WO2009130502A1

WO2009130502A1 - Network monitoring system

Info

Publication number: WO2009130502A1
Application number: PCT/GB2009/050401
Authority: WO
Inventors: Andrew Peter Fleet; Donald Glynn Elvin; Barry George Holleran; Andrew John Hutley
Original assignee: Samdale Limited
Priority date: 2008-04-21
Filing date: 2009-04-21
Publication date: 2009-10-29
Also published as: GB0807220D0

Abstract

A digital radio network monitoring system (10) comprises at least one probe (11) which is arranged autonomously to monitor network service at the location of the probe (11) and produce data dependant thereon. The probe (11) has a communication interface for transmission of the data relating to the monitored network service. A server (12) receives and stores the network data, and comprises a management console (13) to enable manual configuration of the probe (11) and a browser-based interface (14) arranged to provide reports on the stored service data. The communication interface of the probe (11) has multiple communication modes and is arranged to select the most appropriate mode for the transmission of the data to the server (12).

Description

NETWORK MONITORING SYSTEM

This invention relates to a system for the real-time monitoring and optimisation of digital radio networks, and to a method of monitoring a digital radio network utilising such a system.

The present invention has been developed in connection with the monitoring and optimisation of Terrestrial Trunked Radio (TETRA) networks, and therefore will be described herein with particular emphasis on this application. However, the apparatus and method of the present invention may be applied to the monitoring and optimisation of many other types of digital radio network.

TETRA is a digital trunked mobile radio standard developed by the European Telecommunications Standards Institute (ETSI). The largest TETRA network market is public safety, where the trend is for the deployment of nationwide networks shared by all public safety organisations, such as police, ambulance and fire services, coast guard, mountain rescue etc.

Network monitoring tools for TETRA network operators and users rely mainly on fixed link telemetry from TETRA switching and base station components or manually conducted off-air surveys. However, some issues that users experience, such as problems with broadcast neighbour and reselection parameters, co-channel interference and signal quality, are not detected by such systems. Existing network monitoring tools rarely capture or isolate many of the problems that users experience on an operational TETRA network and it is possible to receive very poor TETRA service in a location mostly receiving very good TETRA coverage. As a result there are often instances where the operator is completely unaware that there are no communications. Coverage area and signal quality are important parameters for all mobile radio networks. However, where the network has security or public safety implications, the need for reliable coverage and good service is vital.

TETRA networks typically provide one or more fallback modes, for example enabling a base station to process local calls. The present invention seeks to provide a network monitoring system for use in TETRA networks which enables real-time monitoring of the network and which provides notification and backup in the case of network fallback. The invention further provides a network monitoring system which enables storage of the network data for further analysis.

According to this invention, there is provided a digital radio network monitoring system, comprising:

- at least one probe arranged autonomously to monitor network service at the location of the probe and produce data dependant thereon, the probe having a communication interface for transmission of the data relating to the monitored network service; and

- a server for reception and storage of network data, said server having a management console to enable manual configuration of said at least one probe and a browser-based interface arranged to provide reports on the stored service data; and wherein the communication interface of the probe has multiple communication modes and is arranged to select the most appropriate mode for the transmission of the data to the server.

Each probe may be self-configuring and is adapted to monitor a range of network service parameters. The range of service parameters monitored includes one or more of the following:

(a) Received Signal Strength Indicator (RSSI);

(b) Downlink signal quality;

(c) Uplink and downlink Perceptual Evaluation of Speech Quality (PESQ);

(d) Path delay;

(e) Frequency re-use and interference problems;

(f) Channel acquisition failures;

(g) Uplink access failures; (h) Receive path problems;

(i) Call setup success and completion statistics; (j) Call setup times; (k) Call setup failures; (I) Cell reselection and handover statistics;

(m) Fragmentation failures;

(n) Cell handover failures;

(o) Dropped calls;

(p) Broadcast parameter discrepancies; and

(q) Broadcast neighbour discrepancies.

Each probe continuously monitors the network service and gathers the network coverage and performance data, which preferably is then encrypted. Encryption of the data serves to ensure reliable communication thereof over noisy networks by increasing the receiver's ability to determine the correct data.

Each probe autonomously monitors the service in accordance with one or more of the above defined service parameters (a) to (q), and reports information and alerts back to the server whenever a connection is present. This can be via a Local Area Network (LAN), Wide Area Network (WAN), Wireless Fidelity (Wifi), Global System for Mobile communications over General Packet Radio System (GSM/GPRS), the TETRA Packet Data Service, or any other suitable means. To this end, the communication interface may provide at least two of the following communication modes: Local Area Network (LAN), Wide Area Network (WAN), WiFi, GSM/GPRS, and radio.

Preferably, the probe includes a buffer for storing network data on the probe when data transmission to the server is not available. Advantageously, each probe can store approximately 180 days of logged data thereon. Ideally, the probes are configured automatically to transmit any stored data to the server when data transmission becomes available.

At least some of the probes may be fixed, positioned and arranged to monitor the network system at particular locations. A fixed probe is intended for mounting at a fixed position where there is a good average signal and is designed continuously to monitor a TETRA service or site at all times. At least some of the probes may be roaming probes, arranged for mounting on a moveable object, such as a vehicle, for monitoring network service at a plurality of discrete locations. A roaming probe is preferably adapted to be easily retrofitted to existing terminal installations for use with operational vehicles and - A -

monitor the TETRA service as the vehicle travels, with no user intervention at all. Drive testing can be a time-consuming and costly exercise. However, by providing roaming probes on operational vehicles which are already patrolling an area, there is no need to define a route and dedicate time to conduct the tests. Essentially the roaming probes provide "free" coverage and performance data for the area without the need to undertake expensive dedicated drive testing.

There may be at least one fixed probe and at least one roaming probe. Preferably however, the system comprises a plurality of fixed and/or roaming probes.

One or more servers are preferably configured to receive monitoring and performance data from one or more probes. Each server ideally includes a database and the data received by the server is processed, analysed and stored in said database. Essentially, the server comprises an event handler and the database. The event handler is a software process which receives event messages from the probes and processes them before storing the data in the database. The database stores processed event data from the probes in a structured manner that allows real-time pushing of data to connected consoles and querying of the stored historical data by means of online reports from the browser-based reports interface. The server may use industry standard Microsoft^® SQL Server 2005 database and Message Queuing Technologies to communicate with the probes and store the received data.

The server provides a real-time viewer and management console which provides management functions for the probe network and real-time information from the probes connected to the server. The management console provides system operators and engineers with an application to configure the probes and view in real-time a range of key performance indicators from a selected probe. The management console preferably allows user configuration of selected elements of the database. The selected elements of the database may include one or more of the following: network site information; RSSI range groups; probe information; probe organisational structures. The browser-based interface is part of the server and is preferably a web browser interface adapted to allow access using Internet Protocol (IP) to data stored on the database. The web browser interface provides the user with the ability to run one of a number of predefined online reports on the data captured and stored in the server database. Possible reports available will include at least one of the following:

Call details: provides information about call setup time, call duration period, call setup and completion success rates;

Parameter mismatch: provides details of differences between expected and actual broadcast parameter values;

Site neighbour information: provides information about the validity and accuracy of the network site database in terms of unknown and asymmetric sites;

Site service levels: provides information about the service levels measured by the selected probes;

Call stats: provides information about call setup and completion performance;

Site frequencies: provides information about frequencies in use;

Site RSSI levels: provides information about the spread and quantity of

RSSI samples for each RSSI band and also high and low RSSI values and the percentage of samples from each site;

Test summary: provides summary information about a test identity in terms of test detail, key performance metrics, cell reselection metrics, service affecting events etc;

Map builder: provides a mechanism to generate a Google^® Earth

Keyhole Markup Language (KML) Map file for selected captured date.

The generated file can then be downloaded and viewed in a standard

Google^® Earth viewer application. Maps can also be generated in other formats;

Site frequencies: provides information about carrier frequencies and service affecting events; Site service affecting events: provides details about instances of service affecting events.

The web browser interface may provide filtering and export options as well as the ability to customise reports. It can also produce mapping data for export to third party applications in addition to automatically produced RSSI service level, affiliation activity and frequency maps. The interface may also provide a detailed breakdown of service performance metrics by RSSI level, base site and transceiver/frequency so that problems can be isolated quickly and efficiently. The reports may be accessed via a standard web-browser and ideally require secure login to the server using an authorised account username and password.

Preferably, the web browser based interface also provides data drill- down data extraction facilities to assist with TETRA Network optimization in terms of cell handover performance and call setup process.

At least one probe may be a field survey probe, having a user interface adapted to enable analysis of the network service performance. The field survey system incorporates core components from the probes with a user interface to provide a field survey system for engineers and also allows export of event data to a server database. The field survey system provides data capture, real-time analysis and active testing functions to enable analysis of the TETRA service performance. It uses a range of performance metrics that record not just signal strength and quality but many other factors that can affect service performance such as configuration, co-channel interference, path delay problems and handover performance.

Ideally, the field survey system can plot performance data in real-time and produce a unified log file which marks every signal event with Global Positioning System (GPS) position, date, time, heading and speed which can then be further processed. The browser-based interface also provides the capability to post-process one or more field survey system log files in comprehensive detail when required. The field survey system may be capable of operating independently of the remainder of the monitoring system. At least one probe may be a fallback probe provided with means to detect deterioration of the network service and configured to transmit an alert to the server if the service becomes unavailable. The fallback probe provides the same monitoring functions as a fixed probe but also detects sites entering "fallback" and alerts control room operators. The fallback probe provides a virtual console interface to allow control room staff to switch to a pre-arranged fallback talkgroup and communicate with users in the probe's local area when the site they are operating on is disconnected from the network. The prearranged fallback talkgroup is preferably Voice over Internet Protocol (VoIP). VoIP is a technology used to transmit voice conversations over an internal or external data network using IP packets (digital form). Essentially, the fallback dispatcher probe enables communications to continue to work in the event of disruption. Should access to a base station be completely lost, it can revert to fallback mode where users within its coverage area can continue to benefit from voice and data communications, even though they have lost contact with the main control.

The system may comprise at least one dispatcher probe having a touch screen and audio interface, and a virtual console. The dispatcher probe provides the same probe functions as the standard fixed probe but also adds in a custom built touch screen and audio module and virtual console. The dispatcher probe also provides automatic vehicle location system (AVLS), automatic person location system (APLS) and other features such as text messaging.

According to a second aspect of the present invention, there is provided a method of monitoring a digital radio network, which method comprises positioning at least one probe at a network monitoring location, said probe being arranged autonomously to monitor network service, produce data dependant thereon and transmit said data to a server for storage thereby, the at least one probe being manually configurable by means of a management console provided by the server and whereby the server is arranged to provide browser-based reports on the stored service data; and wherein there are multiple data transmission modes and the probe automatically selects the most appropriate mode for the transmission of data to the server.

Preferably, the data is transmitted to the server by at least one of the following transmission modes: Local Area Network (LAN), Wide Area Network (WAN), WiFi, GSM/GPRS, radio.

Ideally, the data is buffered and stored on the probe when data transmission to the server is not available, said probe automatically transmitting the data to the server when data transmission becomes available.

The monitoring system of this invention may also be used to optimise a digital radio network. The optimisation process for a TETRA network is preferably as follows:

- A survey is performed on a number of sites using one or more field survey systems. This may be achieved by conducting a drive test the route of which navigates between all of the sites being tested in turn. It is then important to ensure that the Call Generator function on the field survey system is set periodically to make outgoing test group calls, preferably operating a cycle time of 15 seconds Press-To-Talk (PTT) hold and PTT release. It is important to ensure that at least 10 minutes of data is collected on each site.

- The data is then analysed using the web browser-based interface. The following conditions may then be checked: i) that data is collected from all sites; ii) that the broadcast configuration information matches that expected; iii) that the cell handovers are occurring as expected with reference to the best server plots from the planning tool; iv) that the minimum RSSI values recorded for each site are in line with expected minimum service levels; v) that call setup and completion success are in line with expectations; and vi) that no service affecting events of significance have been recorded. The system may then be optimised, preferably by performing one or more of the following actions: vii) ensuring that the minimum receiver (Rx) access level and maximum transmitter (Tx) power-in-cell for each site is consistent across all sites; viii) ensuring that the minimum Rx access level, maximum transmitter (Tx) power-in-cell, Slow Reselect Threshold (SRT),

Fast Reselect Threshold (FRT), Slow Reselection Hysteresis

(SRH) and Fast Reselection Hysteresis (FRH) are set so that logical cell handover is possible with reference to the best server plots; ix) ensuring that SRT/FRT are not set so low that cell dragging occurs; x) ensuring that neighbour cell lists are sufficient to minimise cell dragging and that they are consistent and symmetrical; xi) ensuring that the maximum path delay values are not restricting coverage in areas where it is required; xii) ensuring that the terminal is not receiving foreign networks; xiii) ensuring that the Main Control Channel (MCCH) frequencies broadcast in neighbour cell information are correct and consistent; xiv) ensuring that any frequency re-use problems are addressed and resolved; and xv) ensuring that any downlink signal quality failures are resolved by inspection of site antenna systems and transceiver checks. Preferably, after each period of fault rectification and optimisation a re- test is performed to verify the changes and measure the improvements and optimisations made.

By way of example only, one specific embodiment of network monitoring system according to the present invention will now be described in detail, reference being made to the accompanying drawings in which:- Figure 1 illustrates a preferred layout of a network monitoring system according to the present invention;

Figure 2 illustrates a fixed probe for use in the network monitoring system of Figure 1 ;

Figure 3 illustrates a portable probe for use in the network monitoring system of Figure 1 ;

Figure 4 illustrates a processor module of the probe of Figure 2;

Figure 5 illustrates the probe of Figure 2 with a wall mount connection;

Figure 6 illustrates a roaming probe for use in the network monitoring system of Figure 1 ;

Figure 7 illustrates a plan view of the roaming probe of Figure 6;

Figure 8 illustrates a rear view of the roaming probe of Figure 6;

Figure 9 illustrates a rack probe module for use in the network monitoring system of Figure 1 ;

Figure 10 illustrates a front view of the probe of Figure 9;

Figure 1 1 illustrates a back view of the probe of Figure 9; and

Figure 12 illustrates the construction of a probe for use in the network monitoring system of Figure 1.

Referring initially to Figure 1 , there is shown a network monitoring system 10 comprising five probes 1 1 adapted to monitor the network service and produce network service data for transmission to a server 12. The server 12 includes a database for storage of the network service data received from the probes 1 1. The probes 1 1 transmit the service data to the server 12 by the most appropriate means and each probe has multiple communication modes, for this purpose. In this embodiment, the data is transmitted to the server 12 by one or more of Local Area Network (LAN), Wide Area Network (WAN), Wireless Fidelity (WiFi), GSM/GPRS, radio.

The server 12 provides a management console 13 which enables operators to configure the probes 1 1 and view in real time a range of key performance indicators from a selected probe 1 1. The server 12 also includes a web browser-based interface 14, which enables users to run reports on the TETRA service data stored on the server database. A network of probe variants are shown in Figure 1 , and these generally comprise a fixed probe 15, a roaming probe 16, a fallback probe 17, a dispatcher probe 18 and a field survey probe 19, each of which will now be described in more detail.

The fixed probe 15 is designed to mount at a particular location and continuously to monitor a TETRA service or site from that location. The fixed probe 15 is adapted to transmit information and alerts to the server 12 whenever a connection is present.

The roaming probe 16 is designed to fit to a TETRA terminal, mounted to a vehicle 20. The roaming probe 16 monitors the TETRA service as the vehicle 20 travels and also transmits information and alerts back to the server 12 whenever a connection is available. Both the fixed probe 15 and the roaming probe 16 buffer data for storage locally on the probe when a connection to the server 12 is not available, and can store data for up to approximately 180 days.

The fallback probe 17 is provided to detect sites entering fallback. The fallback probe 17 provides the same probe monitoring functions as the fixed probe 15, but also detects sites entering fallback and alerts control room operators. The fallback probe 17 provides a virtual console interface 21 to allow control room staff to switch to a fallback talkgroup, such as VoIP, when the TETRA service is unavailable.

The PC dispatcher probe 18 provides the same probe functions as the fixed probe 15, but also includes a touch screen and audio module 22 to provide a PC based dispatcher built around the virtual console and also providing automatic vehicle location system (AVLS), automatic person location system (APLS) and text messaging.

The field survey system 19 uses core components from the probes 1 1 but additionally includes a user interface 23 to provide a field survey system 19 for engineers. The field survey system 19 can operate independently of the monitoring system 10, but also allows export of event data to the server 12.

A fixed probe 15 and a portable probe 24 are shown in Figures 2 and 3 respectively. The fixed probe 15 is essentially identical to the portable probe 24, except that, the fixed probe 15 is provided with a handle 56 to enable the probe 15 to be transported to a particular location and the portable probe 24 is provided with a frame 57 to facilitate handling of the probe and also to provide protection to the probe surface. Both probes 15, 24 include a radio module 27 on the top surface, a mains power module 28 on one side surface and a processor module 26 on the opposing side surface, as shown in Figure 4. The modular design of the probe 1 1 allows various different configurations to be used. As seen in Figure 5, the fixed probe may be provided with a wall mount 58, to enable it to attach to a surface at a fixed location.

Referring again to Figure 2, the radio module 27 includes a modem interface 31 for wireless communication to the server 12. The modem interface 31 is essentially a Universal Serial Bus (USB) V1.1 port for connection of an external USB 2G/3G/HSDPA(3¹/2G) modem. A GPS interface 32 is provided which comprises a USB V1.1 port for connection of a USB GPS receiver. Additionally, the radio module 27 provides a radio antenna interface 36 and a radio GPS interface 37. The radio antenna interface 36 is a 50 Ohm BNC radio antenna connector for use with helical, VA wave whip, or magnetic mount antennas. The radio GPS interface 37 is a SMC radio GPS connector to enable use of a radio's internal GPS receiver.

Each probe 1 1 can be configured to operate in automatic or manual mode. In automatic mode the probe operates autonomously, whereas in manual mode, the probe 1 1 requires user action to start capturing and reporting data. The radio module 27 includes a toggle button 33 which switches between monitoring and reporting modes. When the probe 1 1 is in automatic mode, the user may switch the probe to manual mode by operating the toggle button 33. However, the change of mode is temporary and upon next power-up, the probe will revert back to automatic mode. Similarly, when the probe 1 1 is in manual mode it will only start capturing and reporting data once the toggle button 33 is pressed to change the state from monitoring to reporting. The toggle button 33 is illuminated to indicate a good 5v Direct Current (DC) output from the internal regulated power supply.

The radio module 27 further comprises a reset button 34. This is an illuminated button which enables the processor module to be reset. A DC power indicator 35 is also provided on the radio module and this is essentially an LED which, when illuminated indicates a good 12V DC input to the regulated 5V power supply. On mains Alternating Current (AC) powered probes, illumination of the LED means a good 12V DC output from the mains to the DC power supply, whereas on DC powered probes, this means a good 12V DC input to the probe via the XLR interface.

The mains power module 28 includes a mains input 40 for connection of a mains cable, and a mains switch 41 which controls the supply of power to the probe. The mains power module 28 also includes a DC input 42 which comprises a male XLR type DC input, 12 to 14.4v DC, for connection of a XLR female plug with suitably terminated wire ends.

A RJ45 network Ethernet port 44 is provided on the mains power module 28 for connection of the probe 1 1 to a LAN or WAN for communication to the server 12. A RJ45 maintenance Ethernet port 43 is also provided on the power module 28, for connection of a computer for diagnostics, maintenance or engineering purposes.

The processor module 26 is shown in Figure 4 and includes a D-SUB 15 pin Video Graphics Array (VGA) port 49 and two USB v2.0 ports 50, 51 for connection of external USB devices to the processor module 26. The processor module 26 also includes a radio data port 47, for connection to a radio for the purposes of re-programming or to provide software updates.

A roaming probe 16 is shown in Figures 6 to 8, and comprises a radio module 27 on the top side and a processor module 26 at the opposed end. The processor module 26 includes a DC power input interface 42. The roaming probe is designed for mounting in a vehicle 20.

Another probe variant 25, as shown in Figures 9 to 1 1 , is designed to fit in a support rack. The cuboidal shape of the probe enables it to easily fit into a rack (not shown), whilst still providing an easy to view display 53 on the front surface.

Each probe 1 1 has an LCD display 53 on the front face 54, which is used to display key information about the probe 1 1 and the service being monitored. In this arrangement, the LCD provides 2 lines. The first line alternates between showing the probe version and the current message queue count, which indicates the number of messages buffered at the probe 1 1 , awaiting transmission to the server 12. The first line also provides an activity display which indicates that data is being logged. The second line cycles around a number of information items pertinent to the probe 1 1 and the network service being monitored. Each of the probes 1 1 are also provided with heat sinks 60 on opposed sides to dissipate heat generated by the probe.

Figure 12 illustrates the structure and organisation of the hardware of a probe 1 1. Each probe 1 1 comprises an embedded computer 62. A TETRA transceiver 63 is connected to the embedded computer 62 and is arranged to transmit radio data 64 thereto and also to transmit and receive console data 65. An interface unit 66 is connected to both the embedded computer 62 and the transceiver 63 and provides audio 67, PTT 68 and microphone 69 connections.

Claims

1. A digital radio network monitoring system, comprising:

2. A system as claimed in claim 1 , wherein the communication interface provides at least two of the following communication modes: Local Area Network (LAN), Wide Area Network (WAN), WiFi, GSM/GPRS, radio.

3. A system as claimed in claim 2, wherein the probe includes a buffer for storing network data on the probe when data transmission to the server is not available, and the probe is configured automatically to transmit the data to the server when data transmission becomes available.

4. A system as claimed in any of the preceding claims, wherein the probe is a fixed probe arranged for mounting at a pre-determined location for monitoring the network service at said location.

5. A system as claimed in any of claims 1 to 3 wherein the probe is a roaming probe arranged for mounting on a movable object for monitoring network service at a plurality of discrete locations.

6. A system as claimed in any of the preceding claims, comprising at least one fixed probe and at least one roaming probe.

7. A system as claimed in any of the preceding claims, comprising a plurality of fixed probes and roaming probes.

8. A system as claimed in any of the preceding claims, wherein the server includes a database and the data received by the server is processed, analysed and stored in said database.

9. A system as claimed in claim 8, wherein the management console is adapted to enable configuration of selected elements of the database.

10. A system as claimed in claim 8 or claim 9, wherein the browser-based interface is a web browser interface adapted to allow access, using IP, to data stored on the database.

1 1. A system as claimed in claim 10, wherein the browser-based interface provides data extraction facilities to assist with network optimisation.

12. A system as claimed in any of the preceding claims, wherein at least one probe is a field survey probe having a user interface adapted to enable analysis of the network service performance.

13. A system as claimed in any of the preceding claims, wherein at least one probe is provided with means to detect deterioration of the network service and is configured to transmit an alert to the server if the service becomes unavailable.

14. A system as claimed in any of the preceding claims, wherein at least one probe further comprises a touch screen and audio interface, and a virtual console.

15. A method of monitoring a digital radio network, which method comprises positioning at least one probe at a network monitoring location, said probe being arranged autonomously to monitor network service, produce data dependant thereon and transmit said data to a server for storage thereby, the at least one probe being manually configurable by means of a management console provided by the server and whereby the server is arranged to provide browser-based reports on the stored service data; and wherein there are multiple data transmission modes and the probe automatically selects the most appropriate mode for the transmission of data to the server.

16. A method as claimed in claim 15, wherein the data is transmitted to the server by at least one of the following transmission modes: Local Area Network (LAN), Wide Area Network (WAN), WiFi, GSM/GPRS, radio.

17. A method as claimed in claim 15 or claim 16, wherein the data is buffered and stored on the probe when data transmission to the server is not available, said probe automatically transmitting the data to the server when data transmission becomes available.