Mobile communication method, wireless base station and mobile station

The present invention relates to mobile communication methods, radio base stations and mobile stations.

In the LTE (Rel-8) type mobile communication system, K is the key used for communication between the mobile station UE and the cell in the X2 handover process._eNBThe update method of, that is, the "key chain" is shown in FIG.

Specifically, first, the radio base station S-eNB that manages the handover source cell is K used for communication between the mobile station UE and the handover source cell._eNBFor K, apply "PCI (Physical Cell ID) / ARFCN (Absolute Radio Frequency Channel Number) binding processing"._eNB^*To generate.

Here, the radio base station S-eNB shall perform such "PCI / ARFCN binding processing" using PCI (Target PCI) and ARFCN (Target ARFNC) of the handover destination cell.

Second, the radio base station S-eNB generated K_eNB^*Is transmitted to the radio base station T-eNB that manages the handover destination cell together with the NCC.

Third, the radio base station T-eNB received K from the radio base station S-eNB._eNB^*As it is K_eNBIs used in communication between the mobile station UE and the handover source cell.

Fourth, the mobile station UE generates NH based on the NCC included in the "HO Command" received from the radio base station S-eNB, if necessary, and between the mobile station UE and the handover source cell. K used in communication_eNBOr K based on NH_eNB^*And generated K_eNB^*As it is K_eNBIs used in communication with the handover source cell.

Here, the reason why the "PCI / ARFCN binding process" is performed by the wireless base station S-eNB is that the handover process is repeated, the handover process is canceled in the middle, and then the handover process is performed again, or a plurality of cases. The same K for multiple radio base stations eNB, such as when handover preparation processing is performed for the radio base station eNB._eNB^*This is to prevent the situation where is transmitted.

The same K for multiple radio base stations eNB_eNB^*Is sent, the system becomes vulnerable for security reasons.

<p><nplcit num="1"><text>3GPP TS33.401</text></nplcit><nplcit num="2"><text>3GPP TS36.331</text></nplcit></p>

<p> However, if "Carrier Aggregation (CA)" is applied in the LTE-Advanced system (LTE (Rel-10) system mobile communication system, which is the successor to the LTE system, each "Component Carrier (CC)" PCI and E-ARFCN may be different, K in handover processing_eNB^*There is a problem that it may not be possible to uniquely determine the PCI and ARFCN to be used in the "PCI / ARFCN binding process" when generating.</p><p> When performing "CA", the same K for each "CC"_eNBHowever, since the PCI and ARFCN of each "CC" may be different, it is necessary to specify the main "CC", that is, "Anchor CC".</p><p> However, at the time of handover, it may be necessary to change "Anchor CC" depending on the circumstances of the radio base station of the handover destination. For example, when the same ARFCN "CC" does not exist in the handover source and the handover destination, or when the load of the handover destination "CC" corresponding to the ARFCN which was "Anchor CC" in the handover source is high. is there.</p><p> Since the handover source radio base station does not know which "CC" is selected as the "Anchor CC" in the handover destination radio base station, the handover source radio base station is K._eNB^*According to the PCI and ARFCN of each "CC" managed by the handover destination radio base station when generating and transferring to the handover destination radio base station_eNB^*It is necessary to generate and transfer all of these to the radio base station of the handover destination in the handover preparation procedure.</p><p> However, K according to each "CC"_eNB^*There is a problem that the processing load of the radio base station increases because of the generation. Also, multiple K_eNB^*There is a problem that the amount of backhaul signaling increases because the backhaul is transferred.</p><p> Therefore, the present invention has been made in view of the above-mentioned problems, and even when "CA" is applied, the processing load of the radio base station and the signaling amount of the backhaul are suppressed in the handover processing. While K_eNB^*It is an object of the present invention to provide a mobile communication method, a radio base station and a mobile station capable of generating the above.</p>

<p> The first feature of the present invention is a mobile communication method in which a mobile station is handed over from a first cell to a second cell, and a random number generated by a radio base station that manages the first cell and the first cell. The second key used in the communication between the second cell and the mobile station based on the first key used in the communication between the mobile station and the predetermined information notified from the exchange. The gist is to have a step of generating an intermediate key for generating the above.</p><p> The second feature of the present invention is a mobile communication method in which a mobile station is handed over from a first cell to a second cell, and a predetermined information received from a switching station by a radio base station that manages the second cell, and It is a gist to have a step of generating an intermediate key for generating a second key used in communication between the second cell and the mobile station based on the generated random number.</p><p> The third feature of the present invention is a random number that is a radio base station that manages the first cell in the handover process of the mobile station from the first cell to the second cell and is configured to generate a random number. Based on the generation unit, the generated random number, and the first key used in the communication between the first cell and the mobile station, or predetermined information notified from the exchange, the second cell and the second cell. The gist is to include a key generation unit configured to generate an intermediate key for generating a second key used in communication with the mobile station.</p><p> The fourth feature of the present invention is a mobile station, which is a predetermined counter and a predetermined counter received from a radio base station that manages the first cell via a handover instruction signal in the handover process from the first cell to the second cell. A second used in communication with the second cell based on a random number and predetermined information calculated using the first key or the parent key used in the communication with the first cell. The gist is to include a key generation unit configured to generate an intermediate key for generating a key.</p><p> The fifth feature of the present invention is a random number that is a radio base station that manages the second cell in the handover process of the mobile station from the first cell to the second cell and is configured to generate a random number. An intermediate for generating a second key used in communication between the second cell and the mobile station based on a generation unit, predetermined information and a predetermined counter received from the exchange, and the generated random number. The gist is to include a key generation unit configured to generate a key.</p><p> The sixth feature of the present invention is a mobile station, which is calculated by using a predetermined counter and a random number received via a handover instruction signal and a master key in the handover process from the first cell to the second cell. The gist is to include a key generation unit configured to generate an intermediate key for generating a second key used in communication with the second cell based on predetermined information.</p>

<p> As described above, according to the present invention, even when "CA" is applied, K can be safely performed in the handover process._eNB^*Can provide mobile communication methods, radio base stations and mobile stations capable of generating.</p>

<figref num="1">It is an overall block diagram of the mobile communication system which concerns on 1st Embodiment of this invention.</figref><figref num="2">It is a functional block diagram of the radio base station which concerns on 1st Embodiment of this invention.</figref><figref num="3">It is a figure for demonstrating the key update method in the mobile communication system which concerns on 1st Embodiment of this invention.</figref><figref num="4">It is a functional block diagram of the mobile station which concerns on 1st Embodiment of this invention.</figref><figref num="5">It is a sequence diagram which shows the operation of the mobile communication system which concerns on 1st Embodiment of this invention.</figref><figref num="6">It is a sequence diagram which shows the operation of the mobile communication system which concerns on 1st Embodiment of this invention.</figref><figref num="7">It is a sequence diagram which shows the operation of the mobile communication system which concerns on 1st Embodiment of this invention.</figref><figref num="8">It is a figure for demonstrating the key update method in the LTE (Rel-8) type mobile communication system.</figref>

(Structure of Mobile Communication System According to First Embodiment of the Present Invention) The configuration of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

The mobile communication system according to the present embodiment is an LTE-Advenced type mobile communication system, and includes an exchange station MME and a radio base station eNB # 1 / eNB # 2 as shown in FIG.

The radio base station eNB # 1 includes cell # 1 specified by "PCI = 1" and "ARFCN = F1", cell # 2 specified by "PCI = 2" and "ARFCN = F2", and "PCI". It manages cell # 3 specified by "= 3" and "ARFCN = F3".

Further, the radio base station eNB # 2 includes cell # 4 specified by "PCI = 4" and "ARFCN = F1" and cell # 5 specified by "PCI = 5" and "ARFCN = F2". It manages cell # 6 identified by "PCI = 6" and "ARFCN = F3".

In the present embodiment, the configuration of the radio base station eNB # 1 and the configuration of the radio base station eNB # 2 are basically the same, and therefore, the configuration of the radio base station eNB will be described below.

As shown in FIG. 2, the radio base station eNB includes a random number generation unit 11, a key generation unit 12, and a handover processing unit 13.

The random number generation unit 11 is configured to generate a random number Rand in the handover process.

Specifically, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, cell # 4) that manages the first cell is used. The random number generator 11 of the radio base station eNB # 1) is configured to generate a Rand.

Further, in the S1 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, radio base station) that manages the second cell The random number generator 11 of eNB # 2) is configured to generate Rand.

The key generation unit 12 uses the key K used for communication between the mobile station UE and the cell under the radio base station eNB in the handover process._eNBIntermediate key "K" to generate_eNB^*Is configured to generate.

Specifically, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, cell # 4) that manages the first cell is used. The key generator 12 of the radio base station eNB # 1) is K._eNB^*Is configured to generate.

For example, as shown in FIG. 3, a radio base station that manages the first cell in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4). The key generator 12 of the eNB (for example, the radio base station eNB # 1) uses the first key K used for communication between the mobile station UE and the first cell._eNBAnd the second key "K" used in the communication between the mobile station UE and the second cell based on the random number "Rand" generated by the random number generator 11._eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the key generation unit 12 of the radio base station eNB that manages the first cell does not perform the conventional "PCI / ARFCN binding process", but the first key "K"._eNBBy performing "binding processing" using the random number "Rand" for "", specifically, "K"_eNB^*= KDF (K_eNB, Rand) , the intermediate key K_eNB^*May be configured to generate.

The "KDF (Key Derivation Function)" is an irreversible conversion function, and the output (K)_eNB^*) To input (K_eNB) Cannot be calculated.

As a result, the radio base station eNB that manages the second cell is the first key "K" used for communication between the mobile station UE and the first cell._eNBIt has the effect of not being able to estimate.

Alternatively, as shown in FIG. 3, the radio base station that manages the first cell in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4). The key generation unit 12 of the eNB (for example, the radio base station eNB # 1) uses the mobile station UE based on the predetermined information NH notified from the exchange station MME and the random number Rand generated by the random number generation unit 11. The second key "K" used for communication between and the second cell_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the key generation unit 12 of the radio base station eNB that manages the first cell does not perform the conventional PCI / ARFCN binding process, and the predetermined counter NCC (FIG. 3) notified from the exchange station MME. By performing "binding processing" using a random number "Rand" for the predetermined information "NH" corresponding to "line number)", specifically, "K"_eNB^*By calculating "= KDF (NH, Rand)", the intermediate key "K"_eNB^*May be configured to generate.

As a result, the line in Figure 3 can be changed, and the previously updated K_eNBBy breaking the chain, the security of the system can be increased.

Further, in the S1 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, radio base station) that manages the second cell The key generator 12 of eNB # 2) is K_eNB^*Is configured to generate.

As shown in FIG. 3, the radio base station eNB (for example, cell # 1) that manages the second cell in the S1 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4) For example, the key generation unit 12 of the radio base station eNB # 2) sets the mobile station UE and the first unit based on the predetermined information NH notified from the exchange station MME and the random number Rand generated by the random number generation unit 11. Second key "K" used for communication between 2 cells_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the key generation unit 12 of the radio base station eNB that manages the second cell does not perform the conventional PCI / ARFCN binding process, and the predetermined counter NCC (FIG. 3) notified from the exchange station MME. By performing "binding processing" using a random number "Rand" for the predetermined information "NH" corresponding to "line number)", specifically, "K"_eNB^*By calculating "= KDF (NH, Rand)", the intermediate key "K"_eNB^*May be configured to generate.

As a result, the radio base station eNB that manages the first cell uses the second key "K" used for communication between the mobile station UE and the second cell._eNBBecause it is not possible to know, the security of the system can be increased.

The handover processing unit 13 is configured to transmit and receive a signal related to the handover processing to and from the mobile station UE, the switching station MME, and another radio base station eNB.

For example, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, radio base station) that manages the first cell. The handover processing unit 13 of the eNB # 1) transmits "HO Preparation (handover preparation signal)" to the radio base station eNB (for example, the radio base station eNB # 2) that manages the second cell, and the second cell. Receives "HO Preparation Ack (handover preparation response signal)" and "Release Resource (resource release signal)" from the radio base station eNB that manages, and sends "HO Command (handover instruction signal)" to the mobile station UE. However, it may be configured to receive a "Measurement Report" from the mobile station UE.

Further, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, radio base station) that manages the second cell. The handover processing unit 13 of the eNB # 2) receives "HO Preparation (handover preparation signal)" from the radio base station eNB (for example, the radio base station eNB # 1) that manages the first cell, and manages the first cell. Sends "HO Preparation Ack (handover preparation response signal)" and "Release Resource (resource release signal)" to the radio base station eNB, and receives "HO Complete (handover completion signal)" from the mobile station UE. It may be configured to transmit a "Path Switch (path switching signal)" to the switching station MME and receive a "Path Switch Ack (path switching response signal)" from the switching station MME.

Further, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, radio base station) that manages the first cell. The handover processing unit 13 of eNB # 1) transmits a "HO Command (handover instruction signal)" to the mobile station UE, receives a "Measurement Report" from the mobile station UE, and receives the "Measurement Report (measurement report signal)" from the mobile station UE. It is configured to send "HO Required (handover request signal)" to and receive "HO Required Ack (handover request response signal)" and "Release Resource (resource release signal)" from the exchange MME. May be good.

Further, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the radio base station eNB (for example, radio base station) that manages the second cell. The handover processing unit 13 of eNB # 2) receives "HO Complete (handover completion signal)" from the mobile station UE, and "HO Preparation Ack (handover preparation response signal)" or "HO Complete (HO Complete (handover preparation response signal)" to the exchange station MME. It may be configured to transmit a handover completion signal) and receive a HO Preparation (handover preparation signal) from the exchange MME.

As shown in FIG. 4, the mobile station UE includes a handover processing unit 21 and a key generation unit 22.

The handover processing unit 21 is configured to transmit and receive signals related to handover processing to and from the switching station MME and the radio base station eNB.

For example, in the X2 handover processing and the S1 handover processing of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the handover processing unit 21 manages the first cell. A "Measurement Report" is transmitted to the radio base station eNB (for example, the radio base station eNB # 1), and the radio base station eNB that manages the first cell sends a "HO Command (handover instruction signal)". Is received and "HO Complete (handover completion signal)" may be transmitted to the radio base station eNB (for example, radio base station eNB # 2) that manages the second cell.

The key generation unit 22 uses the second key K used for communication with the handover destination cell in the handover process._eNBIntermediate key "K" to generate_eNB^*Is configured to generate.

For example, as shown in FIG. 3, in the X2 handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the key generation unit 22 uses the first cell. The first key "K" used for communication with_eNBAnd in communication with the second cell based on the random number "Rand" notified via "HO Command" by the radio base station eNB (eg, radio base station eNB # 1) that manages the first cell. Second key used "K"_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the key generation unit 22 does not perform the conventional "PCI / ARFCN binding process", but the first key "K"._eNBBy performing "binding processing" using the random number "Rand" for "", specifically, "K"_eNB^*= KDF (K_eNB, Rand) , the intermediate key K_eNB^*May be configured to generate.

Alternatively, as shown in FIG. 3, in the X2 handover processing and the S1 handover processing of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4), the key generation unit 22 , Calculates the predetermined information "NH" corresponding to the predetermined counter "NCC" notified via "HO Command", and the calculated predetermined information "NH" and the random number "Rand" notified via "HO Command". The second key "K" used for communication with the second cell based on_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the key generation unit 22 does not perform the conventional PCI / ARFCN binding process, but uses the random number Rand for the predetermined information NH corresponding to the predetermined counter NCC to perform the binding process. By doing, specifically, "K_eNB^*By calculating "= KDF (NH, Rand)", the intermediate key "K"_eNB^*May be configured to generate.

The key generator 22 is described as "NH = KDF (K)._ASME, NH) may be configured to calculate the predetermined information NH corresponding to the predetermined counter NCC .

(Operation of the mobile communication system according to the first embodiment of the present invention) The operation of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS. 5 to 7.

First, with reference to FIG. 5, in the mobile communication system according to the present embodiment, an operation when performing an X2 handover process (horizontal derivation) of the mobile station UE from cell # 1 to cell # 4 will be described.

As shown in FIG. 5, in step S1001, the mobile station UE transmits a Measurement Report to the radio base station eNB # 1 that manages the cell # 1.

In step S1002, when the radio base station eNB # 1 decides to start the X2 handover process of the mobile station UE from cell # 1 to cell # 4, it generates a random number "Rand" to generate cell # 1 and the mobile station. The first key "K" used for communication with the UE_eNBBy performing "binding processing" using the random number "Rand" for "", specifically, "K"_eNB^*= KDF (K_eNB, Rand) , the second key K used for communication between cell # 4 and the mobile station UE_eNBIntermediate key "K" to generate_eNB^*Is generated.

In step S1003, for the radio base station eNB # 2 that manages cell # 4, the predetermined counter "NCC" and the intermediate key "K"_eNB^*And the random number "Rand" to send "HO Prepaartion".

In step S1004, the radio base station eNB # 2 has the intermediate key "K" included in the received "HO Prepaartion"._eNB^*Is used as it is in the communication between cell # 4 and the mobile station UE, the second key "K"_eNB".

In step S1005, the radio base station eNB # 2 transmits "HO Prepaartion Ack" including a predetermined counter "NCC" and a random number "Rand" to the radio base station eNB # 1.

In step S1006, the radio base station eNB # 1 transmits a HO Command including a predetermined counter NCC and a random number Rand to the mobile station UE.

In step S1007, the mobile station UE is the first key "K" used in communication with cell # 1._eNBBy performing "binding processing" using the random number "Rand" for "", specifically, "K"_eNB^*= KDF (K_eNB, Rand) , the second key K used for communication between cell # 4 and the mobile station UE_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the mobile station UE is the generated intermediate key "K"._eNB^*Is used as it is for communication with cell # 4, the second key "K"_eNB".

In step S1008, the mobile station UE transmits "HO Complete" to the radio base station eNB # 2, and in step S1009, the radio base station eNB # 2 sends a "Path Switch" to the switching station MME. To send.

In step S1010, the exchange MME states that "NH = KDF (K)._ASME, NH) is updated to update the predetermined information NH , and in step S1011, the updated predetermined information NH and the predetermined information NH are supported for the radio base station eNB # 2. Sends "Path Switch Ack" including the predetermined counter "NCC".

In step S1012, the radio base station eNB # 2 instructs the radio base station eNB # 1 to release the radio link established between the mobile station UE and the cell # 1 "Release Resource". To send.

Secondly, with reference to FIG. 6, in the mobile communication system according to the present embodiment, an operation when performing an X2 handover process (vertical derivation) of the mobile station UE from cell # 1 to cell # 4 will be described.

As shown in FIG. 6, in step S2001, the mobile station UE transmits a Measurement Report to the radio base station eNB # 1 that manages the cell # 1.

In step S2002, when the radio base station eNB # 1 decides to start the X2 handover process of the mobile station UE from cell # 1 to cell # 4, it generates a random number "Rand" and is notified by the exchange station MME. By performing "binding processing" using a random number "Rand" for the latest predetermined information "NH", specifically, "K"_eNB^*The second key "K" used in the communication between cell # 4 and the mobile station UE by calculating "= KDF (NH, Rand)"_eNBIntermediate key "K" to generate_eNB^*Is generated.

In step S2003, for the radio base station eNB # 2 that manages cell # 4, the predetermined counter NCC and the intermediate key K corresponding to the predetermined information NH used in step S2002._eNB^*And the random number "Rand" to send "HO Prepaartion".

In step S2004, the radio base station eNB # 2 has the intermediate key "K" included in the received "HO Prepaartion"._eNB^*Is used as it is in the communication between cell # 4 and the mobile station UE, the second key "K"_eNB".

In step S2005, the radio base station eNB # 2 transmits "HO Prepaartion Ack" including a predetermined counter "NCC" and a random number "Rand" to the radio base station eNB # 1.

In step S2006, the radio base station eNB # 1 transmits a HO Command including a predetermined counter NCC and a random number Rand to the mobile station UE.

In step S2007, the mobile station UE sets the predetermined information "NH" corresponding to the predetermined counter "NCC" included in the received "HO Command" to "NH = KDF (K)._ASME, NH) is calculated.

Then, the mobile station UE performs "binding processing" using the random number "Rand" for the calculated predetermined information "NH", and specifically, "K"_eNB^*The second key "K" used in the communication between cell # 4 and the mobile station UE by calculating "= KDF (NH, Rand)"_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the mobile station UE is the generated intermediate key "K"._eNB^*Is used as it is for communication with cell # 4, the second key "K"_eNB".

Hereinafter, the operations of steps S2008 to S2012 are the same as the operations of steps S1008 to S1012 shown in FIG.

Thirdly, with reference to FIG. 7, in the mobile communication system according to the present embodiment, an operation when performing S1 handover processing (vertical derivation) of the mobile station UE from cell # 1 to cell # 4 will be described.

As shown in FIG. 7, in step S3001, the mobile station UE transmits a Measurement Report to the radio base station eNB # 1 that manages the cell # 1.

In step S3002, when the radio base station eNB # 1 decides to start the S1 handover process of the mobile station UE from cell # 1 to cell # 4, it transmits "HO Required" to the exchange MME. ..

In step S3003, the exchange MME states that "NH = KDF (K)._ASME, NH) is calculated to update the predetermined information NH , and in step S3004, the updated predetermined information NH is applied to the radio base station eNB # 2 that manages the cell # 4. "HO Preparation" including the predetermined counter "NCC" corresponding to the predetermined information "NH" is transmitted.

In step S3005, the radio base station eNB # 2 generates a random number "Rand" and performs "binding processing" using the random number "Rand" for the predetermined information "NH" notified from the exchange station MME. In the end, "K_eNB^*The second key "K" used in the communication between cell # 4 and the mobile station UE by calculating "= KDF (NH, Rand)"_eNBIntermediate key "K" to generate_eNB^*Is generated.

Here, the radio base station eNB # 2 uses the generated intermediate key "K"._eNB^*Is used as it is in the communication between cell # 4 and the mobile station UE, the second key "K"_eNB".

In step S3006, the radio base station eNB # 2 transmits "HO Preparation Ack" including a predetermined counter "NCC" and a random number "Rand" to the exchange station MME.

In step S3007, the exchange station MME transmits "HO Required Ack" including the predetermined counter "NCC" and the random number "Rand" to the radio base station eNB # 1.

In step S3008, the radio base station eNB # 1 transmits a HO Command including a predetermined counter NCC and a random number Rand to the mobile station UE.

In step S3009, the mobile station UE sets the predetermined information "NH" corresponding to the predetermined counter "NCC" included in the received "HO Command" to "NH = KDF (K)._ASME, NH) is calculated.

Then, the mobile station UE performs "binding processing" using the random number "Rand" for the calculated predetermined information "NH", and specifically, "K"_eNB^*The second key "K" used in the communication between cell # 4 and the mobile station UE by calculating "= KDF (NH, Rand)"_eNBIntermediate key "K" to generate_eNB^*May be configured to generate.

Here, the mobile station UE is the generated intermediate key "K"._eNB^*Is used as it is for communication with cell # 4, the second key "K"_eNB".

In step S3010, the mobile station UE transmits "HO Complete" to the radio base station eNB # 2, and in step S3011 the radio base station eNB # 2 sends "HO Complete" to the exchange MME. To send.

In step S3012, the exchange MME sends a "Release Resource" instructing the radio base station eNB # 1 to release the radio link established between the mobile station UE and cell # 1. ..

In the X2 handover process of the mobile station UE from cell # 1 to cell # 4, the radio base station eNB # 1 that manages cell # 1 replaces the radio base station eNB # 2 that manages cell # 4. Generate a random number "Rand" and generate the above intermediate key "K"_eNB^*May be configured to generate.

The present invention is also applicable to the Intra-eNB handover process of the mobile station UE from the first cell (for example, cell # 1) to the second cell (for example, cell # 4). In such Intra-eNB handover processing, since the first cell and the second cell are managed by the same radio base station eNB (for example, radio base station eNB # 1), the radio base station eNB that manages the first cell Signal exchange between the radio base station eNB that manages the second cell, and the signal between the radio base station eNB that manages the first cell or the radio base station eNB that manages the second cell and the exchange station MME. The exchange may be omitted.

In the above-described embodiment, it is stated that the first cell of the handover source is, for example, cell # 1, and the second cell of the handover destination is, for example, cell # 4.

When "CA" is applied, the first cell of the handover source may be composed of a plurality of "CCs". Further, the second cell of the handover destination may also be composed of a plurality of "CCs". In addition, each "CC" may correspond to "cell # 1", "cell # 2", "cell # 3", "cell # 4", "cell # 5", "cell # 6", etc., respectively. ..

That is, for example, the first cell may be composed of two "CCs" of cells # 1 and cell # 2, and the second cell may be composed of three "CCs" of cells # 4, cell # 5, and cell # 6. May be composed of.

In the present invention, the same K is used in each "CC" constituting the first cell and the second cell._eNBThe purpose is to apply. As a result, K according to each "CC"_eNB^*No need to generate multiple Ks for each "CC"_eNB^*Eliminates the need to transfer at the time of handover. Also, there is no need to dare to clarify "Anchor CC".

(Action / Effect of Mobile Communication System According to First Embodiment of the Present Invention) According to the mobile communication system according to the first embodiment of the present invention, even when "CA" is applied, in the X2 handover processing and the S1 handover processing, the processing load of the radio base station and the backhaul K while suppressing the amount of signaling_eNB^*Can be generated.

The features of the present embodiment described above may be expressed as follows.

The first feature of the present embodiment is a mobile communication method in which the mobile station UE is handed over from cell # 1 (first cell) to cell # 4 (second cell), and is a radio base station that manages cell # 1. The K used by eNB # 1 for communication between the generated Rand (random number) and cell # 1 and the mobile station UE._eNBK used in communication between cell # 4 and mobile station UE based on (1st key) or NH (predetermined information) notified from the exchange MME._eNBK to generate (second key)_eNB^*The gist is to have a process to generate (intermediate key).

In the first feature of the present embodiment, the radio base station eNB # 1 that manages the cell # 1 sends an NCC (predetermined counter) related to NH to the mobile station UE by "HO Command (handover instruction signal)". And K used in the process of transmitting Rand and in the communication between the received NCC and Rand and cell # 1 by the mobile station UE._eNBOr K_ASMEK used in communication with cell # 4 based on NH calculated using (parent key)_eNBK to generate_eNB^*May have a step of producing.

The second feature of the present embodiment is a mobile communication method in which the mobile station UE is handed over from cell # 1 to cell # 4, and the radio base station eNB # 2 that manages cell # 4 receives from the exchange station MME. K used in communication between cell # 4 and mobile station UE based on the generated NH and the generated Rand._eNBK to generate_eNB^*The gist is to have a process to generate.

In the second feature of the present embodiment, the switching station MME relates to the radio base station eNB # 1 that manages the cell # 1 and the NH related to the NH received from the radio base station eNB # 2 that manages the cell # 4. And the process of transmitting Rand, the process of transmitting the received NCC and Rand to the mobile station UE by the radio base station eNB # 1 that manages cell # 1 by "HO Command", and the process of transmitting the received NCC and Rand, and the mobile station UE , K based on the NCC for the received NH_ASMEK used in the process of generating NH using the mobile station UE and the communication between cell # 4 based on the received Rand and the generated NH._eNBK to generate_eNB^*May have a step of producing.

The third feature of the present embodiment is the radio base station eNB # 1 that manages the cell # 1 in the handover process of the mobile station UE from the cell # 1 to the cell # 4, and is configured to generate a Rand. Random number generator 11 generated, Rand generated, and K used in communication between cell # 1 and mobile station UE_eNBOr Intial K_eNBK used in communication between cell # 4 and mobile station UE based on NH calculated using_eNBK to generate_eNB^*It is a gist to include a key generation unit 12 configured to generate the above.

In the third feature of the present embodiment, the handover processing unit 13 configured to transmit the NCC and Rand related to NH to the mobile station UE by "HO Command" may be further provided.

The fourth feature of the present embodiment is the mobile station UE, and in the handover process from cell # 1 to cell # 4, the radio base station eNB # 1 that manages cell # 1 via "HO Command" K used for communication between the received NCC and Rand and cell # 1._eNBOr K_ASMEK used in communication with cell # 4 based on NH calculated using_eNBK to generate_eNB^*The gist is to include a key generation unit 22 that is configured to generate.

The fifth feature of the present embodiment is the radio base station eNB # 1 that manages the cell # 4 in the handover process of the mobile station from the cell # 1 to the cell # 4, and is configured to generate a Rand. K used in communication between cell # 4 and mobile station UE based on the random number generator 11, NH and NCC received from the exchange MME, and the generated Rand._eNBK to generate_eNB^*It is a gist to include a key generation unit 12 configured to generate the above.

The sixth feature of this embodiment is the mobile station UE, which is the NCC and Rand received via the "HO Command" in the handover process from cell # 1 to cell # 2, and K._ASMEK used in communication with cell # 4 based on NH calculated using_eNBK to generate_eNB^*The gist is to include a key generation unit 22 that is configured to generate.

The above-mentioned operations of the radio base station eNB, the mobile station UE, and the switching station MME may be performed by hardware, by a software module executed by a processor, or by a combination of both. May be done.

Software modules include RAM (Random Access Memory), flash memory, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electronically Erasable and Programmable ROM), registers, hard disks, and removable disks. Or, it may be provided in an arbitrary format storage medium such as a CD-ROM.

Such a storage medium is connected to the processor so that the processor can read and write information to the storage medium. Further, such a storage medium may be integrated in the processor. Further, such a storage medium and a processor may be provided in the ASIC. Such an ASIC may be provided in the radio base station eNB, the mobile station UE, or the exchange station MME. Further, such a storage medium and a processor may be provided as discrete components in a radio base station eNB, a mobile station UE, or an exchange station MME.

Although the present invention has been described in detail using the above-described embodiments, it is clear to those skilled in the art that the present invention is not limited to the embodiments described in the present specification. The present invention can be implemented as modifications and modifications without departing from the spirit and scope of the invention as defined by the claims. Therefore, the description of the present specification is for the purpose of exemplification and does not have any limiting meaning to the present invention.

eNB ... wireless base station UE ... mobile station 11 ... Random number generator 12, 22 ... Key generator 13, 21 ... Handover processing unit