WO2015101933A1

WO2015101933A1 - Data-collection device for monitoring mobile telecommunications networks

Info

Publication number: WO2015101933A1
Application number: PCT/IB2014/067419
Authority: WO
Inventors: Paolo Marini; Enrico Bendinelli; Lodovico Binda; Barbara MOSCHINI
Original assignee: Prisma Engineering S.R.L.
Priority date: 2013-12-30
Filing date: 2014-12-30
Publication date: 2015-07-09
Also published as: ITMI20132217A1

Abstract

A data-collection device for collecting data from an LTE mobile telecommunications network includes an antenna (2), a processing stage (3), a control module (5), and a mass-storage device (6). The processing stage (3) is configured to receive and decode information transmitted between a base node (eNB) of a mobile telecommunications network (50) and user equipments (UE) connected to the base node (eNB). The control module (5) is configured to extract traffic and interference data generated by the user equipments (UE) connected to the base node (eNB) from the information transmitted by the base node (eNB) to the user equipments (UE) and decoded by the processing stage (3).

Description

"DATA-COLLECTION DEVICE FOR MONITORING MOBILE

TELECOMMUNICATIONS NETWORKS"

TECHNICAL FIELD

The present invention relates to a device for collecting data from mobile telecommunications networks.

BACKGROUND ART

As is known, the development and management of voice or data mobile telecommunications networks requires testing campaigns that enable verification not only of the territorial coverage, but also of the efficiency and quality of the connections and the capacity of supporting the traffic locally. The testing campaigns, normally referred to as "drive tests", are thus basically aimed at collecting data for optimising the coverage and capacity of the network and verifying quality of service. Drive tests may prove necessary both during development of new network technologies and for verifying the conditions of existing networks. Above all in urban areas, in fact, the configuration of the territory may change considerably following upon erection or modification of buildings and structures, which are such as to affect transmission of the signals .

As a rule, drive tests are carried out using vehicles equipped with data-collection devices, which travel along predetermined and repeatable routes. Data-collection devices are in general commercial mobile terminals, possibly adapted for storing the information collected in a portable computer. Data-collection devices further record additional information on the test conditions, in particular information regarding the position, speed, and direction of the terminal at the moment when the measurements are made.

Known data-collection devices present, however, limited functionalities from the standpoint of drive tests, in so far as they do not enable evaluation of numerous aspects that are instead of determining importance. In the first place, by commercial mobile terminals, it is not possible to detect the presence of other mobile terminals within the test area (for example, mobile terminals attached to very same cell with which the data-collection device communicates) . It is thus not possible to evaluate the traffic and interference generated by the population of mobile terminals in the vicinity of the test device. Further, known data-collection devices are unable to recognize the effects of interference coming from adjacent cells, the effects of the traffic generated on the cell, which determines a low efficiency of use of the radio resources, and the re-transmissions made by the radio base stations and by the mobile terminals.

Recent evolution of standards (3GPP Release 10) envisages use of functions incorporated in the user mobile terminals in order to reduce the costs of drive tests. Said functions enable storage of measurements made directly by the user mobile terminals both in the idle state and during communication. In practice, the user mobile terminals, during normal operation, collect sets of measurements useful for monitoring the conditions of the network in addition to carrying out the operations necessary for communication. The measurements are progressively stored and subsequently sent through the network itself to be received by processing centres . However, even though this approach is much less costly, it basically presents the same limitations as do drive tests, and in addition there are issues linked to confidentiality of the data. The user mobile terminals must in fact send to the network also information regarding the voice/data traffic as well as their own position, without there being a direct and conscious control of the user-person on the operations carried out .

DISCLOSURE OF INVENTION

The aim of the present invention is thus to provide a device for collecting data from an LTE (Long-Term Evolution) mobile telecommunications network.

According to the present invention, a device for collecting data from an LTE mobile telecommunications network is provided as defined in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the annexed drawings, which illustrate some non-limiting examples of embodiment thereof, and in which:

- Figure 1 is a simplified block diagram of a data-collection device for monitoring mobile telecommunications networks according to one embodiment of the present invention;

- Figure 2 is a simplified block diagram of a mobile telecommunications network including the data-collection device of Figure 1;

- Figure 3 is a flowchart regarding a first procedure executed by the data-collection device of Figure 1; and

- Figure 4 is a flowchart regarding a second procedure executed by the data-collection device of Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figure 1, a data-collection device for monitoring mobile telecommunications networks, in particular LTE (Long-Term Evolution) networks is designated as a whole by the reference number 1. The data-collection device 1 comprises an antenna 2, a processing stage 3, a control module 5, and a mass-storage device 6.

The control module 5 is configured to connect the data- collection device 1 to a radio base station or base node eNB (Evolved Node B) of a mobile telecommunications network 50 (Figure 2), to which user mobile terminals or user equipments UE may be connected.

With reference once again to Figure 1, the processing stage 3 is coupled to the antenna 2 for exchanging uplink and downlink radio-frequency signals with a base node eNB of the mobile telecommunications network 50. For this purpose, the processing stage 3 comprises a frequency downconverter 8, a first processing module 10, a second processing module 11, and a third processing module 12.

The frequency downconverter 8 receives a radio-frequency signal from the antenna 2 and converts it into a base-band signal or a signal into an intermediate band between the base band and the radio frequencies.

The first processing module 10 implements a Software Defined Radio platform, comprising, for example, DSPs (Digital Signal Processors) and/or FPGAs (Field-Programmable Gate Arrays), and basically presides over the functions of layer 1 of the LTE standard. In particular, the first processing module 10 performs functions regarding adaptation of the connection, power control, search for the cell for initial synchronisation, and handover. Further, the first processing module 10 carries out demodulation of the signal received from the frequency downconverter 8 and extracts the physical channels transmitted by the base node eNB to which the data- collection device 1 is connected. In addition, the first processing module extracts information on the modulation of the signal received, such as the MAC (Medium Access Control) channels of the LTE standard, which are supplied to the second processing module 11.

The second processing module 11 implements the functions of layer 2 of the LTE standard. In particular, the second processing module 11 implements the protocols MAC/RLC (Radio Link Control) and PDCP (Packed Data Convergence Protocol), regarding the downlink logic channels. The second processing module 11 extracts the information contained in the common channels transmitted by the base node eNB in non-encrypted mode and regarding both control of the radio resources and access to the physical layer. The third processing module 12 implements the functions of layer 3 of the LTE standard. In particular, the third processing module 12 comprises implementation and decoding of the protocols RRC (Radio Resource Control) and NAS (Non-Access Stratum) , for management of the radio resources and of the network layer, respectively. The third processing module enables decoding of the information transmitted on the downlink channels and detection of the physical and network parameters for access to the cell. The control module 5 supervises management of the system and controls operation of the various components, in particular of the processing stage 3. Further, the control module 5 collects the information and measurements supplied by the processing stage 3 and organizes them in a database 13 in the mass- storage device 6.

The information entered in the database 13 is subsequently retrieved and processed by the control module 5 for extracting information on the traffic in the cell to which the data- collection device 1 is connected. The result of the processing operations may in turn be organized in files 15 and stored in the mass-storage device 6. From the information present in the database 13, amongst other things, the control module 5 extracts data on the traffic and interference generated by the population of user equipments UE connected to the base node eNB in the vicinity of the data-collection device 1. Hereinafter, the operations carried out by the processing stage 3 and by the control module 5 will be described in greater detail.

Synchroni zation

With reference to Figure 3, the synchronization procedure comprises operations of search for signals transmitted by a base node eNB (block 100), steps of frequency synchronization (block 110), and subsequent detection of the common channels transmitted by the cell (block 120) . In particular, the synchronization stage 3 receives and decodes the channel BCCH (Broadcast Control CHannel, defined by the 3GPP 44.108 specifications) .

The processing stage 3 enables use of the data-collection device 1 according to three distinct operating modes:

1) the data-collection device 1 synchronizes only with a known cell via the parameters Cell-ID and EARFCN corresponding to the frequency of the known cell;

2) the device is set on a programmed value of the parameter EARFCN and synchronizes on a cell according to programmed rules (for example, the synchronization is carried out on the cell from which the strongest signal is arriving; in this way, the data-collection device 1 may be used with an operator that uses a known frequency) ; and

3) cell synchronization is carried out according to the standard procedure specified in 3GPP 36.304, which regards the standard functions of a user equipment UE and does not require a-priori knowledge of which RF channels correspond to cells in the LTE standard.

Reception of the physical channels

The processing stage 3 is configured to receive (through the frequency downconverter 8) and decode (in particular through the second processing stage 11) the downlink physical channels defined in the 3GPP specifications for the LTE standard.

In particular, the data-collection device 1 is configured to receive the transmission channels PBCH (Physical Broadcast CHannel), used for transmitting the system information regarding the operating modes of the network, and PDSCH (Physical Downlink Shared CHannel), which is a downlink shared channel and is used for transmitting all the information addressed at one or more user equipments UE and regarding the control plane, the user plane, and paging procedures. The data-collection device 1 is further configured to receive the physical control channels that manage downlink and uplink transmission, re-transmissions, and information necessary for decoding the transmission channel PDSCH and specifying to the user equipments UE the uplink transmission modes. The physical control channels may be received and decoded by all the user equipments UE within the coverage area of one cell. The data- collection device 1 implements decoding of the physical control channels like a standard user equipment UE .

Reception of the system information

In mobile telecommunication systems, the System Information (or Broadcast Information) is accessible to all the user equipments UE that are located within the coverage area and may be decoded without a-priori knowledge of other parameters, in particular user identifiers. The System Information comprises an information block MIB (Master Information Block) and information blocks SIB (System Information Block) .

The information block MIB contains information regarding operation of the network, in particular time-division or frequency-division mode, bandwidth, configuration of the channel PHICH (Physical Hybrid-ARQ Indicator CHannel), and system frame number SFN.

The information blocks SIB contain more detailed information regarding the network operating modes.

The information blocks MIB and SIB are encoded according to the protocol RRC (Radio Resource Control), specified in 3GPP 36.331. Decoding is carried out by the second processing module 11 as regards the protocols MAC, RLC, and PDCP according to the 3GPP specifications, and by the third processing module 12 for the protocol RRC. The information is transmitted without encryption and may be decoded without the need for further information.

Reception of the paging signals

The paging procedure is used by the network for contacting a user equipment UE that is in an "Idle" state, and thus is not transmitting or receiving data, in order to set up a connection .

The paging messages enable identification of the information on the terminated calls, their number, and the distinct occurrences of the user equipments UE called within the coverage area of the base node eNB. The paging messages and procedure are specified in 3GPP 36.331. In the paging messages, the user equipments UE are identified by a temporary identifier code TMSI (Temporary Mobile Subscriber Identity) and/or by the respective international identifier codes IMSI (International Mobile Subscriber Identity), which are unique.

The information on the paging procedures is available to all the user equipments UE present in the coverage area and is not encrypted . The control module 5 receives from the processing stage 3 and stores in the database 13 the paging information for each individual occurrence regarding each user equipment UE attached to the base node eNB, including date and time tags and recording the temporary identifiers TMSI and the international identifiers IMSI.

Detection of the network identifiers

The network identifiers RNTI (Radio Network Temporary Identifier) identify within the coverage area of a cell the user equipments UE served. Each user equipment UE in the "Connected" state receives a network identifier RNTI from the mobile telecommunications network. The network identifier RNTI is used for identification of the user equipment UE in all the subsequent transmissions. Various network identifiers RNTI are available, amongst which temporary identifiers T-RNTI (Temporary RNTI) and cell identifiers C-RNTI (Cell RNTI), which are assigned, respectively, in an initial step and in a more advanced step of the attach procedure.

The processing stage 3 is configured to decode the network identifiers RNTI assigned by the network to the user equipments UE in the coverage area.

The control module 5 stores in the database 13 the occurrences of the network identifiers RNTI, in addition to date and time of the individual occurrences.

For decoding, the processing stage 3 uses selectively one of the possible modes described hereinafter. 1 - Detection during the cell-attach procedure

Decoding of the network identifier RNTI is performed when a user equipment UE carries out a procedure of P-RACH for attaching to a cell of the network.

In particular (Figure 4), the processing stage 3 decodes the message RA-response (Random Access response) that is sent during the attach procedure (block 200), identifying the field RA-RNTI (Random Access Radio Network Temporary Identifier) in the message RA-response received (block 210) . Reception of a subsequent symbol or message DCI (Downlink Control Information, block 220) addressed to the user equipment UE identified by a temporary identifier T-RNTI already decoded previously makes it possible to establish that the temporary identifier T-RNTI has been confirmed as cell identifier C- RNTI. The cell identifier C-RNTI indicates the presence of a user equipment UE attached to the cell.

2 - Blind detection

Some user equipments UE may attach to the base node eNB surveyed by the data-collection device 1 after they have started communication with a different base node eNB (for example, by a handover procedure) . In this case, a user equipment UE identified by a cell identifier C-RNTI is considered as being present in the cell and attached to the corresponding base node eNB if a given number of messages DCI allocated in the specific cell region are addressed to the same cell identifier C-RNTI.

3 - DCI detection

The messages DCI have a different length according to the respective format and include cyclic codes that depend upon the cell identifier C-RNTI.

Traffic monitoring

The control module 5 is configured to monitor the traffic from and to the base node eNB to which the data-collection device 1 is attached. Monitoring of the traffic is carried out by decoding of the downlink control information DCI addressed to the various network identifiers RNTI on the channel PHICH. Decoding of the downlink control information DCI, carried out by the processing stage 3, enables the following information to be obtained, which is stored in respective memory elements 20 in the mass-storage device 6 (Figure 1) :

- number of resource blocks RB allocated;

- modulation and code schemes MCS;

- length of the transport blocks, which may be extracted from the number of resource blocks RB and the modulation and code schemes MCS;

- number of transport blocks;

- number of re-transmissions of downlink transport blocks (due, in particular to the fact that the user equipment UE does not acknowledge reception) ; and

- number of re-transmissions of uplink transport blocks (this information may be obtained from the physical channel PHICH, decoding of which depends exclusively upon allocation of the downlink control information DCI) .

The traffic at the level of the first layer may be measured entirely by storing the number of bits transported and the number of the re-transmissions.

Monitoring of the timing advance

In order to maintain reception consistency of the base node eNB and prevent inter-symbol interference, the user equipments UE start the individual transmissions with a Timing Advance TA that depends upon the distance of the base node eNB to which the user equipments UE themselves are attached. Decoding by the processing stage 3 and storage of the information regarding the timing advance enable the control device 5 to determine the spatial distribution of the user equipments UE in the cell served by the base node eNB.

Monitoring of corrections of transmission power

The base node eNB transmits to the user equipments UE connected information regarding variations required in the level of transmission power with respect to the current level. The information is represented in an incremental form with respect to the current level, and thus it is not possible to derive the power effectively transmitted. However, the information may be decoded by the processing stage 3 and recorded in the database 7. The data-collection device described advantageously allows to collect information on operation of the mobile telecommunications network using the control communications exchanged between a base node of the network itself and all the user equipments connected thereto. In particular, the device collects the non-encrypted information available and, albeit in the obvious impossibility of gaining access to the encrypted communications intended exclusively for the recipient user equipment, enables extrapolation of data regarding the overall traffic, the distribution of the mobile terminals within a cell, and the interference generated, as it is likewise able to recognize the effects of the interference coming from adjacent cells, the effects of the traffic generated on the cell, and the re-transmissions carried out by the radio base stations and by the mobile terminals.

The device described further presents the advantage of being flexible and may be conveniently used for making measurements both as it is moving, during a drive test, and from a fixed station .

Data collection does not require any direct interaction with the network and does not present problems of confidentiality because in any case the specific user equipment may not be identified from the data available.

Finally, it is evident that modifications and variations may be made to the data-collection device described herein, without thereby departing from the scope of the present invention, as defined in the annexed claims.

Claims

1. A data-collection device for collecting data from an LTE mobile telecommunications network, comprising an antenna (2), a processing stage (3), a control module (5), and a mass- storage device (6), wherein:

the processing stage (3) is configured to receive and decode information transmitted between a base node (eNB) of a mobile telecommunications network (50) and user equipments (UE) connected to the base node (eNB); and

the control module (5) is configured to extract traffic and interference data generated by the user equipments (UE) connected to the base node (eNB) from the information transmitted by the base node (eNB) to the user equipments (UE) and decoded by the processing stage (3) .

2. A device according to claim 1, wherein the control module (5) is configured to receive and store in the mass-storage device (6) paging information for each occurrence regarding each user equipment (UE) attached to the base node (eNB) .

3. A device according to claim 2, wherein the control module (5) is configured to record temporary identifiers (TMSI) and international identifiers (IMSI) contained in the paging information for each occurrence regarding each user equipment (UE) attached to the base node (eNB) .

4. A device according to any one of the preceding claims, wherein the processing stage (3) is configured to decode network identifiers (RNTI) assigned to the user equipments (UE) connected to the base node (eNB) .

5. A device according to claim 4, wherein the control module (5) is configured to store in the mass-storage device (6) each occurrence of the network identifiers (RNTI) and a date and time of each occurrence.

6. A device according to claim 4 or 5, wherein the processing stage (3) is configured to decode the network identifiers (RNTI) using selectively one of the following modalities: detection during a procedure of attach of a user equipment (UE) to the base node (eNB) , blind detection, detection of downlink-control-information (DCI) messages.

7. A device according to any one of claims 4 to 6, wherein the processing stage (3) is configured to decode downlink-control- information (DCI) addressed to respective network identifiers (RNTI) on the channel PHICH (Physical Hybrid-ARQ Indicator CHannel ) .

8. A device according to claim 7, the control module (5) is configured to extract from the decoded downlink-control- information (DCI) and to store in the mass-storage device (6) :

- a number of allocated resource blocks RB;

- modulation and code schemes MCS;

- length of the transport blocks;

- a number of the transport blocks;

- a number of re-transmissions of downlink transport blocks;

- a number of re-transmissions of uplink transport blocks.

9. A device according to claim 8, wherein the processing stage (3) is configured to decode information regarding timing advance TA and the control module (5) is configured to determine a spatial distribution of the user equipments (UE) connected to the base node (eNB) on the basis of the timing advance TA.

10. A device according to any one of the preceding claims, wherein the processing stage (3) is configured to decode information regarding requests to adjust a of transmission power level that are sent by the base node (eNB) to the user equipments (UE) connected.

11. A device according to any one of the preceding claims, wherein the processing stage (3) is configured to extract information contained in common channels that are transmitted by the base node (eNB) in non-encrypted mode and regard radio resources control and physical layer access.