MXPA98000524A - Method of switching in adaptable way between authentication schemes of personal communication systems - Google Patents

Abstract

The present invention relates to a method for adaptably switching between the authentication schemes WS and S is based on the use of the subscriber. A first preferred embodiment provides an automatic operating device of 2n-1 states (where n> 1), which switches from the WS scheme to the S scheme when the automatic operation device passes from state n-1 to state n, and vice versa. At each new record, the automatic operation device increases a state if more than one call is made (ie, incoming or outgoing) during the cycle, decreases a state if no calls are made during the cycle, and continues to do the same if a call was made during the cycle. The value of n is preferably determined by the PSP based on the use of the subscriber. A second preferred mode begins with each cycle with the WS scheme, and will switch to the S scheme if a call is made during the registration.

Description

METHOD OF COMMUNICATION ADAPTABLE WAY BETWEEN AUTHENTICATION SCHEMES OF PNAL COMMUNICATION SYSTEMS FIELD OF THE INVENTION The present invention is directed to an improved method for selecting authentication schemes of pnal communication systems, and more particularly, with a method to improve the flow of authentication signals of PCS networks (Pnal Communication Systems) by selecting from Adaptive way between two authentication schemes used in the Interim Standards of the cellular communication industry IS 41 Revision C.

BACKGROUND OF THE INVENTION Mobile communication networks, such as cellular telephone networks and / or pnal communication systems (PCS) allow uswho travel, still remain connected to the network. Figure 1 illustrates the portion 10 of such network. A subscriber who has a cell phone or ~ - pnal communications device collectively referred to as "telephone set" 12) is connected to a wireless communication network 14 provided by a REP: 26722 cellular or pnal communication service provider (collectively referred to as PSP). When the subscriber travels, he can enter a number of Registration Areas (RA) such as RAi 16, RA2 18, which are different geographical areas served by the same or different PSPs. The service area of the PCS within the PSPs 14 can be populated with base stations 20 to provide wireless access to the telephone apparatus and mobile switching cent(MSC) 22 which controls the base stations. According to the standard commonly used in North America, the subscriber may have pnal information, such as a telephone number or pnal communications, account information, credit or billing information, and the like stored in a database of the PSP network 14 that serves the area of the subscriber's domicile. This database is known as the Home Location Register (HLR) 24. When the subscriber travels to different RAs, that is, the telephone apparatus 12 crosses the dotted line 26 of Figure 1 to exit RAi 16 and enter to RA2 18, (the telephone handset in dotted lines is located in the geographical area served by the RA2) the subscriber is automatically registered in the new database of the local PSP 14 network of the area. Typically, a subset of the information stored in the HLR 24 is stored in this remote database. This remote database is known as Visitor Location Registration (VLR) 28. The network can also store pnal information about the subscriber which identifies the subscriber as an authorized user of the network. This authentication information is typically stored in a database known as Authentication Center (AC) 30. A subscriber is "authenticated" to identify the user and ensure that the user is authorized to receive the mobile service. The Electronic Industry Association / Telecommunications Industry Association (EIA / TIA) has proposed a revised system for cellular communications known as Interim Standard IS 41 Revision C. This standard has defined authentication protocols, voice privacy, and privacy of signal messages, and includes two different user authentication algorithms. The algorithms for the authentication and privacy of voice and signaling are based on coding techniques which use shared secret data (SSD), shared between the subscriber's telephone device 12 and the AC 30, which maintain the SSD for each subscriber of the net. One of the authentication algorithms, known as the WS Scheme, makes the most efficient use of authenticating signal traffic in a cellular network when the subscriber changes the RA, that is, 16, 18 more frequently than it does or receives calls. This relationship between the records and calls is known as the mobility call relationship (CMR). The second algorithm, known as Scheme S, makes efficient use of authentication signal traffic where the user makes or receives more calls than records in the new RAs (ie, the CMR >; 1) . The WS scheme shares the SSDs between the telephone set 12 and the AC 30 only. In Scheme S, the SSDs are also shared with the VLR 28. Only the VLR 28 and the telephone set 12 are involved in the authentication of calls. In this way, the cost is "cheaper" then in the WS scheme, where the HLR 24 and the AC 30 are involved in the authentication. However, the registration requires an additional message flow beyond the requirements of the WS Scheme. Thus, there is a transaction between the two schemes depending on the subscriber's CMR. No authentication system will provide the most efficient use of network resources for all subscribers of a PSP, or in many cases, even for a single subscriber.

The WS Scheme In Scheme WS, SSDs are shared between telephone set 12 and AC 30. Each telephone set has a Mobile Identification Number (MIN), which is stored in the telephone during manufacturing and can not be changed. Also associated with the telephone set 12 is an Electronic Serial Number (ESN). Figure 2 illustrates the flow of messages 50 between the PSPs, VLR, HLR, and AC during the registration of the WS Scheme. When a subscriber enters a new RA, the telephone apparatus receives the signal emitted from the local base station informing the latter that it has entered a new RA and authentication is required. The telephone apparatus executes a Cellular Authentication and Voice Coding (CAVE) algorithm, using the SSD, ESN, and MIN stored in the telephone set, and a random number (RAND), which the telephone device obtains from the PSPs. . The result of this algorithm is a result of registration authentication (AUTHR). The telephone apparatus then requests the MSC 22 to register to the new RA. This is done by supplying the AUTHR, ESN, MIN, the eight most significant bits of the RAND (RANDC), and a number of significant events initiated by the device, such as the history of the log, origins of calls, and terminations of calls. This amount is known as ACCOUNT. The ACCOUNT is also maintained by the AC. The MSCs send the authentication request in an AUTHRQST message to the VLR serving the new RA (line 52). The VLR sends the AUTHRQST to the HLR with the parameters it has received (line 54). The HLR sends the AUTHRQST to the AC (line 56). When the AC receives the AUTHRQST, it receives the SSDs associated with the MIN, and performs the CAVE algorithm using the MIN, ESN, and RAND received from the HLR. The result of the authentication of the CAVE algorithm is compared with the AUTHR generated by the telephone device. The ACCOUNT stored in the AC is also compared to the ACCOUNT received from the telephone set. If the comparisons are favorable, the AC provides an authrqst authentication response, which is sent to the HLR (line 58), VLR (line 60), and MSC (line 62). When the MSC notifies that the record is authorized, the MCS issues a registration notification message. Figure 3 illustrates the message flow 100 when a telephone device registered in a new RA originates a call. When the subscriber wishes to make a call, the telephone apparatus executes the CAVE algorithm using the same parameters above and the digits dialed by the subscriber. This results in the AUTHR signal, a VPMASK voice privacy screen, and an SMEKEY signal message encoding key. Those three signals are sent to the PSP server system. The PSP sends the AUTHRQST to the VLR (line 102) which sends the signal to the HLR (line 104), which sends the AC signal (line 106). The AC checks the AUTHR and ACCOUNT values and generates VPMASK and SMEKEY. The authrqst response is sent to the HLR (line 108), VLR (line 110), and the PSP (line 112). When the telephone device is authenticated, the server PSP initiates a location request message IS 41 LOCREQ to determine the current location of the called party. When the subscriber's telephone apparatus is the location of a call termination (ie, that the user is receiving a call on the telephone set), the flow of the message is similar to the flow described in Figure 3. The SPS server pages the telephone device called. In response, the telephone apparatus executes the CAVE algorithm using the AUTHR, ACCOUNT, ESN, MIN, and RANDC. The flow of the message is the same as that shown in Figure 3. When the telephone is authenticated, a voice channel is established between the telephone set and the calling party.

The Scheme S In Scheme S, the SSDs are shared with the VLR 28. In this way, the registration of the telephone device during authentication requires more steps than the registration under the Scheme WS. This is because the value of the ACCOUNT is stored in the VLR of the previous RA 28. For AC 30 to authenticate the telephone device, you must request the VLR ACCOUNT of the previous RA 28. Once the telephone device is registered in the new VLR 28, all other transactions such as the origin of calls and termination of calls, can be authenticated by the VLR 28. Access to the AC 30 is not necessary again until the telephone device enters a new RA and registration is required. Figure 4 illustrates the flow of messages 150 between the MSCs, the VLR of the previous RA (the "Old VLR"), the VLR of the new RA ("VLR"), HLR, and AC during the Scheme of Registered S. When the telephone device determines that it has entered a new RA, registration is required and the telephone device must be authenticated to access the services on PSP. The telephone apparatus executes the CAVE algorithm using the SSD, ESN, and MIN associated with the telephone set, and the RADN obtained from the PSP at that time. The algorithm results in a registration authentication result in AUTHR. The telephone apparatus then requests the MSC 22 to register in the new RA. This is done by supplying the AUTHR, ESN, MIN, RAND, and ACCOUNT. Unlike the Scheme WS, in Scheme S, the ACCOUNT is not maintained by the AC. He AUTHRQST is sent from the MSC to the VLR (line 152), the HLR (line (154), and AC (line 156) AC can not verify the telephone device without the ACCOUNT, therefore, the AC issues a COUNTREQ message, requesting the ACCOUNT This COUNTREQ is sent to the HLR (line 158) ) and then to the Old VLR (line 160). The Old VLR responds by sending the ACCOUNT in a COUNTREQ message to the HLR (line 162) which is directed to the AC (line 164). The AC can now verify the telephone set and, if verified, the AC issues a response AUTREQ to the AUTHRQST that is sent to the HLR (line 166), VLR (line 168), and the PSP (line 170). Figure 5 illustrates message flow 200 when a telephone set registered in a new RA under Scheme S originates or terminates the call. When the user makes or receives a call, the telephone apparatus executes the CAVE algorithm using the same previous parameters and the digits dialed by the subscriber. The results in the signal AUTHR, VPMASK, and SMEKEY. Those three parameters and the dialed digits and the marked digits are sent to the PSP server system. The PSP sends the AUTHREQ to the VLR (line 202). The VLR, which stores the value of the ACCOUNT, performs the CAVE algorithm and generates the AUTHR, VPMASK, and SMEKEY. If you verify the AUTHR and the ACCOUNT, those results are sent in an authreq message with VPMASK and SMEKEY to the PSP (line 204). As used in this patent application, a "cycle" means the period of time between two consecutive records for the subscribers. The "cycle cost" as used in this patent application means the number of messages sent to access the database (AC / HLR / VLR) during a cycle. The messages for registration are included in the cost of the cycle in which the subscriber is being registered (for example, the new cycle). As seen in Figures 2 and 3, in the Scheme WS, 5 accesses to the database are required to authenticate a record and 5 access to the database is required to authenticate each origin or call termination. In this way, the total expected cost of the user per cycle for Scheme WS is 5 + 5i, where i is the number of calls originated or terminated during the cycle .. As can be seen in Figures 4 and 5, in the Scheme S, 9 accesses to the database are necessary to authenticate a record and an access to database 1 is needed to authenticate each origin or call termination. In this way, the total expected cost of the subscriber per cycle of Scheme S is 9 + li. Please note that the costs of the two schemes are the same when i = 1. The WS Scheme is more expensive the CMR <; 1; Scheme S is more expensive when the CMR > 1. Because in an authentication scheme provides the most efficient use of authentication signals for all PSP subscribers, and in no case, even for a single subscriber, an object of the present invention is to provide a method for switching adaptively between the WS and S schemes depending on the use of the user's mobile communications.

BRIEF DESCRIPTION OF THE INVENTION These and other objects of the invention are achieved by the present invention. The present invention provides a method for adaptively switching between the authentication schemes WS and S based on the use of the subscriber. A first preferred embodiment provides an automatic operating device with 2n-1 states which switches from Scheme WS to Scheme S when the automatic operating device passes from state n-1 to state n, and vice versa. In each new record, the transitions from the automatic operation device to the next higher state if more than one call was made (eg incoming or outgoing) during the previous cycle; transitions to the next lowest state if no calls were made during the cycle; and it remains the same if a call was made during the cycle. The value of n is preferably determined by the PSP based on the use of the subscriber. A second preferred mode begins each new cycle with Scheme WS, and will switch to Scheme S if a call is made during the cycle.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is described with reference to the following Figures: Figure 1 illustrates a portion of a wireless communication network; Figure 2 illustrates a message flow for registration authentication in Scheme WS; Figure 3 illustrates a message flow for call authentication in Scheme WS; Figure 4 illustrates a message flow for registration authentication in Scheme S; Figure 5 illustrates a message flow for call authentication in Scheme S; Figure 6 is a state diagram illustrating the operation of one embodiment of the present invention; and Figure 7 is a diagram of four states illustrating the operation of one embodiment of the present invention. Appendix as Appendix A contains a glossary of the acronyms used in this specification DESCRIPTION OF THE PREFERRED MODALITIES An efficient mobile or PCS communication system must reduce the number of accesses to the database needed to authenticate a record or call. This reduces the traffic flow in the system. Thus, it is desirable to switch between Scheme WS and Scheme S when it becomes efficient to do so. The present invention provides two methods for determining when to switch from one scheme to another. These methods are referred to as Method 1 and Method 2.

A. Method 1 Figure 6 is a state diagram 300 illustrating the operation of Method 1. Method 1 is a 2n automatic state operating device that resides in AC 30. The automatic operating device has the states 0 to 2n-l ( 302-316). When the automatic operating device is between state 0 (302) and state n-l (308), Scheme WS is performed. When the automatic operating device is between state n (130) and 2n-l (316), Scheme S is performed. The automatic operating device may change states in each register. In each record, the ACCOUNT is received by the AC 30 of the telephone set 12. The automatic operating device will remain in the same state if the number of calls completed or originated during the registration is 1. The automatic operating device will make the transition to the same. next lower state, if the. number of calls terminated or originated during registration is 0, except when the automatic operation device is in state 0. In state 0, the automatic operation device will remain in the same state when the number of originated or terminated calls is 0 or 1. The automatic operation device will transition to the next higher state if the number of calls completed or originated during registration is greater than 1, except when the automatic operating device is in the 2n-1 state. In the state 2n-l, the automatic operating device will remain in the same state when the number of originated or terminated calls is 1 or more. When the state transitions are from state n-l 308 to n 310, the authentication scheme switches from WS to S, when the state transitions are from state n 310 to n-l 308, the authentication scheme moves from S to WS. The authentication scheme will remain the same for all other status changes. The value of n is chosen by the PSP verifying its use of the subscriber. The value of n may vary during different times of the day or different days. To implement this method, the AC preferably maintains a number of bits of the Current State to represent the current state. Preferably, the AC stores [log2n] + l Current State bits (ie, enough bits to indicate the digital status value up to 2n). Also, each VLR preferably maintains a bit of Authentication Scheme (AS) to represent the appropriate authentication scheme for the subscriber. Figure 7 illustrates an example of the operation of Method 1. Assume for illustrative purposes that n = 2. In this way the states 350 of the automatic operating device are 0 (352), 1 (which is nl) (354), 2 (n), (356), and 3 (which is 2n-1) (358). The operation is: 1. A user registers in a first RA and the automatic operating device is in state 0 (352) and Schema WS is executed; 2. The subscriber makes several calls during the residence time of the first RA; 3. The subscriber travels to a new RA; 4. The ACCOUNT maintained in the telephone set is sent to the AC; 5. The AC determines that the number of calls made or received during the previous registration is > 1; 6. The AC makes the transition from the automatic operation device to the state 1 (line 360), and the authentication scheme remains unchanged; 7. The subscriber receives several calls during the residence time in the second RA; 8. The subscriber travels to a new RA; 9. The ACCOUNT kept on the telephone is sent to the AC; 10. The AC determines that the number of calls made or received during the previous registration is > 1; 11. The AC makes the transition from the automatic operating device to state 2 (line 362), and the authentication scheme is connected from WS to S; 12. The subscriber makes a call during the time of residence the third RA; 13. The subscriber travels to a new RA; 14. The ACCOUNT kept on the telephone is sent to the AC; 15. The CA determines that the number of calls made or received during the previous registration is = 1; 16. The AC does not change the state and the authentication scheme remains S (line 364); 17. The subscriber does not make or receive a call during the time of residence in the fourth RA; 18. The subscriber travels to a new RA; 19. The ACCOUNT kept on the telephone is sent by the AC; . The AC determines that the number of calls made or received during the previous registration is = 0; and 21. The AC makes the transition from the automatic operating device from state 2 to state 1 (line 366) and the switching scheme is switched from S to WS. Preferably, n should be selected so that it is a relatively low number. The inventors have found that the greater number of states, they need to switch more cycles. An automatic operating device having a relatively large n value will more slowly reflect a change in a user CMR than an automatic operating device having a relatively small n value. This is due to the fact that several consecutive cycles can happen in which the number of calls originated or terminated from the telephone set is 0 or greater than 1, even without switching the authentication scheme.

B. Method 2 In the second method, at the beginning of each cycle, the WS Scheme is carried out. One bit of the authentication scheme (AS) in the AC and the VLR indicates that the Scheme ES. When a call is originated or terminated in the telephone set, Scheme S is exercised. The bits of AS in the AC and the VLR are changed to reflect that Scheme S is now being used. An example of the operation of Method 2 is : 1. A subscriber registers in an RA, using Schema WS, as shown in Figure 2; 2. When a call originates or terminates in the telephone set, the authentication is the same as in Figure 3, except that the AC bit in AC is switched to reflect that the S scheme is being used and the SSDs are sent to the VLR in the authrqst message. When the VLR receives the SSDs, its AS bit is also switched to reflect that the S scheme is being used. At the time when the VLR AS bit is switched, Scheme S is implemented; 3. All origins and terminations of subsequent calls during the cycle are authenticated using Scheme S; 4. The subscriber travels to a new RA; 5. The message AUTHRQST is sent to AC; 6. The bit of the AS in the AC is S, and the message flow is as shown in Figure 4; 7. After registration, the bit of the AS in the AC is sent to reflect that the WS Schema is being used; 8. During the cycle, calls are not originated or terminated in the telephone set; 9. The user travels to a new RA; 10. An AUTHRQST message is sent to the AC; and 11. The bit in the AC is WS, and the message flow is as shown in Figure 2. The inventors have determined that the operation of the two methods depends in part on the variation of the residence time of the subscriber in the RA. If the variation in the subscriber's residence time is large, Method 2 is more efficient than Method 1 that has 2 states (ie, n = 1, n-l is 0, 2n-l is 1). However, even when the user variation is large, methods 1 and 2 are equally efficient where Method 1 has four states (ie, n = 2, n-l is 1, 2n-l is 3). If the variation in residence time in the user is small, Method 1 is more efficient than Method 2 for both states 2 and 4. With both methods, no changes are needed in the HLR or the telephone set. The AC can be revised to keep the additional Current Status bits in Method 1. The AC determines the Authentication Scheme to be performed. The VLR can be modified to include the bits of the AS in Method 2. In conclusion, the methods to adaptively switch between the WS and S schemes based on the actual use of the subscriber are shown. These methods effectively reduce the number of accesses to the database for the call authentication record. In this way, message traffic in a wireless communication network is handled efficiently. The embodiments of the invention described above are intended to be illustrative only. Many alternative embodiments may be devised by those skilled in the art without departing from the spirit and scope of the following claims.

APPENDIX A Glossary of Acronyms AC Authentication Center AC bits Authentication Scheme Bits AUTHR AUTHRQST Registry Authentication Result Authentication request to VLR CAVE Cellular Authentication and Voice Verification CMR Call to Mobility Ratio COUNT Consideration of Significant Events Initiated by the Telephone Appliance EA / TIA Electronic Industry Association / Telecommunications Industry Association ESN Electronic Serial Number HLR LOCREQ Origin Location Register Location Request Message MIN Number MSC Mobile Identification Centers PCS Mobile Switching Centers Personal Communications Services PSP Cellular or Personal Communication Services Provider RA RAND Registration Area Random number used for RANDC authentication Eight most significant bits of RAND SMEKEY Coding Code of SSD Signal Message Data Shared Secrets VLR Visitor Location Registration VPMASK Voice Privacy Screen It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (17)

1. A method of co-routing adaptively between a first and a second authentication scheme in a mobile communication system, characterized in that it comprises the steps of: a. determine a number of calls that are released and received on a telephone device during a cycle; b. if the number of calls (1) exceeds the predetermined amount, make the transition to a higher state of an automatic operating device; (2) equal to the predetermined amount, follow in a current state of the automatic operating device; and (3) is less than the predetermined amount, to transition to a lower state of an automatic operating device; c. switching from the first to the second authentication scheme when the transition is made from a first predetermined state to a second preselected state; d. switching from the second to the first authentication scheme when the transition from the second predetermined state to the first preselected state is made; and e. do not switch the authentication schemes at all other times.

2. The method according to claim 1, characterized in that the step of determining a number of calls comprises the steps of: a. keep an account of incoming and outgoing calls in the telephone during the cycle; and b. Send the account to an authentication center during registration.

3. The method according to claim 1, characterized in that it also comprises: a. make the transition to the higher state when the number of calls exceeds one; b. remain in the same state when the number of calls is equal to one; and c. make the transition to the lower state when the number of calls is zero.

4. The method in accordance with the claim 1, characterized in that the step of switching from the first to the second authentication scheme is selected so that it occurs when the transition from state n-l to state n is made.

5. The method in accordance with the claim 4, characterized in that it further comprises selecting a value for n based on the subscriber's use of the mobile communications system.

6. The method in accordance with the claim 5, characterized in that it also comprises the step of verifying the subscriber's use of the mobile communications system.

7. The method according to claim 1, characterized in that the step of switching from the second to the first authentication scheme is selected so that it occurs when the transition from state n to state n-l is made.

8. The method in accordance with the claim 7, characterized in that it further comprises selecting a value for n based on the subscriber's use of the mobile communications system.

9. The method in accordance with the claim 8, characterized in that it also comprises the step of verifying the subscriber's use of the mobile communications system.

10. The method according to claim 1, characterized in that it further comprises the step of storing a plurality of bits in an authentication center to indicate a current state.

11. The method in accordance with the claim 10, characterized in that the storage step comprises storing enough bits to indicate which of a total number of states of an automatic operating device is the current one.

, * ^? • "'- • • 12. A method of adaptable switching between a first and second authentication schemes in a mobile communication system, characterized in that it comprises the steps of: a. perform the first authentication scheme at the beginning of a cycle; b. switch to the second authentication scheme if a call is released and received on a telephone device during the cycle; and c. Return to the first authentication scheme at the beginning of a second cycle.

13. The method in accordance with the claim 12, characterized in that it further comprises storing a bit in an authentication center and storing a bit in a visitor location register (VLR) to indicate which authentication scheme should be performed.

14. The method in accordance with the claim 13, characterized in that the switching step further comprises the step of switching the bit in the authentication center and the bit in the VLR to indicate that the second authentication scheme should be performed.

15. The method according to claim 14, characterized in that the switching step further comprises switching to the second authentication scheme after the bit in the authentication center and the bit in the VLR indicate that the second authentication scheme must be performed.

16. The method according to claim 12, characterized in that if the mobile communication system has switched the second authentication scheme, it performs the second authentication scheme to authenticate a subsequent registration before returning to the first authentication scheme.

17. A method for reducing message traffic in a mobile communication system, characterized in that it comprises: a. provide at least two authentication schemes; b. verify the use of the subscriber's system; and c. switching between the two authentication schemes made by the subscriber based on the use of the user's system.