UTC parameter is obtained. Occurrence: When "date / time of UTC parameter" entry in GPSps sentence is displayed as "000000000000" Remedy: Notifying BTS when a valid date / time stamp is displayed: GPSS Status = (3) PPS not Synchronized GPSS Faulty = ( 0) GPS Receiver Running number Warning condition Explanation 9 GPS time not valid Flashing tan (flashing green) GPS time was not determined. Occurrence: When the "validity flag" entry in the GPgpt statement displays "GPS time not yet determined" Remedy: Notifying BTS when "GPS time is valid": GPSS Status = (3) PPS not Synchronized GPSS Faulty = (0) GPS Receiver Running 10 GPS positioning mode, invalid Flashing tan (flashing green) GPS indicates that the positioning data is invalid. Occurrence: When "Location Check System Mode Display" in the GPGLL, GPRMC, and GPVTG sentences shows "Data Not Valid" or "GPS Quality Indication" in the GPGGA sentence shows "0: Fixed is unavailable or invalid." Resolution: Notify BTS when "Automonous mode" or "Differential mode" is displayed: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (0) GPS Receiver Running 11 PPS not detected Flashing tan (flashing green) The information provided from the GPS is in the process of generating a PPS, but the PPS is not detected by the CPU. Occurrence: PPS output is expected but PPS is not detected for 2 seconds Resolution: Notify BTS when PPS is detected: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (0) GPS Receiver Running 12 GPS navigation receiver warning Flashing tan (flashing green) GPS displays navigation receiver warnings among the status items in the GPGLL, GPRMC, or GPRMC sentences. Occurrence: When "navigation receiver warning" is displayed Resolution: Notify BTS when "data valid" is displayed: GPSS Status = (3) PPS not Synchronized GPSS Faulty = (0) GPS Receiver Running 13 4 or less GPS satellites Continuous green The "Number of satellites used for positioning" item in the GPGGA or GPGSA sentence indicates that no more than four satellites are available. Occurrence: When 1,2, or 3 satellites are displayed. Resolution: Notify BTS when 4 or more satellites are displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 14 GPS PPS TRAIM Alarm Continuous green TRAIM is available but indicates a problem with PPS timing. Occurrence: When the "PPS output result status" entry in the GPrrm sentence indicates 1 Remedy: Notify BTS when a value other than 1 is displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running

number Warning condition Explanation  15 GPS antenna malfunction Continuous green GPS self-test reported poor GPS antenna connection. The GPS self test is performed following a CPU reset. Occurrence: According to self test result Resolution: Only by reset Notify BTS: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 16 GPS positioning mode, reader mode Continuous green GPS is operating in magnetic mode. Occurrence: When the "Show positioning system mode" entry in the GPGLL, GPRMC, and GPVTG sentences shows "Reader mode" Remedy: Notifying BTS when "Reader mode" is not displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 17 GPS positioning mode, differential mode Continuous green GPS is operating in differential mode. Occurrence: When "Display positioning system mode" entry in GPGLL, GPRMC and GPVTG sentences shows "Differential mode" Remedy: Notify BTS when "Differential mode" is not displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 18 GPS DGPS not received Continuous green GPS is not receiving DGPS data. Occurrence: When the "DGPS Status" item in the GPdie statement is displayed as 0 Resolved: The BTS is notified when the "DGPS Status" in the GPdie statement is displayed as non-zero: GPSS Status = (0) PPS Locked GPSS Faulty = ( 0) GPS Receiver Running 19 GPS DGPS Base Station is Unstable Continuous green The GPS is receiving DGPS information but the DGPS base station is unstable, so the GPS will operate on its own. Occurrence: When "Good Status of DGPS Base Station" entry in the GPdie sentence is displayed as "unstable" Remedy: Notify BTS when "Good" is displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 20 GPS DGPS data is bad Continuous green Although the GPS is receiving DGPS information but the DGPS data is bad, the GPS will operate on its own. Occurrence: When the "Status of DGPS Data" item in the GPDie sentence is displayed as "abnormal" Remedy: Notifying BTS when "Normal" is displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running

number Warning condition Explanation 21 GPS DGPS Error Continuous green The GPS indicates that there is an error associated with the DGPS. Occurrence: When "DGPS error code" entry in GPDie sentence is not "0" Remedy: Notify BTS when "0" is displayed: GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 22 GPS TRAIM only detected Continuous green TRAIM is available but there are only enough satellites to detect an alarm condition and no cancellation of abnormal satellites is possible. Occurrence: When "TRAIM Status" entry in GPrrm sentence is "1" Remedy: Notify BTS when it is anything other than "1": GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running 23 GPS TRAIM not available Continuous green TRAIM is not available. Occurrence: When "TRAIM Status" entry in GPrrm sentence is "2" Remedy: Notify BTS when it is anything other than "2": GPSS Status = (0) PPS Locked GPSS Faulty = (0) GPS Receiver Running

[Operating Procedure]

This chapter describes the procedures performed by the example TMU software. With the exception of some of the initial startup procedures, all procedures relate to the normal operating mode.

<Startup>

The startup procedure is performed following the reset that occurs at C51. The purpose of the startup procedure is to initialize the platform and to establish a normal operating state. The startup procedure also performs a self check and software integrity test for the TMU platform. If the software integrity test fails, the TMU enters boot mode.

<C51 control state building>

The first part of the startup procedure is to set up the operation of the C51 and to set up input / output (I / O) for control of the TMU platform.

1. Check for the existence of software images

2. Check the integrity of the software image

3. Configure I / O Mapping for C51

4. Disable PPS and serial output for BTS

5. LED driver

6. Check external oscillator and switch to external oscillator

7. Configure serial communication ports

<Build GPS Control Status>

The second part of the startup procedure is establishing control of the GPS. Once the control of the GPS is established, the TMU will perform either a warm restart or a cold restart. Cold restart assumes that the GPS engine must be completely reinitialized and all previous information is destroyed. Under these circumstances, several minutes may be needed until timing can be resumed. Warm restart attempts to recover timing faster by preserving the information stored in the GPS. This is possible because the GPS is an independent subsystem of the TMU. In such a situation, for example, in the case of a button reset, C51 is reset, but GPS is not reset. Also, since the power is not disconnected, the GPS still works normally. In such a case, a warm restart can reestablish control of the GPS without disrupting the operation of the GPS.

Cold restart of the GPS will be performed if any of the following conditions exist, otherwise a warm restart is attempted.

­ C51 experiences a power-on-reset

A hard self-reset command is issued

­ GPS does not respond to communication

­ The GPS self test displays an error

리셋 The reset button is disabled while the LED indication is not "green".

   If pressed

<Cold restart>

Cold restart of GPS goes through the following steps:

1. Send a hard reset signal to the GPS by activating the reset signal line.

2. Send $ PFEC, GPclr, 1 command.

3. Stop all periodic report messages.

4. Perform a "Self-Test".

5. Set the timing for periodic messages.

6. Set the PPS delay time considering the cable length.

7. Set the "PPS Control Mode" to always be output.

8. Proceed with the positioning step.

<Warm restart>

The warm restart of the GPS goes through the following steps:

1. Send a hard reset signal to the GPS by activating the reset signal line.

2. Send $ PFEC, GPclr, 2 commands.

3. Stop all periodic report messages.

4. If the GPS fails to reply to the response message, try cold restart.

   To perform.

5. Perform a "Self-Test".

6. If the self test indicates a bad backed up data, cold

   Perform a restart.

7. Set the timing for periodic messages.

8. Set the PPS delay time considering the cable length.

9. Set the "PPS Control Mode" to always be output.

10. Proceed with the positioning step.

<Check location steps>

Once the TMU has control of the GPS, the next goal is to determine its location. GPS must determine its location before generating accurate time information. Following a warm reset, the TMU checks whether the GPS has already determined whether the location information is already recognized and fixed (fixed observation mode). If the location is already known and fixed, the TMU reads the location information from the GPS and performs the procedure normally. If the location is known but not fixed, the TMU reads the location information and performs a self-survey as described in the next section. If the location information is unknown (or cold start), the TMU performs the location check step.

The TMU can obtain its location information (latitude, longitude, and altitude) from one of three sources of information: console input, nonvolatile memory, or its own survey. The TMU stores the last known location information in a nonvolatile memory. To determine the current position, the TMU sets the GPS to an estimated observation mode and sets its initial position using the most recently known position value. The TMU then conducts its own investigation.

Location information may also be entered manually via console commands. If this step is performed, such location information is replaced with the location data stored in the nonvolatile memory, the GPS is set to the estimated observation mode, and the specified location data is recorded in the GPS as an initial location value. The TMU then conducts its own investigation.

In the absence of any location information, no last saved location information, and no console input, the TMU relies entirely on its own search procedures. In this case, the GPS is set to the estimated observation mode, and the last known position is used as the initial position value. The self-search procedure can then correct the location information. If the last known location is very far from the actual location, the TMU will need longer time to establish its time synchronization.

Self-Servey

The TMU uses its own search procedure to determine the exact location, thereby generating the most accurate timing. To determine the location, the TMU puts the GPS into an estimated observation mode. In this mode, the GPS can determine its position from the satellites it can observe. During the self-search, the TMU periodically reads the location data from the GPS and calculates an average location value. Note that self-investigation does not prevent the TMU from outputting time synchronization information once the initial position has been set by GPS. Self-investigation procedures can continue for up to 12 hours. When the self investigation period is completed, the GPS is set to the fixed observation mode and the calculated average position is set. The location information determined by self-inspection replaces the last known location information stored in the TMU's nonvolatile memory.

<Position Averaging>

While performing its own investigation, the TMU obtains the estimated location information contained in the $ GPGGA message every minute. The TMU is implemented to obtain independent means for latitude, longitude, and altitude parameters. The TMU implements a majority-voting algorithm for the integer portion of each parameter and average calculations for the fractional portion. The integral part of latitude and longitude includes a degree part and an integral minute part. The integral part of altitude contains all values greater than 100 meters. Fractional portions include a fractional portion of latitude or longitude and a modulo up to 100 meters of altitude.

For integer portions, the majority decision algorithm observes the current reported value, the two previously reported values, and the last known location (LKL) value. If the integer parts of the three report values match each other but do not match the LKL value, the LKL value is discarded and replaced with the matched integer part value. For example, if the integer portion of the three most recent latitude values match each other but does not match the LKL value, the integer portion of LKL is replaced with the integer value matched above. The fractional part of LKL is replaced with the average of the fractional part of the matching values.

If the integer parts of all four values match, the fractional part of the newest value is inserted into the mean and updated with the LKL value. If all values except the newest value match, the fractional part of the newest value is not inserted into the mean. The fractional part is calculated as the simple average of all contributions since the last LKL replacement.

The majority decision algorithm can protect against the effect that such mean value is subjected to from abnormal position measurements. Additional rules or algorithms can be used to determine the stability of the position average and can be changed to the fixed position mode more quickly.

<Last Known Location>

The TMU stores its last known location in nonvolatile memory. This position is used to facilitate the confirmation of the GPS time output. In order to minimize non-volatile memory capacity consumption, the location value can be updated only when one of the following situations is true.

위치 If the position value is entered manually via console command

­ If the self-investigation process is completed

평균 the latitude or longitude is compared

   Every 1/100 minute, or 10 meters above altitude

<Antenna Cable Length>

The length of the cable leading to the GPS antenna can also affect the accuracy of the PPS. The TMU needs to enter these values manually during installation. POSITION console commands are provided for this purpose. The length of the cable is stored in nonvolatile memory and can be used whenever GPS is set.

<Start output with BTS>

The TMU sets up the GPS to immediately start outputting timing data. The TMU sets the GPS to immediately start outputting the PPS signal. If the GPS is operating in a fixed observation mode, the PPS may be accurate as long as even one satellite is available. If the GPS is operating in the Estimated Observation Mode, the PPS has four satellites available for position fixation, UTC parameters are available, satellite ephemeris data for the satellites is available, and the UTC calculation is It will be accurate when it is finished.

Immediately after initialization, the TMU begins sending periodic pulse reports (GPppr) and position data reports (GPGGA) to the BTS. As soon as the PPS signal is available from the GPS, the TMU also begins supplying the PPS signal to the BTS. However, the GPSS status item of GPppr will be displayed as "PPS Not Synchronized" until all alert conditions indicated by flashing green in the above table are resolved.

<Supports improved timing accuracy>

The TMU seeks to support the greatest timing accuracy possible by allowing GPS to utilize the DPGS and TRAIM functions. These features are enabled by default.

<Synchronization Loss>

Once the output of the timing information has begun successfully, any serious alarm can be made to cause the GPppr GPSS status item to display "PPS Not Synchronized" until the condition is cleared.

<Supported BTS Messages>

The TMU only supports messages of compulsory nature. Furthermore, only mandatory items of these messages are supported. These messages are as follows:

1. Periodic PPS Report

2. Location Data Report

<Periodic PPS Report ($ PTP, GPppr)>

The GPS TOW Standard Deviation item in the periodic PPS report is made as follows.

5 if five or more satellites are used for positioning,

   The item is set to 50 nsec.

4 if four or fewer satellites are used for positioning,

   The item is set to 100 nsec.

아무런 If no satellite is available,

   The GPS status item is set to (3) PPS Not Synchronized.

<Location Data Report & GPGGA>

Optional items, DGPS Data Time, DGPS Station ID, and checksum may not be provided. The following items DOP, Geoid of Altitude, and Unit of Geoid are set to blanks.

Console Port Behavior

The console port enables human interaction and monitoring of the TMU through an ASCII terminal or terminal demonstration software. Following a reset, or by entering "escape" at the command prompt, the console interface enters "status display mode". In this mode, events driven by alerts or other status strings are sent to the console. The console can collect these strings to monitor the operation and steady state of the TMU.

If the Enter key is pressed in the middle of the status display mode, the console interface switches to command entry mode and generates a command prompt. The command prompt shows the current mode of TMU operation, that is, boot, test or normal operation. You can then enter the commands and the results will be sent to the console. All current alarm and status string outputs are suppressed while in command input mode.

The commands that can be entered are limited according to the operating mode of the TMU. The operator can switch modes to enter the desired command. The operator should be familiar with the causal relationships that cause the TMU to operate.

4. External Interface Unit (EIU) (example embodiment)

As discussed, for synchronized GSM operation, one PPS signal would have to be provided to the BTSs. At sites where the LMU is already equipped together, one PPS signal may be used in existing LMUs (since LMUs will include built-in GPS receivers). However, for some types of BTS equipment, the following may be true.

P 1 PPS signal does not need to be converted to RS-422 signal level for these devices

   have.

에 In addition to 1 PPS signal conversion, timing information related to 1 PPS signal is also

   Dedicated as required by the manufacturer of the BTS equipment (eg Ericsson)

   It needs to be sent over the RS-422 interface using the protocol.

A protocol conversion hardware unit that performs these two operations is a device called an EIU and can be applied to cell sites that already have an LMU.

<Impact on the possibility of connecting GBE and mE boards>

The EIU can be connected to a 9-pin RS-232 serial port on the LMU. this is

   It can also be used to connect to ground based electronics (GBE) in AOA facilities.

   It is the same port used. Thus, in its current form, GBE and EIU together

   It cannot be installed. Therefore, installation of EIU precludes AOA installation.

   The solution to this problem is to use TMU instead of EIU if AOA is needed.

   will be.

유사한 Similar to the above problem, the peripheral board

  (Often called a mini environmental board, or mE board

   May be used). This also uses the same port,

   If an EIU is required, it cannot be deployed.

[Architecture]

An example architecture of the EIU is depicted in FIG. 6. 6 shows the internal architecture and external interface of the EIU. The architecture connects to a 9-pin serial port and 1 PPS on the LMU side, and converts both of these interfaces to RS-422 signal levels for connection to the BTS. One PPS signal and serial data signals are fanned out to four four ports, each with a quad output connection. Each output port provides one PPS signal and serial data output at the RS-422 signal level.

[LMU-N Interface]

The exemplary EIU receives timing messages in RS-232 signal format / level via the LMU interface. The RS-232 signal connection pin outputs are shown in Table 2 below. The EIU receives 1 PPS signals from the LMU through the 1 PPS port. The 1 PPS EIU port appears to be 50 ohm load externally.

RS-232 Connector Pinouts pin Signal name Explanation 1,7,8,9 NC 2 RX Port 1 ingress, from PC to processor 3 TX Port 1 Send, Processor to PC 4 DTR Data Terminal Preparation-From PC 5 GND grounding 6 DSR Data set preparation

[BTS Interface]

The EIU transmits LMU synchronization data messages and 1 PPS signal to the BTS at RS-422 signal level, as shown in FIG. The interface of the synchronization data sent to the BTS is a serial communication link.

The 1 PPS signal will have a frequency of 1 Hz and will have an accuracy of 100 ns based on UTC time at the 1 PPS EIU output port.

The signal connection pin assignments for each port are shown in the following table.

RS-422 Unique Port Pinouts pin Signal name Explanation One TX + send 2 TX- Send return 3 TX + Send (Preliminary) 4 1 PPS PPS signal 5 1 PPS- PPS signal regression 6 TX- Send Regression (Preliminary) 7, 8 NC 9, 10 GND

Serial communication link

The physical layer of the serial communication link is based on the RS-422 UART. Specific features are as follows.

RS-422 Interface with 100 Ohm Termination on BTS Side

600 9600 bps / s

­ No parity bit

시작 Start bit of 1 bit

8-bit data length

종료 1 bit end bit

[1 PPS]

The EIU's RS-422 transmitter drives one PPS signal. The 10% to 90% rise time will be less than 10 ns on the EIU output. The BTS has a built-in 100 ohm termination.

5. Conclusion

The true scope of the invention is not limited to the exemplary, presently preferred embodiments disclosed herein. For example, the disclosures of the above-described wireless positioning system (WLS) use descriptive terms, such as LMU, TMU, EIU, BTS, BSC, SMLC and the like, which is the scope of protection of the following claims. Should not be construed as limiting the terminology or implying limitations to the particular methods or apparatuses disclosed. Furthermore, as will be apparent to one of ordinary skill in the art, many of the aspects of the invention disclosed herein may be applied to location systems that are not based on TDOA technology. In the case of such non-TDOA systems, the SMLC described above will not need to perform TDOA calculations. Similarly, the invention is not limited to systems employing LMUs built in a particular manner, or systems employing certain types of receivers, computers, signal processing devices, and the like. The LMUs, SMLCs, etc. are essentially programmable data collection and data processing devices and may have various forms without departing from the inventive concept disclosed herein. With regard to digital signal processing and other processing functions, given the radically reduced costs, certain functional elements described herein can be used to process processing for a particular function, for example, without changing the original operation of the system. It may be easy to move from one (eg SMLC) to another functional element (eg LMU). In many cases, the implementation manners (ie, functional elements) described herein are merely a matter of designer's preferences and are not stringent requirements. Accordingly, except as expressly limited to such, the protection scope of the following claims is not intended to be limited to the specific embodiments described above.

In addition, reference in any way to the control channels or voice channels refers to all forms of control channel or voice channels, whatever the preferred technique for a particular air interface. Furthermore, more types of airwave interfaces (e.g., IS-95 CDMA, CDMA 2000, and UMTS WCDMA) are being used throughout the world, and unless the contradiction is specified, the inventive concept described herein. There is no intention of excluding any airwave interface from them. Indeed, those skilled in the art will recognize that other interfaces being used elsewhere may be derived from or similar in kind to the interfaces described above.

Claims (23)

A spectrum enhancement method used in a network overlay wireless positioning solution for a wireless communication system including a network having base transceiver stations (BTS), Synchronizing a plurality of BTSs using a timing signal, At least one BTS is provided with the timing signal by a timing measurement unit (TMU). The method of claim 1, wherein the wireless communication system comprises a GSM communication network. The method of claim 1, wherein the wireless communication system comprises a UMTS communication network. 4. A method according to any one of the preceding claims, wherein the timing signal is provided to each BTS by either a Location Measurement Unit (LMU) or a Timing Measurement Unit (TMU). 5. The method of claim 4, wherein each LMU and TMU comprises a GPS based timing reference module and means for generating a periodic timing signal that is synchronized to timing signals generated by other LMUs and TMUs within a predetermined accuracy. A spectrum enhancement method, characterized in that. 6. The method of claim 5, wherein the LMUs are used to measure the timing of uplink signals or downlink signals in a cellular network, assisted by a positioning technique. 7. The method of claim 6, wherein the LMUs and TMUs distribute timing signals comprising periodic electrical pulses and time description information. 8. The method of claim 7, wherein the format of the electrical pulse and time description information is hardware and software modified to suit the formats required by the various BTS types. The BTS of claim 8, wherein the BTSs co-located with the LMUs receive a synchronization signal without incurring hardware costs, and BTS sites without the LMUs are in BTS time in the same formats as provided by the LMUs. A TMU with a unique function of providing signals, wherein the time signals provided by the TMUs are synchronized with the signals provided by the LMUs, the TMU having only the timing function being uplink or downlink It has a lower cost than the LMU because it does not support a signal measurement function. A network overlay wireless positioning system used in connection with a wireless communication system comprising a network of transmit and receive base stations (BTS), A plurality of position measuring units (LMU) and at least one timing measuring unit (TMU) and a mechanism for synchronizing a plurality of BTSs with a timing signal, wherein at least one BTS is driven by the at least one TMU for the timing; Network overlay wireless positioning system, characterized in that the signal is provided. 12. The network overlay wireless positioning system of claim 10, wherein said wireless communications system comprises a GSM communications network. The system of claim 10, wherein the wireless communication system comprises a UMTS communication network. 13. A network overlay wireless positioning system according to any of claims 10 to 12, wherein said timing signal is provided to each BTS by either a position measuring unit (LMU) or a timing measuring unit (TMU). 14. The apparatus of claim 13, wherein each LMU and TMU comprises a GPS based timing reference module and means for generating a periodic timing signal that is synchronized to timing signals generated by other LMUs and TMUs within a predetermined accuracy. Network overlay wireless positioning system, characterized in that. 15. The system of claim 14, wherein the LMUs are used to measure the timing of uplink signals or downlink signals within a cellular network, assisted by a positioning technique. The system of claim 15, wherein the LMUs and TMUs distribute timing signals comprising periodic electrical pulses and time description information. 17. The system of claim 16, wherein the format of the electrical pulse and time description information is hardware and software modified to meet the formats required by the various BTS types. 18. The system of claim 17, wherein the BTSs with LMUs receive a synchronization signal without incurring hardware costs, and BTS sites without LMUs are unique in providing BTS time signals in the same formats as provided by LMUs. A TMU with a single function, wherein the time signals provided by the TMUs are synchronized with the signals provided by the LMUs, and the TMU only with the timing function supports an uplink or downlink signal measurement function. Network overlay wireless positioning system, characterized in that it has a lower cost than the LMU. A wireless location system used in connection with a wireless communication system including a network of transmit and receive base stations (BTS), A plurality of position measuring units (LMU) and at least one timing measuring unit (TMU), The LMUs and at least one TMU operate to synchronize a plurality of BTSs with a timing signal, at least one of the BTSs being provided with the timing signal by the at least one TMU, wherein each of the LMUs and TMUs A GPS-based timing reference module and means for generating a periodic timing signal synchronized with time description information and timing signals generated by other LMUs and TMUs. 20. The system of claim 19, wherein the BTSs with LMUs receive a synchronization signal without incurring hardware costs, and BTS sites without LMUs provide BTS time signals in the same formats as provided by LMUs. With a TMU with its own functionality, the time signals provided by the TMUs are synchronized with the signals provided by the LMUs, since the TMU does not support uplink or downlink signal measurement. And a lower cost than the LMU. 21. The system of claim 20 wherein the wireless communication system comprises a GSM communication network. 21. The system of claim 20 wherein the wireless communication system comprises a UMTS communication network. 21. The system of claim 20, wherein the format of the timing signal and time description information is hardware and software modified to accommodate formats required for various BTS types.

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