WO2015192264A1

WO2015192264A1 - Method for checking the integrity of data transmitted through c-ran

Info

Publication number: WO2015192264A1
Application number: PCT/CN2014/000589
Authority: WO
Inventors: Tao Zheng; Richard Wang; Feng Yang
Original assignee: Orange
Priority date: 2014-06-16
Filing date: 2014-06-16
Publication date: 2015-12-23

Abstract

A method for checking the integrity of data emitted by at least a first transceiver equipment (21, 30) to at least a second transceiver equipment (30, 21) belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment (11) belonging to a second telecommunication operator, the method comprising the following steps executed by the second transceiver equipment (30, 21): receiving data packets emitted by the first transceiver equipment (21, 30), said data packets comprising the emitted data and data intended for integrity checking of the emitted data, called integrity checking data, the emitted data and the integrity checking data being encrypted prior the emission of the data packet; deciphering the encrypted emitted data and the encrypted integrity checking data by means of a decryption key corresponding to an encryption key associated to the first transceiver equipment (21, 30) and used to generate the encrypted emitted data and the encrypted integrity checking data; processing the integrity checking data in order to check the integrity of the emitted data.

Description

METHOD FOR CHECKING THE INTEGRITY OF DATA TRANSMITTED THROUGH C-RAN

[0001] The present invention relates to the field of Radio Access (RAN) sharing.

[0002] Centralized-RAN, or C-RAN, is a new cellular network architecture designed for the future mobile network infrastructure. A C-RAN can support Second Generation, Third Generation, Fourth Generation and future wireless communication standards.

[0003] Such a C-RAN is represented on figure 1. When Third Generation networks were deployed, distributed base station architecture was introduced. In this architecture the radio function unit, also referred to as the remote radio unit (RRU), is separated from the digital function unit, also referred to as BBU by a section of optical fiber. The RRUs can be installed on the top of towers, close to the antennas. This reduces the cable loss compared to the traditional base stations where the signals had to travel through a long cable connecting the base station cabinet to the. The optical fiber link connecting the RRUs and the BBU also allows much more flexibility in network planning and deployment as the BBU can be placed a few hundred meters or a few kilometers away from the RRUs. The C-RAN comprises a digital unit DU comprising a plurality of Base-Band units 10-12. The digital unit DU is connected to a pool of remote RRUs 20-23 by means of a fronthaul FH. The fronthaul FH consists in optical fiber links connecting the RRUs 20-23 to the DU. Such a RAN is managed by a unique telecom operator. Each RRU 20-23 covers a cell Cl- C4 respectively.

[0004] In order to reduce the operational expenditure and the capital expenditure generated by the management and the maintenance of RANs, solutions for sharing a RAN between a plurality of network operators are being developed. RAN sharing consists in at least two network operators sharing part or the whole RAN infrastructure, and in certain cases part or the whole radio frequency spectrum.

[0005] One way of building a shared RAN consists for example in upgrading a C- RAN managed by a first network operator, without modifying the existing RRUs and fronthaul. Such a shared C-RAN is represented on figure 2. The shared C-RAN comprises a first digital unit DU_A comprising a plurality of Base-Band units 10-12. The digital unit DU_A is managed by a first network operator A. The first digital unit DU_A is connected to a pool of remote R Us 20-23 by means of a fronthaul FH. The fronthaul FH consists in optical fiber links connecting the RRUs 20-23 to the DU. Each RRU 20-23 covers a cell C1-C4 respectively. [0006] A second digital unit DU_B is connected to the first digital unit DU_A- The second digital unit DU_B is managed by a second network operator B. the second digital unit DU_B comprises a plurality of Base-Band units 30-32. The first digital unit DU_A and the second digital unit DU_B each comprise means for enabling data signaling and data transfer between them. [0007] Two user equipments UE1 and UE2 are attached to the RRU 21 serving the cell C2. The user equipment UE1 is registered in the network of operator A, i.e. the owner of the user equipment UE1 is a customer of the network operator A. The user equipment UE2 is registered in the network of operator B, i.e. the owner of the user equipment UE2 is a customer of the network operator B. When the user equipment UE1 establishes a communication session with a remote user equipment (not represented on the figures), the user equipment UE1 establishes a connection with the RRU 21. The RRU 21 receives the data transmitted by the user equipment UE1 and then sends these data to the digital unit DU_A through the fronthaul FH. Upon reception of the data sent by the user equipment UE1 , the digital unit DU_A determines that the user equipment UE1 is a user equipment registered in the network A and consequently handles the data sent by user equipment UE1 , i.e. transmits the data to the remote user equipment with which the user equipment UE1 has established a communication session.

[0008] When the user equipment UE2 establishes a communication session with a remote user equipment (not represented on the figures), the user equipment UE2 establishes a connection with the RRU 21. The RRU 21 receives the data transmitted by the user equipment UE2 and then sends these data to the digital unit DU_A through the fronthaul FH. Upon reception of the data sent by the user equipment UE2, the digital unit DU_A determines that the user equipment UE2 is an user equipment registered in the network B and consequently transmits the data to the digital unit DU_B . Upon reception of the data transmitted by the digital unit DU_A, the digital unit DU_B handles the data sent by user equipment UE2, i.e. transmits the data to the remote user equipment with which the user equipment UE2 has established a communication session. [0009] In a shared C-RAN, since the data of the two network operators A and B are transmitted through the same network infrastructure. As the data of the network operator B are processed by the digital unit DU_A of the network operator A, there are issues in terms of confidentiality and security of the data of the network operator B since these data can be tampered, discarded or eavesdropped by the network operator A through the digital unit DU_A.

[0010] Therefore there is a need for a solution improving the level of confidentiality and security of data transmitted through a shared C-RAN.

[001 1 ] In that respect, the present invention relates to a method for checking the integrity of data emitted by at least a first transceiver equipment to at least a second transceiver equipment belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment belonging to a second telecommunication operator, the method comprising the following steps executed by the second transceiver equipment :

[0012] Receiving data packets emitted by the first transceiver equipment, said data packets comprising the emitted data and data intended for integrity checking of the emitted data, called integrity checking data, the emitted data and the integrity checking data being encrypted prior the emission of the data packet,

[0013] Deciphering the encrypted emitted data and the encrypted integrity checking data by means of a decryption key corresponding to an encryption key associated to the first transceiver equipment and used to generate the encrypted emitted data and the encrypted integrity checking data, and

[0014] Processing the integrity checking data in order to check the integrity of the emitted data.

[0015] The method of checking the integrity of data of the invention allows the detection of the tampering and the discarding of data of a first operator network, e.g. network operator B, when said data are transmitted through a shared C-RAN and are handled by network equipments belonging to a second network operator, e.g. network operator A by checking the integrity of said data. Such a method ensures the fairness between network operators sharing a RAN.

[0016] In the method for checking the integrity of data according to the invention, the confidentiality of the data of network operator B transmitted through the shared C- RAN is provided by the encrypting of the data. Since the decryption key is not known by the network equipments belonging to the network operator A, the data cannot be deciphered by any of these network equipments making the content of the data inaccessible to network operator A. [0017] According to a feature of the method for checking the integrity of data, said method further comprises a step of generating a pair of cryptographic keys consisting in the encryption key and the decryption key.

[0018] The cryptographic keys used to encrypt and decipher the emitted data are generated by the second transceiver equipment. Thus, these cryptographic keys are unknown of the intermediate transceiver equipment.

[0019] According to a feature of the method for checking the integrity of data, said method further comprises a step of transmitting the encryption key to the first transceiver equipment.

[0020] The encryption key is only sent to transceiver equipments selected, and therefore trusted, by the second transceiver equipment.

[0021] According to a feature of the method for checking the integrity of data, the integrity checking data consisting in a first checksum computed from the data to be emitted, the step of processing the integrity checking data consists in :

[0022] Computing a second checksum from the deciphered emitted data, and [0023] Comparing the first checksum and the second checksum in order to check the integrity of the emitted data.

[0024] If the network operator managing the intermediate transceiver equipment tampered the data of the network operator managing the second transceiver equipment, the second checksum will be different from the first checksum. Thus, the network operator managing the second transceiver equipment knows if its data were tempered by the network operator managing the intermediate transceiver.

[0025] According to a feature of the method for checking the integrity of the data object of the invention, the integrity checking data consisting in a part of the data emitted by the first transceiver equipment to the intermediate transceiver equipment, the step of processing the integrity checking data consists in : [0026] Transmitting the deciphered integrity checking data to the intermediate transceiver equipment in order for the intermediate transceiver equipment to recover all the data emitted by the first transceiver equipment to the intermediate transceiver equipment.

[0027] Since the integrity checking data consist in data meant for the intermediate transceiver equipment, the second transceiver equipment decipher them and transfer them to the intermediate transceiver equipment in order to be processed and thus enabling the integrity check of the data meant for the second transceiver equipment.

[0028] According to a feature of the method for checking the integrity of the data object of the invention, the second transceiver equipment transmits the deciphered emitted data.

[0029] Another objet of the invention concerns a method for transmitting data from at least a first transceiver equipment to at least a second transceiver equipment belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment belonging to a second telecommunication operator, the method comprising the following steps executed by the intermediate transceiver equipment :

[0030] Transmitting the data packets received from the first transceiver equipment and meant for the second transceiver equipment to the second transceiver equipment, said transmitted data packets comprising the data meant for the second transceiver equipment and a part of the data meant for the intermediate transceiver equipment, called missing data, the data meant for the second transceiver equipment and the missing data being encrypted, and

[0031] Receiving from the second transceiver equipment the missing data deciphered by means of a decryption key corresponding to an encryption key associated to the first transceiver equipment and used to generate the encrypted emitted data and the encrypted missing data.

[0032] If the network operator managing the intermediate transceiver equipment tampers or discard intentionally data meant for the second transceiver equipment, then the data meant for the intermediate transceiver equipment and transmitted in the same data packet as the data meant for the second transceiver equipment are tampered or discarded as well. Thus, the quality of experience of the customers of the network operator managing the intermediate transceiver equipment is deteriorated.

[0033] According to a feature of the method for transmitting data object of the invention, the intermediate transceiver equipment receives the deciphered data meant for the second transceiver equipment along with the deciphered missing data.

[0034] The intermediate transceiver equipment can directly regenerate its data. The data meant for the second transceiver equipment re sent to the intermediate transceiver equipment for verification, in order for the intermediate transceiver equipment to check that the second transceiver equipment did not tamper the data meant for the intermediate transceiver equipment.

[0035] According to a feature of the method for transmitting data object of the invention, the method further comprises the following steps:

[0036] Encrypting the data meant for the second transceiver equipment along with the missing data received from the second transceiver equipment using the encryption key used to generate the encrypted emitted data and the encrypted missing data, and

[0037] Comparing the data meant for the second transceiver equipment along with the missing data encrypted by the intermediate transceiver equipment with the encrypted data meant for the second transceiver equipment and the encrypted missing data received from the first transceiver equipment.

[0038] If the network operator managing the second transceiver equipment tampered the data of the network operator managing the intermediate transceiver equipment, the data encrypted by the intermediate transceiver equipment will differ from the encrypted data received from the first transceiver equipment. Thus, the network operator managing the intermediate transceiver equipment knows if its data were tempered by the network operator managing the second transceiver.

[0039] Another object of the invention is a transceiver equipment capable of checking the integrity of data emitted by at least another transceiver equipment, the transceiver equipment belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment belonging to a second telecommunication operator, the transceiver equipment comprising means for : [0040] Receiving data packets emitted by the other transceiver equipment, said data packets comprising the emitted data and data intended for integrity checking of the emitted data, called integrity checking data, the emitted data and the integrity checking data being encrypted prior the emission of the data packet,

[0041] Deciphering the encrypted emitted data and the encrypted integrity checking data by means of a decryption key corresponding to an encryption key associated to the other transceiver equipment and used to generate the encrypted emitted data and the encrypted integrity checking data, and

[0042] Processing the integrity checking data in order to check the integrity of the emitted data.

[0043] The invention also concerns a transceiver equipment capable of transmitting data received from at least a first transceiver equipment and meant to at least a second transceiver equipment belonging to a first telecommunication operator, the transceiver equipment belonging to a second telecommunication operator, the transceiver equipment comprising means for :

[0044] Transmitting the data packets received from the first transceiver equipment and meant for the second transceiver equipment to the second transceiver equipment, said transmitted data packets comprising the data meant for the second transceiver equipment and a part of the data meant for the intermediate transceiver equipment, called missing data, the data meant for the second transceiver equipment and the missing data being encrypted, and

[0045] Receiving from the second transceiver equipment the missing data deciphered by means of a decryption key corresponding to an encryption key associated to the first transceiver equipment and used to generate the encrypted emitted data and the encrypted missing data.

[0046] Finally, one object of the invention concerns computer programs, in particular computer programs on or in an information medium or memory, suitable for implementing the methods object of the invention. These programs can use any programming language, and be in the form of source code, binary code, or of code intermediate between source code and object code such as in a partially compiled form, or in any other desirable form for implementing the communication methods according to the invention. [0047] The information medium may be any entity or device capable of storing the programs. For example, the medium can comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or else a magnetic recording means, for example a diskette (floppy disk) or a hard disk. [0048] Moreover, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The programs according to the invention may in particular be downloaded from a network of Internet type.

[0049] The present system and method are explained in further detail, and by way of example, with reference to the accompanying drawings wherein:

[0050] FIG. 1 represents a Centralized Radio Access Network, or C-RAN, according to prior art,

[0051] FIG. 2 represents a shared C-RAN according to prior art,

[0052] FIG. 3 represents a C-RAN in which the methods of the invention are executed, [0053] FIG. 4Arepresents the exchanges between the different elements of the shared C-RAN involved in the execution of a first embodiment of the method for checking the integrity of the data exchanged in the C-RAN for the uplink,

[0054] FIG. 4Brepresents the exchanges between the different elements of the shared C-RAN involved in the execution of a first embodiment of the method for checking the integrity of the data exchanged in the C-RAN for the downlink,

[0055] FIG. 5Arepresents the exchanges between the different elements of the shared C-RAN involved in the execution of a second embodiment of the method for checking the integrity of the data exchanged in the C-RAN for the uplink,

[0056] FIG. 5B represents the exchanges between the different elements of the shared C-RAN involved in the execution of a second embodiment of the method for checking the integrity of the data exchanged in the C-RAN for the downlink,

[0057] The purpose of the invention is to improve the confidentiality and the security of the data transmitted through a RAN shared by a plurality of network operators.

[0058] Figure 3 represents a shared C-RAN comprising a first digital unit DU_A comprising a plurality of Base-Band units 10-12. The digital unit DU_A is managed by a first network operator A. The first digital unit DUA is connected to a pool of remote RRUs 20-23 by means of a fronthaul FH. The fronthaul RH consists in optical fiber links connecting the RRUs 20-23 to the DU. Each RRU 20-23 covers a cell C1-C4 respectively.

[0059] A second digital unit DUB is connected to the first digital unit DUA. The second digital unit DU_B is managed by a second network operator B. the second digital unit DUB comprises a plurality of Base-Band units 30-32. The first digital unit DUA and the second digital unit DUB each comprise means for enabling data signaling and data transfer between them.

[0060] Two user equipments UE1 and UE2 are attached to the RRU 21 serving the cell C2. The user equipment UE1 is registered in the network of operator A, i.e. the owner of the user equipment UE1 is a customer of the network operator A. The user equipment UE2 is registered in the network of operator B, i.e. the owner of the user equipment UE2 is a customer of the network operator B.

[0061 ] Figure 4A represents the exchanges between the different elements of the shared C-RAN involved in the execution of a first embodiment of the method for checking the integrity of the data exchanged in the C-RAN according to the invention. The method is described hereafter for uplink communications, i.e. for data transmitted from a user equipment UE1 , UE2 to a digital unit DUA, DUB.

[0062] In a step E0, a base band unit BBU 30 belonging to the digital unit DUB of the second network operator B generates a pair of cryptographic keys consisting in an encryption key ECK and a decryption key DCK. The base band unit BBU 30 sends the encryption key ECK to the remote radio unit RRU 21.

[0063] As an alternative, in a step EO', the base band unit BBU 30 transmits the encryption key ECK to an operations, administration and maintenance OAM equipment (not represented on the figures). The OAM equipment, then transmits the encryption key ECK directly to the remote radio unit RRU 21.

[0064] In a step El , the user equipment UE1 sends data DA to the remote radio unit RRU 21. In a step E2, the user equipment UE2 sends data DB to the remote radio unit RRU 21. These data DA and DB may be sent to the remote radio unit as the payload of data packets compliant to the transport protocol used to establish the connection between the user equipments UE1 and UE2 and the remote radio unit RRU 21. [0065] During a step E3, the remote radio unit R U21 adapts some features of the data D_A received from the user equipment UE1, such as the modulation, the format, etc., to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital unit DU_A which is for example Common Public Radio Interface or CPRI Protocol. Those adapted data IQ_A are then transmitted to the digital unit DU_A in a step E4.

[0066] During a step E5, the remote radio unit RRU 21 adapts some features of the data D_B received from the user equipment UE2 to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital unit DU_A.

[0067] In a step E6, the remote radio unit RRU 21 computes a first checksum CKS1 from the adapted data IQ_B. The first checksum CKS1 is computed, for example, according to the MD5sum algorithm.

[0068] In a step E7, the remote radio unit RRU 21 encrypts both the adapted data IQ_B and the checksum CKS1 by means of the encryption key ECK received during step E0, E0'.

[0069] In a step E8, the remote radio unit RRU 21 transmits the encrypted data IQ_B and the encrypted checksum CKS1 to the digital unit DU_A although these data IQ_B and checksum CKS1 are meant for the digital unit DU_B, since the second user equipment UE2 is registered in the network B.

[0070] In a step E9, the base band unit 11 of the digital unit DU_A receives the data IQ_A and the encrypted data IQ_B and the encrypted checksum CKS 1. [0071] In a step E10, the base band unit BBU 11 sorts the received data between the data meant for the digital unit DU_A, i-e. data IQ_A, and the data meant for the base band unit BBU 30 of the digital unit DU_B, i-e. the encrypted data IQ_B and the encrypted checksum CKS 1. Thus data of network B are handled by an equipment belonging to network A. the base band unit BBU 11 uses information stored in the headers of data IQ_A, IQ_B and checksum CKS1 in order to determine the destination of the data, i.e. which network equipment is to handle said data between the base band unit BBU 11 of the network A and the base band unit BBU 30 of the network B.

[0072] In a step El l, the encrypted data IQ_B and the encrypted checksum CKS1 are transmitted to the base band unit BBU30 while the data IQ_A are processed normally by the base band unit BBU 11. [0073] In a step E12, the base band unit BBU 30 deciphers the encrypted data IQ_B and the encrypted checksum CKS 1 by means of the decryption key DCK generated during step E0. The decryption key DCK corresponds to the encryption key ECK which is intended for the remote radio unit RRU 21. The remote radio unit RRU 20 would receive another encryption key ECK' from the base band unit 30; said encryption key ECK' may bethe same or different from the encryption key ECK sent to the remote radio unit RRU 21.

[0074] In a step El 3, the base band unit BBU 30 computes a second checksum CKS2 from the deciphered data IQ_B. The second checksum CKS2 is computed, for example, according to the MD5sum algorithm.

[0075] In a step E14, the base band unit BBU 30 compares the first checksum CKS1 and the second checksum CKS2 in order to check the integrity of the data IQ_B. If the two checksums CKS 1 and CKS2 are identical, that means that the IQ_B data were not tampered while handled by the base station BBU 11. If the two checksums CKS1 and CKS2 are different, that means that the IQ_B data were tampered while handled by the base station BBU 11.

[0076] Figure 4B represents the exchanges between the different elements of the shared C-RAN involved in the execution of a first embodiment of the method for checking the integrity of the data exchanged in the C-RAN according to the invention. The method is described hereafter for downlink communications, i.e. for data transmitted from a digital unit DU_A, DU_Btoa user equipment UE1, UE2.

[0077] In a step F0, a remote radio unit RRU 21 generates a pair of cryptographic keys consisting in an encryption key ECK and a decryption key DCK. The remote radio unit RRU 21 sends the encryption key ECK to a base bad unit BBU 30 belonging to the digital unit DU_B of the second network operator B.

[0078] As an alternative, in a step F0', the remote radio unit RRU 21transmits the encryption key ECK to an operations, administration and maintenance OAM equipment (not represented on the figures). The OAM equipment, then transmits the encryption key ECK directly to the base band unit BBU 30.

[0079] During a step Fl, the base band unit BBU 30 adapts some features of data D_B intended for the user equipment UE2 attached to the remote radio unit RRU 21, such as the modulation, the format, etc., to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital units DU_Aand DU_B which is for example Common Public Radio Interface or CPRI Protocol.

[0080] In a step F2, the base band unit BBU 30 computes a first checksum CKS1 from the data IQ_B. The first checksum CKS1 is computed, for example, according to the MD5sum algorithm.

[0081] In a step F3, the base band unit BBU 30 encrypts both the data IQ_B and the checksum CKS1 by means of the encryption key ECK received during step E0, E0'.

[0082] In a step F4, the base band unit BBU 30 transmits the encrypted data IQ_B and the encrypted checksum CKS1 to the digital unit DU_A although these data IQ_B and checksum CKS1 are meant for the second user equipment UE2 which is registered in the network B.

[0083] In a step F5, the base band unit 11 of the digital unit DU_A receives the encrypted data IQ_Band encrypted checksum CKS 1.

[0084] In a step F6, the base band unit BBU 11 adapts some features of data D_A intended for the user equipment UE1 attached to the remote radio unit RRU 21, such as the modulation, the format, etc., to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital units DU_A which is for example Common Public Radio Interface or CPRI Protocol.

[0085] In a step F7, the base band unit BBU 11 sends the data IQ_A, the encrypted data IQ_B and encrypted checksum CKS 1 to the remote radio unit RRU 21.

[0086] In a step F8, the remote radio unit RRU 21 sorts the received data between the data meant for the first user equipment UE1, i.e. data IQ_A, and the data meant for the second user equipment UE2, i.e. the encrypted data IQ_B and the encrypted checksum CKS1. The remote radio unit RRU 21 uses information stored in the headers of data IQ_A, IQ_B and checksum CKS1 in order to determine the destination of the data, i.e. the first user equipment UE1 or the second user equipment UE2.

[0087] In a step F9, the data IQ_A are processed normally by the remote radio unit RRU 21, i.e. data IQ_A are adapted as data D_A that can be emitted over the air by the remote radio unit RRU 21, and sent in a step F10 to the first user equipment UE1. [0088] In a step Fl l,the remote radio unit RRU 21 deciphers the encrypted data IQB and the encrypted checksum CKS 1 by means of the decryption key DCK generated during step EO. The decryption key DCK corresponds to the encryption key ECK which is intended for the base band unit BBU 30. The base band unit RRU 31 would receive another encryption key ECK' from the remote radio unit RRU 21 ; said encryption key ECK' may be the same to or different from the encryption key ECK sent to the base band unit BBU 30.

[0089] In a step F12, the remote radio unit RRU 21 computes a second checksum CKS2 from the deciphered data IQ_B. The second checksum CKS2 is computed, for example, according to the MD5sum algorithm.

[0090] In a step F13, the remote radio unit RRU 21 compares the first checksum CKS l and the second checksum CKS2 in order to check the integrity of the data IQB. If the two checksums CKS l and CKS2 are identical, that means that the IQB data were not tampered while handled by the base station BBU 1 1. If the two checksums CKS l and CKS2 are different, that means that the IQB data were tampered while handled by the base station BBU 1 1. [0091 ] In a step F14, if the integrity of the data IQB is checked, the remote radio unit RRU 21 sends data D to the user equipment UE2. Data IQB are adapted as data Ds that can be emitted over the air by the remote radio unit RRU 21.These data DB may be sent by the remote radio unit as the payload of data packets compliant to the transport protocol used to establish the connection between the user equipments UE1 and UE2 and the remote radio unit RRU 21.

[0092] Figure 5Arepresents the exchanges between the different elements of the shared C-RAN involved in the execution of a second embodiment of the method for checking the integrity of the data exchanged in the C-RAN according to the invention. The method is described hereafter for uplink communications, i.e. for data transmitted from a user equipment UE1 , UE2 to a digital unit DUA, DUB. in this second embodiment of the method for checking the integrity according to the invention, a joint decoding of data destined to equipments belonging to both operator A and operator B is performed.

[0093] In a step GO, a base band unit BBU 30 belonging to the digital unit DUB of the second network operator B generates a pair of cryptographic keys consisting in an encryption key ECK and a decryption key DCK. The base band unit BBU 30 sends the encryption key ECK to the remote radio unit RRU 21. [0094] As an alternative, in a step GO', the base band unit BBU 30 transmits the encryption key ECK to an operations, administration and maintenance OAM equipment (not represented on the figures). The OAM equipment, then transmits the encryption key ECK directly to the remote radio unit RRU 21. [0095] In a step Gl, the user equipment UE1 sends data D_A to the remote radio unit RRU 21. In a step G2, the user equipment UE2 sends data D_B to the remote radio unit RRU 21. These data D_A and D_B may be sent to the remote radio unit as the payload of data packets compliant to the transport protocol used to establish the connection between the user equipments UE1 and UE2 and the remote radio unit RRU 21. [0096] During a step G3, the remote radio unit RRU 21 adapts some features of the data D_A received from the user equipment UE1, such as the modulation, the format, etc., to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital unit DU_A which is for example Common Public Radio Interface or CPRI Protocol. During a step G4, the remote radio unit RRU 21 adapts some features of the data D_B received from the user equipment UE2 to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital unit DU_A.

[0097] In a step G5, the remote radio unit RRU 21 encrypts the adapted data IQ_B and a portion of the adapted data IQ_A by means of the encryption key ECK received during step E0, E0'. The portion of the data IQ_A is, for example, one percent of the data IQ_A. The portion of the data IQ_A that is encrypted depends on the transmission capacity of the link established between the digital unit DU_A and the digital unit DU_B; the highest the transmission capacity, the biggest the portion of data IQ_A that can be encrypted. The portion of the data IQ_A is called missing data MIQ_A.

[0098] In a step G6, the remote radio unit RRU 21 transmits the encrypted data IQ_B, the encrypted missing data MIQ_A and the remainder of the data IQ_A, called remainder data RIQ_A to the digital unit DU_A although these data IQ_B and missing data MIQ_A are meant for the digital unit DU_B.

[0099] In a step G7, the base band unit 11 of the digital unit DU_A receives the remainder data RIQ_A and the encrypted data IQ_B and the encrypted missing data MIQ_A. [0100] In a step G8, the base band unit BBU 11 sorts the received data between the data meant for the digital unit DU_A, i.e. the remainder data RIQ_A, and the data meant for the base band unit BBU 30 of the digital unit DU_B, i-e. the encrypted data IQ_B and the encrypted missing data MIQ_A. Thus data of network B are handled by an equipment belonging to network A. The base band unit BBU 11 uses information stored in the headers of remainder data RIQ_A, IQ_B and missing data MIQ_A in order to determine the destination of the data, i.e. which network equipment is to handle said data between the base band unit BBU 11 of the network A and the base band unit BBU 30 of the network B.

[0101] In a step G9, the encrypted data IQ_B and the encrypted missing data MIQ_A are transmitted to the base band unit BBU 30. .

[0102] In a step G10, the base band unit BBU 30 deciphers the encrypted data IQ_B and the encrypted missing data MIQ_A by means of the decryption key DCK generated during step E0. The decryption key DCK corresponds to the encryption key ECK which is intended for the remote radio unit RRU 21. The remote radio unit RRU 20 would receive another encryption key ECK' from the base band unit 30; said encryption key ECK' may be to the same or different from the encryption key ECK sent to the remote radio unit RRU 21. [0103] In a step Gi l, the base band unit BBU 30 transmits the deciphered missing data MIQ_A to the base band unit BBU11 in order to check the integrity of the data IQ_A.

[0104] In a step G12, the base band unit BBU 11 combines the missing data MIQ_A with the remainder data RIQ_A in order to recover the data IQ_A. .

[0105] In an embodiment of the method of the invention, during a step G13, the base band unit BBU 30 transmits the deciphered data IQ_B to the base band unit BBU11 in order to check the integrity of the data MIQ_A.

[0106] In a step G14, the base station BBU 11 encrypts the data IQ_B received during the step G13and the missing data MIQ_A received during the step Gi l by means of the encryption key ECK. The base band unit BBU 11 then compares the data IQ_B and the missing data MIQ_A encrypted by the base band unit BBU 11 with the encrypted data IQ_B and the encrypted missing data MIQ_A received from the remote radio unit RRU 21 during a step G15.

[0107] If the two sets of encrypted data IQ_B and missing data MIQ_A are the same, that means that the MIQ_A data were not tampered while handled by the base station BBU 30. If the two sets of encrypted data IQ_B and missing data MIQ_A are different, that means that MIQ_A were tampered while handled by the base station BBU 30. [0108] Figure 5Brepresents the exchanges between the different elements of the shared C-RAN involved in the execution of a second embodiment of the method for checking the integrity of the data exchanged in the C-RAN according to the invention. The method is described hereafter for downlink communications, i.e. for data transmitted from a digital unit DU_A, DU_B to a user equipment UE 1 , UE2.

[0109] In a step HO, a remote radio unit RRU 21 generates a pair of cryptographic keys consisting in an encryption key ECK and a decryption key DCK. The remote radio unit RRU 21 sends the encryption key ECK to a base bad unit BBU 30 belonging to the digital unit DU_B of the second network operator B. [01 10] As an alternative, in a step HO', the remote radio unit RRU 21transmits the encryption key ECK to an operations, administration and maintenance OAM equipment (not represented on the figures). The OAM equipment, then transmits the encryption key ECK directly to the base band unit BBU 30.

[01 1 1] During a step HI, the base band unit BBU 30 adapts some features of data D_B intended for the user equipment UE2 attached to the remote radio unit RRU 21, such as the modulation, the format, etc., to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital units DU_A and DU_B which is for example Common Public Radio Interface or CPRI Protocol.

[01 12] In a step H2, the base band unit BBU 11 sends a portion of the adapted data to the base band unit BBU 30. The portion of the data IQ_A is, for example, one percent of the data IQ_A. The portion of the data IQ_A that is encrypted depends on the transmission capacity of the link established between the digital unit DU_A and the digital unit DU_B; the highest the transmission capacity, the biggest the portion of data IQ_A that can be encrypted. The portion of the data IQ_A is called missing data MIQ_A. [01 13] In a step H3, the base band unit BBU 30 encrypts both the data IQ_B and the missing data MIQ_Aby means of the encryption key ECK received during step E0, E0'.

[01 14] In a step H4, the base band unit BBU 30 transmits the encrypted data IQ_B and the encrypted missing data MIQ_A to the digital unit DU_A although these data IQ_B are meant for the second user equipment UE2 which is registered in the network B. [01 15] In a step H5, the base band unit BBU 11 of the digital unit DU_A receives the data IQ_B. The base band unit BBU 11 uses these non-encrypted data IQ_B in order to check the integrity of the missing data MIQ_A. [01 16] In a step H6, the base station BBU 11 encrypts the data IQ_B received during the step H5 and the missing data MIQ_A sent to the base band unit BBU 11 during the step H2 by means of the encryption key ECK. The base band unit BBU 11 then compares the data IQ_B and the missing data MIQ_A encrypted by the base band unit BBU 11 with the encrypted data IQ_B and the encrypted missing data MIQ_A received from the base band unit BBU 30.

[01 17] If the two sets of encrypted data IQ_B and missing data MIQ_A are identical, that means that the missing data MIQ_A data were not tampered while handled by the base station BBU 30. If the two sets of encrypted data IQ_B and missing data MIQ_A are different, that means that the missing data MIQ_A data were tampered while handled by the base station BBU 11. In a step H7, the base band unit BBU 11 adapts some features of and the remainder of the data IQ_A, called remainder data RIQ_A intended for the user equipment UE1 attached to the remote radio unit RRU 21, such as the modulation, the format, etc., to the transport protocol used to establish the connection between the remote radio unit RRU 21 and the digital units DU_A which is for example Common Public Radio Interface or CPRI Protocol.

[01 18] In a step H8, the base band unit BBU 11 combines encrypted data IQ_B plus the missing data MIQ_A received during the step H4 with the remainder data RIQ_A and then sends the combined data to the remote radio unit RRU 21. [01 19] In a step H9, the remote radio unit RRU 21 deciphers the encrypted data IQ_B and the missing data MIQA by means of the decryption key DCK generated during step HO. The decryption key DCK corresponds to the encryption key ECK which is intended for the base band unit BBU 30. The base band unit RRU 31 would receive another encryption key ECK' from the remote radio unit RRU 21; said encryption key ECK' maybe the same or different from the encryption key ECK sent to the base band unit BBU 30.

[0120] In a step H10, the remote radio unit RRU 21 sorts the decrypted data IQ_B and MIQA with the non-encrypted data RIQ_A to form the data meant for the first user equipment UE1, i.e. data IQ_A, and the data meant for the second user equipment UE2, i.e. the encrypted data IQ_B. The remote radio unit RRU 21 uses information stored in the headers of data IQ_A, IQ_B in order to determine the destination of the data, i.e. the first user equipment UE1 or the second user equipment UE2. [0121] In a step Hl l, the remote radio unit RRU 21 sends the data D_A, a variant of IQ_A that can be emitted over the air, to the user equipment UEl .

[0122] In a step HI 2, the remote radio unit RRU 21 sends the data D_B (a variant of Ι(¾)ΐο the user equipment UE2. These data D_B may be sent by the remote radio unit as the payload of data packets compliant to the transport protocol used to establish the connection between the user equipments UEl and UE2 and the remote radio unit RRU 21.

Claims

1. A method for checking the integrity of data emitted by at least a first transceiver equipment to at least a second transceiver equipment belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment belonging to a second telecommunication operator, the method comprising the following steps executed by the second transceiver equipment : - Receiving data packets emitted by the first transceiver equipment, said data packets comprising the emitted data and data intended for integrity checking of the emitted data, called integrity checking data, the emitted data and the integrity checking data being encrypted prior the emission of the data packet,

Deciphering the encrypted emitted data and the encrypted integrity checking data by means of a decryption key corresponding to an encryption key associated to the first transceiver equipment and used to generate the encrypted emitted data and the encrypted integrity checking data,

Processing the integrity checking data in order to check the integrity of the emitted data.

2. The method for checking the integrity of data according to claim 1 comprising a step of generating a pair of cryptographic keys consisting in the encryption key and the decryption key.

3. The method for checking the integrity of data according to claim 2, comprising a step of transmitting the encryption key to the first transceiver equipment.

4. The method for checking the integrity of data according to claim 1 wherein, the integrity checking data consisting in a first checksum computed from the data to be emitted, the step of processing the integrity checking data consists in : - Computing a second checksum from the deciphered emitted data, Comparing the first checksum and the second checksum in order to check the integrity of the emitted data.

5. The method for checking the integrity of data according to claim 1 wherein, the integrity checking data consisting in a part of the data emitted by the first transceiver equipment to the intermediate transceiver equipment, the step of processing the integrity checking data consists in :

Transmitting the deciphered integrity checking data to the intermediate transceiver equipment in order for the intermediate transceiver equipment to recover all the data emitted by the first transceiver equipment to the intermediate transceiver equipment.

6. The method for checking the integrity of data according to claim 5, wherein the second transceiver equipment transmits the deciphered emitted data.

7. A method for transmitting data from at least a first transceiver equipment to at least a second transceiver equipment belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment belonging to a second telecommunication operator, the method comprising the following steps executed by the intermediate transceiver equipment :

Transmitting the data packets received from the first transceiver equipment and meant for the second transceiver equipment to the second transceiver equipment, said transmitted data packets comprising the data meant for the second transceiver equipment and a part of the data meant for the intermediate transceiver equipment, called missing data, the data meant for the second transceiver equipment and the missing data being encrypted,

Receiving from the second transceiver equipment the missing data deciphered by means of a decryption key corresponding to an encryption key associated to the first transceiver equipment and used to generate the encrypted emitted data and the encrypted missing data.

8. The method for transmitting data according to claim 5, wherein the intermediate transceiver equipment receives the deciphered data meant for the second transceiver equipment along with the deciphered missing data.

9. The method for transmitting data according to claim 6 further comprising the following steps:

Encrypting the data meant for the second transceiver equipment along with the missing data received from the second transceiver equipment using the encryption key used to generate the encrypted emitted data and the encrypted missing data, - Comparing the data meant for the second transceiver equipment along with the missing data encrypted by the intermediate transceiver equipment with the encrypted data meant for the second transceiver equipment and the encrypted missing data received from the first transceiver equipment.

10. A transceiver equipment capable of checking the integrity of data emitted by at least another transceiver equipment, the transceiver equipment belonging to a first telecommunication operator, the data being transmitted through at least one intermediate transceiver equipment belonging to a second telecommunication operator, the transceiver equipment comprising means for :

Receiving data packets emitted by the other transceiver equipment, said data packets comprising the emitted data and data intended for integrity checking of the emitted data, called integrity checking data, the emitted data and the integrity checking data being encrypted prior the emission of the data packet,

Deciphering the encrypted emitted data and the encrypted integrity checking data by means of a decryption key corresponding to an encryption key associated to the other transceiver equipment and used to generate the encrypted emitted data and the encrypted integrity checking data,

11. A transceiver equipment capable of transmitting data received from at least a first transceiver equipment and meant to at least a second transceiver equipment belonging to a first telecommunication operator, the transceiver equipment belonging to a second telecommunication operator, the transceiver equipment comprising means for :

12. A computer program characterized in that it comprises program code instructions for the implementation of the steps of the method for checking the integrity of data as claimed in claim 1 when the program is executed by a processor.

13. A computer program characterized in that it comprises program code instructions for the implementation of the steps of the method for transmitting data as claimed in claim 7 when the program is executed by a processor.