# US 12,015,921 B2 · Method and apparatus for avoiding denial of services in mobile communications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,921 B2 - Document ID: US12015921B2 - Status: Granted - Kind: B2 - Application number: 15/808,754 - Filed: 2017-11-09 - Published: 2018-03-08 - Granted: 2024-06-18 - Earliest claimed: 2016-11-10 - Assignees: MediaTek Singapore Pte. Ltd. - Applicants: MediaTek Singapore Pte. Ltd. - Inventors: Vidha Agarwal; Matti Moisanen; Marko Niemi - Web page: https://patentgrep.com/patent/US12015921B2 ## CPC - H04W 12/10: Integrity - H04L 63/1458: {Denial of Service} - H04W 12/12: Detection or prevention of fraud - H04W 12/122: Counter-measures against attacks; Protection against rogue devices - H04W 48/16: Discovering, processing access restriction or access information - H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management - H04L 2463/141: Denial of service attacks against endpoints in a network - H04W 12/63: Location-dependent; Proximity-dependent - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Various solutions for avoiding denial of services with respect to mobile station (MS) and network apparatus in mobile communications are described. A MS may receive a first reject message from a network apparatus in a location area. The first reject message may comprise a first reject cause. The MS may also receive a second reject message from the network apparatus in the location area. The second reject message may comprise a second reject cause. The MS may store an identification of the location area in a forbidden location area list in an event that both the first reject cause and the second reject cause are received from the same location area. The MS may further search for another location area or tracking area. ## Claims ### Claim 1 A method, comprising: transmitting, by a processor of an apparatus, a first kind of request and a second kind of request to a network apparatus of a network, wherein the first kind of request and the second kind of request are transmitted separately, and wherein the network is a Network Operation Mode II (NMO-II) network; receiving, by the processor, a non-integrity protected first reject message with a first reject cause from one of a circuit switch (CS) domain and a packet switch (PS) domain of the network apparatus in a first location area as a result of transmitting the first kind of request to the network apparatus; receiving, by the processor, a non-integrity protected second reject message with a second reject cause different than the first reject cause from the other one of the CS domain and the PS domain of the network apparatus in the first location area as a result of transmitting the second kind of request which is different from the first kind of request and separately transmitted to the network apparatus; determining, by the processor responsive to receiving the first and the second reject messages, that an access to the PS domain and the CS domain in the first location area is not allowed; storing, by the processor, an identification of the first location area in a list of forbidden location areas for roaming responsive to the first and the second reject messages being respectively received from the CS domain and the PS domain of the network apparatus of the first location area; and searching, by the processor, for a second location area or tracking area different from the first location area, wherein the storing of the identification of the first location area comprises: maintaining a flag to record whether a reject cause in the PS domain or another reject cause in the CS domain is received; setting the flag when one of the PS domain and the CS domain is rejected; and storing the identification of the first location area responsive to the flag being set and receiving the reject cause from the other one of the CS domain and the PS domain. ### Claim 2 (depends on 1) The method of claim 1, wherein at least one of the first reject cause and the second reject cause indicates that a general packet radio service (GPRS) is not allowed. ### Claim 3 (depends on 1) The method of claim 1, wherein at least one of the first reject cause and the second reject cause indicates that an international mobile subscriber identity (IMSI) is unknown in a home location register (HLR). ### Claim 4 (depends on 1) The method of claim 1, wherein one of the first reject cause and the second reject cause is a reject cause number 7 as defined in a 3rd Generation Partnership Project (3GPP) specification, and wherein the other one of the first reject cause and the second reject cause is a reject cause number 2 as defined in the 3GPP specification. ### Claim 5 (depends on 1) The method of claim 1, wherein the network apparatus supports both CS domain services and PS domain services. ### Claim 6 (depends on 1) The method of claim 1, wherein at least one of the first reject message and the second reject message also comprises a location area update reject message. ### Claim 7 (depends on 1) The method of claim 1, further comprising: recording, by the processor, that the first reject cause is received from the first location area. ### Claim 8 (depends on 1) The method of claim 1, wherein the first reject cause comprises a reject cause in the PS domain, wherein the second reject cause comprises a reject cause in the CS domain, and wherein the storing of the identification of the first location area in the forbidden location area list comprises storing the identification of the first location area in the forbidden location area list upon receiving the reject cause in the PS domain and the reject cause in the CS domain. ### Claim 9 A method, comprising: receiving, by a processor of an apparatus, system information broadcasted by a network apparatus in a first location area; receiving, by the processor, a reject message from the network apparatus; determining, by the processor and based on the system information, that the network apparatus supports solely single domain services in either a circuit switch (CS) domain or a packet switch (PS) domain; and in response to receiving the reject message and determining that the network apparatus supports solely the single domain services and that an access to either the CS or the PS domain is denied: storing, by the processor, an identification of the first location area in a list of forbidden location areas for roaming; ignoring, by the processor, the network apparatus in the first location area; and searching, by the processor, for a cell from a second location area or tracking area different from the first location area, wherein the storing of the identification of the first location area comprises: maintaining a flag to record whether a reject cause in the PS domain or another reject cause in the CS domain is received; setting the flag when one of the PS domain and the CS domain is rejected; and storing the identification of the first location area responsive to the flag being set and receiving the reject cause from the other one of the CS domain and the PS domain. ### Claim 10 (depends on 9) The method of claim 9, wherein the reject message comprises a respective reject cause. ### Claim 11 (depends on 10) The method of claim 10, wherein the reject cause indicates that a general packet radio service (GPRS) is not allowed. ### Claim 12 (depends on 10) The method of claim 10, wherein the reject cause indicates that an international mobile subscriber identity (IMSI) is unknown in a home location register (HLR). ### Claim 13 (depends on 10) The method of claim 10, wherein the reject cause is a reject cause number 7 as defined in a 3rd Generation Partnership Project (3GPP) specification or a reject cause number 2 as defined in the 3GPP specification. ### Claim 14 (depends on 9) The method of claim 9, wherein the network apparatus supports solely CS domain services or PS domain services.